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2021 Volume 36 Issue 6
2021, 36(6): 200707
doi: 10.3866/PKU.DXHX202007078
Abstract:
With the improvement of environmental protection consciousness, the photopolymerization technology has greatly developed over the past ten years due to its high efficiency and environmental protection, and become one of the most advanced technologies. In the present paper, the kinds and related initiating mechanisms of photoinitiators as the key component in photopolymerization system were discussed, and furthermore the progress of photoinitiators for free radical photopolymerization in the recent years was reviewed.
With the improvement of environmental protection consciousness, the photopolymerization technology has greatly developed over the past ten years due to its high efficiency and environmental protection, and become one of the most advanced technologies. In the present paper, the kinds and related initiating mechanisms of photoinitiators as the key component in photopolymerization system were discussed, and furthermore the progress of photoinitiators for free radical photopolymerization in the recent years was reviewed.
2021, 36(6): 200805
doi: 10.3866/PKU.DXHX202008053
Abstract:
This paper conducted a questionnaire survey to record the statistics and analyze the status quo of National Examination for Teacher Certificate among pre-service chemistry teachers in X Normal University. The results revealed a relatively low examination pass rate, insufficient knowledge depth among the pre-service teachers, and a highly uniform method of exam preparation. Moreover, the analysis also showed that the course completion was not in harmony with the tested content, the teaching content as well as methods require further revision, and the practical teaching training conducted was below par. Subsequently, regression analysis was conducted with respect to the level of attention put by the university teachers, the curriculum arrangement, the teaching content and methods, as well as practical teaching training, based on which result the targeted countermeasures were proposed. This study was aimed at guiding the pre-service chemistry teachers to actively face the national examination as well as improve their qualities as teachers-to-be.
This paper conducted a questionnaire survey to record the statistics and analyze the status quo of National Examination for Teacher Certificate among pre-service chemistry teachers in X Normal University. The results revealed a relatively low examination pass rate, insufficient knowledge depth among the pre-service teachers, and a highly uniform method of exam preparation. Moreover, the analysis also showed that the course completion was not in harmony with the tested content, the teaching content as well as methods require further revision, and the practical teaching training conducted was below par. Subsequently, regression analysis was conducted with respect to the level of attention put by the university teachers, the curriculum arrangement, the teaching content and methods, as well as practical teaching training, based on which result the targeted countermeasures were proposed. This study was aimed at guiding the pre-service chemistry teachers to actively face the national examination as well as improve their qualities as teachers-to-be.
2021, 36(6): 200801
doi: 10.3866/PKU.DXHX202008019
Abstract:
The "Senior High School Students Elite Program" is a training program developed by the State to train top-notch talents for scientific and technological innovation. The "elite plan" summer camp is a key part for experience and practice. Taking the summer camp of the 2019 Elite Program as an example, this paper introduces the specific practice direction and some thoughts on the training of top-notch talents for middle school students, hoping to explore with the colleagues.
The "Senior High School Students Elite Program" is a training program developed by the State to train top-notch talents for scientific and technological innovation. The "elite plan" summer camp is a key part for experience and practice. Taking the summer camp of the 2019 Elite Program as an example, this paper introduces the specific practice direction and some thoughts on the training of top-notch talents for middle school students, hoping to explore with the colleagues.
2021, 36(6): 200807
doi: 10.3866/PKU.DXHX202008073
Abstract:
This paper uses "the structure and properties of alkali metal elements as well as their applications in lithium-ion battery" to illustrate the concrete methods in the classroom teaching of elementary chemistry. It is aimed at guiding the students to understand the structure and properties of alkali metal elements and arising their interest in applications of alkali metal elements in lithium-ion battery in the classroom land discussion. The relationships among the structure, chemical performance and applications in lithium-ion battery for alkali metal elements have been discussed in detail. Furthermore, a series of experiments including synthesis and characterization of electrode materials, and fabrication and measurement of devices, will be executed. Finally, the students have also been encouraged to execute "Students Research Training Program, SRTP" in new energy materials related institutes, and in this way the classroom knowledge and scientific research have been linked closely.
This paper uses "the structure and properties of alkali metal elements as well as their applications in lithium-ion battery" to illustrate the concrete methods in the classroom teaching of elementary chemistry. It is aimed at guiding the students to understand the structure and properties of alkali metal elements and arising their interest in applications of alkali metal elements in lithium-ion battery in the classroom land discussion. The relationships among the structure, chemical performance and applications in lithium-ion battery for alkali metal elements have been discussed in detail. Furthermore, a series of experiments including synthesis and characterization of electrode materials, and fabrication and measurement of devices, will be executed. Finally, the students have also been encouraged to execute "Students Research Training Program, SRTP" in new energy materials related institutes, and in this way the classroom knowledge and scientific research have been linked closely.
2021, 36(6): 200603
doi: 10.3866/PKU.DXHX202006030
Abstract:
Nitrogen-containing heterocycles exist widely in natural products, pharmaceuticals and optical materials. These molecules often exhibit high levels of biological and optical activities. Especially, the pyrrolidine derivatives are privileged structural units existed in natural products and pharmaceuticals. Therefore, the development of efficient methods to construct this ubiquitous structure unit is highly desirable. This paper introduces the development of Hofmann-Löffler-Freytag (HLF) reaction in synthesis of pyrrolidine derivatives. The major contents are including two aspects:1) Halogen-mediated HLF reactions; 2) Non halogen-mediated HLF reactions.
