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2023 Volume 38 Issue 4
2023, 38(4): 1-6
doi: 10.3866/PKU.DXHX202210056
Abstract:
In the context of innovative education, experiments on the synthesis of Prussian blue films and investigation of their photoelectric properties are proposed to introduce the results of scientific research into comprehensive university experiments. The Prussian blue film was prepared on the surface of ITO-conductive glass by simple electrochemical polymerization methods, and the physical and chemical properties of Prussian blue film were studied by scanning electron microscopy, X-ray diffraction, cyclic voltammetry, and UV-Vis absorption spectroscopy, among other methods. Based on the experimental skills already acquired by the university students in chemistry experiments, we designed and built an in situ UV-Vis spectroscopy electrochemical and photocurrent test platform in combination with the existing comprehensive electrochemical experiments. Through specific experiments and by understanding the principle of mutual transformation of Prussian blue and Prussian white, the electrochromic phenomenon and photocurrent generation of Prussian blue were further understood; this stimulated students’ interest in photoelectrochemical experiments and helped them expand their scientific divergent thinking and improve their experimental skills.
In the context of innovative education, experiments on the synthesis of Prussian blue films and investigation of their photoelectric properties are proposed to introduce the results of scientific research into comprehensive university experiments. The Prussian blue film was prepared on the surface of ITO-conductive glass by simple electrochemical polymerization methods, and the physical and chemical properties of Prussian blue film were studied by scanning electron microscopy, X-ray diffraction, cyclic voltammetry, and UV-Vis absorption spectroscopy, among other methods. Based on the experimental skills already acquired by the university students in chemistry experiments, we designed and built an in situ UV-Vis spectroscopy electrochemical and photocurrent test platform in combination with the existing comprehensive electrochemical experiments. Through specific experiments and by understanding the principle of mutual transformation of Prussian blue and Prussian white, the electrochromic phenomenon and photocurrent generation of Prussian blue were further understood; this stimulated students’ interest in photoelectrochemical experiments and helped them expand their scientific divergent thinking and improve their experimental skills.
2023, 38(4): 7-12
doi: 10.3866/PKU.DXHX202212026
Abstract:
In the traditional “acetone iodination” experiment, there are problems such as corrosion, irritation caused by HCl volatilization, and inconsistent temperature or time between the spectrophotometric test and the actual reaction process. These problems are inevitably encountered and have not been effectively addressed. With a focus on these problems, the improved experiment presented a colorimetric analysis system based on a smartphone and new glass reactor; the test method was also proposed. The improved experiment avoids instrument corrosion, human body stimulation caused by HCl, improves the accuracy of the experimental data, and is helpful for students to gain theoretical and experimental expertise on the Lambert-Beer law and its offset phenomenon. In addition, since a spectrophotometer is not required, the improved experiment is easier to popularize and more interesting. It also provides a new strategy for online experimental teaching under difficult conditions such as the epidemic.
In the traditional “acetone iodination” experiment, there are problems such as corrosion, irritation caused by HCl volatilization, and inconsistent temperature or time between the spectrophotometric test and the actual reaction process. These problems are inevitably encountered and have not been effectively addressed. With a focus on these problems, the improved experiment presented a colorimetric analysis system based on a smartphone and new glass reactor; the test method was also proposed. The improved experiment avoids instrument corrosion, human body stimulation caused by HCl, improves the accuracy of the experimental data, and is helpful for students to gain theoretical and experimental expertise on the Lambert-Beer law and its offset phenomenon. In addition, since a spectrophotometer is not required, the improved experiment is easier to popularize and more interesting. It also provides a new strategy for online experimental teaching under difficult conditions such as the epidemic.
2023, 38(4): 13-21
doi: 10.3866/PKU.DXHX202212007
Abstract:
The experimental device of the physical chemistry experiment “Determination of the molar mass by freezing point depression” was innovatively improved to overcome the problems of the existing devices. A metal cold trap cooled by semiconductor chilling plates and a freezing point test tube integrated turbine agitator and heater were designed; a precise temperature measurement circuit was built. And each part was integrated into a complete set of equipment. The improved device was applied to the measurement of the urea-water, sucrose-water and naphthalene-cyclohexane systems. The results show that compared with the existing experimental device, the improved device has better repeatability, higher accuracy, higher experimental efficiency, and is more in accord with the needs of laboratory teaching. And it is more beneficial to cultivating the innovative thinking and scientific research ability of students.
The experimental device of the physical chemistry experiment “Determination of the molar mass by freezing point depression” was innovatively improved to overcome the problems of the existing devices. A metal cold trap cooled by semiconductor chilling plates and a freezing point test tube integrated turbine agitator and heater were designed; a precise temperature measurement circuit was built. And each part was integrated into a complete set of equipment. The improved device was applied to the measurement of the urea-water, sucrose-water and naphthalene-cyclohexane systems. The results show that compared with the existing experimental device, the improved device has better repeatability, higher accuracy, higher experimental efficiency, and is more in accord with the needs of laboratory teaching. And it is more beneficial to cultivating the innovative thinking and scientific research ability of students.
2023, 38(4): 22-34
doi: 10.3866/PKU.DXHX202209091
Abstract:
The Maillard reaction, which is the main source of food color and flavor, is one of the most recognized chemical reactions in cooking. The simplified experimental methods of the complex Maillard reaction were innovatively designed using common amino acids, proteins, and sugars as raw materials. These reactions were easily preformed in a household microwave oven. The flavor products were analyzed by ultraviolet-visible (UV-Vis) spectroscopy and gas chromatography-mass spectroscopy (GC-MS) to evaluate the fundamental relationship between flavor and chemical components. Moreover, delicious and nutritious cuisines can be cooked in the kitchen facilitated by the Maillard reaction mechanism. This study explored the chemical mysteries of delicacy, and demonstrated the magic and charm of chemistry. It is rich in content, diverse in forms, and suitable to popularize chemical knowledge in society.
The Maillard reaction, which is the main source of food color and flavor, is one of the most recognized chemical reactions in cooking. The simplified experimental methods of the complex Maillard reaction were innovatively designed using common amino acids, proteins, and sugars as raw materials. These reactions were easily preformed in a household microwave oven. The flavor products were analyzed by ultraviolet-visible (UV-Vis) spectroscopy and gas chromatography-mass spectroscopy (GC-MS) to evaluate the fundamental relationship between flavor and chemical components. Moreover, delicious and nutritious cuisines can be cooked in the kitchen facilitated by the Maillard reaction mechanism. This study explored the chemical mysteries of delicacy, and demonstrated the magic and charm of chemistry. It is rich in content, diverse in forms, and suitable to popularize chemical knowledge in society.
2023, 38(4): 35-43
doi: 10.3866/PKU.DXHX202210037
Abstract:
To develop new long afterglow luminescent materials based on organics or coordination compounds, and improve the long afterglow performance through studying the relationship between the molecular structures and properties becomes one of the hot research topics currently. This experiment is mainly related to the Cu(I)-iodide cluster-based coordination polymer (CuIU). There are two phases for CuIU, C-CuIU and T-CuIU crystallized in the cubic and trigonal space groups, respectively. Though the molecular formulas of C- and T-CuIU are same, T-CuIU displays much better long afterglow property than C-CuIU. The synthesis of CuIU is performed in NaI aqueous solution at room temperature under gentle environment. The whole experiment is carried out through easy stirring, centrifugation and drying operations, which is appropriate for undergraduate laboratory teaching. The product obtained by short stirring time is verified as C-CuIU, while that with long stirring time is verified as T-CuIU. The transformation between C and T is easily controlled and they display notably different lifetimes. The plastic models of these two structures, preparation of luminescent ink and silk-screen printing are also introduced in teaching to further improve the vividness and interest of the course. This experiment is helpful for students to understand the synthesis method of metal cluster compounds and the deep relation between structures and properties in coordination compounds. Meanwhile, the experiment involves the operations of X-ray powder diffractometer, spectrofluorometer and thermal gravimetric analyzer, which promote the science and education integration in the teaching process.
To develop new long afterglow luminescent materials based on organics or coordination compounds, and improve the long afterglow performance through studying the relationship between the molecular structures and properties becomes one of the hot research topics currently. This experiment is mainly related to the Cu(I)-iodide cluster-based coordination polymer (CuIU). There are two phases for CuIU, C-CuIU and T-CuIU crystallized in the cubic and trigonal space groups, respectively. Though the molecular formulas of C- and T-CuIU are same, T-CuIU displays much better long afterglow property than C-CuIU. The synthesis of CuIU is performed in NaI aqueous solution at room temperature under gentle environment. The whole experiment is carried out through easy stirring, centrifugation and drying operations, which is appropriate for undergraduate laboratory teaching. The product obtained by short stirring time is verified as C-CuIU, while that with long stirring time is verified as T-CuIU. The transformation between C and T is easily controlled and they display notably different lifetimes. The plastic models of these two structures, preparation of luminescent ink and silk-screen printing are also introduced in teaching to further improve the vividness and interest of the course. This experiment is helpful for students to understand the synthesis method of metal cluster compounds and the deep relation between structures and properties in coordination compounds. Meanwhile, the experiment involves the operations of X-ray powder diffractometer, spectrofluorometer and thermal gravimetric analyzer, which promote the science and education integration in the teaching process.
