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2018 Volume 81 Issue 7
2018, 81(7): 579-586, 597
Abstract:
The C-N bond as a common chemical bond widely exists in many organic molecules and biomacromolecules. The formation and cleavage of C-N bonds play a crucial role in the process of organic reactions and biochemistry. The cleavage of C-N bonds by transition-metal-catalysis, strong oxidization, enzyme catalysis, photocatalysis and other methods were reviewed. The advantages, disadvantages and mechanisms of the described methods were summarized, and the faced challenges and development directions were also discussed.
The C-N bond as a common chemical bond widely exists in many organic molecules and biomacromolecules. The formation and cleavage of C-N bonds play a crucial role in the process of organic reactions and biochemistry. The cleavage of C-N bonds by transition-metal-catalysis, strong oxidization, enzyme catalysis, photocatalysis and other methods were reviewed. The advantages, disadvantages and mechanisms of the described methods were summarized, and the faced challenges and development directions were also discussed.
Study on Synthesis of La2-xSrxFeNiO6 Catalysts and Their Catalytic Activities for Methane Combustion
2018, 81(7): 587-591
Abstract:
La2-xSrxFeNiO6 (x=0, 0.5, 1, 1.5, 2) series catalysts were prepared by sol-gel method using citric acid as a complexing agent. The influence of Sr doping on catalyst La2FeNiO6 was investigated. The titled catalysts were characterized by XRD, BET, H2-TPR and TG-DSC techniques, and their catalytic activities were evaluated for methane combustion. The results showed that the doping of Sr can change the crystal structure of double perovskites and increase the amount of lattice oxygen. The catalyst LaSrFeNiO6 retains a specific surface area of 7.9 m2·g-1 and shows an excellent activity for methane combustion (the conversion of 10% and 90% is obtained at 370℃ and 535℃, respectively). Its reaction activation energy is 78.8 kJ·mol-1, which is smaller than reaction of as-prepared other catalysts.
La2-xSrxFeNiO6 (x=0, 0.5, 1, 1.5, 2) series catalysts were prepared by sol-gel method using citric acid as a complexing agent. The influence of Sr doping on catalyst La2FeNiO6 was investigated. The titled catalysts were characterized by XRD, BET, H2-TPR and TG-DSC techniques, and their catalytic activities were evaluated for methane combustion. The results showed that the doping of Sr can change the crystal structure of double perovskites and increase the amount of lattice oxygen. The catalyst LaSrFeNiO6 retains a specific surface area of 7.9 m2·g-1 and shows an excellent activity for methane combustion (the conversion of 10% and 90% is obtained at 370℃ and 535℃, respectively). Its reaction activation energy is 78.8 kJ·mol-1, which is smaller than reaction of as-prepared other catalysts.
2018, 81(7): 592-597
Abstract:
TiO2 is widely used in semiconductor photocatalysis due to its excellent features. However, TiO2 particles with nanoscale is difficult to separate and recycle after the photocatalytic reactions. In this paper, we successfully synthesized the magnetic Fe3O4/TiO2 composite by the simple and mild dip-molding method. Both the TiO2 and Fe3O4 are originated by the cheap ilmenite as raw material. A series of characterization means including XRD, FT-IR, SEM and EDS were used to analyze the surface structure of the Fe3O4/TiO2 composite. Furthermore, the performance of Fe3O4/TiO2 composites was investigated by using of photocatalytic degradation of Rhodamine B (Rh B) as a probe reaction. The results demonstrated that the Fe3O4/TiO2 composite with mass ratio of 1:10 are stable and uniform, has the best photocatalytic activity for Rh B, and shows outstanding recyclability. The photocatalytic degradation reaction coincides with the first-order reaction kinetics.
TiO2 is widely used in semiconductor photocatalysis due to its excellent features. However, TiO2 particles with nanoscale is difficult to separate and recycle after the photocatalytic reactions. In this paper, we successfully synthesized the magnetic Fe3O4/TiO2 composite by the simple and mild dip-molding method. Both the TiO2 and Fe3O4 are originated by the cheap ilmenite as raw material. A series of characterization means including XRD, FT-IR, SEM and EDS were used to analyze the surface structure of the Fe3O4/TiO2 composite. Furthermore, the performance of Fe3O4/TiO2 composites was investigated by using of photocatalytic degradation of Rhodamine B (Rh B) as a probe reaction. The results demonstrated that the Fe3O4/TiO2 composite with mass ratio of 1:10 are stable and uniform, has the best photocatalytic activity for Rh B, and shows outstanding recyclability. The photocatalytic degradation reaction coincides with the first-order reaction kinetics.
