Distribution behavior of mandelic acid enantiomers was examined in a two-phase aqueous-organic solvent mixture containing L-tartaric esters. The influences of pH, length of alkyl chain of L-tartraic esters, organic so...Distribution behavior of mandelic acid enantiomers was examined in a two-phase aqueous-organic solvent mixture containing L-tartaric esters. The influences of pH, length of alkyl chain of L-tartraic esters, organic solvents and concentrations of phosphate salt on partition coefficient(K) and separation factor(α) were investigated. The results show that L-tartaric esters studied all form more stable diastereomeric complexes with D-enantiomer than with L-enantiomer. With rise of pH, K decrease, but α increase. With addition of length of alkyl chain of L-tartaric esters, K and α decrease. Organic solvents and concentrations of phosphate salt also show a great influence on K and α. K L, K D and α are 2.523, 2.674 and 1.06, respectively, when mandelic acid enantiomers were extracted by di-O-pentyl-L-tartaric ester in n-decanol at pH=2.3.展开更多
Based on chiral ligand exchange, the distribution behavior of mandelic acid enantiomers in the two-phase system containing copper ion(Ⅱ)(Cu2+) and N-n-dedecane-L-hydroxyproline (L), was studied. At different pH, the ...Based on chiral ligand exchange, the distribution behavior of mandelic acid enantiomers in the two-phase system containing copper ion(Ⅱ)(Cu2+) and N-n-dedecane-L-hydroxyproline (L), was studied. At different pH, the partition of Cu2+ in the two-phase system containing N-n-dedecane-L-hydroxyproline, was investigated. The formation constant of binary cpmplex(Li2Cu) was obtained by regression. The influence of pH, concentrations of Cu2+ and chiral ligand, and solvents on partition coefficients(K) and separation factor(α), was discussed. The experimental results show that Li forms more stable ternary complex with D-mandelic acid than with L- mandelic acid. There is a large influence of pH on K and α. At low pH values (<3.5), formation of binary complexes is thermodynamically unfavourable. K and α are best when pH values are above 3.5 and the molar ratio of chiral ligand to Cu2+ is 2:1. At the same time, solvents influence K and α very much.展开更多
以L aC l3.7H2O替代传统液体无机酸为催化剂,以合成异丁酸正丁酯为探针反应考察催化酯化反应的优化条件,并在此条件下合成了多种异丁酸酯,比较了不同催化剂对催化合成异丁酸正丁酯的影响。实验结果表明,L aC l3.7H2O对酯化反应具有良好...以L aC l3.7H2O替代传统液体无机酸为催化剂,以合成异丁酸正丁酯为探针反应考察催化酯化反应的优化条件,并在此条件下合成了多种异丁酸酯,比较了不同催化剂对催化合成异丁酸正丁酯的影响。实验结果表明,L aC l3.7H2O对酯化反应具有良好的催化活性,并能避免液体无机酸催化剂所引起的弊端,异丁酸正丁酯的酯化率可达96.5%。且催化剂易回收,反应后处理简单,无废酸排放,是一种环境友好型催化剂。展开更多
文摘Distribution behavior of mandelic acid enantiomers was examined in a two-phase aqueous-organic solvent mixture containing L-tartaric esters. The influences of pH, length of alkyl chain of L-tartraic esters, organic solvents and concentrations of phosphate salt on partition coefficient(K) and separation factor(α) were investigated. The results show that L-tartaric esters studied all form more stable diastereomeric complexes with D-enantiomer than with L-enantiomer. With rise of pH, K decrease, but α increase. With addition of length of alkyl chain of L-tartaric esters, K and α decrease. Organic solvents and concentrations of phosphate salt also show a great influence on K and α. K L, K D and α are 2.523, 2.674 and 1.06, respectively, when mandelic acid enantiomers were extracted by di-O-pentyl-L-tartaric ester in n-decanol at pH=2.3.
文摘Based on chiral ligand exchange, the distribution behavior of mandelic acid enantiomers in the two-phase system containing copper ion(Ⅱ)(Cu2+) and N-n-dedecane-L-hydroxyproline (L), was studied. At different pH, the partition of Cu2+ in the two-phase system containing N-n-dedecane-L-hydroxyproline, was investigated. The formation constant of binary cpmplex(Li2Cu) was obtained by regression. The influence of pH, concentrations of Cu2+ and chiral ligand, and solvents on partition coefficients(K) and separation factor(α), was discussed. The experimental results show that Li forms more stable ternary complex with D-mandelic acid than with L- mandelic acid. There is a large influence of pH on K and α. At low pH values (<3.5), formation of binary complexes is thermodynamically unfavourable. K and α are best when pH values are above 3.5 and the molar ratio of chiral ligand to Cu2+ is 2:1. At the same time, solvents influence K and α very much.
文摘以L aC l3.7H2O替代传统液体无机酸为催化剂,以合成异丁酸正丁酯为探针反应考察催化酯化反应的优化条件,并在此条件下合成了多种异丁酸酯,比较了不同催化剂对催化合成异丁酸正丁酯的影响。实验结果表明,L aC l3.7H2O对酯化反应具有良好的催化活性,并能避免液体无机酸催化剂所引起的弊端,异丁酸正丁酯的酯化率可达96.5%。且催化剂易回收,反应后处理简单,无废酸排放,是一种环境友好型催化剂。