Nitrogen-containing heterocycles exist widely in natural products, pharmaceuticals and optical materials. These molecules often exhibit high levels of biological and optical activities. Especially, the pyrrolidine derivatives are privileged structural units existed in natural products and pharmaceuticals. Therefore, the development of efficient methods to construct this ubiquitous structure unit is highly desirable. This paper introduces the development of Hofmann-Löffler-Freytag (HLF) reaction in synthesis of pyrrolidine derivatives. The major contents are including two aspects:1) Halogen-mediated HLF reactions; 2) Non halogen-mediated HLF reactions.
2021, 36(6): 200603
doi: 10.3866/PKU.DXHX202006034
Abstract:
Hydrogen peroxide is a small molecule with a fine structure and wide applications. It plays important roles in bleaching, medicine, the chemical industry, environmental protection, food industry, rocket fuel etc. Here, in addition to providing a brief comprehensive introduction on the structure, chemical properties and syntheses of hydrogen peroxide, we primarily present its biological functions, detection methods, applications and safety, with the aim of enhancing the understanding of this smart molecule.
Hydrogen peroxide is a small molecule with a fine structure and wide applications. It plays important roles in bleaching, medicine, the chemical industry, environmental protection, food industry, rocket fuel etc. Here, in addition to providing a brief comprehensive introduction on the structure, chemical properties and syntheses of hydrogen peroxide, we primarily present its biological functions, detection methods, applications and safety, with the aim of enhancing the understanding of this smart molecule.
2021, 36(6): 200702
doi: 10.3866/PKU.DXHX202007029
Abstract:
Conjugated system, the moiety that the electronic orbitals of adjacent atoms or groups overlap, the electrons delocalize and the bond lengths become average, has special electronic effects, i.e., the conjugate effect that is crucial and difficult in organic chemistry course. It is very important to master the classification and structural characteristics of conjugated systems for understanding the conjugate effect, as well as physical and chemical properties of compounds. However, these have not been systematically discussed in general organic chemistry textbooks and literature. Here, the broad and narrow sense of conjugated systems, the classification and structural characteristics of narrow-sense conjugated system, hyper-conjugated system, through-bond and through-space conjugations were illustrated through the molecular structures of examples and the electronic orbital figures of valence bond and molecular orbital theories.
Conjugated system, the moiety that the electronic orbitals of adjacent atoms or groups overlap, the electrons delocalize and the bond lengths become average, has special electronic effects, i.e., the conjugate effect that is crucial and difficult in organic chemistry course. It is very important to master the classification and structural characteristics of conjugated systems for understanding the conjugate effect, as well as physical and chemical properties of compounds. However, these have not been systematically discussed in general organic chemistry textbooks and literature. Here, the broad and narrow sense of conjugated systems, the classification and structural characteristics of narrow-sense conjugated system, hyper-conjugated system, through-bond and through-space conjugations were illustrated through the molecular structures of examples and the electronic orbital figures of valence bond and molecular orbital theories.
2021, 36(6): 200703
doi: 10.3866/PKU.DXHX202007030
Abstract:
This paper introduces the main metrics that have been commonly used to test and compare the "greenness" of processes and products, including atom economy, the carbon efficiency, the reaction mass efficiency, the environmental fact, the environmental quotient, the process mass intensity, the life cycle assessment and the green aspiration level. The definition, difference and connection of these metrics are described in detail. Application examples are also presented to illustrate key concepts and their calculation. The green metrics cover aspects of starting materials, processing, products, wastes, and amongst others. The advent of these metrics not only promotes the advances of green chemistry, but also drives business, government and communities towards the standard of more sustainable practices.
This paper introduces the main metrics that have been commonly used to test and compare the "greenness" of processes and products, including atom economy, the carbon efficiency, the reaction mass efficiency, the environmental fact, the environmental quotient, the process mass intensity, the life cycle assessment and the green aspiration level. The definition, difference and connection of these metrics are described in detail. Application examples are also presented to illustrate key concepts and their calculation. The green metrics cover aspects of starting materials, processing, products, wastes, and amongst others. The advent of these metrics not only promotes the advances of green chemistry, but also drives business, government and communities towards the standard of more sustainable practices.
2021, 36(6): 200808
doi: 10.3866/PKU.DXHX202008082
Abstract:
[1,2]-Phospha-Brook rearrangement is an important organic name reaction that is widely used in several research fields such as organic synthetic chemistry and medicinal chemistry. This article reviews the recent progress of the[1,2]-Phospha-Brook rearrangement reaction, with regard to its use in the synthesis of α-phosphoryloxy esters and different ternary, five- and six-membered cyclic functional compounds. We also provide insights into the future development direction of the[1,2]-Phospha-Brook rearrangement reaction.
[1,2]-Phospha-Brook rearrangement is an important organic name reaction that is widely used in several research fields such as organic synthetic chemistry and medicinal chemistry. This article reviews the recent progress of the[1,2]-Phospha-Brook rearrangement reaction, with regard to its use in the synthesis of α-phosphoryloxy esters and different ternary, five- and six-membered cyclic functional compounds. We also provide insights into the future development direction of the[1,2]-Phospha-Brook rearrangement reaction.
2021, 36(6): 201105
doi: 10.3866/PKU.DXHX202011056
Abstract:
When lithium is close to the electronegative atom or group with lone pair electrons (which can also be extended to the less electronegative group), the electrostatic interaction is called lithium bond, which is similar to hydrogen bond. In this paper, the development and the latest progress of lithium bond are reviewed, and meanwhile the similarities and differences between lithium bond and hydrogen bond are discussed, so as to expand the knowledge of hydrogen bond in general chemistry teaching. We aim to deepen the students' understanding of hydrogen bonding concept as well as enhance students' awareness of scientific frontier, students' vision and innovative ability.