2018, 81(7): 604-609
Abstract:
A series of β-alkoxypropionamides were synthesized by the oxa-Michael addition reaction of alcohol with acrylamide. The structure of product was characterized by NMR and HRMS. The effects of catalyst, reaction temperature, and ratio of reactants on the reaction were explored. At 40℃, the oxa-Michael addition reaction of primary alcohol with acrylamide went smoothly under promotion of 5 (mol)% activated potassium carbonate. The activity of secondary alcohol is lower. As for tertiary alcohol and phenol, almost no reaction was observed. At higher temperature, the acrylamide underwent the aza-Michael addition to generate dimer of acrylamide. The reaction of alcohol with acrylamide can be run at equivalent ratio as the solvent-free mode. Intramolecular hydrogen bond can increase the reactivity of secondary hydroxyl group.
A series of β-alkoxypropionamides were synthesized by the oxa-Michael addition reaction of alcohol with acrylamide. The structure of product was characterized by NMR and HRMS. The effects of catalyst, reaction temperature, and ratio of reactants on the reaction were explored. At 40℃, the oxa-Michael addition reaction of primary alcohol with acrylamide went smoothly under promotion of 5 (mol)% activated potassium carbonate. The activity of secondary alcohol is lower. As for tertiary alcohol and phenol, almost no reaction was observed. At higher temperature, the acrylamide underwent the aza-Michael addition to generate dimer of acrylamide. The reaction of alcohol with acrylamide can be run at equivalent ratio as the solvent-free mode. Intramolecular hydrogen bond can increase the reactivity of secondary hydroxyl group.
2018, 81(7): 610-615, 609
Abstract:
Based on the previous work, this paper further investigated the reaction of 2-position branched benzofuran units with thiol to form C-S bond at the 3-position. The study found that K2CO3 can efficiently promoted the reaction with benzofuran units to produce 3-arylthiobenzofuran derivatives which the functional groups at the 2-position are aliphatic ketones with different chain lengths. All the products were characterized by NMR and HRMS. The reaction has the advantages of mild reaction conditions, wide range of substrate application, simple operation, high yield, environmental friendliness and so on. It can provide a potential synthetic pathway for the synthesis of natural products containing aromatic sulfur-substituted groups and complex drug molecules.
Based on the previous work, this paper further investigated the reaction of 2-position branched benzofuran units with thiol to form C-S bond at the 3-position. The study found that K2CO3 can efficiently promoted the reaction with benzofuran units to produce 3-arylthiobenzofuran derivatives which the functional groups at the 2-position are aliphatic ketones with different chain lengths. All the products were characterized by NMR and HRMS. The reaction has the advantages of mild reaction conditions, wide range of substrate application, simple operation, high yield, environmental friendliness and so on. It can provide a potential synthetic pathway for the synthesis of natural products containing aromatic sulfur-substituted groups and complex drug molecules.
2018, 81(7): 616-624
Abstract:
The activated carbon (AC) supported chitosan (CS) catalyst, denoted as CS/AC, was prepared by a simple method. The physicochemical properties of the as-prepared catalyst were characterized by FT-IR, XRD, TG-DTG, SEM, BET, and elemental analysis. The catalytic performance was tested by the Knoevenagel condensation reaction, and the results showed that the catalyst can efficiently catalyze the Knoevenagel condensation reaction of a series of aromatic aldehydes with active methylene compounds at solvent-free and room temperature conditions, affording more than 80% products yield. Furthermore, when the reaction system is scaled up by 100 times, the catalyst still maintains high catalytic efficiency. Moreover, the catalyst can be recovered by simple filtration and reused at least 8 times without significant loss of activity, indicating that the catalyst is very stable.
