Login In
2007 Volume 24 Issue 1
2007, 24(1): 1-7
Abstract:
The study on the supramolecular inclusion complex of cyclodextrin and C60 has drawn a lot of attention, not only because the formation of the complex increases the solubility of C60 in aqueous solution for possible applications in biology and medicinal chemistry, but also because the complex has displayed some interesting catalytic reduction properties such as dinitrogen fixation and reducing ability toward C=O, C=C and N-N+ bonds under mild conditions.Several methods have been developed for the preparation of CD/C60 complex, including refluxing, stirring and solid state ball/high-speed vibration milling.However, the methods are limited to the preparation of C60 inclusion complex withγ-cyclodextrin, while they are not successful in preparing C60 inclusion complex with cyclodextrins having smaller cavity dimension such as α- and β-cyclodextrin.Recently, we have developed a novel method to prepare the supramolecular complexes of CDs/C60 using monoanionic C60, which has been show to be effective in preparing inclusion complexes of α-,β- andγ-cyclodextrin with C60.Herein, the recent development on the preparation of cyclodextrin/fullerene supramolecular complexes is reviewed.
The study on the supramolecular inclusion complex of cyclodextrin and C60 has drawn a lot of attention, not only because the formation of the complex increases the solubility of C60 in aqueous solution for possible applications in biology and medicinal chemistry, but also because the complex has displayed some interesting catalytic reduction properties such as dinitrogen fixation and reducing ability toward C=O, C=C and N-N+ bonds under mild conditions.Several methods have been developed for the preparation of CD/C60 complex, including refluxing, stirring and solid state ball/high-speed vibration milling.However, the methods are limited to the preparation of C60 inclusion complex withγ-cyclodextrin, while they are not successful in preparing C60 inclusion complex with cyclodextrins having smaller cavity dimension such as α- and β-cyclodextrin.Recently, we have developed a novel method to prepare the supramolecular complexes of CDs/C60 using monoanionic C60, which has been show to be effective in preparing inclusion complexes of α-,β- andγ-cyclodextrin with C60.Herein, the recent development on the preparation of cyclodextrin/fullerene supramolecular complexes is reviewed.
2007, 24(1): 8-11
Abstract:
In the synthesis of N-substituted derivatives of 4,4'-bipyridine(2a~2c) via the fusion reaction of tosylate with 4,4'-bipyridine, it was found that the reaction was completed within 30 min, but the molar ratio of the tosylate to 4,4'-bipyridine had significantly influence on the yields of N-substituted derivatives of 4,4'-bipyridine.If the ratio was 1:1, N, N'-disubstituted derivatives of 4,4'-bipyridine was major products.Increasing the ratio of tosylate to 4,4'-bipyridine, the yields of (2a~2c) were increased.When the ratio was 1:10, it generated the N-substituted derivatives of 4,4'-bipyridine(2a~2c) in about 90% yields.By reacting intermediates (2a~2c)(0.6 mmol) with 4,4'-di(bromomethyl)-2,2'-bipyridine (0.3 mmol) according to the same method as above, the dumbbell-shape compounds containing two units of 4,4'-bipyridine bridged by 2,2'-bipyridine(3a~3c) were obtained in 79%~87%.
In the synthesis of N-substituted derivatives of 4,4'-bipyridine(2a~2c) via the fusion reaction of tosylate with 4,4'-bipyridine, it was found that the reaction was completed within 30 min, but the molar ratio of the tosylate to 4,4'-bipyridine had significantly influence on the yields of N-substituted derivatives of 4,4'-bipyridine.If the ratio was 1:1, N, N'-disubstituted derivatives of 4,4'-bipyridine was major products.Increasing the ratio of tosylate to 4,4'-bipyridine, the yields of (2a~2c) were increased.When the ratio was 1:10, it generated the N-substituted derivatives of 4,4'-bipyridine(2a~2c) in about 90% yields.By reacting intermediates (2a~2c)(0.6 mmol) with 4,4'-di(bromomethyl)-2,2'-bipyridine (0.3 mmol) according to the same method as above, the dumbbell-shape compounds containing two units of 4,4'-bipyridine bridged by 2,2'-bipyridine(3a~3c) were obtained in 79%~87%.
2007, 24(1): 12-16
Abstract:
Nanoparticle ammonium zinc phosphate with dodecahedron morphology was synthesized via the solid-state reaction at room temperature.The standard enthalpy for the reaction and the standard enthalpy of the formation of ammonium zinc phosphate were measured with a microcalorimeter at 298.15 K.Four kinds of thermal analysis methods were used to investigate its decomposition kinetic equations.The experimental results show that the obtained product is nanoparticle NH4ZnPO4 with size distribution between 100 nm and 300 nm, which belongs to hexagonal crystal system, the standard enthalpy of the reaction is 23.880 kJ/mol, and the standard enthalpy of the formation of ammonium zinc phosphate is-1 568.784 kJ/mol.There are two decomposition stages between 300 K and 950 K during the thermal decomposition.The de-ammonia reaction between 603 K and 692 K is controlled by three-dimensional diffusion with an activated energy of 210.434 kJ/mol and a pre-exponential factor of 5.45×1013 s-1.The dehydrate process between 692 K and 773 K is controlled by nucleating and growing with an activated energy of 287.557 kJ/mol, and a pre-exponential factor of 9.62×1019 s-1.The kinetic compensative effect is shown between ln A and E.