2023, 38(4): 44-52
doi: 10.3866/PKU.DXHX202211053
Abstract:
In this study, the preparation method of acetanilide, which is commonly taught in current undergraduate experimental courses, is improved. While acetic acid and aniline were used as starting materials in the improved method, zinc powder was replaced with stannous chloride (which is listed as an easy-to-make tube explosion product) as a reducing agent to prevent aniline from being oxidized. At the same time, p-toluene sulfonic acid was added as a catalyst. A fixed bed dehydration reflux device was used instead of the classical fractionation device, and a packed rectification column was used as the fixed bed. The column was filled with glass spring packing, a 4A molecular sieve and color-changing silica gel from bottom to top in turn. During the reaction, distilled water and acetic acid were fractionated by the glass spring packing, acetic acid was refluxed to the reaction flask, and water was absorbed by the 4A molecular sieve and color-changing silica gel. After absorbing water, the color of the silica gel changed from orange to green, which is a clear indication of the reaction process. The improved experiment does not require control reagents, the reaction time is shortened, and the phenomenon is rich, making it more suitable for undergraduate teaching. In addition, two extended experiments were designed in this study, which can be selected according to the needs of teaching. One is to prepare phenyl 4-acetylaminoacetate from acetanilide; the second is to determine the unreacted aniline content in the waste liquid by constant pH titration. This modified experimental procedure employs extraction, column chromatography, titration, and data processing and analysis, which can effectively improve the comprehensive experimental ability of the students.
In this study, the preparation method of acetanilide, which is commonly taught in current undergraduate experimental courses, is improved. While acetic acid and aniline were used as starting materials in the improved method, zinc powder was replaced with stannous chloride (which is listed as an easy-to-make tube explosion product) as a reducing agent to prevent aniline from being oxidized. At the same time, p-toluene sulfonic acid was added as a catalyst. A fixed bed dehydration reflux device was used instead of the classical fractionation device, and a packed rectification column was used as the fixed bed. The column was filled with glass spring packing, a 4A molecular sieve and color-changing silica gel from bottom to top in turn. During the reaction, distilled water and acetic acid were fractionated by the glass spring packing, acetic acid was refluxed to the reaction flask, and water was absorbed by the 4A molecular sieve and color-changing silica gel. After absorbing water, the color of the silica gel changed from orange to green, which is a clear indication of the reaction process. The improved experiment does not require control reagents, the reaction time is shortened, and the phenomenon is rich, making it more suitable for undergraduate teaching. In addition, two extended experiments were designed in this study, which can be selected according to the needs of teaching. One is to prepare phenyl 4-acetylaminoacetate from acetanilide; the second is to determine the unreacted aniline content in the waste liquid by constant pH titration. This modified experimental procedure employs extraction, column chromatography, titration, and data processing and analysis, which can effectively improve the comprehensive experimental ability of the students.
2023, 38(4): 53-57
doi: 10.3866/PKU.DXHX202211025
Abstract:
The electrophilic addition reactions of alkenes and the elimination reactions of alkyl halides are two fundamental reactions that undergraduates should master in basic organic chemistry course, but are rarely included in the laboratory course. The disconnection between theory and practice leads to the poor understanding of the reaction mechanisms. To address this disconnection in organic chemistry instruction, we design an experiment containing an electrophilic addition reaction and an elimination reaction. In this experiment, we use isopulegol as the starting material to synthesize the expensive R-citronellal in a one-pot two-step manner at room temperature through an electrophilic addition and a Grob fragmentation (a special elimination). The experiment features low cost of reagents, simple operation, mild reaction conditions and comprehensive skill training, therefore, it is a qualified teaching experiment that could help students deepen their understanding of theoretical knowledge while polishing their organic laboratory techniques.
The electrophilic addition reactions of alkenes and the elimination reactions of alkyl halides are two fundamental reactions that undergraduates should master in basic organic chemistry course, but are rarely included in the laboratory course. The disconnection between theory and practice leads to the poor understanding of the reaction mechanisms. To address this disconnection in organic chemistry instruction, we design an experiment containing an electrophilic addition reaction and an elimination reaction. In this experiment, we use isopulegol as the starting material to synthesize the expensive R-citronellal in a one-pot two-step manner at room temperature through an electrophilic addition and a Grob fragmentation (a special elimination). The experiment features low cost of reagents, simple operation, mild reaction conditions and comprehensive skill training, therefore, it is a qualified teaching experiment that could help students deepen their understanding of theoretical knowledge while polishing their organic laboratory techniques.
2023, 38(4): 58-67
doi: 10.3866/PKU.DXHX202210051
Abstract:
Chirality is the essential attribute of life. Molecular chirality is closely related to the fine regulation of life phenomena. The pharmacology and toxicology of drugs with different enantiomers vary significantly different. Owing to the recent advancements in the chiral drug market, the development of efficient and accurate chiral separation strategy has become critical. Aiming at the construction of new engineering subjects 2.0, the idea of “chiral separation workshop” comprehensive experiment was proposed for the first time. The chiral recognition mechanism based on intermolecular weak interaction was investigated using the click-chemical green synthesis strategy to realize the highly efficient grafting of single-positively charged cyclodextrins and the construction of positively charged supramolecular chiral media; the chiral separation conditions of racemic amino acid derivatives were optimized, and the resolution of racemic dansyl amino acids were obtained as well. The experiment is based on the construction of new engineering chemistry specialty, covering the basic chemical knowledge of green synthesis, accurate instrument analysis, physical and chemical separation mechanism, and inorganic material chemistry, as well as integrating the advanced technical theories and industrial applications, thereby creating a new paradigm for the cultivation of chemistry talents under the guidance of ideological and political education.
Chirality is the essential attribute of life. Molecular chirality is closely related to the fine regulation of life phenomena. The pharmacology and toxicology of drugs with different enantiomers vary significantly different. Owing to the recent advancements in the chiral drug market, the development of efficient and accurate chiral separation strategy has become critical. Aiming at the construction of new engineering subjects 2.0, the idea of “chiral separation workshop” comprehensive experiment was proposed for the first time. The chiral recognition mechanism based on intermolecular weak interaction was investigated using the click-chemical green synthesis strategy to realize the highly efficient grafting of single-positively charged cyclodextrins and the construction of positively charged supramolecular chiral media; the chiral separation conditions of racemic amino acid derivatives were optimized, and the resolution of racemic dansyl amino acids were obtained as well. The experiment is based on the construction of new engineering chemistry specialty, covering the basic chemical knowledge of green synthesis, accurate instrument analysis, physical and chemical separation mechanism, and inorganic material chemistry, as well as integrating the advanced technical theories and industrial applications, thereby creating a new paradigm for the cultivation of chemistry talents under the guidance of ideological and political education.
2023, 38(4): 68-77
doi: 10.3866/PKU.DXHX202211076
Abstract:
Electroplating is an important part of electrochemical system. In order to broaden the knowledge structure, and cultivate innovation consciousness and scientific literacy of students, zinc electroplating is introduced into the laboratory teaching of applied electrochemistry major. In this experiment, the cause of the zinc dendrites formation in the process of zinc electroplating is analyzed theoretically, and then two corresponding strategies of eliminating surface heterogeneity and adding cationic additives are proposed to inhibit the production of zinc dendrites. In order to deepen the understanding of zinc plating process, we set up an in situ optical microscope to directly observe the change of zinc deposition behavior. This experiment deeply integrates the scientific thinking and innovative ideas of frontier research, guides students to jump out of the textbook framework, stimulates students’ interest in scientific research, and therefore contributes to the cultivation of students’ scientific thinking ability.
Electroplating is an important part of electrochemical system. In order to broaden the knowledge structure, and cultivate innovation consciousness and scientific literacy of students, zinc electroplating is introduced into the laboratory teaching of applied electrochemistry major. In this experiment, the cause of the zinc dendrites formation in the process of zinc electroplating is analyzed theoretically, and then two corresponding strategies of eliminating surface heterogeneity and adding cationic additives are proposed to inhibit the production of zinc dendrites. In order to deepen the understanding of zinc plating process, we set up an in situ optical microscope to directly observe the change of zinc deposition behavior. This experiment deeply integrates the scientific thinking and innovative ideas of frontier research, guides students to jump out of the textbook framework, stimulates students’ interest in scientific research, and therefore contributes to the cultivation of students’ scientific thinking ability.
2023, 38(4): 78-87
doi: 10.3866/PKU.DXHX202211048
Abstract:
As we all know, heavy metal ions are difficult to degrade in nature, and a certain amount of heavy metal ions will be enriched in living organisms, which seriously threatens the health of life. Yunnan Province has abundant freshwater resources in plateau lakes. The research on heavy metal pollution in plateau lakes is conducive to in-depth understanding of the current situation of heavy metal pollution in plateau lakes, which can provide a basis for its comprehensive control. Fluorescent nanoprobes exhibit advantages such as high sensitivity, good selectivity and simple operation in the detection of heavy metal ions. Three nanomaterials with different fluorescence-emission including carbon dots (CDs, blue), quantum dots (CdTe QDs, green), and gold nanoclusters (Au NCs, red) were successfully synthesized. Then, the above three fluorescent nanoprobes and the mixed ratiometric probes of CDs and Au NCs were added into the 96-well plate to form a 5 × 12 array which was used to detect Pb2+, Cu2+ and Hg2+ in the plateau lake water sample based on the fluorescence quenching and ratiometric fluorescence. In addition, the RGB values of the above solution in 96-well plate were recorded by APP-Colorimeter X in smartphone under the ultraviolet lamp. This proposed method exhibited superior testing performances toward Pb2+, Cu2+ and Hg2+, including portability, high-throughout, sensitivity, good visual effect, miniaturization, and small volume. Finally, this newly created experiment can solve the shortage problems of experimental instruments in some universities, boring undergraduate experiments, and derailment with the frontier of scientific research, which can facilitate the development of comprehensive experiments in universities.