The activated carbon (AC) supported chitosan (CS) catalyst, denoted as CS/AC, was prepared by a simple method. The physicochemical properties of the as-prepared catalyst were characterized by FT-IR, XRD, TG-DTG, SEM, BET, and elemental analysis. The catalytic performance was tested by the Knoevenagel condensation reaction, and the results showed that the catalyst can efficiently catalyze the Knoevenagel condensation reaction of a series of aromatic aldehydes with active methylene compounds at solvent-free and room temperature conditions, affording more than 80% products yield. Furthermore, when the reaction system is scaled up by 100 times, the catalyst still maintains high catalytic efficiency. Moreover, the catalyst can be recovered by simple filtration and reused at least 8 times without significant loss of activity, indicating that the catalyst is very stable.
2018, 81(7): 625-629
Abstract:
In this paper, zein/Tween-20 composite nanoparticles were prepared by anti-solvent precipitation. By measuring the encapsulation efficiency, stability, and fluorescence properties of curcumin in zein/Tween-20 composite nanoparticles, the influence of Tween-20 concentration on the interaction between zein/Tween-20 composite nanoparticles and curcumin was investigated. Compared to zein nanoparticles, zein/Tween-20 composite nanoparticles can significantly increase the encapsulation efficiency, stability, fluorescence emission intensity, and anisotropy of curcumin. These results indicate that curcumin is bound in hydrophobic domains of zein/Tween-20 composite nanoparticles via hydrophobic interactions. Tween-20 as a stabilizer not only helps to produce smaller zein/Tween-20 composite nanoparticles, but also provides a more suitable hydrophobic binding environment for curcumin.
In this paper, zein/Tween-20 composite nanoparticles were prepared by anti-solvent precipitation. By measuring the encapsulation efficiency, stability, and fluorescence properties of curcumin in zein/Tween-20 composite nanoparticles, the influence of Tween-20 concentration on the interaction between zein/Tween-20 composite nanoparticles and curcumin was investigated. Compared to zein nanoparticles, zein/Tween-20 composite nanoparticles can significantly increase the encapsulation efficiency, stability, fluorescence emission intensity, and anisotropy of curcumin. These results indicate that curcumin is bound in hydrophobic domains of zein/Tween-20 composite nanoparticles via hydrophobic interactions. Tween-20 as a stabilizer not only helps to produce smaller zein/Tween-20 composite nanoparticles, but also provides a more suitable hydrophobic binding environment for curcumin.
2018, 81(7): 630-635
Abstract:
A series of β-CD modified carboxymethyl cellulose hydrogel particles (gel CMC-β-CD) were prepared through inverse suspension polymerization under alkaline condition, and their adsorption and encapsulation abilities were investigated. The results showed that the hydrogel had excellent adsorption and release properties. When the environmental pH was 11.0, the highest equilibrium swelling ratio was 1765.1%. The equilibrium swelling ratio would decrease when feed ratio of β-CD to CMC increase. The modified hydrogel has excellent vanillin encapsulation ability, the maximum encapsulation efficiency is 95.8% at low vanillin initial concentration, and the maximum release efficiency is 93.9% under neutral condition, indicating that it has excellent reusability. The results of this paper can provide guidance for the industrial application of substances which are sensitive to light, air or other external conditions.
A series of β-CD modified carboxymethyl cellulose hydrogel particles (gel CMC-β-CD) were prepared through inverse suspension polymerization under alkaline condition, and their adsorption and encapsulation abilities were investigated. The results showed that the hydrogel had excellent adsorption and release properties. When the environmental pH was 11.0, the highest equilibrium swelling ratio was 1765.1%. The equilibrium swelling ratio would decrease when feed ratio of β-CD to CMC increase. The modified hydrogel has excellent vanillin encapsulation ability, the maximum encapsulation efficiency is 95.8% at low vanillin initial concentration, and the maximum release efficiency is 93.9% under neutral condition, indicating that it has excellent reusability. The results of this paper can provide guidance for the industrial application of substances which are sensitive to light, air or other external conditions.