Nanoparticle ammonium zinc phosphate with dodecahedron morphology was synthesized via the solid-state reaction at room temperature.The standard enthalpy for the reaction and the standard enthalpy of the formation of ammonium zinc phosphate were measured with a microcalorimeter at 298.15 K.Four kinds of thermal analysis methods were used to investigate its decomposition kinetic equations.The experimental results show that the obtained product is nanoparticle NH4ZnPO4 with size distribution between 100 nm and 300 nm, which belongs to hexagonal crystal system, the standard enthalpy of the reaction is 23.880 kJ/mol, and the standard enthalpy of the formation of ammonium zinc phosphate is-1 568.784 kJ/mol.There are two decomposition stages between 300 K and 950 K during the thermal decomposition.The de-ammonia reaction between 603 K and 692 K is controlled by three-dimensional diffusion with an activated energy of 210.434 kJ/mol and a pre-exponential factor of 5.45×1013 s-1.The dehydrate process between 692 K and 773 K is controlled by nucleating and growing with an activated energy of 287.557 kJ/mol, and a pre-exponential factor of 9.62×1019 s-1.The kinetic compensative effect is shown between ln A and E.
2007, 24(1): 17-20
Abstract:
Porous alumina material was prepared with activated carbon as template and aluminum acetylacetonate as precursor in supercritical carbon dioxide (SC-CO2).The effects of coating temperature and pressure on the coating ratio in the supercritical CO2 were studied, and optimal coating conditions at 80℃ and 22 MPa were explored.The X-ray diffraction (XRD) result shows that the product is α-Al2O3, the BET surface areas calculated from the nitrogen adsorption isotherms of the product is up to 67.20 m2/g and the average pore diameter is about 4 nm.SEM experimental results indicated the activated carbon template was well replicated by the porous product and TEM results showed the Al2O3 nanoparticles were well dispersed in the product.
Porous alumina material was prepared with activated carbon as template and aluminum acetylacetonate as precursor in supercritical carbon dioxide (SC-CO2).The effects of coating temperature and pressure on the coating ratio in the supercritical CO2 were studied, and optimal coating conditions at 80℃ and 22 MPa were explored.The X-ray diffraction (XRD) result shows that the product is α-Al2O3, the BET surface areas calculated from the nitrogen adsorption isotherms of the product is up to 67.20 m2/g and the average pore diameter is about 4 nm.SEM experimental results indicated the activated carbon template was well replicated by the porous product and TEM results showed the Al2O3 nanoparticles were well dispersed in the product.
2007, 24(1): 21-24
Abstract:
A comparison between the initial reaction rates of nano- and commercial NaH has been studied in four test reactions:(1) hydrogenolysis of chlorobenzene; (2) selective reduction of cinnamaldehyde to cinnamyl alcohol; (3)metallation of dimethyl sulfoxide; (4) catalytic hydrogenation of 1-octene.The experimental results indicate that when NaH is used as a chemical reagent in the first three reactions, the initial reaction rates of nano-NaH is 230, 120 and 110 times higher than those of the commercial ones respectively, and it is in agreement with the difference in specific surface areas between these two forms of NaH.When NaH is used as a catalyst component together with Cp2TiCl2 in the fourth reaction, catalyst with nano-NaH gives extremely high activity in the hydrogenation of 1-octene, while the one with commercial NaH gives no activity at all even if a large amount of the commercial NaH is used to make the total surface area equivalent to that of nano-NaH.Thus, it is evident that although large specific surface area is important for nano-NaH to be used as a catalyst component, high surface energy with surface defects seems to be more important.The large specific surface and the activated surface of nano-NaH with high surface energy should be the main factors for their extremely high chemical reactivity, while whether the former or the latter one plays a leading role depends on the type of reactions it is involved.
A comparison between the initial reaction rates of nano- and commercial NaH has been studied in four test reactions:(1) hydrogenolysis of chlorobenzene; (2) selective reduction of cinnamaldehyde to cinnamyl alcohol; (3)metallation of dimethyl sulfoxide; (4) catalytic hydrogenation of 1-octene.The experimental results indicate that when NaH is used as a chemical reagent in the first three reactions, the initial reaction rates of nano-NaH is 230, 120 and 110 times higher than those of the commercial ones respectively, and it is in agreement with the difference in specific surface areas between these two forms of NaH.When NaH is used as a catalyst component together with Cp2TiCl2 in the fourth reaction, catalyst with nano-NaH gives extremely high activity in the hydrogenation of 1-octene, while the one with commercial NaH gives no activity at all even if a large amount of the commercial NaH is used to make the total surface area equivalent to that of nano-NaH.Thus, it is evident that although large specific surface area is important for nano-NaH to be used as a catalyst component, high surface energy with surface defects seems to be more important.The large specific surface and the activated surface of nano-NaH with high surface energy should be the main factors for their extremely high chemical reactivity, while whether the former or the latter one plays a leading role depends on the type of reactions it is involved.
2007, 24(1): 25-29
Abstract:
La0.6Sr0.4Fe0.8Co0.2O3 powder was synthesized via citrate/nitrate sol-gel method.XRD results show that the powder consists of single phase of perovskite.The particle size is from 100 to 200 nm observed by means of TEM.EDS show that the atom percentage of the elements in the powder is consistent with the theoretical value.When the powder was used as the cathode to compose a H2-O2 solid oxide fuel cell, and Ce0.8Gd0.2O1.9 and NiO/Ce0.8Gd0.2O1.9 were used as electrolyte and anode, respectively, the electrical output properties were measured.At 650℃ the maximum output power density of the cell was 0.23 W/cm2 while its current density and voltage were 0.45 A/cm2 and 0.5 V, respectively.XRD results show that there was no solid reaction between La0.6Sr0.4Fe0.8Co0.2O3 and Ce0.8Gd0.2O1.9.