As we all know, heavy metal ions are difficult to degrade in nature, and a certain amount of heavy metal ions will be enriched in living organisms, which seriously threatens the health of life. Yunnan Province has abundant freshwater resources in plateau lakes. The research on heavy metal pollution in plateau lakes is conducive to in-depth understanding of the current situation of heavy metal pollution in plateau lakes, which can provide a basis for its comprehensive control. Fluorescent nanoprobes exhibit advantages such as high sensitivity, good selectivity and simple operation in the detection of heavy metal ions. Three nanomaterials with different fluorescence-emission including carbon dots (CDs, blue), quantum dots (CdTe QDs, green), and gold nanoclusters (Au NCs, red) were successfully synthesized. Then, the above three fluorescent nanoprobes and the mixed ratiometric probes of CDs and Au NCs were added into the 96-well plate to form a 5 ×
2023, 38(4): 88-97
doi: 10.3866/PKU.DXHX202211050
Abstract:
Even though chiral compounds are ubiquitous, the general public is rarely aware of them. In this study, we perform three basic experiments using a kaleidoscope, simple optometer, and chiral indicator. Kaleidoscopes can be used to easily distinguish chiral compounds from non-chiral ones. Simple optometers can be used to directly distinguish levorotary from dextrorotary substances and determine the rotation degree of chiral substances. Chiral indicators can be used to distinguish enantiomers via color changes, which are visible to the naked eye. Because chiral indicators do not require instrumentation, they are suitable for identifying chiral substances in research settings. The experiments are thorough and easy to perform, and the observed phenomena are vivid and thought-provoking. Therefore, we believe that the experiments herein can be used by the general public to evaluate the physical and chemical properties of chiral compounds. Moreover, the experiments emphasize the practical applications of science concepts, demonstrating the attractiveness of chirality and chemistry.
Even though chiral compounds are ubiquitous, the general public is rarely aware of them. In this study, we perform three basic experiments using a kaleidoscope, simple optometer, and chiral indicator. Kaleidoscopes can be used to easily distinguish chiral compounds from non-chiral ones. Simple optometers can be used to directly distinguish levorotary from dextrorotary substances and determine the rotation degree of chiral substances. Chiral indicators can be used to distinguish enantiomers via color changes, which are visible to the naked eye. Because chiral indicators do not require instrumentation, they are suitable for identifying chiral substances in research settings. The experiments are thorough and easy to perform, and the observed phenomena are vivid and thought-provoking. Therefore, we believe that the experiments herein can be used by the general public to evaluate the physical and chemical properties of chiral compounds. Moreover, the experiments emphasize the practical applications of science concepts, demonstrating the attractiveness of chirality and chemistry.
2023, 38(4): 98-105
doi: 10.3866/PKU.DXHX202211090
Abstract:
Facing the lack of modernity and innovation in the current polymer science laboratory course during undergraduate education, this experiment proposes a new project for the preparation of photo-thermal responsive soft actuating hydrogel materials based on the combination of UV-initiated polymerization and in situ oxidation polymerization. The proposed experiment will first prepare thermal-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogel through UV-initiated polymerization. Then the conducting polymer with photo-thermal effect was further introduced into the PNIPAM hydrogel networks based on in situ oxidation polymerization to obtain composite hydrogel with photo-thermal responsive actuating features. Finally, the smart responsive actuating performance of the prepared composite actuating hydrogel was characterized through exposing the hydrogel under NIR irradiation. The proposed experiment focuses on the research hotspot of functional polymer materials, covering both the preparation of polymer materials based on basic polymerization methods and the characterization of functional polymer materials with specific features. The proposed experiment will not only consolidate students’ understanding of polymer polymerization methods, but also expand students’ knowledge of the research frontier of functional polymer materials. The proposed experiment possesses innovation and challenge, which is highly beneficial for improving students’ ability and quality.
Facing the lack of modernity and innovation in the current polymer science laboratory course during undergraduate education, this experiment proposes a new project for the preparation of photo-thermal responsive soft actuating hydrogel materials based on the combination of UV-initiated polymerization and in situ oxidation polymerization. The proposed experiment will first prepare thermal-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogel through UV-initiated polymerization. Then the conducting polymer with photo-thermal effect was further introduced into the PNIPAM hydrogel networks based on in situ oxidation polymerization to obtain composite hydrogel with photo-thermal responsive actuating features. Finally, the smart responsive actuating performance of the prepared composite actuating hydrogel was characterized through exposing the hydrogel under NIR irradiation. The proposed experiment focuses on the research hotspot of functional polymer materials, covering both the preparation of polymer materials based on basic polymerization methods and the characterization of functional polymer materials with specific features. The proposed experiment will not only consolidate students’ understanding of polymer polymerization methods, but also expand students’ knowledge of the research frontier of functional polymer materials. The proposed experiment possesses innovation and challenge, which is highly beneficial for improving students’ ability and quality.
2023, 38(4): 106-115
doi: 10.3866/PKU.DXHX202212010
Abstract:
The introduction of the frontier research in the photocatalysis field is important in the teaching of organic chemistry laboratory. It not only expands students’ knowledge of photochemical, multi-component catalytic cascade and free radical reactions, but also deepen students’ understanding of nucleophilic reaction mechanism and radical and ionic intermediates. The experiment involves three parts: product preparation, mechanism exploration and experimental expansion of imidazoline compounds, including various organic experimental operations such as anhydrous and anaerobic, reaction monitoring, separation, purification and product characterization.
The introduction of the frontier research in the photocatalysis field is important in the teaching of organic chemistry laboratory. It not only expands students’ knowledge of photochemical, multi-component catalytic cascade and free radical reactions, but also deepen students’ understanding of nucleophilic reaction mechanism and radical and ionic intermediates. The experiment involves three parts: product preparation, mechanism exploration and experimental expansion of imidazoline compounds, including various organic experimental operations such as anhydrous and anaerobic, reaction monitoring, separation, purification and product characterization.
2023, 38(4): 116-123
doi: 10.3866/PKU.DXHX202211071
Abstract:
The chemical world is abundant and diverse. One of the main purposes of laboratory teaching is revealing the mystery of product generation, speculating the micro process of product growth through the observation of macro chemical phenomena, and enhancing students’ interest in chemistry, to deepen students’ understanding of various chemical synthesis processes. In this experiment, the colorful molecular aggregates were taken as the target products to create an “interface reaction” in a self-designed reactor. The colorful (such as white, blue, green and pink) molecular aggregates with hollow tubular and coral reef-like structures were prepared on the surface of a ceramic core based on permeation and diffusion effects, surface tension, and the interfacial reaction mechanism. The method of this popular science experiment is safe, novel, and simple. Meanwhile, the phenomenon of this experiment is obvious with high ornamental value. The objective of discovering the utility and appeal of chemistry and stimulating students’ enthusiasm for learning chemistry in the process of exploring the formation of the micro world will be realized.
The chemical world is abundant and diverse. One of the main purposes of laboratory teaching is revealing the mystery of product generation, speculating the micro process of product growth through the observation of macro chemical phenomena, and enhancing students’ interest in chemistry, to deepen students’ understanding of various chemical synthesis processes. In this experiment, the colorful molecular aggregates were taken as the target products to create an “interface reaction” in a self-designed reactor. The colorful (such as white, blue, green and pink) molecular aggregates with hollow tubular and coral reef-like structures were prepared on the surface of a ceramic core based on permeation and diffusion effects, surface tension, and the interfacial reaction mechanism. The method of this popular science experiment is safe, novel, and simple. Meanwhile, the phenomenon of this experiment is obvious with high ornamental value. The objective of discovering the utility and appeal of chemistry and stimulating students’ enthusiasm for learning chemistry in the process of exploring the formation of the micro world will be realized.
2023, 38(4): 124-133
doi: 10.3866/PKU.DXHX202212011
Abstract:
Anthocyanin is a kind of natural pigments widely found in plants. It is colorful and has many physiologic functions. In this science popularization experiment, we have extracted anthocyanin from red cabbage both at home and in the lab. By mixing the extracted anthocyanin with aqueous solutions of different pH and iodophor, we have designed three schemes including “The Change of Four Seasons”, “Belt and Road” and “Write with Anthocyanin” respectively, to introduce the structure of anthocyanin, the colour changes of anthocyanin at different pH, and the principle of oxidation resistance. We have also designed a drawing activity called “Freestyle”, in which the audience at different levels can take part in person. From the above mentioned, not only are the beauty and magic of chemistry shown, but also ideological education is concluded. In addition, we have created lovely purple cabbage images and animation to show the functions and applications of anthocyanin in a vivid and interesting way. We have also indicated some common misunderstandings about anthocyanin in daily life and tried to help people use anthocyanin in the proper way. In a word, this science popularization experiment combines science and art, knowledge and education ingeniously. It is also easy and safe enough to be performed at home.
Anthocyanin is a kind of natural pigments widely found in plants. It is colorful and has many physiologic functions. In this science popularization experiment, we have extracted anthocyanin from red cabbage both at home and in the lab. By mixing the extracted anthocyanin with aqueous solutions of different pH and iodophor, we have designed three schemes including “The Change of Four Seasons”, “Belt and Road” and “Write with Anthocyanin” respectively, to introduce the structure of anthocyanin, the colour changes of anthocyanin at different pH, and the principle of oxidation resistance. We have also designed a drawing activity called “Freestyle”, in which the audience at different levels can take part in person. From the above mentioned, not only are the beauty and magic of chemistry shown, but also ideological education is concluded. In addition, we have created lovely purple cabbage images and animation to show the functions and applications of anthocyanin in a vivid and interesting way. We have also indicated some common misunderstandings about anthocyanin in daily life and tried to help people use anthocyanin in the proper way. In a word, this science popularization experiment combines science and art, knowledge and education ingeniously. It is also easy and safe enough to be performed at home.