When lithium is close to the electronegative atom or group with lone pair electrons (which can also be extended to the less electronegative group), the electrostatic interaction is called lithium bond, which is similar to hydrogen bond. In this paper, the development and the latest progress of lithium bond are reviewed, and meanwhile the similarities and differences between lithium bond and hydrogen bond are discussed, so as to expand the knowledge of hydrogen bond in general chemistry teaching. We aim to deepen the students' understanding of hydrogen bonding concept as well as enhance students' awareness of scientific frontier, students' vision and innovative ability.
2021, 36(6): 200604
doi: 10.3866/PKU.DXHX202006045
Abstract:
A Fe(II)-Pd(II) heteronuclear metal-organic cages (MOC-42) is obtained by stepwise synthesis. The solution structure of MOC-42 is characterized by NMR, and the decomposition kinetics is studied by UV-Vis absorption spectra. This new comprehensive chemistry experiment is appropriate in difficulty, and the studying methods are various, which enables students to flexibly apply the existing basic chemical knowledge and modern instrument techniques. It is beneficial to train the ability of initiative thinking and practice competency of the students.
A Fe(II)-Pd(II) heteronuclear metal-organic cages (MOC-42) is obtained by stepwise synthesis. The solution structure of MOC-42 is characterized by NMR, and the decomposition kinetics is studied by UV-Vis absorption spectra. This new comprehensive chemistry experiment is appropriate in difficulty, and the studying methods are various, which enables students to flexibly apply the existing basic chemical knowledge and modern instrument techniques. It is beneficial to train the ability of initiative thinking and practice competency of the students.
2021, 36(6): 200604
doi: 10.3866/PKU.DXHX202006044
Abstract:
Ferrihydrite loaded sugarcane bagasse composite adsorbent with good adsorption performances for phosphate was prepared by in situ precipitation. The adsorbent was characterized by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD) and Zeta potential. Adsorption behavior and mechanism of phosphate on the composite adsorbent were investigated. Results showed that the adsorption capacity of bagasse increased significantly after loaded with ferrihydrite, and equilibrium reached within 30 min. Adsorption isotherm and kinetics of phosphate on the composite adsorbents could be predicted well by the Langmuir and pseudo-second-order model, respectively. Practical waste water treatment showed that 99.8% of phosphate could be removed from aqueous solution. This research content could be used as a comprehensive experiment for industrial analysis, applied chemistry and environmental engineering majors. It could improve students' study interesting, develop their capability to apply knowledge, and stimulate their innovation ability.
Ferrihydrite loaded sugarcane bagasse composite adsorbent with good adsorption performances for phosphate was prepared by in situ precipitation. The adsorbent was characterized by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD) and Zeta potential. Adsorption behavior and mechanism of phosphate on the composite adsorbent were investigated. Results showed that the adsorption capacity of bagasse increased significantly after loaded with ferrihydrite, and equilibrium reached within 30 min. Adsorption isotherm and kinetics of phosphate on the composite adsorbents could be predicted well by the Langmuir and pseudo-second-order model, respectively. Practical waste water treatment showed that 99.8% of phosphate could be removed from aqueous solution. This research content could be used as a comprehensive experiment for industrial analysis, applied chemistry and environmental engineering majors. It could improve students' study interesting, develop their capability to apply knowledge, and stimulate their innovation ability.
2021, 36(6): 200700
doi: 10.3866/PKU.DXHX202007004
Abstract:
A comprehensive experiment was conducted on the lignin extracted from waste cotton straw in Xinjiang and its antioxidant properties of polypropylene (PP). Based on the actual situation of polymer related major in Xinjiang University, combining the teachers' scientific research projects with the undergraduate teaching, the comprehensive experiment mainly included the extraction of lignin from cotton stalks, artificial accelerated aging experiment and characteristic experimental system of antioxidant characterization analysis. In the practical teaching, students not only learned the extraction process of lignin from cotton straw, but also understood the effect of artificial accelerated aging experiment on the aging mechanism of materials and its anti-oxidation properties, and broadened their comprehensive understanding of professional knowledge, which provided reference for the transformation of scientific research results into teaching experiments.
A comprehensive experiment was conducted on the lignin extracted from waste cotton straw in Xinjiang and its antioxidant properties of polypropylene (PP). Based on the actual situation of polymer related major in Xinjiang University, combining the teachers' scientific research projects with the undergraduate teaching, the comprehensive experiment mainly included the extraction of lignin from cotton stalks, artificial accelerated aging experiment and characteristic experimental system of antioxidant characterization analysis. In the practical teaching, students not only learned the extraction process of lignin from cotton straw, but also understood the effect of artificial accelerated aging experiment on the aging mechanism of materials and its anti-oxidation properties, and broadened their comprehensive understanding of professional knowledge, which provided reference for the transformation of scientific research results into teaching experiments.
2021, 36(6): 200603
doi: 10.3866/PKU.DXHX202006032
Abstract:
The online service platform of chemical biology laboratory is a student-oriented and experimental teaching centered diversified innovation service platform, which is built with the help of modern information technology and WeChat public platform and WeChat group as the carrier. The platform includes three modules, namely, Alarm Bell, Laboratory Teaching and Platform Management, which are combined with safety education, assistant teaching and high-quality laboratory management. The construction of the platform conforms to the trend of laboratory information construction and the development needs of education and teaching reform, which is of great significance to laboratory teaching.