La0.6Sr0.4Fe0.8Co0.2O3 powder was synthesized via citrate/nitrate sol-gel method.XRD results show that the powder consists of single phase of perovskite.The particle size is from 100 to 200 nm observed by means of TEM.EDS show that the atom percentage of the elements in the powder is consistent with the theoretical value.When the powder was used as the cathode to compose a H2-O2 solid oxide fuel cell, and Ce0.8Gd0.2O1.9 and NiO/Ce0.8Gd0.2O1.9 were used as electrolyte and anode, respectively, the electrical output properties were measured.At 650℃ the maximum output power density of the cell was 0.23 W/cm2 while its current density and voltage were 0.45 A/cm2 and 0.5 V, respectively.XRD results show that there was no solid reaction between La0.6Sr0.4Fe0.8Co0.2O3 and Ce0.8Gd0.2O1.9.
2007, 24(1): 30-34
Abstract:
Irradiated polyamide (PA) 1010 system was investigated by using WAXD, DSC and gel fraction measurement techniques.The result indicates that the mechanism of irradiation cross linking of PA1010 is closely related to the structures of molecule aggregation and the second component.The mechanism of cross linking is multiplicity, which is a process from end-effect and strengthened cross linking to non-ruleless reactions to ruleless cross linking of main chains in the amorphous sections.For the strengthened cross linking PA1010 system, the monomers exist in the amorphous sections or between the boundary of amorphous sections and the crystalline ones, which results in the irradiated cross linking in the amorphous sections in a ruleless way during the initial stages, accelerates the cross linking and promotes the formation and accumulation of the defects on the crystalline surfaces.The crystalline surfaces were damaged when the system of PA1010 and M/P were irradiated.For the crystalline samples, when the ratio of m(BMI):m(PA1010) varied from 1:100 to 5:100, the jumping-off point of crystalline damaging decreased from 10 000 kGy to 4 500 kGy with the increasing of the content on BMI.The results indicated that the variation of△Hm of irradiated PA1010 system only had relation with the degree of cross linking, and△Hm could be regarded as the measurement and character for irradiated cross linking.For amorphous PA1010, when the cross linking exponent v>0.7, the cold-crystallizing process would be blocked during the heating process, as for crystalline PA1010, the crystal began to be damaged when v> 1.3.
Irradiated polyamide (PA) 1010 system was investigated by using WAXD, DSC and gel fraction measurement techniques.The result indicates that the mechanism of irradiation cross linking of PA1010 is closely related to the structures of molecule aggregation and the second component.The mechanism of cross linking is multiplicity, which is a process from end-effect and strengthened cross linking to non-ruleless reactions to ruleless cross linking of main chains in the amorphous sections.For the strengthened cross linking PA1010 system, the monomers exist in the amorphous sections or between the boundary of amorphous sections and the crystalline ones, which results in the irradiated cross linking in the amorphous sections in a ruleless way during the initial stages, accelerates the cross linking and promotes the formation and accumulation of the defects on the crystalline surfaces.The crystalline surfaces were damaged when the system of PA1010 and M/P were irradiated.For the crystalline samples, when the ratio of m(BMI):m(PA1010) varied from 1:100 to 5:100, the jumping-off point of crystalline damaging decreased from 10 000 kGy to 4 500 kGy with the increasing of the content on BMI.The results indicated that the variation of△Hm of irradiated PA1010 system only had relation with the degree of cross linking, and△Hm could be regarded as the measurement and character for irradiated cross linking.For amorphous PA1010, when the cross linking exponent v>0.7, the cold-crystallizing process would be blocked during the heating process, as for crystalline PA1010, the crystal began to be damaged when v> 1.3.
2007, 24(1): 35-39
Abstract:
2,3,6,3',4'-Penta-O-acetylsucrose(6-PAS) was synthesized from sucrose via tritylation, acetylation, detritylation and acetyl migration.An effective reagent protecting the hydroxyls of sucrose was used to improve the yield of the reaction.In the process of protecting, the effects of reaction temperature and reaction time were studied.The two steps of detritylation and acetyl migration were analyzed by HPLC to chose the better route.The products were characterized by means of 1H NMR and IR.The result shows that the optimum conditions for protecting hydroxyl are:tritylation at 50℃ for 4 h and acetylation at 105℃ for 3 h.The yield is 81.9%.
2,3,6,3',4'-Penta-O-acetylsucrose(6-PAS) was synthesized from sucrose via tritylation, acetylation, detritylation and acetyl migration.An effective reagent protecting the hydroxyls of sucrose was used to improve the yield of the reaction.In the process of protecting, the effects of reaction temperature and reaction time were studied.The two steps of detritylation and acetyl migration were analyzed by HPLC to chose the better route.The products were characterized by means of 1H NMR and IR.The result shows that the optimum conditions for protecting hydroxyl are:tritylation at 50℃ for 4 h and acetylation at 105℃ for 3 h.The yield is 81.9%.
2007, 24(1): 40-44
Abstract:
A new class of star-shaped four-armed liquid crystals based on pentaerythritol as a flexible core was synthesized by aromatic esterification.Their chemical structures were confirmed by means of elemental analysis, IR and 1H NMR characterizations, their mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction.The results show that tm,ti,tic and tc decreases as the carbon chain of the terminal groups increases.They displayed broken focal-conic and focal-conic texture in liquid crystal states, and had a wide mesophase temperature range.The tm and ti of D1~D4 were 92.3℃, 80.6℃, 68.3℃, 51.1℃ and 159.2℃, 145.1℃, 127.5℃, 109.8℃ respectively, the mesogenic region △t1 decreased from 66.9℃ to 58.7℃; while the tic and tc were 138.6℃, 127.4℃, 111.6℃, 99.1℃ and 57.1℃, 52.6℃, 42.0℃, 31.8℃ respectively, the mesogenic region △t2 decreased from 81.5℃ to 67.3℃.
