环己烷一步催化氧化合成己二酸的动力学和反应机理初步探讨

环己烷在醋酸溶液中,以醋酸钴为催化剂,用氧气一步氧化生成己二酸。 分别进行了反应温度、环己烷浓度、催化剂浓度、溶剂醋酸用量和氧气压力与己二酸生成速度的定量研究,己二酸的生成速度方程为 反应速度常数k的温度效应可用Arrhenius方程来表述,即 lnk=-△E/RT+A视活化能△E=32.7kcal/g-mol 从反应动力学研究,认为环己烷与Co作用生成阳离子自由基(C_6H_(12))的过程是反应的控制步骤,[Co]与[Co]在反应期保持恒定,它们参与了整个反应过程、并起着链载体的作用。

A Study on Kinetics of Oxidation of Cyclohexane to Adipic Acid by One Step Process

The cobalt catalyzed oxidation of cyclohexane in acetic acid solution to adipic acid by pure oxygen has been studied. Under the following conditions of investigation:reaction temperature 80-95℃;concentration of cyclohexane 1.08-2.97 mol/1;concentration of Co(OAc)2.4H2O 0.0301-0.0803 mol/l; acetic acid/cyclohexane 10-20(by weight) and oxygen pressure, 5-30 kg/cm2, it is shown that the kinetics of adipic acid formation can be expressed by the following equationwhere r-rate of formation of adipic acid [C6H12]-concentration of cyclohexane [Co]-concentration of cobaltic ion[Co#]- concentration of cobaltous ion [po2]-pressure of oxygen k-rate constant of reaction.The temperature dependance of the rate constant can be correlated with the Arrhenius equationThe apparant activited energy △E is 32.74 kcal/g-mol.A tentative reaction mechanism is offered to explain the phenomena observed, in which the rate determining step is the formation of cation radical species through the interaction of Co and cyclohexane molecules with Co and Co serving as chain carriers.