The ring opening of β-sultam v/a an H2O-assisted ammonolysis process was studied by using Density Functional Theory（DFT） method at the B3LYP/6-31G level as a further step in the theoretical investigation of the amm...The ring opening of β-sultam v/a an H2O-assisted ammonolysis process was studied by using Density Functional Theory（DFT） method at the B3LYP/6-31G level as a further step in the theoretical investigation of the ammonolysis reaction of β-sultams. The calculated pathways are analogous to those previously described for the non-assisted ammonolysis reaction. Solvent effects were assessed by using the polarized continuum model（PCM） method. The results show that mode 1 and pathway a in channel Ⅱ are the most favorable ones in both the cases. The energy barrier of the cleavage of C-S bonds producing P1 is the highest among all the energy barriers. The presence of a solvent in the continuum model disfavors the reaction, whereas the participation of water in the ammonolysis reaction plays a positive role and reduces the active energy greatly. The relative energies of all the transition states in the assisted ammonolysis are 20-80 kJ/mol lower than those for the non-assisted reaction.展开更多
To understand the reaction behaviour of the reactive dye with amino groups on protein fibres,the reaction kinetics of competitive hydrolysis and ammonolysis of a monochlorotriazina reactive dye were studied at 50-80℃...To understand the reaction behaviour of the reactive dye with amino groups on protein fibres,the reaction kinetics of competitive hydrolysis and ammonolysis of a monochlorotriazina reactive dye were studied at 50-80℃ and pH=8-10 by high performance liquid chromatography(HPLC).The results showed the pseudo-first-order phenomenon for the general reaction of concurrent hydrolysis and ammonolysis of the dyes.The ammonolysis reaction was always faster than the hydrolysis reaction in the range of temperature and pH employed,but the preference for ammonolysis to hydrolysis reaction decreased with the increase of temperature and pH value.The ratios of ammonolysis/hydrolysis rate constant reduced from 17.6 to 5.4 when the temperature increased from 50 to 80℃ in pH=10,and from 7.2 to 5.4 when the pH value increased from 8 to 10 at 80℃.展开更多
Studying urea formation by ammonolysis of propylene carbonate in a liquid phase showed that this process is two-stage, and proceeds through preferred formation of 2-hydroxypropyl carbamate, besides, the rate of the fi...Studying urea formation by ammonolysis of propylene carbonate in a liquid phase showed that this process is two-stage, and proceeds through preferred formation of 2-hydroxypropyl carbamate, besides, the rate of the first stage is much higher than the rate of the second stage （urea formation）. With the aid of the HPLC and HPLC/MS methods found some other intermediate products and offered consecutive-parallel scheme of the process. The obtained results explain the composition of impurities obtained during the production of the 13C-urea for diagnostic breath tests.展开更多
Hexaphenyl cyclotrisilazane was synthesized from diphenyl dichlorosilane and ammonia with toluene as solvent.The effects of input material concentration, reaction temperature, ammonia flow rate and separation method o...Hexaphenyl cyclotrisilazane was synthesized from diphenyl dichlorosilane and ammonia with toluene as solvent.The effects of input material concentration, reaction temperature, ammonia flow rate and separation method on product yield were investigated.The structure of hexaphenyl cyclotrisilazane was characterized with FTIR and XRD.It was found that when diphenyl dichlorosilane concentration was 0.96 mol·L -1 , reaction temperature was 111—112℃,NH3 flow rate was 0.02 m3·h -1 , the yield of hexaphenyl cyclotrisilazane could reach 91.1%.Using ammonia water was better than hot filtration to weed out ammonium chloride at the period of product separation.It enhanced separation efficiency and simplified the process.At the same time it also decreased pollution to the environment by reducing volatile matter of toluene.展开更多