The online service platform of chemical biology laboratory is a student-oriented and experimental teaching centered diversified innovation service platform, which is built with the help of modern information technology and WeChat public platform and WeChat group as the carrier. The platform includes three modules, namely, Alarm Bell, Laboratory Teaching and Platform Management, which are combined with safety education, assistant teaching and high-quality laboratory management. The construction of the platform conforms to the trend of laboratory information construction and the development needs of education and teaching reform, which is of great significance to laboratory teaching.
2021, 36(6): 200608
doi: 10.3866/PKU.DXHX202006087
Abstract:
Cyanobacteria fructose-1,6-/sedoheptanose-1,7-diphosphatase (Cy-FBP/SBPase) was used as the target enzyme, which was obtained through heterologous expression and purification. The purity and content of the target enzyme and the interaction between the enzyme and its ligands (substrate, metal ion and inhibitor) were analyzed. Through the experimental study and exploration, students can master the biosynthesis method to obtain the target enzyme, master the method to analyze the interaction between the target enzyme and its ligand, understand research ideas and experimental techniques needed to establish a drug screening model based on the target enzyme, upgrade the abilities to analyze and solve problems and use chemical biology knowledge, strengthen the social consciousness of scientific research service and social responsibility.
Cyanobacteria fructose-1,6-/sedoheptanose-1,7-diphosphatase (Cy-FBP/SBPase) was used as the target enzyme, which was obtained through heterologous expression and purification. The purity and content of the target enzyme and the interaction between the enzyme and its ligands (substrate, metal ion and inhibitor) were analyzed. Through the experimental study and exploration, students can master the biosynthesis method to obtain the target enzyme, master the method to analyze the interaction between the target enzyme and its ligand, understand research ideas and experimental techniques needed to establish a drug screening model based on the target enzyme, upgrade the abilities to analyze and solve problems and use chemical biology knowledge, strengthen the social consciousness of scientific research service and social responsibility.
2021, 36(6): 200704
doi: 10.3866/PKU.DXHX202007044
Abstract:
Constant current electrolysis is an important content of instrumental analysis courses in high education. When this method was used to detect copper in solution, it was found that the neglected trace copper in the electrolytic residue caused the lower recovery of the copper sample. In response to this problem, the experiment was improved:the copper residue in electrolytic was detected with atomic absorption spectrometry and included in the total amount. The result from the constant current electrolysis was revised to improve the accuracy of the experimental result. The improved experiment is conducive to cultivating students' comprehensive ability of analysis and solving problem; at the same time, it provides an example for the reform of experiment teaching in instrumental analysis.
Constant current electrolysis is an important content of instrumental analysis courses in high education. When this method was used to detect copper in solution, it was found that the neglected trace copper in the electrolytic residue caused the lower recovery of the copper sample. In response to this problem, the experiment was improved:the copper residue in electrolytic was detected with atomic absorption spectrometry and included in the total amount. The result from the constant current electrolysis was revised to improve the accuracy of the experimental result. The improved experiment is conducive to cultivating students' comprehensive ability of analysis and solving problem; at the same time, it provides an example for the reform of experiment teaching in instrumental analysis.
2021, 36(6): 200606
doi: 10.3866/PKU.DXHX202006067
Abstract:
The classic experiment "determination of alkali hydroxide concentration" is widely used in chemical and pharmaceutical industries, as well as in university chemistry laboratory teaching. Therefore, disposal of the solutions produced by titration and prevention of their environmental pollution are very important in chemistry laboratory teaching, as well as in the industrial processes. We have selected the methods of visual colorimetry and potentiometric titration to determine potassium hydroxide concentration as an experiment for chemistry lab teaching based on green consideration. The solution produced by titration can be used directly in irrigating the plant, Spathiphyllum kochii. The teaching experiment will help students acquire methods for designing chemical experiments based on green consideration and inspire their interests of learning chemical courses.
The classic experiment "determination of alkali hydroxide concentration" is widely used in chemical and pharmaceutical industries, as well as in university chemistry laboratory teaching. Therefore, disposal of the solutions produced by titration and prevention of their environmental pollution are very important in chemistry laboratory teaching, as well as in the industrial processes. We have selected the methods of visual colorimetry and potentiometric titration to determine potassium hydroxide concentration as an experiment for chemistry lab teaching based on green consideration. The solution produced by titration can be used directly in irrigating the plant, Spathiphyllum kochii. The teaching experiment will help students acquire methods for designing chemical experiments based on green consideration and inspire their interests of learning chemical courses.
2021, 36(6): 200800
doi: 10.3866/PKU.DXHX202008007
Abstract:
Alcohol gel for hand-washing disinfection is a kind of daily chemical which has 75% alcohol. It belongs to the category of fine chemicals and is prepared by adjusting the viscosity of alcohol with a thickener. It has played an important role in the fight against the COVID-19 pandemic, and is familiar to people. The basic formula is simple and the ingredients are easy to obtain. Although the production process is simple, the experiment is still a bit difficult. Thus, the preparation process is very suitable for designing the teaching content of "Fine Chemical Laboratory" or similar courses. By setting up this experiment in applied chemistry specialty or related majors, the course can not only enhance students' professional interest in the fine chemical industry, but also cultivate theirs ability to design product formula and practical experience. At the same time, the course also contains many ideological and political elements, which is very suitable for carrying out ideological and political education in laboratory course. Through this course, we can enhance students' awareness of preventing COVID-19 infections, and strengthen their confidence to Chinese characteristic socialism.