A new class of star-shaped four-armed liquid crystals based on pentaerythritol as a flexible core was synthesized by aromatic esterification.Their chemical structures were confirmed by means of elemental analysis, IR and 1H NMR characterizations, their mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction.The results show that tm,ti,tic and tc decreases as the carbon chain of the terminal groups increases.They displayed broken focal-conic and focal-conic texture in liquid crystal states, and had a wide mesophase temperature range.The tm and ti of D1~D4 were 92.3℃, 80.6℃, 68.3℃, 51.1℃ and 159.2℃, 145.1℃, 127.5℃, 109.8℃ respectively, the mesogenic region △t1 decreased from 66.9℃ to 58.7℃; while the tic and tc were 138.6℃, 127.4℃, 111.6℃, 99.1℃ and 57.1℃, 52.6℃, 42.0℃, 31.8℃ respectively, the mesogenic region △t2 decreased from 81.5℃ to 67.3℃.
2007, 24(1): 45-48
Abstract:
The effect of herbicide(ZJ0273) on nonionic surfactant(TX-10)/fatty acid methyl ester/hexanol/herbicide/water system was studied based on the "fish" diagrams.A temperature-insensitive microemulsion was formed with the addition of the anionic surfactant LAS.The total surfactant concentration required to form the single phase microemulsion was increased in the presence of the herbicide.In addition, the temperature required for the formation of transparent single phase microemulsion was omcreased, while the temperature region of the transparent single phase was narrowed by the addition of herbicide.
The effect of herbicide(ZJ0273) on nonionic surfactant(TX-10)/fatty acid methyl ester/hexanol/herbicide/water system was studied based on the "fish" diagrams.A temperature-insensitive microemulsion was formed with the addition of the anionic surfactant LAS.The total surfactant concentration required to form the single phase microemulsion was increased in the presence of the herbicide.In addition, the temperature required for the formation of transparent single phase microemulsion was omcreased, while the temperature region of the transparent single phase was narrowed by the addition of herbicide.
Synthesis and Photocatalytic Activity of A Novel ZnS Compound Coordinated with Triethylene Tetramine
2007, 24(1): 49-52
Abstract:
A novel inorganic-organic hybrid polymeric compound[(ZnS)3(NH2CH2CH2NHCH2)2)]n was synthesized by solvothermal techique from sulfur and zinc(Ⅱ) salt in triethylene tetramine.Detailed characterizations comfirmed the coordination of triethylene tetramine to ZnS moiety and the formation of the new compounds.The structure of the compound was characterized by IR, XRD and TEM.The compound is a stable polymer and has little solubility in water, ethanol, acetone and chloroform.The compound exhibited a considerably good photocatalytic activity in degradation of a dye reactive violet X-2R and kept nearly the same activity after 10 repeated experiments.
A novel inorganic-organic hybrid polymeric compound[(ZnS)3(NH2CH2CH2NHCH2)2)]n was synthesized by solvothermal techique from sulfur and zinc(Ⅱ) salt in triethylene tetramine.Detailed characterizations comfirmed the coordination of triethylene tetramine to ZnS moiety and the formation of the new compounds.The structure of the compound was characterized by IR, XRD and TEM.The compound is a stable polymer and has little solubility in water, ethanol, acetone and chloroform.The compound exhibited a considerably good photocatalytic activity in degradation of a dye reactive violet X-2R and kept nearly the same activity after 10 repeated experiments.
2007, 24(1): 53-57
Abstract:
The visible-light responding region was extended by Mo6+ doping because the doping of Mo6+ could introduce crystal cavities into TiO2 nanoparticles and reduce its energy band gap.Effects of doping concentration on visible-light responding region, crystal phase, grain size and cell parameters of TiO2 catalyzer were studied by means of UV-Vis, XRD, XPS and TG-DTA techniques, at the same time, the style of doping, valence state of doped ions and the physical and chemical reaction in the course of heating were also studied.The photocatalytic activity was evaluated by the photodegradation of methylene blue under visible-light radiation.It was found that the visible-light responding region and the photocatalytic activity of nanosized TiO2 were affected by the doping amount.The UV-Visible absorption band of 4.5% Mo doped TiO2 reached to about 460 nm, the removal efficiency of methylene blue was 58.3%, and TOC was 52.5%.For nano TiO2 with 3.0% and 6.0% Mo doping, the removal of methylene blue were 56.6% and 52.0%, and TOC were 49.2% and 44.2%, and both of them had a ratio of 4:1 of anatase to rutile and smaller grain size.
The visible-light responding region was extended by Mo6+ doping because the doping of Mo6+ could introduce crystal cavities into TiO2 nanoparticles and reduce its energy band gap.Effects of doping concentration on visible-light responding region, crystal phase, grain size and cell parameters of TiO2 catalyzer were studied by means of UV-Vis, XRD, XPS and TG-DTA techniques, at the same time, the style of doping, valence state of doped ions and the physical and chemical reaction in the course of heating were also studied.The photocatalytic activity was evaluated by the photodegradation of methylene blue under visible-light radiation.It was found that the visible-light responding region and the photocatalytic activity of nanosized TiO2 were affected by the doping amount.The UV-Visible absorption band of 4.5% Mo doped TiO2 reached to about 460 nm, the removal efficiency of methylene blue was 58.3%, and TOC was 52.5%.For nano TiO2 with 3.0% and 6.0% Mo doping, the removal of methylene blue were 56.6% and 52.0%, and TOC were 49.2% and 44.2%, and both of them had a ratio of 4:1 of anatase to rutile and smaller grain size.