2018, 81(7): 636-640
Abstract:
Based on topological chemical theory, electrotopological state indice(Mk) of atom type were used to describe the chemical microenvionment of 18 triazinyl-oxadiazolyl-pyrazole derivatives. The Quantitative Structure-Activity Relationship(QSAR) models for the inhibitory enzyme activities(Pt, Cd) of above compounds to protein tyrosine phosphatase 1B(PTP1B) and cell division cycle 25 phosphatase B(Cdc25B) was developed based on the Mk and leaps-and-bounds regression, respectively. The coefficient of multiple determination(R2) and cross-validated coefficient of multiple determination (Rcv2) of leave-one-out (LOO) of the optimal three variable QSAR model for Pt were 0.896, 0.830, respectively. R2 and Rcv2 of the optimal three variable QSAR model for Cd were 0.828, 0.688, respectively. The QSAR model has both favorable estimation stability and good prediction capability by Rcv2, VIF, FT, AC tests. Verified by the training set, the models have good external prediction ability. The models showed that dominant influence factors of Pt, Cd are different structural groups (-CH3, -O-, -NH2 and -N=in aromatic rings) as well as the same factors (-C=in aromatic rings).
Based on topological chemical theory, electrotopological state indice(Mk) of atom type were used to describe the chemical microenvionment of 18 triazinyl-oxadiazolyl-pyrazole derivatives. The Quantitative Structure-Activity Relationship(QSAR) models for the inhibitory enzyme activities(Pt, Cd) of above compounds to protein tyrosine phosphatase 1B(PTP1B) and cell division cycle 25 phosphatase B(Cdc25B) was developed based on the Mk and leaps-and-bounds regression, respectively. The coefficient of multiple determination(R2) and cross-validated coefficient of multiple determination (Rcv2) of leave-one-out (LOO) of the optimal three variable QSAR model for Pt were 0.896, 0.830, respectively. R2 and Rcv2 of the optimal three variable QSAR model for Cd were 0.828, 0.688, respectively. The QSAR model has both favorable estimation stability and good prediction capability by Rcv2, VIF, FT, AC tests. Verified by the training set, the models have good external prediction ability. The models showed that dominant influence factors of Pt, Cd are different structural groups (-CH3, -O-, -NH2 and -N=in aromatic rings) as well as the same factors (-C=in aromatic rings).
2018, 81(7): 641-645
Abstract:
The dual scale structure formed after the drying based on the three-dimensional kinetic Monte Carlo model. The effects of liquid chemical potential, nanoparticle migration rate, chemical potential sharpness and liquid critical evaporation rate on the structure of film are explored. The results indicate that, when the film is drying, the nanoparticles in the film move along with the three phase lines, and a variety of sedimentary structures are formed in the substrate. With the increase of the initialization chemical potential of the liquid, the deposition structure gradually becomes a dense network structure with uniform distribution. With the decrease of the critical evaporation rate of liquid, the deposition structure become more obvious after the liquid chemical potential is abrupt. The faster the nanoparticle moves, the less the branched structure in the deposition structure. The sharpness of chemical potential has a great influence on the difference of the structure of the double-scale sedimentary structure. With the greater the sharpness, the difference between the two kinds of sedimentary structures will be greater.
The dual scale structure formed after the drying based on the three-dimensional kinetic Monte Carlo model. The effects of liquid chemical potential, nanoparticle migration rate, chemical potential sharpness and liquid critical evaporation rate on the structure of film are explored. The results indicate that, when the film is drying, the nanoparticles in the film move along with the three phase lines, and a variety of sedimentary structures are formed in the substrate. With the increase of the initialization chemical potential of the liquid, the deposition structure gradually becomes a dense network structure with uniform distribution. With the decrease of the critical evaporation rate of liquid, the deposition structure become more obvious after the liquid chemical potential is abrupt. The faster the nanoparticle moves, the less the branched structure in the deposition structure. The sharpness of chemical potential has a great influence on the difference of the structure of the double-scale sedimentary structure. With the greater the sharpness, the difference between the two kinds of sedimentary structures will be greater.