Alcohol gel for hand-washing disinfection is a kind of daily chemical which has 75% alcohol. It belongs to the category of fine chemicals and is prepared by adjusting the viscosity of alcohol with a thickener. It has played an important role in the fight against the COVID-19 pandemic, and is familiar to people. The basic formula is simple and the ingredients are easy to obtain. Although the production process is simple, the experiment is still a bit difficult. Thus, the preparation process is very suitable for designing the teaching content of "Fine Chemical Laboratory" or similar courses. By setting up this experiment in applied chemistry specialty or related majors, the course can not only enhance students' professional interest in the fine chemical industry, but also cultivate theirs ability to design product formula and practical experience. At the same time, the course also contains many ideological and political elements, which is very suitable for carrying out ideological and political education in laboratory course. Through this course, we can enhance students' awareness of preventing COVID-19 infections, and strengthen their confidence to Chinese characteristic socialism.
2021, 36(6): 200700
doi: 10.3866/PKU.DXHX202007002
Abstract:
The maximum bubble pressure method is a classical method to determine the surface tension of solution in physical chemistry laboratory. Due to the influence of various factors, the results from students have large standard deviation. In this study, concentration and temperature were used as variables to explore experimental conditions, and the results obtained were in good agreement with literature values.
The maximum bubble pressure method is a classical method to determine the surface tension of solution in physical chemistry laboratory. Due to the influence of various factors, the results from students have large standard deviation. In this study, concentration and temperature were used as variables to explore experimental conditions, and the results obtained were in good agreement with literature values.
2021, 36(6): 200804
doi: 10.3866/PKU.DXHX202008044
Abstract:
The idea of integrating science and education has become the choice for "double first-class" universities to pay equal attention to science and education. This article introduces the research results of the instantaneous nano-precipitation technology to prepare porous TiO2 nanospheres and the photocatalytic degradation of dyes into the undergraduate teaching, such as the Student Research Program (SRP). The content of this experiment can meet the development needs of the integration of science and education. Through the experiment, it helps to deepen students' comprehensive understanding of knowledge points, arise students' enthusiasm and interest in learning, and cultivate students' innovative ability and practical ability.
The idea of integrating science and education has become the choice for "double first-class" universities to pay equal attention to science and education. This article introduces the research results of the instantaneous nano-precipitation technology to prepare porous TiO2 nanospheres and the photocatalytic degradation of dyes into the undergraduate teaching, such as the Student Research Program (SRP). The content of this experiment can meet the development needs of the integration of science and education. Through the experiment, it helps to deepen students' comprehensive understanding of knowledge points, arise students' enthusiasm and interest in learning, and cultivate students' innovative ability and practical ability.
2021, 36(6): 200806
doi: 10.3866/PKU.DXHX202008065
Abstract:
1,1-diacetylferrocene (DAF) was synthesized through Friedel-Crafts acylation reaction by using ferrocene and acetylchloride as starting materials. This process involves basic laboratory skills, such as low temperature control, anhydrous and anoxic operation, extraction, vacuum distillation and recrystallization. The photo-ligand exchange reaction between DAF and 1,10-phenanthroline (phen) was carried out under visible light irradiation due to the photosensitivity of DAF and the strong chelating ability of phen. Phen substituted acetyl cyclopentadiene ligand, and produced complex[Fe(phen)3](C5H4COCH3)2·CH3CN·2H2O. The composition of the photoreaction product was determined by means of powder X-ray diffraction, elemental analysis, infrared spectrum and 1H NMR spectra. This comprehensive chemistry experiment is appropriate in difficulty, and the testing methods are diversified, which enables junior or senior undergraduates to complete a basic scientific research training process independently on the basis of comprehensive laboratory (I) and basic inorganic, analytical and organic chemistry laboratories.
1,1-diacetylferrocene (DAF) was synthesized through Friedel-Crafts acylation reaction by using ferrocene and acetylchloride as starting materials. This process involves basic laboratory skills, such as low temperature control, anhydrous and anoxic operation, extraction, vacuum distillation and recrystallization. The photo-ligand exchange reaction between DAF and 1,10-phenanthroline (phen) was carried out under visible light irradiation due to the photosensitivity of DAF and the strong chelating ability of phen. Phen substituted acetyl cyclopentadiene ligand, and produced complex[Fe(phen)3](C5H4COCH3)2·CH3CN·2H2O. The composition of the photoreaction product was determined by means of powder X-ray diffraction, elemental analysis, infrared spectrum and 1H NMR spectra. This comprehensive chemistry experiment is appropriate in difficulty, and the testing methods are diversified, which enables junior or senior undergraduates to complete a basic scientific research training process independently on the basis of comprehensive laboratory (I) and basic inorganic, analytical and organic chemistry laboratories.
2021, 36(6): 200804
doi: 10.3866/PKU.DXHX202008040
Abstract:
A solvent-free grinding reaction for the synthesis of 3-substituted isoindolin-1-ones from 2-cyanoarylaldehydes and various activated methylene compounds (such as dimethyl malonate and ethyl acetoacetate) has been developed. All the products were obtained without the tedious column chromatographic purification and were characterized using NMR spectroscopy and mass spectrometry. This method is advantageous because of its simple manipulation, short reaction time, wide substrate scope, high product yield, and high atom economy. It also has potential uses in novel-drug designing and natural product synthesis.