2007, 24(1): 58-62
Abstract:
Benzenediazonium chloride reacted with the solutions of the sodium salts of four nitro compounds in an ice-bath to provide four α-nitrohydrazones in yields of 66%~89%, then the α-nitrohydrazones were refluxed with primary amine for 3 h, the resulting mixtures were oxidized with sodium nitrite for 2~3 h in the presence of TEBAC to afford nine novel 3,5-disubstituted-1-phenyl-1,2,4-triazole derivatives in 54%~71% yields.All the target compounds were characterized by means of 1H NMR, IR and elemental analysis.This synthetic strategy widens the application of a-nitrohydrazones and enriches the methodology for the synthesis of triazole derivatives.The methodolgy also has advantages such as common available materials, mild reaction conditions and high yields.
Benzenediazonium chloride reacted with the solutions of the sodium salts of four nitro compounds in an ice-bath to provide four α-nitrohydrazones in yields of 66%~89%, then the α-nitrohydrazones were refluxed with primary amine for 3 h, the resulting mixtures were oxidized with sodium nitrite for 2~3 h in the presence of TEBAC to afford nine novel 3,5-disubstituted-1-phenyl-1,2,4-triazole derivatives in 54%~71% yields.All the target compounds were characterized by means of 1H NMR, IR and elemental analysis.This synthetic strategy widens the application of a-nitrohydrazones and enriches the methodology for the synthesis of triazole derivatives.The methodolgy also has advantages such as common available materials, mild reaction conditions and high yields.
2007, 24(1): 63-66
Abstract:
One kind of screened lipase from Candida sp.CXU08 was used as a catalyst to synthesize cyclopen-tadecanolide.Methyl ω-hydroxy-pentadecanate was used as the substrate.The effects of activity of lipase, time of reaction, temperature, pH, dielectric constant of organic solvent etc on the conversion of ω-hydroxy-pentadecanate were studied.The results indicate that GXU08 has a good specificity and no cyclononalide, cyclotridecanolide or other polymers were found.Under the optimum reaction conditions: 40℃, 180 r/min, pH=6.0, activity of lipase 1 245 U, 72 h, the conversion is 17% in cyclohexane.
One kind of screened lipase from Candida sp.CXU08 was used as a catalyst to synthesize cyclopen-tadecanolide.Methyl ω-hydroxy-pentadecanate was used as the substrate.The effects of activity of lipase, time of reaction, temperature, pH, dielectric constant of organic solvent etc on the conversion of ω-hydroxy-pentadecanate were studied.The results indicate that GXU08 has a good specificity and no cyclononalide, cyclotridecanolide or other polymers were found.Under the optimum reaction conditions: 40℃, 180 r/min, pH=6.0, activity of lipase 1 245 U, 72 h, the conversion is 17% in cyclohexane.
2007, 24(1): 67-70
Abstract:
The process of extraction of isoliquiritigenin(ISL) from licorice with supercritical CO2 was studied by both orthogonal and single factors analysis experiments.Factors affecting the yield of ISL including extraction pressure, extraction temperature, kind of entrainer, ratio of solvent to soild, CO2 flow rate, etc, were optimized, and the results were compared to those of Soxhlet extraction method.It was found that the optimized technological parameters were as follows:extraction pressure 30 MPa, extraction temperature 45℃, entrainer 85% ethanol, the ratio of solvent to solid 5:1, CO2 flow rate 10 kg/h, separation pressure 5.5 MPa, separation temperature 35℃.At the optimized conditions, the extraction yield of ISL was 0.035% and the content of ISL in extract was 0.84%, which were 3.5 and 3.0 times those of by Soxhlet extraction, respectively.Supercritical CO2 extraction of ISL requires less extraction time and solvent, with a higher extraction yield, and no pollution, it is thus an efficient and rapid method for extracting ISL from licorice.
The process of extraction of isoliquiritigenin(ISL) from licorice with supercritical CO2 was studied by both orthogonal and single factors analysis experiments.Factors affecting the yield of ISL including extraction pressure, extraction temperature, kind of entrainer, ratio of solvent to soild, CO2 flow rate, etc, were optimized, and the results were compared to those of Soxhlet extraction method.It was found that the optimized technological parameters were as follows:extraction pressure 30 MPa, extraction temperature 45℃, entrainer 85% ethanol, the ratio of solvent to solid 5:1, CO2 flow rate 10 kg/h, separation pressure 5.5 MPa, separation temperature 35℃.At the optimized conditions, the extraction yield of ISL was 0.035% and the content of ISL in extract was 0.84%, which were 3.5 and 3.0 times those of by Soxhlet extraction, respectively.Supercritical CO2 extraction of ISL requires less extraction time and solvent, with a higher extraction yield, and no pollution, it is thus an efficient and rapid method for extracting ISL from licorice.
2007, 24(1): 71-75
Abstract:
In a medium of HAc-NaAc(pH=3.51), a triple complex is formed via Pb(Ⅱ) reacting with 1-phenyl-3-methyl-4-(α-furoyl) pyrazolone-5 (HPMαFP) and 2, 2'-dipyridine (dipy), and there appears a sensitive polarographic wave at -0.73 V(vs.SCE) for the triple complex.The peak current exhibits linear relation with the concentration of Pb(Ⅱ) from 2×10-9 g/mL to 9×10-6 g/mL.The detection limit is 2×10-9 g/mL.By using different electrochemical methods, the properties of the polarographic wave and the mechanism of electrode reaction were studied.The results indicate that the polarographic wave at-0.73 V is an adsorptive wave of the complex.The peak current is produced by the reduction of the Pb (Ⅱ) ion.The molar ratio of Pb(Ⅱ) with dipy to HPMaFP in the complex is 1:1:1; and the conditional formation constant of the complex is 5.06×106.The method was used to determine lead in thick salt, cane sugar and comestic samples.The recovery is 99.3%~100.4%.