2023, 38(4): 134-142
doi: 10.3866/PKU.DXHX202211077
Abstract:
Fluorescent anti-counterfeit printing technology is applied in the special fluorescent printing ink used for logos, which in conjunction with additional light excitation to expose the encrypted information play an anti-counterfeiting role. Fluorescent anti-counterfeiting is mostly used in film or solid state; therefore, it is necessary for fluorescent ink to have strong luminescent properties in both states. Aggregation-induced emission (AIE) molecules are a class of molecules that emit weak or even no light in a single molecule state and exhibit strong luminescence in an aggregated state. As a typical AIE molecule with simple synthesis and high fluorescence intensity, the salicylaldehyde Schiff base molecule has a stimulus-responsive fluorescence mechanism. Its different fluorescence characteristics in acid-base environments make this kind of molecule outstanding in the field of anti-counterfeit printing. In this study, the salicylaldehyde Schiff base AIE molecule was prepared by a one-step nucleophilic addition reaction of salicylaldehyde and amine, and its application in anti-counterfeit printing was further demonstrated. Through the characterization of the molecule in different environments, the role of its AIE characteristics and stimulus response fluorescence mechanism in anti-counterfeit printing applications was elucidated. The experimental raw materials are easy to obtain, safe, low cost, and the required instruments are routine, which meets the requirements of laboratory teaching. Through this experimental training, students not only master the preparation method of Schiff base compounds, but also learn the application of stimulus response fluorescence of salicylaldehyde Schiff base molecules in anti-counterfeit printing. The combination of classroom teaching and extended reading, enables students to further understand the characteristics of anti-counterfeit printing products and design concepts.
Fluorescent anti-counterfeit printing technology is applied in the special fluorescent printing ink used for logos, which in conjunction with additional light excitation to expose the encrypted information play an anti-counterfeiting role. Fluorescent anti-counterfeiting is mostly used in film or solid state; therefore, it is necessary for fluorescent ink to have strong luminescent properties in both states. Aggregation-induced emission (AIE) molecules are a class of molecules that emit weak or even no light in a single molecule state and exhibit strong luminescence in an aggregated state. As a typical AIE molecule with simple synthesis and high fluorescence intensity, the salicylaldehyde Schiff base molecule has a stimulus-responsive fluorescence mechanism. Its different fluorescence characteristics in acid-base environments make this kind of molecule outstanding in the field of anti-counterfeit printing. In this study, the salicylaldehyde Schiff base AIE molecule was prepared by a one-step nucleophilic addition reaction of salicylaldehyde and amine, and its application in anti-counterfeit printing was further demonstrated. Through the characterization of the molecule in different environments, the role of its AIE characteristics and stimulus response fluorescence mechanism in anti-counterfeit printing applications was elucidated. The experimental raw materials are easy to obtain, safe, low cost, and the required instruments are routine, which meets the requirements of laboratory teaching. Through this experimental training, students not only master the preparation method of Schiff base compounds, but also learn the application of stimulus response fluorescence of salicylaldehyde Schiff base molecules in anti-counterfeit printing. The combination of classroom teaching and extended reading, enables students to further understand the characteristics of anti-counterfeit printing products and design concepts.
2023, 38(4): 143-150
doi: 10.3866/PKU.DXHX202210001
Abstract:
The preserved egg, a well-known food in China, has become a key part of China’s egg industry after hundreds of years of development and improvement. After pickling, fresh duck eggs are subjected to thinning, solidification, color transformation, and maturation during preservation. The chemical principles of the four stages of preserved egg formation were illustrated by the following tests: duck egg white with sodium hydroxide, duck egg white with tannic acid, and L-arginine with glucose to simulate chemical changes by combining visualization and instrumental detection. The color change of magneson was used to verify that the pine flower contained magnesium hydroxide. Additionally, an interesting interactive program was designed to stimulate readers to explore chemistry and enhance their love of traditional Chinese cuisine.
The preserved egg, a well-known food in China, has become a key part of China’s egg industry after hundreds of years of development and improvement. After pickling, fresh duck eggs are subjected to thinning, solidification, color transformation, and maturation during preservation. The chemical principles of the four stages of preserved egg formation were illustrated by the following tests: duck egg white with sodium hydroxide, duck egg white with tannic acid, and L-arginine with glucose to simulate chemical changes by combining visualization and instrumental detection. The color change of magneson was used to verify that the pine flower contained magnesium hydroxide. Additionally, an interesting interactive program was designed to stimulate readers to explore chemistry and enhance their love of traditional Chinese cuisine.
2023, 38(4): 151-159
doi: 10.3866/PKU.DXHX202211092
Abstract:
Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) click chemistry and fluorescent probe are hot research topics of organic chemistry. Introducing it into undergraduate laboratory could help to cultivate creativity of students. However, how to avoid the use of azides is a great challenge to promote CuAAC click chemistry in undergraduate education. Herein, we report a modified CuAAC click reaction experiment for undergraduate laboratory teaching, featuring improved safety and interestingness. 5,7-dimethyltetrazolo[1,5-a]pyrimidine can be tautomerized into azide form in solution. Elegantly using this property could achieve the CuAAC reaction between 5,7-dimethyltetrazolo[1,5-a]pyrimidine and 4-acetylene anisole for the generation of triazole compound 5, avoiding the toxicity and explosive risk from the operation of azide compound. The synthesized compound 5 could selectively recognize zinc ions as a fluorescent probe. It is potentially useful for quantitative analysis of zinc ion concentration.
Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) click chemistry and fluorescent probe are hot research topics of organic chemistry. Introducing it into undergraduate laboratory could help to cultivate creativity of students. However, how to avoid the use of azides is a great challenge to promote CuAAC click chemistry in undergraduate education. Herein, we report a modified CuAAC click reaction experiment for undergraduate laboratory teaching, featuring improved safety and interestingness. 5,7-dimethyltetrazolo[1,5-a]pyrimidine can be tautomerized into azide form in solution. Elegantly using this property could achieve the CuAAC reaction between 5,7-dimethyltetrazolo[1,5-a]pyrimidine and 4-acetylene anisole for the generation of triazole compound 5, avoiding the toxicity and explosive risk from the operation of azide compound. The synthesized compound 5 could selectively recognize zinc ions as a fluorescent probe. It is potentially useful for quantitative analysis of zinc ion concentration.
2023, 38(4): 160-168
doi: 10.3866/PKU.DXHX202210032
Abstract:
“Electrochemically oxidizing glucose to prepare zinc gluconate” is a typical organic synthesis experiment for undergraduates, in which H-cell is usually used as the reactor. There are some shortcomings, including the long synthesis time, the high applied voltage and the low current efficiency. A kind of new device, electrochemical microchannel reactor, can overcome these shortcomings, because of the decreased applied voltage and the enhanced mass transfer. Guided by the cultivation of students’ independent thinking and logical thinking skills, this experiment improves the previous organic synthesis experiment into a comprehensive experiment, in which paired electro-synthesis of zinc gluconate and sorbitol is carried out through a home-made electrochemical microchannel reactor. In the teaching process, the principles and basic knowledge about electro-synthesis are introduced at first. Next, the students are guided to apply the cyclic voltammetry to select the appropriate applied voltage, then assemble the reactor to carry out the paired electro-synthesis. Finally, the products are separated and identified, and the results are analyzed and discussed. Through this experiment, students will understand why electroanalytical methods such as cyclic voltammetry can provide guiding information for electro-synthesis, the advantages of paired electro-synthesis, application advantages of new device of electrochemical microchannel reactors, and the relationship between organic electro-synthesis and green chemistry. The improved experiment has a rich teaching content, including electro-synthesis, electrochemical analysis, titration analysis and other typical laboratory skills, which helps students to cultivate scientific thinking and innovation ability in the process of analyzing and solving problems.
“Electrochemically oxidizing glucose to prepare zinc gluconate” is a typical organic synthesis experiment for undergraduates, in which H-cell is usually used as the reactor. There are some shortcomings, including the long synthesis time, the high applied voltage and the low current efficiency. A kind of new device, electrochemical microchannel reactor, can overcome these shortcomings, because of the decreased applied voltage and the enhanced mass transfer. Guided by the cultivation of students’ independent thinking and logical thinking skills, this experiment improves the previous organic synthesis experiment into a comprehensive experiment, in which paired electro-synthesis of zinc gluconate and sorbitol is carried out through a home-made electrochemical microchannel reactor. In the teaching process, the principles and basic knowledge about electro-synthesis are introduced at first. Next, the students are guided to apply the cyclic voltammetry to select the appropriate applied voltage, then assemble the reactor to carry out the paired electro-synthesis. Finally, the products are separated and identified, and the results are analyzed and discussed. Through this experiment, students will understand why electroanalytical methods such as cyclic voltammetry can provide guiding information for electro-synthesis, the advantages of paired electro-synthesis, application advantages of new device of electrochemical microchannel reactors, and the relationship between organic electro-synthesis and green chemistry. The improved experiment has a rich teaching content, including electro-synthesis, electrochemical analysis, titration analysis and other typical laboratory skills, which helps students to cultivate scientific thinking and innovation ability in the process of analyzing and solving problems.
2023, 38(4): 169-176
doi: 10.3866/PKU.DXHX202210019
Abstract:
Fire safety propaganda and education is crucial for protecting the public and their property. However, popularization of science regarding fire- and flame-retardant-related knowledge, as an important strategy to improve the national awareness of fire safety and reduce the occurrence of fire accidents, is currently limited. This paper presents a simple method for fabricating “expandable” flame retardant fabric coatings. Chemical knowledge, especially the three aspects of combustion, flame retardant materials, and flame retardant mechanisms, is popular among young people owing to the public’s accessible and popular art forms, including the design of interesting and vivid experiments, and the animation of mechanisms. The flame retardant fabrics may be prepared in the laboratory and at home. In this study, the multidimensional popular science experiments on the “Prevent Fire in Unburnt” fabrics designed for the public of all ages not only attracts teenagers to chemistry but also enables practical frontier scientific achievements, which facilitates the improvement of the public’s awareness of fire safety and scientific quality.
Fire safety propaganda and education is crucial for protecting the public and their property. However, popularization of science regarding fire- and flame-retardant-related knowledge, as an important strategy to improve the national awareness of fire safety and reduce the occurrence of fire accidents, is currently limited. This paper presents a simple method for fabricating “expandable” flame retardant fabric coatings. Chemical knowledge, especially the three aspects of combustion, flame retardant materials, and flame retardant mechanisms, is popular among young people owing to the public’s accessible and popular art forms, including the design of interesting and vivid experiments, and the animation of mechanisms. The flame retardant fabrics may be prepared in the laboratory and at home. In this study, the multidimensional popular science experiments on the “Prevent Fire in Unburnt” fabrics designed for the public of all ages not only attracts teenagers to chemistry but also enables practical frontier scientific achievements, which facilitates the improvement of the public’s awareness of fire safety and scientific quality.