A solvent-free grinding reaction for the synthesis of 3-substituted isoindolin-1-ones from 2-cyanoarylaldehydes and various activated methylene compounds (such as dimethyl malonate and ethyl acetoacetate) has been developed. All the products were obtained without the tedious column chromatographic purification and were characterized using NMR spectroscopy and mass spectrometry. This method is advantageous because of its simple manipulation, short reaction time, wide substrate scope, high product yield, and high atom economy. It also has potential uses in novel-drug designing and natural product synthesis.
2021, 36(6): 200704
doi: 10.3866/PKU.DXHX202007047
Abstract:
Comprehensive experiments can improve not only the students' experimental skills, but also their understanding of the basic process of chemical research. Furthermore, comprehensive experiments can cultivate students' independent scientific research ability, which is paid more and more attention by college educators. In this paper, a comprehensive experiment is designed:the surface modification of fly ash is carried out and the modified fly ash is replaced with light calcium and carbon black as rubber filler. The experimental data show that the surface-modified fly ash has a better reinforcement effect on rubber. At the same time, using modified fly ash as rubber filler can reduce industrial cost and have great economic and social benefits.
Comprehensive experiments can improve not only the students' experimental skills, but also their understanding of the basic process of chemical research. Furthermore, comprehensive experiments can cultivate students' independent scientific research ability, which is paid more and more attention by college educators. In this paper, a comprehensive experiment is designed:the surface modification of fly ash is carried out and the modified fly ash is replaced with light calcium and carbon black as rubber filler. The experimental data show that the surface-modified fly ash has a better reinforcement effect on rubber. At the same time, using modified fly ash as rubber filler can reduce industrial cost and have great economic and social benefits.
2021, 36(6): 200603
doi: 10.3866/PKU.DXHX202006036
Abstract:
Based on the dissociation equilibrium constants of six arsenic species, including arsenic acid, arsenite, monomethyl arsenate, dimethylarsenic acid, arsenicone and betaine, and corresponding distribution fraction at different pH, the retention differences in chromatographic/non chromatographic separation process, and the possible reasons for simultaneous enrichment of these species are discussed. It was used as an example to improve the teaching of the basic concept of "distribution score" in the course of analytical chemistry, and to achieve the teaching goal of deepening cognition, firmly mastering and stimulating interest.
Based on the dissociation equilibrium constants of six arsenic species, including arsenic acid, arsenite, monomethyl arsenate, dimethylarsenic acid, arsenicone and betaine, and corresponding distribution fraction at different pH, the retention differences in chromatographic/non chromatographic separation process, and the possible reasons for simultaneous enrichment of these species are discussed. It was used as an example to improve the teaching of the basic concept of "distribution score" in the course of analytical chemistry, and to achieve the teaching goal of deepening cognition, firmly mastering and stimulating interest.
2021, 36(6): 200800
doi: 10.3866/PKU.DXHX202008008
Abstract:
In the acid-base titration curve of titration from NaOH to HAc, shown in the sixth edition of Analytical Chemistry edited by Wuhan University, we found that there was an obvious protruding part of the curve at the initial stage of titration, which was significantly different from the curve of titration from NaOH to HCl at the same concentration. In this paper, the mathematical expression of fitting the curve is derived by using various equilibrium relations in acid-base reaction. The correlation law of acid-base titration is proved by combining with the image of mathematical function. The mathematical model can explain not only the differences between two curves, but also the reasons and influencing factors of the initial titration curve difference of weak acids by strong alkali titration.
In the acid-base titration curve of titration from NaOH to HAc, shown in the sixth edition of Analytical Chemistry edited by Wuhan University, we found that there was an obvious protruding part of the curve at the initial stage of titration, which was significantly different from the curve of titration from NaOH to HCl at the same concentration. In this paper, the mathematical expression of fitting the curve is derived by using various equilibrium relations in acid-base reaction. The correlation law of acid-base titration is proved by combining with the image of mathematical function. The mathematical model can explain not only the differences between two curves, but also the reasons and influencing factors of the initial titration curve difference of weak acids by strong alkali titration.
2021, 36(6): 200607
doi: 10.3866/PKU.DXHX202006075
Abstract:
Rapid development of mass spectrum technology (MS) brings about its wide applications in many fields such as chemistry, material science and life sciences, and its application in biochemistry and chemical biology have been greatly expanding the knowledge of novel protein post-translation modification (PTM). This manuscript starts from the basic principles of mass spectrum and later elaborates the application of MS in discovering lysine post-translation modifications over histones as model proteins, showing a path incorporating fundamental organic chemistry and biochemistry knowledge into cutting-edge researches. By analyzing roles of mass spectrum throughout post-translation modification studies under different research logistics, this manuscript was aimed to help establishing a way of thinking that associates fundamental chemistry and biology education with practical applications for students.
Rapid development of mass spectrum technology (MS) brings about its wide applications in many fields such as chemistry, material science and life sciences, and its application in biochemistry and chemical biology have been greatly expanding the knowledge of novel protein post-translation modification (PTM). This manuscript starts from the basic principles of mass spectrum and later elaborates the application of MS in discovering lysine post-translation modifications over histones as model proteins, showing a path incorporating fundamental organic chemistry and biochemistry knowledge into cutting-edge researches. By analyzing roles of mass spectrum throughout post-translation modification studies under different research logistics, this manuscript was aimed to help establishing a way of thinking that associates fundamental chemistry and biology education with practical applications for students.