In a medium of HAc-NaAc(pH=3.51), a triple complex is formed via Pb(Ⅱ) reacting with 1-phenyl-3-methyl-4-(α-furoyl) pyrazolone-5 (HPMαFP) and 2, 2'-dipyridine (dipy), and there appears a sensitive polarographic wave at -0.73 V(vs.SCE) for the triple complex.The peak current exhibits linear relation with the concentration of Pb(Ⅱ) from 2×10-9 g/mL to 9×10-6 g/mL.The detection limit is 2×10-9 g/mL.By using different electrochemical methods, the properties of the polarographic wave and the mechanism of electrode reaction were studied.The results indicate that the polarographic wave at-0.73 V is an adsorptive wave of the complex.The peak current is produced by the reduction of the Pb (Ⅱ) ion.The molar ratio of Pb(Ⅱ) with dipy to HPMaFP in the complex is 1:1:1; and the conditional formation constant of the complex is 5.06×106.The method was used to determine lead in thick salt, cane sugar and comestic samples.The recovery is 99.3%~100.4%.
2007, 24(1): 76-79
Abstract:
An in-column derivatization high performance liquid chromatographic method for the determination of formaldehyde in inner wall paints and adhesives was developed.The reaction mechanism of formaldehyde and unsymmetrical dimethyl hydrazine (UDMH), and the effect of pH on nucleophilic addition were discussed.The optimal range was between 2 and 6, and chromatographic conditions were:the column:Zorbax ODS(150 mm×4.6 mm i.d.,5μm), the mobile phase:mixture of methanol-20 mmol/L acetate buffer(pH=5.0) containing 12 mmol/L UDMH (15:85, volume ratio), the flow rate: 0.8 mL/min, the column temperature; 40℃, the detection wavelength:238 nm.The regression equation is A=8 904X-49.27, and the correlation coefficient is 0.999 9.The linear range and detectable limit were 30~300 mg/L and 5 ng, respectively.The recovery was 95.90%~102.50% and RSD was 1.02%~1.51%.The method has proven to be fast, simple, sensitive, accurate and reproducible with respect to other chromatographic methods that have been reported.It can be used for the routine analysis of formaldehyde in inner wall paints and adhesives.
An in-column derivatization high performance liquid chromatographic method for the determination of formaldehyde in inner wall paints and adhesives was developed.The reaction mechanism of formaldehyde and unsymmetrical dimethyl hydrazine (UDMH), and the effect of pH on nucleophilic addition were discussed.The optimal range was between 2 and 6, and chromatographic conditions were:the column:Zorbax ODS(150 mm×4.6 mm i.d.,5μm), the mobile phase:mixture of methanol-20 mmol/L acetate buffer(pH=5.0) containing 12 mmol/L UDMH (15:85, volume ratio), the flow rate: 0.8 mL/min, the column temperature; 40℃, the detection wavelength:238 nm.The regression equation is A=8 904X-49.27, and the correlation coefficient is 0.999 9.The linear range and detectable limit were 30~300 mg/L and 5 ng, respectively.The recovery was 95.90%~102.50% and RSD was 1.02%~1.51%.The method has proven to be fast, simple, sensitive, accurate and reproducible with respect to other chromatographic methods that have been reported.It can be used for the routine analysis of formaldehyde in inner wall paints and adhesives.
2007, 24(1): 80-84
Abstract:
DHAC modified bentonite was prepared starting from Xiazijie bentonite of Xinjiang.FTIR spectra showed that DHAC cation ions were intercalated into the layers of bentonite.It was shown that the layers spacing of the modified bentonite was 3.772 nm, which is 2.07 times that of bentonite.SEM images showed that the DHAC modified bentonite particles were looser than that of bentonite, and there were evident erosion trails on the surface of montmorillonite.The isotherm adsorption models of DHAC modified bentonite for volatile phenols was in agreement with Freundlich equation.The adsorption enthalpy of modified bentonite for volatile phenols was -2.64 kJ/mol, indicating that the adsorption was physical adsorption.Because its△Gθ<0, the adsorption reaction was a spontaneous exothermic process.At the ambient temperature, the adsorption kinetic model of modified bentonite for volatile phenols obeyed Bingham and Langmuir adsorption dynamic models.
DHAC modified bentonite was prepared starting from Xiazijie bentonite of Xinjiang.FTIR spectra showed that DHAC cation ions were intercalated into the layers of bentonite.It was shown that the layers spacing of the modified bentonite was 3.772 nm, which is 2.07 times that of bentonite.SEM images showed that the DHAC modified bentonite particles were looser than that of bentonite, and there were evident erosion trails on the surface of montmorillonite.The isotherm adsorption models of DHAC modified bentonite for volatile phenols was in agreement with Freundlich equation.The adsorption enthalpy of modified bentonite for volatile phenols was -2.64 kJ/mol, indicating that the adsorption was physical adsorption.Because its△Gθ<0, the adsorption reaction was a spontaneous exothermic process.At the ambient temperature, the adsorption kinetic model of modified bentonite for volatile phenols obeyed Bingham and Langmuir adsorption dynamic models.
2007, 24(1): 85-89
Abstract:
A new method of catalytic synthesis of benzyl acetate from acetate acid and benzyl alcohol in task-specific room temperature ionic liquid(TSILs) was studied.Some TSILs with an alkyl sulfonic acid group in a N-methyl imidazlium cation were synthesized for esterification.With 1:1.3 ratio of benzyl alcohol and acetate acid in TSILs for 2.5 h at r.t., the isolated yield reached to 92% and the selectivity was above 99%.The product was immiscible with TSILs and could be separated simply by decantation after the reaction.As environmentally benign dual solvent-catalysts, the TSILs could be reused for several times without noticeable lowering of activity.