2023, 38(4): 177-183
doi: 10.3866/PKU.DXHX202211054
Abstract:
Today, more attention is paid to the production of fine chemicals from sustainable raw materials via atom efficient, safe, and energy-efficient processes in modern organic synthesis. Teaching these “green” concepts also becomes a central task in chemistry education. Herein, we introduce our efforts for developing a series of teaching experiments on the chemistry of renewable substances from biomass and providing an organic chemistry module on the catalytic green epoxidation of limonene. Limonene is a monoterpene isolated from orange peels, and its 1,2-epoxide is found to copolymerize with CO2 leading to a high-performance biodegradable polymer. In our design, with 30% H2O2as a safe and atom efficient oxidant, and recyclable tetrabutylammonium polyphosphotungstate as a phase transfer catalyst, limonene is efficiently oxidized to its 1,2-epoxide in a regioselective fashion. This experiment not only boosts the students’ enthusiasm toward learning a structural based activity in electrophilic addition of alkenes along with 1H NMR and GC directed structural analysis, but also encourages students toward creative thinking and research in green and sustainable chemistry by demonstrating the potential of this epoxidation method on industrial production of biodegradable materials.
Today, more attention is paid to the production of fine chemicals from sustainable raw materials via atom efficient, safe, and energy-efficient processes in modern organic synthesis. Teaching these “green” concepts also becomes a central task in chemistry education. Herein, we introduce our efforts for developing a series of teaching experiments on the chemistry of renewable substances from biomass and providing an organic chemistry module on the catalytic green epoxidation of limonene. Limonene is a monoterpene isolated from orange peels, and its 1,2-epoxide is found to copolymerize with CO2 leading to a high-performance biodegradable polymer. In our design, with 30% H2O2as a safe and atom efficient oxidant, and recyclable tetrabutylammonium polyphosphotungstate as a phase transfer catalyst, limonene is efficiently oxidized to its 1,2-epoxide in a regioselective fashion. This experiment not only boosts the students’ enthusiasm toward learning a structural based activity in electrophilic addition of alkenes along with 1H NMR and GC directed structural analysis, but also encourages students toward creative thinking and research in green and sustainable chemistry by demonstrating the potential of this epoxidation method on industrial production of biodegradable materials.
2023, 38(4): 184-191
doi: 10.3866/PKU.DXHX202210039
Abstract:
Photonic crystals (PCs) are a kind of nanostructure with periodically varying refraction rates, which contain photonic band gaps that can regulate the propagation of light. PCs show beautiful structural colors if the band gaps occur in the visible light band. Due to their unique optical features, PCs have a wide range of applications, such as those in photoelectric material, chemical sensors, and ink-free printing. We introduced the frontier scientific field to the undergraduates. Using the improved Stöber method, we synthesized diameter-controllable monodisperse silica nanoparticles. As a simple and rapid method to obtain a thin layer, drop-coating is innovatively used here to assemble PCs. This experiment can be completed in 4 h. The method is inexpensive, and it helps students understand significant phenomena with interest. As a result, students can consolidate their experimental skills and learn nano-chemistry and colloidal self-assembly. The experiment is related to structural chemistry and optics theories. By integrating these theories, students can understand how structural colors are generated.
Photonic crystals (PCs) are a kind of nanostructure with periodically varying refraction rates, which contain photonic band gaps that can regulate the propagation of light. PCs show beautiful structural colors if the band gaps occur in the visible light band. Due to their unique optical features, PCs have a wide range of applications, such as those in photoelectric material, chemical sensors, and ink-free printing. We introduced the frontier scientific field to the undergraduates. Using the improved Stöber method, we synthesized diameter-controllable monodisperse silica nanoparticles. As a simple and rapid method to obtain a thin layer, drop-coating is innovatively used here to assemble PCs. This experiment can be completed in 4 h. The method is inexpensive, and it helps students understand significant phenomena with interest. As a result, students can consolidate their experimental skills and learn nano-chemistry and colloidal self-assembly. The experiment is related to structural chemistry and optics theories. By integrating these theories, students can understand how structural colors are generated.
2023, 38(4): 192-198
doi: 10.3866/PKU.DXHX202210076
Abstract:
Gallium is well-known for its ability to form alloys and its wide applications in semiconductors; however, it has not been investigated in detail. Therefore, we introduced a series of experiments aiming to unveil the mystery of the gallium. The experiment mainly consists of different gallium beating experiments in sulfuric acid system, alkaline system, and hydrogen peroxide system. Additionally, this experiment is safe in terms of the reagent, easy in terms of operation, and interesting in terms of phenomena, fully demonstrating the charm and profoundness of chemistry, which meets the requirements of popular science experiments. By combining small experiments on the physical properties of gallium and through reasonable designing and arranging, it is suitable for audiences of different age groups with dissimilar educational background.
Gallium is well-known for its ability to form alloys and its wide applications in semiconductors; however, it has not been investigated in detail. Therefore, we introduced a series of experiments aiming to unveil the mystery of the gallium. The experiment mainly consists of different gallium beating experiments in sulfuric acid system, alkaline system, and hydrogen peroxide system. Additionally, this experiment is safe in terms of the reagent, easy in terms of operation, and interesting in terms of phenomena, fully demonstrating the charm and profoundness of chemistry, which meets the requirements of popular science experiments. By combining small experiments on the physical properties of gallium and through reasonable designing and arranging, it is suitable for audiences of different age groups with dissimilar educational background.
2023, 38(4): 199-206
doi: 10.3866/PKU.DXHX202210068
Abstract:
In this work, a 12-h comprehensive chemical experiment was designed. Based on the synthesis of Keggin-type polyoxometalate (POM) and the oxidation reaction of benzaldehyde in current textbooks, an amphiphilic two-dimensional material, g-C3N4, was introduced to construct a Keggin-type POM@Pickering emulsion microreactor, promoting the efficient oxidation of benzaldehyde and optimally designing the reaction site. Different from the original content, the selection of Keggin-type POM was improved from H3PMo12O40 to K3PW12O40. The unique antioxidant properties of K3PW12O40 can promote the catalytic oxidation reaction. Importantly, the synthesis process of K3PW12O40 is simple, raw materials are environmentally friendly and easy to obtain, and flammable solvents (such as diethyl ether) are not used. The amphiphilic g-C3N4 material with large specific surfaces, the hydrophilic group and conjugated skeleton in its structure, can simultaneously adsorb POM molecules, hydrogen peroxide, and benzaldehyde molecules, promoting the equimolar ratio conversion of hydrogen peroxide and benzaldehyde. The improved experiment is more consistent with the characteristics of “atomic economy” in green chemistry. Moreover, the combination of infrared spectroscopy and thin layer chromatography detection technologies can strengthen the integration of theoretical learning and practical operation. This work embodies the development of outcome based education (OBE) education for the cultivation of creative talents by introducing the frontier research into undergraduate experimental teaching, which is conducive to cultivate innovative consciousness of students and to improve their ability of comprehensive analysis and solving practical problems.
In this work, a 12-h comprehensive chemical experiment was designed. Based on the synthesis of Keggin-type polyoxometalate (POM) and the oxidation reaction of benzaldehyde in current textbooks, an amphiphilic two-dimensional material, g-C3N4, was introduced to construct a Keggin-type POM@Pickering emulsion microreactor, promoting the efficient oxidation of benzaldehyde and optimally designing the reaction site. Different from the original content, the selection of Keggin-type POM was improved from H3PMo12O40 to K3PW12O40. The unique antioxidant properties of K3PW12O40 can promote the catalytic oxidation reaction. Importantly, the synthesis process of K3PW12O40 is simple, raw materials are environmentally friendly and easy to obtain, and flammable solvents (such as diethyl ether) are not used. The amphiphilic g-C3N4 material with large specific surfaces, the hydrophilic group and conjugated skeleton in its structure, can simultaneously adsorb POM molecules, hydrogen peroxide, and benzaldehyde molecules, promoting the equimolar ratio conversion of hydrogen peroxide and benzaldehyde. The improved experiment is more consistent with the characteristics of “atomic economy” in green chemistry. Moreover, the combination of infrared spectroscopy and thin layer chromatography detection technologies can strengthen the integration of theoretical learning and practical operation. This work embodies the development of outcome based education (OBE) education for the cultivation of creative talents by introducing the frontier research into undergraduate experimental teaching, which is conducive to cultivate innovative consciousness of students and to improve their ability of comprehensive analysis and solving practical problems.
2023, 38(4): 207-215
doi: 10.3866/PKU.DXHX202210070
Abstract:
In this work, a 4-h inorganic chemistry experiment was designed. Herein, an aggregation-induced emission (AIE) copper iodine cluster was synthesized and used for the construction of long-afterglow emission material. Students can learn about the synthesis of cluster compound and the growth of crystal, and deepen the understanding of coordination compound, cluster compound, enantiomers, and hybrid orbital, among others. Meanwhile, by introducing AIE, which is a research hotspot, and long-afterglow emission, which is an interesting chemical phenomenon, the enthusiasm in learning of students will be aroused. Combining with classroom instruction and literature reading, students can also understand the mechanism behind the experiment. This experiment is compact, and the reagents and instruments used are simple and cost-effective, making it suitable for promotion in undergraduate experiment of chemistry or other related majors. This experiment fitted well with the requirement about “cluster compound” of “synthesis and preparation of compounds” in “chemical experiment teaching suggestions for chemistry majors,” which was issued by the national instruction committee of higher chemistry education of ministry of education. This experiment enriched the content of traditional inorganic chemistry experiment.