2018, 81(7): 646-652
Abstract:
By injecting drying agent into tight reservoir and drying formation water can reduce water saturation and raise gas seepage capacity of reservoir. On the basis of drying principle of tight gas reservoir, the principle drying experiment of selected drying agent showed that the actual water consumption of drying agent is larger than theoretical water consumption. According to analysis, the actual drying effect is also affected by the thermal effect of chemical reaction. Based on thermochemical theory, this paper studies the thermal effect of reaction between drying agent and water, and the affection of thermal effect for drying tight gas reservoir. Considering the fact that the formation is often under different temperature and pressure, the variation of thermal effect with the temperature and pressure of system is also studied. The results showed that the reaction between selected drying agent and water release about 5.28 kJ/g of heat, it accelerates the reaction speed and also makes the water molecules into vapor phase so as to improve the drying efficiency. The heat of chemical reaction of drying agent is increased with temperature and pressure. The change of temperature and pressure has little influence on the water consumption of heat evaporation.
By injecting drying agent into tight reservoir and drying formation water can reduce water saturation and raise gas seepage capacity of reservoir. On the basis of drying principle of tight gas reservoir, the principle drying experiment of selected drying agent showed that the actual water consumption of drying agent is larger than theoretical water consumption. According to analysis, the actual drying effect is also affected by the thermal effect of chemical reaction. Based on thermochemical theory, this paper studies the thermal effect of reaction between drying agent and water, and the affection of thermal effect for drying tight gas reservoir. Considering the fact that the formation is often under different temperature and pressure, the variation of thermal effect with the temperature and pressure of system is also studied. The results showed that the reaction between selected drying agent and water release about 5.28 kJ/g of heat, it accelerates the reaction speed and also makes the water molecules into vapor phase so as to improve the drying efficiency. The heat of chemical reaction of drying agent is increased with temperature and pressure. The change of temperature and pressure has little influence on the water consumption of heat evaporation.
2018, 81(7): 598-603
Abstract:
A copper(I) complex, [Cu2(bpe)(2, 2'-bipyridine)2(PCHO)2] (BF4)2 (1) (PCHO=o-(diphenylphosphino)benzaldehyde, bpe=1, 2-bis(4-pyridyl)ethylene), has been synthesized and characterized by X-ray crystal structure analysis. The structural analysis shows that the complex consists of two crystallographically independent Cu(I) centers, each of which is four coordinate N3P, forming a distorted-tetrahedral geometry. And π…π stacking interactions lead to the formation of 1D π-chain and 2D π-stacking network. Density of states (DOS) and partial density of states (PDOS) studies indicate that the HOMOs are mainly dominated by the copper d-orbital with admixed PCHO and 2, 2'-bipyridine ligand character, while the LUMOs predominantly consist of the π-electron system of bpe. DFT calculation shows that the energy gap is 1.64eV. Complex 1 has a broad peak at 365nm, which is attributed to dπ-π* absorption. Moreover, the copper (I) complex exhibits weak photoluminescence in acetonitrile solution (508nm), which can be attributed to the MLCT transition.
A copper(I) complex, [Cu2(bpe)(2, 2'-bipyridine)2(PCHO)2] (BF4)2 (1) (PCHO=o-(diphenylphosphino)benzaldehyde, bpe=1, 2-bis(4-pyridyl)ethylene), has been synthesized and characterized by X-ray crystal structure analysis. The structural analysis shows that the complex consists of two crystallographically independent Cu(I) centers, each of which is four coordinate N3P, forming a distorted-tetrahedral geometry. And π…π stacking interactions lead to the formation of 1D π-chain and 2D π-stacking network. Density of states (DOS) and partial density of states (PDOS) studies indicate that the HOMOs are mainly dominated by the copper d-orbital with admixed PCHO and 2, 2'-bipyridine ligand character, while the LUMOs predominantly consist of the π-electron system of bpe. DFT calculation shows that the energy gap is 1.64eV. Complex 1 has a broad peak at 365nm, which is attributed to dπ-π* absorption. Moreover, the copper (I) complex exhibits weak photoluminescence in acetonitrile solution (508nm), which can be attributed to the MLCT transition.
