【摘要】 研究了二苯基二氯硅烷与双酚-A在等克分子比条件下的缩聚反应动力学。采用熔融缩聚时反应速率规律性复杂,结果无法处理;而用萘、二苯醚、苯乙酮等溶剂稀释至一定程度后,前期反应动力学呈现二级反应规律。当温度相同时,溶剂极性越大,反应速率越快;在一定温度范围内反应速率常数的对数与绝对温度的倒数标绘呈线性关系,获得在萘、二苯醚、苯乙酮中缩聚反应的活化能分别为:17.1千卡/克分子,24.8千卡/克分子,10.3千卡/克分子。Lewis碱及其盐对此反应有显著的催化效应。验证了缩聚反应过程中体系极性改变时,反应速率即发生对应的变化,阐明了熔融缩聚反应速率不稳定的原因。提出了反应系按S_N2机理进行。更多还原

【Abstract】 The kinetics of the polycondensation between diphenyl-dichlorosilane and bisphenol-A in equal mole ratio has been studied. As the velocity of the polycondensation in the molten state is unstable, the kinetic order can not be evaluated. However, after dilution with solvents such as naphthalene, diphenyl ether, acetophenone, etc. to certain degree, the kinetics of the polycondensation in the initial stage followed a second order reaction. Furthermore, at the same temperature, the stronger is the polarity of the solvent, the greater is the reaction rate. By plotting the logarithm of rate constants in certain range of temperatures against the reciprocal of the absolute temperature, a linear relationship is obtained. The activation energy of the polycondensation in naphthalene, diphenyl ether, and acetophenone was found to be 17.1, 24.8 and 10.3 kcal/mole respectively. The reaction may be catalysed by the Lewis bases and their salts. It is assumed that the complexity of the polycondensation kinetics in the molten state is a manifestation of the changing reaction rate due to the changing polarity of the polycondensation system. An SN2 mechanism for the reaction has been suggested.更多还原