In this work, a 4-h inorganic chemistry experiment was designed. Herein, an aggregation-induced emission (AIE) copper iodine cluster was synthesized and used for the construction of long-afterglow emission material. Students can learn about the synthesis of cluster compound and the growth of crystal, and deepen the understanding of coordination compound, cluster compound, enantiomers, and hybrid orbital, among others. Meanwhile, by introducing AIE, which is a research hotspot, and long-afterglow emission, which is an interesting chemical phenomenon, the enthusiasm in learning of students will be aroused. Combining with classroom instruction and literature reading, students can also understand the mechanism behind the experiment. This experiment is compact, and the reagents and instruments used are simple and cost-effective, making it suitable for promotion in undergraduate experiment of chemistry or other related majors. This experiment fitted well with the requirement about “cluster compound” of “synthesis and preparation of compounds” in “chemical experiment teaching suggestions for chemistry majors,” which was issued by the national instruction committee of higher chemistry education of ministry of education. This experiment enriched the content of traditional inorganic chemistry experiment.
2023, 38(4): 216-226
doi: 10.3866/PKU.DXHX202211081
Abstract:
In this study, we develop an innovative and comprehensive method for extracting Au from electronic scrap. Au recycling from electronic waste is a popular topic for chemistry students and the general public. To implement the latest scientific knowledge and methods, herein, Au recovery via the reaction of α-cyclodextrin with [AuBr4]- is used as the basic principle. The procedure used to recycle Au from electronic waste comprises four steps: dilute nitric acid is used to decrease the unwanted metal content of electronic waste (Au enrichment); Au is subjected to mild oxidation using a potassium bromide-acetic acid-nitric acid system (Au dissolution); α-cyclodextrin is reacted with [AuBr4]- (Au extraction); Au(III) is reduced to Au(0) using sodium metabisulfite, a non-toxic and non-metallic reducing agent (Au formation). The experiments involve multi-disciplinary principles, such as inorganic, supramolecular, and analytical chemistry concepts. Furthermore, they cover the basic operations of synthesis and analytical experiments including reaction monitoring, structural characterization, and purity analysis. The experimental results are conspicuous, the experiments are repeatable, and the purity of Au is above 90%. Moreover, the time required to perform the experiments ranges between 6 and 8 h. Therefore, the experiments are suitable for undergraduate comprehensive chemistry laboratory teaching. In addition, green chemistry concepts and experimental methods are incorporated as the reagents are environmentally friendly and safe to handle. This experiment demonstrates the critical role of chemistry in solving national economy problems and improving the livelihood of humankind. Through a thorough teaching approach comprising online and offline modules, this experiment cultivates the scientific thinking patterns and innate curiosity of students, improves the ability of undergraduate chemistry students to solve complex synthetic chemistry problems, and consolidates the knowledge of chemistry trainees.
In this study, we develop an innovative and comprehensive method for extracting Au from electronic scrap. Au recycling from electronic waste is a popular topic for chemistry students and the general public. To implement the latest scientific knowledge and methods, herein, Au recovery via the reaction of α-cyclodextrin with [AuBr4]- is used as the basic principle. The procedure used to recycle Au from electronic waste comprises four steps: dilute nitric acid is used to decrease the unwanted metal content of electronic waste (Au enrichment); Au is subjected to mild oxidation using a potassium bromide-acetic acid-nitric acid system (Au dissolution); α-cyclodextrin is reacted with [AuBr4]- (Au extraction); Au(III) is reduced to Au(0) using sodium metabisulfite, a non-toxic and non-metallic reducing agent (Au formation). The experiments involve multi-disciplinary principles, such as inorganic, supramolecular, and analytical chemistry concepts. Furthermore, they cover the basic operations of synthesis and analytical experiments including reaction monitoring, structural characterization, and purity analysis. The experimental results are conspicuous, the experiments are repeatable, and the purity of Au is above 90%. Moreover, the time required to perform the experiments ranges between 6 and 8 h. Therefore, the experiments are suitable for undergraduate comprehensive chemistry laboratory teaching. In addition, green chemistry concepts and experimental methods are incorporated as the reagents are environmentally friendly and safe to handle. This experiment demonstrates the critical role of chemistry in solving national economy problems and improving the livelihood of humankind. Through a thorough teaching approach comprising online and offline modules, this experiment cultivates the scientific thinking patterns and innate curiosity of students, improves the ability of undergraduate chemistry students to solve complex synthetic chemistry problems, and consolidates the knowledge of chemistry trainees.
2023, 38(4): 227-236
doi: 10.3866/PKU.DXHX202209093
Abstract:
In this study, the preparation of coumarin-3-carboxylic acid was improved. For the preparation of the intermediate, green and nontoxic L-proline was used as the catalyst under solvent-free conditions. Subsequently, the target product (coumarin-3-carboxylic acid) was obtained in high yield by a “one-pot” reaction without separation. The molecular structure was characterized by infrared and nuclear magnetic resonance spectroscopies. Additionally, the properties of ultraviolet (UV) absorption and fluorescence were characterized. The improved experimental method is environmentally friendly and inexpensive, with high yield, good reproducibility, and strong comprehensiveness. This program cultivates the exploration, innovative research ideas, and teamwork ability of students. Moreover, it helps to improve the comprehensive experimental skills of students for analyzing and processing data and using theoretical knowledge to solve problems, which is suitable for promoting higher-grade undergraduate teaching.
In this study, the preparation of coumarin-3-carboxylic acid was improved. For the preparation of the intermediate, green and nontoxic L-proline was used as the catalyst under solvent-free conditions. Subsequently, the target product (coumarin-3-carboxylic acid) was obtained in high yield by a “one-pot” reaction without separation. The molecular structure was characterized by infrared and nuclear magnetic resonance spectroscopies. Additionally, the properties of ultraviolet (UV) absorption and fluorescence were characterized. The improved experimental method is environmentally friendly and inexpensive, with high yield, good reproducibility, and strong comprehensiveness. This program cultivates the exploration, innovative research ideas, and teamwork ability of students. Moreover, it helps to improve the comprehensive experimental skills of students for analyzing and processing data and using theoretical knowledge to solve problems, which is suitable for promoting higher-grade undergraduate teaching.
2023, 38(4): 237-242
doi: 10.3866/PKU.DXHX202210017
Abstract:
In this experiment, we introduce the organic phosphine frontier to organic laboratory teaching. Starting from easily accessible and cost-effective triphenylphosphine and ethyl propionate, this experiment proceeds successfully under mild conditions to accomplish the highly efficient synthesis of new organic phosphine. It has the advantages of short reaction time and simple operation. The structure of the product was determined by melting point measurements, nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. Through this experiment, students can understand the frontier field of phosphine chemistry, deepen the understanding of the whole process of reaction, and further master the separation and analysis methods commonly used in the laboratory. This experiment is conducive to training students to comprehensively use the knowledge of organic chemistry, analytical chemistry and instrumental analysis to analyze and solve problems. It can also stimulate students’ interest in scientific research and contribute to the cultivation of innovative talents.
In this experiment, we introduce the organic phosphine frontier to organic laboratory teaching. Starting from easily accessible and cost-effective triphenylphosphine and ethyl propionate, this experiment proceeds successfully under mild conditions to accomplish the highly efficient synthesis of new organic phosphine. It has the advantages of short reaction time and simple operation. The structure of the product was determined by melting point measurements, nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. Through this experiment, students can understand the frontier field of phosphine chemistry, deepen the understanding of the whole process of reaction, and further master the separation and analysis methods commonly used in the laboratory. This experiment is conducive to training students to comprehensively use the knowledge of organic chemistry, analytical chemistry and instrumental analysis to analyze and solve problems. It can also stimulate students’ interest in scientific research and contribute to the cultivation of innovative talents.
2023, 38(4): 243-252
doi: 10.3866/PKU.DXHX202210002
Abstract:
Photoenzymatic synthesis and rational engineering of enzymes are among the most emerging research areas. Herein, a highly selective photodecarboxylation of trans fatty acid was achieved by rational repurposing of the photodecarboxylase. Specifically, via molecular docking, a mutant of the photodecarboxylase CvFAP, namely V453E-CvFAP, was rationaly designed, constructed and subjected to the photoactivated decarboxylation of fatty acids. It turned out that the mutant was highly selective towards elaidic acid, thereby enriching oleic acid. Experimental trainings like cells culturing, protein expression, reaction design, and qualitative and quantitative analysis of products were included. The experiment is easy to conduct and safe for undergraduate chemistry experiment.
Photoenzymatic synthesis and rational engineering of enzymes are among the most emerging research areas. Herein, a highly selective photodecarboxylation of trans fatty acid was achieved by rational repurposing of the photodecarboxylase. Specifically, via molecular docking, a mutant of the photodecarboxylase CvFAP, namely V453E-CvFAP, was rationaly designed, constructed and subjected to the photoactivated decarboxylation of fatty acids. It turned out that the mutant was highly selective towards elaidic acid, thereby enriching oleic acid. Experimental trainings like cells culturing, protein expression, reaction design, and qualitative and quantitative analysis of products were included. The experiment is easy to conduct and safe for undergraduate chemistry experiment.
2023, 38(4): 253-259
doi: 10.3866/PKU.DXHX202211017
Abstract:
Under the guidance of carbon peak and neutrality targets, it is one of the necessary ways to promote the reformation of the education and teaching system that will accelerate the cultivation of highly skilled talents in the energy field. Solar desalination has the advantages of energy saving, environmental protection and high effluent purity. Aiming at the scientific frontier of solar driven interface water evaporation, a research-oriented comprehensive experiment is designed in this article. This experiment covers the photothermal conversion mechanism of light absorbing materials, the synthesis of melamine foam, the synthesis of Ni MOFs materials, the synthesis of nickel- carbon microspheres from Ni MOFs precursors, and the characterization and performance of materials. Transforming research achievements with application prospects into a comprehensive experiment can cultivate students’ scientific research thinking and comprehensive analysis ability, and deepen their understanding of the integration of production, teaching and research.