2021, 36(6): 200701
doi: 10.3866/PKU.DXHX202007019
Abstract:
Aromatic electrophilic substitution is a very important method to synthesize different substituted arenes. Its regioselective rule is the theoretical evidence to realize the controlled synthesis of the desired target molecules. Theoretical rationale and experimental evidences on the regioselective rule in the aromatic electrophilic substitution of disubstituted benzenes are discussed here from the viewpoints of stabilities of intermediates, activation energies, and relative reaction rates. It would provide reasonable explanation and experimental evidence for the regioselective rule and is convenient for students to understand correctly.
Aromatic electrophilic substitution is a very important method to synthesize different substituted arenes. Its regioselective rule is the theoretical evidence to realize the controlled synthesis of the desired target molecules. Theoretical rationale and experimental evidences on the regioselective rule in the aromatic electrophilic substitution of disubstituted benzenes are discussed here from the viewpoints of stabilities of intermediates, activation energies, and relative reaction rates. It would provide reasonable explanation and experimental evidence for the regioselective rule and is convenient for students to understand correctly.
2021, 36(6): 200801
doi: 10.3866/PKU.DXHX202008014
Abstract:
The domestic organic chemistry textbooks use different numbers of contributing structures when introducing the resonance structures of benzene. This paper suggests that some of the related textbooks remove Dewar benzene and other ionic structures from the resonance structures of benzene, and adopt the correct resonance representation which constitutes only two Kekulé structures.
The domestic organic chemistry textbooks use different numbers of contributing structures when introducing the resonance structures of benzene. This paper suggests that some of the related textbooks remove Dewar benzene and other ionic structures from the resonance structures of benzene, and adopt the correct resonance representation which constitutes only two Kekulé structures.
2021, 36(6): 200801
doi: 10.3866/PKU.DXHX202008013
Abstract:
After years of teaching inorganic chemistry, it is found that many students lack knowledge of the four quantum numbers in the content of material structure, which seriously affects their learning of the following content. In order to help students to get out of the dilemma, we use analogy teaching method and use the "virtual classroom and teaching building" model to visualize the content of the abstract four quantum numbers. The results show that the students' mastery degree is better than that of previous years, which indicates that the current analogy teaching method has achieved satisfactory teaching effect.
After years of teaching inorganic chemistry, it is found that many students lack knowledge of the four quantum numbers in the content of material structure, which seriously affects their learning of the following content. In order to help students to get out of the dilemma, we use analogy teaching method and use the "virtual classroom and teaching building" model to visualize the content of the abstract four quantum numbers. The results show that the students' mastery degree is better than that of previous years, which indicates that the current analogy teaching method has achieved satisfactory teaching effect.
2021, 36(6): 210103
doi: 10.3866/PKU.DXHX202101038
Abstract:
In a variety of the inorganic chemistry teaching materials and related references that the composition to give the strongest buffer capacity at pH=pKaϴ is not described concisely. We proposed amendment description for buffer capacity in the book written by teaching and research office of Inorganic Chemistry at Dalian University of Technology. The description is based on the distribution curve slope when buffer solution pH as close as possible to pKaϴ.
In a variety of the inorganic chemistry teaching materials and related references that the composition to give the strongest buffer capacity at pH=pKaϴ is not described concisely. We proposed amendment description for buffer capacity in the book written by teaching and research office of Inorganic Chemistry at Dalian University of Technology. The description is based on the distribution curve slope when buffer solution pH as close as possible to pKaϴ.
2021, 36(6): 200800
doi: 10.3866/PKU.DXHX202008009
Abstract:
Hydroboration of olefins is a concerted addition reaction involving only one step. It is generally considered to proceed via a four-center cyclic transition state. We performed theoretical studies on the reaction mechanism of the hydroboration of propene using quantum chemistry calculations, which led to a unique transition state that was inconsistent with the so-called four-center cyclic structure. In the computed transition state, the boron atom is bonded to both of the olefinic carbon atoms, and the degree of the hydrogen shift event is very low. All of these observations are consistent with those reported in the literature. Further theoretical studies revealed that the reaction might involve certain structures similar to the four-center cyclic structure, appearing as the transient states between the transition state and the product. Finally, the reaction mechanism of hydroboration was analyzed from the perspective of the orbital interaction model.
Hydroboration of olefins is a concerted addition reaction involving only one step. It is generally considered to proceed via a four-center cyclic transition state. We performed theoretical studies on the reaction mechanism of the hydroboration of propene using quantum chemistry calculations, which led to a unique transition state that was inconsistent with the so-called four-center cyclic structure. In the computed transition state, the boron atom is bonded to both of the olefinic carbon atoms, and the degree of the hydrogen shift event is very low. All of these observations are consistent with those reported in the literature. Further theoretical studies revealed that the reaction might involve certain structures similar to the four-center cyclic structure, appearing as the transient states between the transition state and the product. Finally, the reaction mechanism of hydroboration was analyzed from the perspective of the orbital interaction model.
2021, 36(6): 200801
doi: 10.3866/PKU.DXHX202008011
Abstract:
A novel approximate formula [H+]p is proposed to obtain the pH of the mixed HA and HB solutions, where[H+]HA and[H+]HB are the estimated values of[H+] for HA solution and HB solution, respectively. If cHA ≥ 2KHAand cHB ≥ 2KHB,[H+]p formula will work very well. The novel approximation formula is simple, easy to remember, and can be widely used to calculate the pH of the mixed monoprotic weak acid HA and HB solutions.