A new method of catalytic synthesis of benzyl acetate from acetate acid and benzyl alcohol in task-specific room temperature ionic liquid(TSILs) was studied.Some TSILs with an alkyl sulfonic acid group in a N-methyl imidazlium cation were synthesized for esterification.With 1:1.3 ratio of benzyl alcohol and acetate acid in TSILs for 2.5 h at r.t., the isolated yield reached to 92% and the selectivity was above 99%.The product was immiscible with TSILs and could be separated simply by decantation after the reaction.As environmentally benign dual solvent-catalysts, the TSILs could be reused for several times without noticeable lowering of activity.
2007, 24(1): 90-94
Abstract:
Metallofullerene Gd@C82 was synthesized via electric arc method and separated by two-step HPLC with 95% purity, and its derivative Gd@C82(OH)x was synthesized by the reaction of Gd@C82 with NaOH catalyzed by tetrabutylammonium hydroxide(TBAH).The hydroxyl number of Gd@C82(OH)x was determined by XPS on its C1s spectrum and the compound was assigned as Gd@C82(OH)16.The proton relaxivity and MRI photographs of Gd@C82(OH)16 were evaluated in vitro and in vivo on a Bruker 4.7T/30 cm Biospec magnetic resonance imaging scanner.Results show that Gd@C82(OH)16 has a high proton relaxivity in vitro, even higher than that of (NMG)2-Gd-DTPA, which is the most popularly used MRI contrast agent clinically.Compared to that of (NMG)2-Gd-DTPA, relaxitivity R1 of Gd@C82(OH)16 increased 3 times, relaxitivity R2 increased 7 times.In vivo experiments found Gd@C82(OH)16 helped to generate high quality MRI photographs.The bio-distribution results indicate that Gd@C82(OH)16 tends to be entrapped in the liver and kidney and remained in these organs for about 2 hours.These results indicate that the metallofullerene derivative Gd@C82(OH)16 might be the potential candidate as a new MRI contrast agent.
Metallofullerene Gd@C82 was synthesized via electric arc method and separated by two-step HPLC with 95% purity, and its derivative Gd@C82(OH)x was synthesized by the reaction of Gd@C82 with NaOH catalyzed by tetrabutylammonium hydroxide(TBAH).The hydroxyl number of Gd@C82(OH)x was determined by XPS on its C1s spectrum and the compound was assigned as Gd@C82(OH)16.The proton relaxivity and MRI photographs of Gd@C82(OH)16 were evaluated in vitro and in vivo on a Bruker 4.7T/30 cm Biospec magnetic resonance imaging scanner.Results show that Gd@C82(OH)16 has a high proton relaxivity in vitro, even higher than that of (NMG)2-Gd-DTPA, which is the most popularly used MRI contrast agent clinically.Compared to that of (NMG)2-Gd-DTPA, relaxitivity R1 of Gd@C82(OH)16 increased 3 times, relaxitivity R2 increased 7 times.In vivo experiments found Gd@C82(OH)16 helped to generate high quality MRI photographs.The bio-distribution results indicate that Gd@C82(OH)16 tends to be entrapped in the liver and kidney and remained in these organs for about 2 hours.These results indicate that the metallofullerene derivative Gd@C82(OH)16 might be the potential candidate as a new MRI contrast agent.
2007, 24(1): 95-99
Abstract:
The real time investigation of the gas products evolved during the thermal degradation of ethylene-butyl acrylate copolymer(EBA) was carried out in an inert atmosphere(nitrogen) with TGA/FTIR technique at 10℃ /min.TG curve shows that EBA has a high thermal stability, and the thermal degradation temperature of EBA is in the range of 330~480℃.Ester pyrolysis accounts for the thermal degradation mechanism of EBA.1-Butene and carboxylic groups are formed when ester pyrolysis occurs.Carboxylic groups decompose to eliminate CO2 as shown by absorptions around 2 350 cm in FTIR spectrum.The main volatile decomposition products are 1-butene, CO2 and acrylate containing fragments in the range of 320℃ ~430℃.However, the main volatile decomposition products from thermal degradation of the main chain of EBA are the low molecular weight chain-alkanes (-(CH2)n-(n≥4)) and acrylate containing fragments at a high temperature (>450℃ ), and the small amounts of CO is also detected.
The real time investigation of the gas products evolved during the thermal degradation of ethylene-butyl acrylate copolymer(EBA) was carried out in an inert atmosphere(nitrogen) with TGA/FTIR technique at 10℃ /min.TG curve shows that EBA has a high thermal stability, and the thermal degradation temperature of EBA is in the range of 330~480℃.Ester pyrolysis accounts for the thermal degradation mechanism of EBA.1-Butene and carboxylic groups are formed when ester pyrolysis occurs.Carboxylic groups decompose to eliminate CO2 as shown by absorptions around 2 350 cm in FTIR spectrum.The main volatile decomposition products are 1-butene, CO2 and acrylate containing fragments in the range of 320℃ ~430℃.However, the main volatile decomposition products from thermal degradation of the main chain of EBA are the low molecular weight chain-alkanes (-(CH2)n-(n≥4)) and acrylate containing fragments at a high temperature (>450℃ ), and the small amounts of CO is also detected.
2007, 24(1): 100-104
Abstract:
Biodiesel was prepared via the transesterification of hempseed oil with methanol in the presence of NaOH as catalyst.Effects of molar ratio of methanol to oil, catalyst amount, reaction time and temperature on the transesterification were investigated.The conversion of methanol was determinated by chromotropic acid colorimrtry, and the products were analyzed by gel permeation chromatography, infrared speetroscopy and GC/MC.The experimental results show that both raising reaction temperature and increasing catalyst amounl were advantageous to the transesterification.The conversion of methanol increased to the maximum and then decreased with the elongation reaction time.With increasing the molar ratio of methanol to oil, the yield oi methyl esters increased, but the conversion of methanol decreased.Gel permeation chromatography analysis showed that it could convert hempseed oil to methyl esters completely by doing the transesterification twice.