Under the guidance of carbon peak and neutrality targets, it is one of the necessary ways to promote the reformation of the education and teaching system that will accelerate the cultivation of highly skilled talents in the energy field. Solar desalination has the advantages of energy saving, environmental protection and high effluent purity. Aiming at the scientific frontier of solar driven interface water evaporation, a research-oriented comprehensive experiment is designed in this article. This experiment covers the photothermal conversion mechanism of light absorbing materials, the synthesis of melamine foam, the synthesis of Ni MOFs materials, the synthesis of nickel- carbon microspheres from Ni MOFs precursors, and the characterization and performance of materials. Transforming research achievements with application prospects into a comprehensive experiment can cultivate students’ scientific research thinking and comprehensive analysis ability, and deepen their understanding of the integration of production, teaching and research.
2023, 38(4): 260-268
doi: 10.3866/PKU.DXHX202210088
Abstract:
Based on the research-oriented laboratory teaching concept of “thick foundation, wide professional, and comprehensive”, this paper combines the theoretical knowledge of supramolecular chemistry and macrocyclic chemistry to design a new comprehensive experiment of selective gradient separation of o-, m-, p-aminophenol isomers with the purity of 91.46%, 94.16% and 96.70%, respectively, based on supramolecular self-assembly using cucurbit[6]uril as the host. All reagents can be recycled after the experiment, fully embodying the concept of green chemistry. This experiment involves TLC, LC, IR, and other important analytical methods to monitor the separation process, purity analysis, and structural characterization of the target product, which enables students to fully master basic theoretical knowledge, experimental principles, and learn to analyze experimental phenomena, thereby improving students’ research-oriented literacy and ability to comprehensively apply knowledge.
Based on the research-oriented laboratory teaching concept of “thick foundation, wide professional, and comprehensive”, this paper combines the theoretical knowledge of supramolecular chemistry and macrocyclic chemistry to design a new comprehensive experiment of selective gradient separation of o-, m-, p-aminophenol isomers with the purity of 91.46%, 94.16% and 96.70%, respectively, based on supramolecular self-assembly using cucurbit[6]uril as the host. All reagents can be recycled after the experiment, fully embodying the concept of green chemistry. This experiment involves TLC, LC, IR, and other important analytical methods to monitor the separation process, purity analysis, and structural characterization of the target product, which enables students to fully master basic theoretical knowledge, experimental principles, and learn to analyze experimental phenomena, thereby improving students’ research-oriented literacy and ability to comprehensively apply knowledge.
2023, 38(4): 269-276
doi: 10.3866/PKU.DXHX202211042
Abstract:
Chemistry laboratory training is an integral part of chemistry teaching. However, outdated experimental protocols present limitations and can hinder students’ initiative and innate inclination toward exploration. In this study, novel scientific concepts were translated into experimental chemistry teaching. Small fluorescent molecules with aggregation-induced emission and excited-state intramolecular proton transfer properties were prepared using a carbonyl nucleophile addition reaction. The basic photophysical properties of the molecules and their fluorescence response to acid-base stimulation were evaluated experimentally. The non-toxic and non-noxious reagents used for the experiments were refluxed in ethanol for 0.5 h to implement green organic synthesis principles. The experiment was compact and the fluorescence and color changes of the as-synthesized molecules were conspicuous and remarkable. This can stimulate students’ enthusiasm for experimental chemistry. In addition to the basic organic synthesis reaction, this experiment included several modern analysis and characterization methods, such as nuclear magnetic resonance, Fourier-transform infrared spectroscopy, ultraviolet-visible absorption spectroscopy, and fluorescence spectroscopy. We are confident that this intuitive and effective basic experiment can effectively stimulate and cultivate the innate curiosity of students.
Chemistry laboratory training is an integral part of chemistry teaching. However, outdated experimental protocols present limitations and can hinder students’ initiative and innate inclination toward exploration. In this study, novel scientific concepts were translated into experimental chemistry teaching. Small fluorescent molecules with aggregation-induced emission and excited-state intramolecular proton transfer properties were prepared using a carbonyl nucleophile addition reaction. The basic photophysical properties of the molecules and their fluorescence response to acid-base stimulation were evaluated experimentally. The non-toxic and non-noxious reagents used for the experiments were refluxed in ethanol for 0.5 h to implement green organic synthesis principles. The experiment was compact and the fluorescence and color changes of the as-synthesized molecules were conspicuous and remarkable. This can stimulate students’ enthusiasm for experimental chemistry. In addition to the basic organic synthesis reaction, this experiment included several modern analysis and characterization methods, such as nuclear magnetic resonance, Fourier-transform infrared spectroscopy, ultraviolet-visible absorption spectroscopy, and fluorescence spectroscopy. We are confident that this intuitive and effective basic experiment can effectively stimulate and cultivate the innate curiosity of students.
2023, 38(4): 277-283
doi: 10.3866/PKU.DXHX202210106
Abstract:
Heating the reaction mixture of diphenylmethanol and acetonitrile for 2 h in the presence of 5% (molar ratio) iodine or p-toluenesulfonic acid as the catalyst can yield the target product N-benzyl acetamide in approximately 85% isolated yield. Based on the concept of green chemistry, this innovative experiment integrates basic knowledge and theories such as the properties of alcohols, carbocation theory, organic Brønsted and Lewis acid-base theories, and the Ritter reaction. Additionally, knowledge regarding basic experimental operations such as thin layer chromatography (TLC), recrystallization, extraction filtration, drying and melting point determination can be strengthened by this experiment. The scientific research methods of product analysis and characterization such as gas chromatography-mass spectrometry, nuclear magnetic resonance, and the basic scientific research rules such as the single-variable method are also employed in this experiment. Notably, it takes approximately 3–4 h to complete the experimental process, the cost of reagents is approximately 1.2 yuan per-person, and it is convenient to carry out the control experiments in groups for practical teaching. In summary, the basic knowledge and theories mentioned in the textbook and the frontier of scientific research can be covered in this innovative experiment, while meeting the requirements for “high-order, innovation and challenge” of the new curriculum reform.
Heating the reaction mixture of diphenylmethanol and acetonitrile for 2 h in the presence of 5% (molar ratio) iodine or p-toluenesulfonic acid as the catalyst can yield the target product N-benzyl acetamide in approximately 85% isolated yield. Based on the concept of green chemistry, this innovative experiment integrates basic knowledge and theories such as the properties of alcohols, carbocation theory, organic Brønsted and Lewis acid-base theories, and the Ritter reaction. Additionally, knowledge regarding basic experimental operations such as thin layer chromatography (TLC), recrystallization, extraction filtration, drying and melting point determination can be strengthened by this experiment. The scientific research methods of product analysis and characterization such as gas chromatography-mass spectrometry, nuclear magnetic resonance, and the basic scientific research rules such as the single-variable method are also employed in this experiment. Notably, it takes approximately 3–4 h to complete the experimental process, the cost of reagents is approximately 1.2 yuan per-person, and it is convenient to carry out the control experiments in groups for practical teaching. In summary, the basic knowledge and theories mentioned in the textbook and the frontier of scientific research can be covered in this innovative experiment, while meeting the requirements for “high-order, innovation and challenge” of the new curriculum reform.
2023, 38(4): 284-290
doi: 10.3866/PKU.DXHX202211045
Abstract:
Organic chemistry experiment is an important course for majoring in chemistry and related fields. Through experiment and laboratory training, students can learn and master the basic skills of organic synthesis and learn to select the correct methods for synthesis, separation, purification, analysis, and identification of organic compounds. “Preparation and Reaction of Diazonium Salts” is a classic experimental project in organic chemistry experimental textbooks but poses several challenges. For example, concentrated hydrochloric acid is corrosive and an irritant, highly acidic wastewater is produced, the product exhibits poor stability and yield, and a strict temperature control is required. This project aims to improve the synthesis method of diazonium salt by optimizing the reaction efficiency, solvent utilization rate, and the post-treatment process, thereby reducing the use of toxic substances and wastewater discharge. The improved experiment is more suitable for use in a teaching environment. Azo dye synthesis and corresponding organic spectroscopy contents are also included in the improved experiment; therefore, students can learn to characterize target compounds using nuclear magnetic resonance and mass spectroscopy as well as the absorption properties of dyes, which is more conducive to the cultivation of comprehension quality.
Organic chemistry experiment is an important course for majoring in chemistry and related fields. Through experiment and laboratory training, students can learn and master the basic skills of organic synthesis and learn to select the correct methods for synthesis, separation, purification, analysis, and identification of organic compounds. “Preparation and Reaction of Diazonium Salts” is a classic experimental project in organic chemistry experimental textbooks but poses several challenges. For example, concentrated hydrochloric acid is corrosive and an irritant, highly acidic wastewater is produced, the product exhibits poor stability and yield, and a strict temperature control is required. This project aims to improve the synthesis method of diazonium salt by optimizing the reaction efficiency, solvent utilization rate, and the post-treatment process, thereby reducing the use of toxic substances and wastewater discharge. The improved experiment is more suitable for use in a teaching environment. Azo dye synthesis and corresponding organic spectroscopy contents are also included in the improved experiment; therefore, students can learn to characterize target compounds using nuclear magnetic resonance and mass spectroscopy as well as the absorption properties of dyes, which is more conducive to the cultivation of comprehension quality.
2023, 38(4): 291-299
doi: 10.3866/PKU.DXHX202301019
Abstract:
In this work, a modular Laser-induced fluorescence (LIF) detection system LEGO LIF for undergraduate laboratory course was developed based on optical modules constructed from commercially available LEGO blocks and 3D-printed blocks. The system was applied to the laboratory teaching of undergraduate instrumental analysis, and the students were instructed to build the LIF system based on functional building blocks and apply it to the determination of sodium fluorescein solutions. The system is characterized by low cost, easy construction and flexible operation. The way of modular construction greatly reduced the threshold of instrument construction, and can be completed within 3 h by undergraduate students without experience. The introduction of the LIF modular construction design into the open teaching session can inspire students’ interest and enthusiasm in the instrumental analysis course, and help deepen students’ understanding of fluorescence analysis principles and LIF detection system structure, exercise students’ hands-on ability as well as improve students’ ability to find and solve problems during the process of system construction.