A novel reaction\|enzymatic ammonolysis discovered in the mid of 1990s has been demonstrated to be a very promising alternative in the preparation of optically pure compounds. The effects of organic solvent, initial w...A novel reaction\|enzymatic ammonolysis discovered in the mid of 1990s has been demonstrated to be a very promising alternative in the preparation of optically pure compounds. The effects of organic solvent, initial water activity, temperature and additives on lipase Novozym435\|catalyzed enantioselective ammonolysis of racemic phenylglycine methyl ester were investigated systematically in this paper. Enzymatic reaction of ammonolysis showed higher activity and enantioselectivity than the corresponding reaction of hydrolysis and alcoholysis.展开更多
文摘The ring opening of β-sultam v/a an H2O-assisted ammonolysis process was studied by using Density Functional Theory（DFT） method at the B3LYP/6-31G level as a further step in the theoretical investigation of the ammonolysis reaction of β-sultams. The calculated pathways are analogous to those previously described for the non-assisted ammonolysis reaction. Solvent effects were assessed by using the polarized continuum model（PCM） method. The results show that mode 1 and pathway a in channel Ⅱ are the most favorable ones in both the cases. The energy barrier of the cleavage of C-S bonds producing P1 is the highest among all the energy barriers. The presence of a solvent in the continuum model disfavors the reaction, whereas the participation of water in the ammonolysis reaction plays a positive role and reduces the active energy greatly. The relative energies of all the transition states in the assisted ammonolysis are 20-80 kJ/mol lower than those for the non-assisted reaction.
文摘To understand the reaction behaviour of the reactive dye with amino groups on protein fibres,the reaction kinetics of competitive hydrolysis and ammonolysis of a monochlorotriazina reactive dye were studied at 50-80℃ and pH=8-10 by high performance liquid chromatography(HPLC).The results showed the pseudo-first-order phenomenon for the general reaction of concurrent hydrolysis and ammonolysis of the dyes.The ammonolysis reaction was always faster than the hydrolysis reaction in the range of temperature and pH employed,but the preference for ammonolysis to hydrolysis reaction decreased with the increase of temperature and pH value.The ratios of ammonolysis/hydrolysis rate constant reduced from 17.6 to 5.4 when the temperature increased from 50 to 80℃ in pH=10,and from 7.2 to 5.4 when the pH value increased from 8 to 10 at 80℃.
文摘Studying urea formation by ammonolysis of propylene carbonate in a liquid phase showed that this process is two-stage, and proceeds through preferred formation of 2-hydroxypropyl carbamate, besides, the rate of the first stage is much higher than the rate of the second stage （urea formation）. With the aid of the HPLC and HPLC/MS methods found some other intermediate products and offered consecutive-parallel scheme of the process. The obtained results explain the composition of impurities obtained during the production of the 13C-urea for diagnostic breath tests.
文摘Hexaphenyl cyclotrisilazane was synthesized from diphenyl dichlorosilane and ammonia with toluene as solvent.The effects of input material concentration, reaction temperature, ammonia flow rate and separation method on product yield were investigated.The structure of hexaphenyl cyclotrisilazane was characterized with FTIR and XRD.It was found that when diphenyl dichlorosilane concentration was 0.96 mol·L -1 , reaction temperature was 111—112℃,NH3 flow rate was 0.02 m3·h -1 , the yield of hexaphenyl cyclotrisilazane could reach 91.1%.Using ammonia water was better than hot filtration to weed out ammonium chloride at the period of product separation.It enhanced separation efficiency and simplified the process.At the same time it also decreased pollution to the environment by reducing volatile matter of toluene.
文摘A novel reaction\|enzymatic ammonolysis discovered in the mid of 1990s has been demonstrated to be a very promising alternative in the preparation of optically pure compounds. The effects of organic solvent, initial water activity, temperature and additives on lipase Novozym435\|catalyzed enantioselective ammonolysis of racemic phenylglycine methyl ester were investigated systematically in this paper. Enzymatic reaction of ammonolysis showed higher activity and enantioselectivity than the corresponding reaction of hydrolysis and alcoholysis.