Biodiesel was prepared via the transesterification of hempseed oil with methanol in the presence of NaOH as catalyst.Effects of molar ratio of methanol to oil, catalyst amount, reaction time and temperature on the transesterification were investigated.The conversion of methanol was determinated by chromotropic acid colorimrtry, and the products were analyzed by gel permeation chromatography, infrared speetroscopy and GC/MC.The experimental results show that both raising reaction temperature and increasing catalyst amounl were advantageous to the transesterification.The conversion of methanol increased to the maximum and then decreased with the elongation reaction time.With increasing the molar ratio of methanol to oil, the yield oi methyl esters increased, but the conversion of methanol decreased.Gel permeation chromatography analysis showed that it could convert hempseed oil to methyl esters completely by doing the transesterification twice.
2007, 24(1): 105-107
Abstract:
Thiophene reacted with bromine and zinc to produce 3-bromothiophene via substitution and reduction reaction.3-Bromothiophene was treated with n-butyllithium, sulfur powder, and halogenated hydrocarbons in subsequence in dried tetrahydrofuran under 70℃ to produce (3-methylthio)thiophene, (3-ethylthio) thiophene, (3-propylthio) thiophene, (3-butylthio) thiophene, (3-allylthio) thiophene and (3-isopropylthio) thiophene.The reaction time was 1.5 h, 2.5 h, 2.5 h, 3 h, 3 h and 3.5 h, respectively.The yield was 82%, 74%, 71%, 70%, 73% and 49%, respectively.These compounds were confirmed by IR, 1H MNR, 13C NMR and MS.Their flavor was evaluated to have meat flavor.
Thiophene reacted with bromine and zinc to produce 3-bromothiophene via substitution and reduction reaction.3-Bromothiophene was treated with n-butyllithium, sulfur powder, and halogenated hydrocarbons in subsequence in dried tetrahydrofuran under 70℃ to produce (3-methylthio)thiophene, (3-ethylthio) thiophene, (3-propylthio) thiophene, (3-butylthio) thiophene, (3-allylthio) thiophene and (3-isopropylthio) thiophene.The reaction time was 1.5 h, 2.5 h, 2.5 h, 3 h, 3 h and 3.5 h, respectively.The yield was 82%, 74%, 71%, 70%, 73% and 49%, respectively.These compounds were confirmed by IR, 1H MNR, 13C NMR and MS.Their flavor was evaluated to have meat flavor.
2007, 24(1): 108-110
Abstract:
A series of new carboxaldehyde thiosemicarbazones was synthesized by the condensation reaction of 2-phenyl-1,2,3-triazol-4-carboxaldehyde with thiosemicarbazide, the product reacted with five substituted α-bromoacetophenone or α-bromo-α-(1H-1,2,4-triazol-1-yl) acetophenone subsequently in EtOH under refluxing to afford a series of carboxaldehyde hydrazone derivatives.Their structures were confirmed by elemental analysis, IR, 1H NMR, and MS spectra.The biological test results show that most of these compounds have no antiviral and fungicidal activity.
A series of new carboxaldehyde thiosemicarbazones was synthesized by the condensation reaction of 2-phenyl-1,2,3-triazol-4-carboxaldehyde with thiosemicarbazide, the product reacted with five substituted α-bromoacetophenone or α-bromo-α-(1H-1,2,4-triazol-1-yl) acetophenone subsequently in EtOH under refluxing to afford a series of carboxaldehyde hydrazone derivatives.Their structures were confirmed by elemental analysis, IR, 1H NMR, and MS spectra.The biological test results show that most of these compounds have no antiviral and fungicidal activity.
2007, 24(1): 111-113
Abstract:
Toluene with different substituted group was selected to react with NBS under diffent conditions.The factors that effect reaction including the polarity of solvent, the electron effect of substituteed group and reaction temperature were discussed.The results indicated that the regioselectivity of substitutent reaction depend greatly on reaction solvent and the electronic effect of substitutent group.It is shown that the electro-phic substitution of benzene ring is favored in more polar solvents and for compounds with strong electron-donating groups.Otherwise, the free radical reaction in the α-site was favorable.On the base of the results, a new synthetic route of brominated Q0 was reported.The method was more favorable for the preparation of Q0, and the yield was above 86%.
Toluene with different substituted group was selected to react with NBS under diffent conditions.The factors that effect reaction including the polarity of solvent, the electron effect of substituteed group and reaction temperature were discussed.The results indicated that the regioselectivity of substitutent reaction depend greatly on reaction solvent and the electronic effect of substitutent group.It is shown that the electro-phic substitution of benzene ring is favored in more polar solvents and for compounds with strong electron-donating groups.Otherwise, the free radical reaction in the α-site was favorable.On the base of the results, a new synthetic route of brominated Q0 was reported.The method was more favorable for the preparation of Q0, and the yield was above 86%.
2007, 24(1): 114-116
Abstract:
The novel title compound was synthesized with benzaldehyde, isobutyraldehyde, phosphorus trichloride as raw materials.The total yield was 40.8%.The structure was confirmed by 1H NMR, 31P NMR and elemental analysis.
The novel title compound was synthesized with benzaldehyde, isobutyraldehyde, phosphorus trichloride as raw materials.The total yield was 40.8%.The structure was confirmed by 1H NMR, 31P NMR and elemental analysis.