In this work, a modular Laser-induced fluorescence (LIF) detection system LEGO LIF for undergraduate laboratory course was developed based on optical modules constructed from commercially available LEGO blocks and 3D-printed blocks. The system was applied to the laboratory teaching of undergraduate instrumental analysis, and the students were instructed to build the LIF system based on functional building blocks and apply it to the determination of sodium fluorescein solutions. The system is characterized by low cost, easy construction and flexible operation. The way of modular construction greatly reduced the threshold of instrument construction, and can be completed within 3 h by undergraduate students without experience. The introduction of the LIF modular construction design into the open teaching session can inspire students’ interest and enthusiasm in the instrumental analysis course, and help deepen students’ understanding of fluorescence analysis principles and LIF detection system structure, exercise students’ hands-on ability as well as improve students’ ability to find and solve problems during the process of system construction.
2023, 38(4): 300-310
doi: 10.3866/PKU.DXHX202210016
Abstract:
In this experiment, the electron-deficient boron and the electron-donating nitrogen were used as the starting points of the rational design. Furthermore, organic carriers of B and N were selected based on the principle of aggregation-induced emission (AIE). An environmentally friendly, economic and convenient “one-pot” synthesis method was employed to obtain crystal compounds, and the structures of these compounds were characterized. The optical properties of compounds, including “presence or absence”, “color”, and “strength”, were regulated by changing ligands. Students will understand the idea that the structure determines properties and will experience the visible and tangible chemical theories.
In this experiment, the electron-deficient boron and the electron-donating nitrogen were used as the starting points of the rational design. Furthermore, organic carriers of B and N were selected based on the principle of aggregation-induced emission (AIE). An environmentally friendly, economic and convenient “one-pot” synthesis method was employed to obtain crystal compounds, and the structures of these compounds were characterized. The optical properties of compounds, including “presence or absence”, “color”, and “strength”, were regulated by changing ligands. Students will understand the idea that the structure determines properties and will experience the visible and tangible chemical theories.
2023, 38(4): 311-318
doi: 10.3866/PKU.DXHX202211083
Abstract:
Self-built ion chromatography and its application in testing inorganic anions offers an experiment for students of chemistry major to build and debug the ion chromatography by themselves. The new experiment includes the assembly and construction of ion chromatographic system including its key component of electrochemical ion suppressor, the debugging of the function and measurement of the performance of the instrument, and the qualitative and quantitative analysis of the inorganic anions in real samples, such as tap water, lake water and tea drink. It is conducive to deepening students’ understanding of the principle and configuration of the instrument for chemical analysis. It also helps improve the creative thinking, practical ability, and team work of students. Furthermore, the students can be heavily involved during the experiment. As the project uses commercially available standard components and home-built components to construct the instrument, the experiment can be finished with a high reproducibility and success rate. This experiment can also serve as a tool to improve the capability of instructors and the teaching performance. This self-built ion chromatography is much cheaper than the commercial one and has low request on the teaching cost, which is suitable to be extended to the fundamental laboratory course in Instrumental Analysis in most universities.
Self-built ion chromatography and its application in testing inorganic anions offers an experiment for students of chemistry major to build and debug the ion chromatography by themselves. The new experiment includes the assembly and construction of ion chromatographic system including its key component of electrochemical ion suppressor, the debugging of the function and measurement of the performance of the instrument, and the qualitative and quantitative analysis of the inorganic anions in real samples, such as tap water, lake water and tea drink. It is conducive to deepening students’ understanding of the principle and configuration of the instrument for chemical analysis. It also helps improve the creative thinking, practical ability, and team work of students. Furthermore, the students can be heavily involved during the experiment. As the project uses commercially available standard components and home-built components to construct the instrument, the experiment can be finished with a high reproducibility and success rate. This experiment can also serve as a tool to improve the capability of instructors and the teaching performance. This self-built ion chromatography is much cheaper than the commercial one and has low request on the teaching cost, which is suitable to be extended to the fundamental laboratory course in Instrumental Analysis in most universities.
2023, 38(4): 319-330
doi: 10.3866/PKU.DXHX202210050
Abstract:
Organic functional materials have attracted significant research attention in organic chemistry. Introducing the synthesis and characterization of advanced organic functional materials into basic organic chemistry experiments can enrich the study content and promote the connection between teaching and academic achievements. Therefore, in this project, one of the research frontiers, i.e., organic long-afterglow materials, were selected and combined with the laboratory teaching of nucleophilic aromatic substitution. This project can help students understand the key role of synthetic reactions in constructing organic functional materials. Furthermore, extending the knowledge system to modern spectroscopy technologies can help students understand correct scientific concepts. This experiment completes the systematic teaching of the “synthesis-molecular structure-photoelectric properties” knowledge chain, thereby developing students’ science literacy and continual innovatory capacity.
Organic functional materials have attracted significant research attention in organic chemistry. Introducing the synthesis and characterization of advanced organic functional materials into basic organic chemistry experiments can enrich the study content and promote the connection between teaching and academic achievements. Therefore, in this project, one of the research frontiers, i.e., organic long-afterglow materials, were selected and combined with the laboratory teaching of nucleophilic aromatic substitution. This project can help students understand the key role of synthetic reactions in constructing organic functional materials. Furthermore, extending the knowledge system to modern spectroscopy technologies can help students understand correct scientific concepts. This experiment completes the systematic teaching of the “synthesis-molecular structure-photoelectric properties” knowledge chain, thereby developing students’ science literacy and continual innovatory capacity.
2023, 38(4): 331-335
doi: 10.3866/PKU.DXHX202210038
Abstract:
In this study, the research hotspot of polycyclic aromatic hydrocarbons was introduced into undergraduate experimental teaching, and a synthesis experiment based on the aldol and Diels-Alder reactions was developed for benzene ring formation. Using 9,10-phenanthrenequinone and dibenzyl ketone as raw materials, the cyclopentadienone derivative 1 was obtained by the aldol reaction, and 1 was further reacted with diethyl acetylene dicarboxylate to obtain triphenylene derivative 2 by the Diels-Alder reaction. The reagents in this study are easily accessible, the reaction conditions are mild, the phenomenon is clear, the purification is simple, and the reliability is high. Students can master the principle and operation of the aldol and Diels-Alder reactions and gain an understanding of the important strategy for forming benzene rings.
In this study, the research hotspot of polycyclic aromatic hydrocarbons was introduced into undergraduate experimental teaching, and a synthesis experiment based on the aldol and Diels-Alder reactions was developed for benzene ring formation. Using 9,10-phenanthrenequinone and dibenzyl ketone as raw materials, the cyclopentadienone derivative 1 was obtained by the aldol reaction, and 1 was further reacted with diethyl acetylene dicarboxylate to obtain triphenylene derivative 2 by the Diels-Alder reaction. The reagents in this study are easily accessible, the reaction conditions are mild, the phenomenon is clear, the purification is simple, and the reliability is high. Students can master the principle and operation of the aldol and Diels-Alder reactions and gain an understanding of the important strategy for forming benzene rings.
2023, 38(4): 336-346
doi: 10.3866/PKU.DXHX202212008
Abstract:
The transformation reactions of indole derivatives are fundamental knowledge in organic chemistry. Using electrons as clean reagents, electrochemistry serves as a sustainable alternative to traditional redox organic transformations and received considerable attention in recent years. In this study, 3-aryl indole was used as raw materials to realize dehydrogenation coupling and coupling-cyclization only by prolonging the electrolysis reaction time. The reaction runs under mild conditions and the reaction operation is simple and safe. The reaction is efficient to gain product in good yield and can be monitored by using thin-layer chromatography. There are various reaction phenomena for students to observe. Moreover, the final product of the reaction is controllable via simply tuning the reaction time. The experiment can be reproduced with similar efficiency after many times. All products are solid and can be purified via silica gel column chromatography. Nuclear magnetic resonance (NMR) spectroscopy and high resolution mass spectrometry (HRMS) were recorded to analyze the structure of products which also show different fluorescence properties. Based on the basic knowledge of indole transformation chemistry, this experiment uses green electrolysis strategies to develop practical synthesis methods for nitrogen-containing heterocyclic compounds, and guides students to learn interdisciplinary knowledge of organic synthesis chemistry and physical chemistry, establishes interdisciplinary knowledge awareness and pays attention to the frontiers of organic chemistry.
The transformation reactions of indole derivatives are fundamental knowledge in organic chemistry. Using electrons as clean reagents, electrochemistry serves as a sustainable alternative to traditional redox organic transformations and received considerable attention in recent years. In this study, 3-aryl indole was used as raw materials to realize dehydrogenation coupling and coupling-cyclization only by prolonging the electrolysis reaction time. The reaction runs under mild conditions and the reaction operation is simple and safe. The reaction is efficient to gain product in good yield and can be monitored by using thin-layer chromatography. There are various reaction phenomena for students to observe. Moreover, the final product of the reaction is controllable via simply tuning the reaction time. The experiment can be reproduced with similar efficiency after many times. All products are solid and can be purified via silica gel column chromatography. Nuclear magnetic resonance (NMR) spectroscopy and high resolution mass spectrometry (HRMS) were recorded to analyze the structure of products which also show different fluorescence properties. Based on the basic knowledge of indole transformation chemistry, this experiment uses green electrolysis strategies to develop practical synthesis methods for nitrogen-containing heterocyclic compounds, and guides students to learn interdisciplinary knowledge of organic synthesis chemistry and physical chemistry, establishes interdisciplinary knowledge awareness and pays attention to the frontiers of organic chemistry.
