论文部分内容阅读
本工作研究了不同链长羧酸的对硝基及其它取代苯酯与不同链长硫醇间的酯交换反应动力学,所用溶剂为Me_2SO-H_2O,CH_3COCH_3-H_2O及C_2H_5OH-H_2O混合体系。在Me_2SO-H_2O中,长链硫醇和长链酯之间的反应速度比相应的短链硫醇与短链酯,长链硫醇与短链酯及短链硫醇和长链酯之间的反应速度快得多。这是由于疏水-亲脂相互作用使两个反应物分子互相接近而引起的加速效应,这种接近效应依赖于溶剂组成。在Me_2SO-H_2O中,接近效应随Me_2SO含量增加而迅速减小;在良溶剂体系中,不存在接近效应。在Φ=0.45Me_2SO中,十二硫醇相对于丁硫醇的加速效应约为160倍。
In this work, the kinetics of transesterification of p-nitro and other substituted phenyl esters with different chain length mercaptans were studied. The solvents used were Me_2SO-H_2O, CH_3COCH_3-H_2O and C_2H_5OH-H_2O mixed systems. In Me_2SO-H_2O, the reaction rate between the long-chain thiol and the long-chain ester is faster than the corresponding reaction between the short-chain thiol and the short-chain ester, the long-chain thiol and the short-chain ester and the short-chain thiol and the long-chain ester Much faster. This is due to the accelerating effect caused by the hydrophobic-lipophilic interactions that bring the two reactant molecules close to each other. This proximity depends on the solvent composition. In Me_2SO-H_2O, the proximity effect decreases rapidly with the increase of Me_2SO content; in the good solvent system, there is no proximity effect. In Φ = 0.45Me_2SO, the accelerating effect of dodecanethiol relative to butanethiol is about 160 times.