在有机溶剂中进行的酶催化反应

介绍了在有机溶剂中进行酶催化反应的进展,包括在有机溶剂中进行酶催化反应的某些性质、特点及必须遵循的原则,并举例说明了在有机合成中应用的可能性,指出了该领域中尚待深入研究的问题。     

醇与极性有机溶剂间氢键的多核NMR研究

醇是一类重要的有机溶剂,对其结构和性质的研究已有很长历史。由于OH的存在,醇分子间存在着较强的氢键缔合作用,使其结构变得复杂,因而较难对它得到一个很清楚的认识。用NMR方法研究氢键也有几十年历史。早在五十年代,Arnold,Becker等就用~1HNMR研究了EtOH在CCl_4中的行为,测量了化学位移随浓度的变化。Becker认为当醇浓度很稀时,体系中只存在单体-二聚体平衡,井结合IR数据求得了平衡常数及缔合物位移。有     

ORGANO-SOLUBLE FLUORINATED POLYIMIDES DERIVED FROM a,a-BIS(4-AMINO-3,5- DIMETHYLPHENYL)-4′-FLUOROPHENYL METHANE AND VARIOUS AROMATIC DIANHYDRIDES

 Organo-soluble fluorinated polyimides were synthesized by the polycondensation of a new aromatic diamine -bis(4-amino-3,5-dimethylphenyl)-4′-fluorophenyl methane with several aromatic dianhydrides. The one-step polymerization procedure was conducted at 180℃ in m-cresol, producing the polyimides with inherent viscosities of 0.680.76 dL•g1. The polyimides could be soluble not only in polar aprotic solvents, such as N-methyl-2-pyrrolidinone, and N,N-dimethylacetamide, but also in common organic solvents, such as chloroform, cyclopentanone, m-cresol and so on. The polyimide films show excellent transparency with the UV-Vis cut-off lengths of 310360 nm and light transmittances of higher than 80% in the visible region. In addition, the polyimides exhibit good thermal stability with an initial decomposition temperature (Td) higher than 530℃ and have more than 60% of residual weight retentions at 700℃.     

不同溶剂中酶催化合成油酸酯研究初探

对几种非水溶剂中脂肪酶催化合成油酸酯 (油酸乙酯、油酸正辛酯和油酸油酯 )进行了初步考察。结果表明 ,在环己烷、正庚烷和甲苯等有机溶剂中 ,上述酯化反应都有很高的转化率 ;在所考察的实验条件下 ,超临界CO2 中反应的转化率略比上述有机溶剂中的低 ,但该结果已初步显示以超临界CO2 替代有机溶剂合成油酸酯具有很大的应用潜力。     

极性有机溶剂对Y（edta）^-／Nd（edta）^-配合物分离的影响

使用极性有机溶剂对稀土的分离有影响，特别是进一步分离。研究表明，聚丙烯阳离子交换剂能够应用于稀土配合物的稀土分离。在大多数情况下，含有EDTA的Ln^3 配合物的分配系数在水-甲醇混合溶液中比在纯水中大。     

UltiMate 3000 DGLC双三元液相色谱的反梯度补偿技术

反梯度补偿技术是指在色谱柱后进入检测器前加入另一与分析时溶剂组成相同但比例相反的溶剂,使进入检测器的有机溶剂浓度保持不变,从而使雾化条件更加稳定一致,提高检测效果。当使用基于雾化机理的检测器(如电雾式检     

Ferric hydrogensulfate catalyzed aerobic oxidative coupling of 2-naphthols in water or under solvent free conditions

The symmetric oxidative coupling reactions of 2-naphthol derivatives withboth ferric hydrogensulfate in water and silica ferric hydrogensulfate in solvent free conditions were carried out. The advantages of this green procedure are: inexpensive catalyst or co-catalyst, reusability of catalyst, organic solvent-free procedures and simple workup.