A novel approximate formula [H+]p is proposed to obtain the pH of the mixed HA and HB solutions, where[H+]HA and[H+]HB are the estimated values of[H+] for HA solution and HB solution, respectively. If cHA ≥ 2KHAand cHB ≥ 2KHB,[H+]p formula will work very well. The novel approximation formula is simple, easy to remember, and can be widely used to calculate the pH of the mixed monoprotic weak acid HA and HB solutions.
2021, 36(6): 200906
doi: 10.3866/PKU.DXHX202009065
Abstract:
Journal cover is an important medium to present the research results ideologically, and further reveals the cultural backgrounds of the authors. In this paper, the covers with Chinese symbols of six well-known chemical journals from January 2011 to April 2020 have been selected. Using several typical cases, we analyze the author's considerations on the fusion with Chinese symbols in the corresponding chemical process or reaction mechanisms, and try to explore the cultural representation of Chinese symbols in the expression of chemical research results.
Journal cover is an important medium to present the research results ideologically, and further reveals the cultural backgrounds of the authors. In this paper, the covers with Chinese symbols of six well-known chemical journals from January 2011 to April 2020 have been selected. Using several typical cases, we analyze the author's considerations on the fusion with Chinese symbols in the corresponding chemical process or reaction mechanisms, and try to explore the cultural representation of Chinese symbols in the expression of chemical research results.
2021, 36(6): 200805
doi: 10.3866/PKU.DXHX202008054
Abstract:
One best way to get insight into the fascinating history of twentieth century chiroptical spectroscopy and its inextricable entanglement with history of quantum physics is to look at the vivid life stories of particular scholars. This article describes the little-known experience of the Belgian theoretical physicist Léon Rosenfeld (1904-1974) in creating a quantum interpretation of the optical activity theory. In the history of science literature Rosenfeld' page was totally a blank sheet, but as a pioneer in the exploration of the quantum origin of optical activity, he has an irreplaceable position in the development history of chiroptical spectroscopy.
One best way to get insight into the fascinating history of twentieth century chiroptical spectroscopy and its inextricable entanglement with history of quantum physics is to look at the vivid life stories of particular scholars. This article describes the little-known experience of the Belgian theoretical physicist Léon Rosenfeld (1904-1974) in creating a quantum interpretation of the optical activity theory. In the history of science literature Rosenfeld' page was totally a blank sheet, but as a pioneer in the exploration of the quantum origin of optical activity, he has an irreplaceable position in the development history of chiroptical spectroscopy.
2021, 36(6): 210203
doi: 10.3866/PKU.DXHX202102030
Abstract:
The paper would revisit the classic story of Fischer-Tropsch process and explore thoroughly the details to get some hints about how an important invention was achieved in the research project. In investigating the conversion of coal into liquid fuels, Franz Fischer and Hans Tropsch at the Kaiser Wilhelm Institute of Coal Research, recognized the potential value of a chemical process of converting carbon monoxide and hydrogen gases into complex mixtures of hydrocarbons, which could be used as alternative liquid fuels. Fischer and Tropsch confirmed their judgements and developed the first practical catalyst in the following 12 years for the process, which initiated the development of indirect coal liquefaction in industrial catalysis. The Fischer-Tropsch process could be used as one classic source of achieving original ideas or solutions for graduate students in their professional careers. Furthermore, for the supervisors or faculty members in universities or research institutes, it would provide an arsenal of spurring scientific discoveries or technological inventions in graduate education programs.
The paper would revisit the classic story of Fischer-Tropsch process and explore thoroughly the details to get some hints about how an important invention was achieved in the research project. In investigating the conversion of coal into liquid fuels, Franz Fischer and Hans Tropsch at the Kaiser Wilhelm Institute of Coal Research, recognized the potential value of a chemical process of converting carbon monoxide and hydrogen gases into complex mixtures of hydrocarbons, which could be used as alternative liquid fuels. Fischer and Tropsch confirmed their judgements and developed the first practical catalyst in the following 12 years for the process, which initiated the development of indirect coal liquefaction in industrial catalysis. The Fischer-Tropsch process could be used as one classic source of achieving original ideas or solutions for graduate students in their professional careers. Furthermore, for the supervisors or faculty members in universities or research institutes, it would provide an arsenal of spurring scientific discoveries or technological inventions in graduate education programs.
2021, 36(6): 200608
doi: 10.3866/PKU.DXHX202006084
Abstract:
Chromium and its compounds possess very diverse color and exhibit useful physical and chemical properties, which is introduced in inorganic chemistry. In this paper, the reaction between chromium (III) and hydrogen peroxide is mainly discussed. With the change of pH, reactant concentration and temperature, the reaction mechanism will be different, which is mainly shown by the color alteration of the solution. The reaction between chromium (III) and hydrogen peroxide is very interesting, because of its complex mechanism and rich colors, which could help students learn and understand the change of different valence states of chromium. In addition, the related practical application and interesting experiments are introduced.
Chromium and its compounds possess very diverse color and exhibit useful physical and chemical properties, which is introduced in inorganic chemistry. In this paper, the reaction between chromium (III) and hydrogen peroxide is mainly discussed. With the change of pH, reactant concentration and temperature, the reaction mechanism will be different, which is mainly shown by the color alteration of the solution. The reaction between chromium (III) and hydrogen peroxide is very interesting, because of its complex mechanism and rich colors, which could help students learn and understand the change of different valence states of chromium. In addition, the related practical application and interesting experiments are introduced.