2018, 81(7): 653-656
Abstract:
7-Substituted 2-amine-8, 9-dihydro-7H-pyrido[1, 2, 3-gh]purin derivatives were synthesized by one-pot reaction with 6-substituted-2, 4-diaminopyrido[3, 2-d] pyrimidine, DMF and trichloroacetyl chloride at 25℃ for 2 h. The effects of different substrate, reaction substrate ratio, reaction time and temperature on reaction yield were investigated. The structures of the products were determined by NMR and HRMS, and the possible reaction mechanism was proposed. The reaction conditions are mild and easy to operate.
7-Substituted 2-amine-8, 9-dihydro-7H-pyrido[1, 2, 3-gh]purin derivatives were synthesized by one-pot reaction with 6-substituted-2, 4-diaminopyrido[3, 2-d] pyrimidine, DMF and trichloroacetyl chloride at 25℃ for 2 h. The effects of different substrate, reaction substrate ratio, reaction time and temperature on reaction yield were investigated. The structures of the products were determined by NMR and HRMS, and the possible reaction mechanism was proposed. The reaction conditions are mild and easy to operate.
2018, 81(7): 657-659
Abstract:
A new and efficient Knoevenagel reaction via microwave irradiation to form 5-arylidene-2, 3-diphenylthiazolidin-4-ones is described. Using K2CO3 as dehydrogenase reagents, H2O as solvent, TBAB as the catalyst, a series of 5-arylidene-2, 3-diphenyl-thiazolidin-4-ones were successfully obtained in excellent yields from 2, 3-diphenylthiazolidin-4-ones.
A new and efficient Knoevenagel reaction via microwave irradiation to form 5-arylidene-2, 3-diphenylthiazolidin-4-ones is described. Using K2CO3 as dehydrogenase reagents, H2O as solvent, TBAB as the catalyst, a series of 5-arylidene-2, 3-diphenyl-thiazolidin-4-ones were successfully obtained in excellent yields from 2, 3-diphenylthiazolidin-4-ones.
2018, 81(7): 660-666
Abstract:
Green chemistry is an emerging interdisciplinary field. It is helpful to discuss the characteristics of contemporary disciplines through grasping the development of green chemistry's knowledge system and research situation. This paper takes authoritative Green Chemistry as research object and makes metrology analysis of journal articles through the visualization tools such as CiteSpace and VOSviewer. It is observed that the impact factor and papers of Green Chemistry have grown fast since its publication, and academic research has made a rapid progress. Currently, the core countries, institutions and researchers in this field are concentrated in United States, China, Britain, Germany, Netherlands and so on, and the international cooperation is very frequent. The research hot points of green chemistry include ionic liquid, biomass, catalysis and other topics.
Green chemistry is an emerging interdisciplinary field. It is helpful to discuss the characteristics of contemporary disciplines through grasping the development of green chemistry's knowledge system and research situation. This paper takes authoritative Green Chemistry as research object and makes metrology analysis of journal articles through the visualization tools such as CiteSpace and VOSviewer. It is observed that the impact factor and papers of Green Chemistry have grown fast since its publication, and academic research has made a rapid progress. Currently, the core countries, institutions and researchers in this field are concentrated in United States, China, Britain, Germany, Netherlands and so on, and the international cooperation is very frequent. The research hot points of green chemistry include ionic liquid, biomass, catalysis and other topics.
2018, 81(7): 667-671
Abstract:
Quantum chemistry has developed into a mature and complete discipline nowadays. German theoretical physicist Friedrich Hermann Hund (1896-1997) have laid the groundwork for the establishment and development of quantum chemistry because of his work on the electronic structure of atoms and molecules. Hund have been called one of the founding fathers of modern molecular orbital theory. He is known in the chemistry community for two major contributions:(a) Hund's rules, (b) molecular orbital (MO) theory. This paper introduces the life of Hund, and describes in detail his scientific research process on Hund's rules and molecular orbital theory.
Quantum chemistry has developed into a mature and complete discipline nowadays. German theoretical physicist Friedrich Hermann Hund (1896-1997) have laid the groundwork for the establishment and development of quantum chemistry because of his work on the electronic structure of atoms and molecules. Hund have been called one of the founding fathers of modern molecular orbital theory. He is known in the chemistry community for two major contributions:(a) Hund's rules, (b) molecular orbital (MO) theory. This paper introduces the life of Hund, and describes in detail his scientific research process on Hund's rules and molecular orbital theory.
