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在酸性介质中用氧化还原滴定法研究了铈(IV)离子在铬(III)离子催化作用下,于25～40℃区间氧化四氢糠醇的反应动力学.结果表明反应对铈(IV)和四氢糠醇均为一级.准一级速率常数kobs随催化剂[Cr(III)]增加而增大,亦随[H+]增加而增大,而随[HSO-4]增加而减小.在氮气保护下,反应不能引发丙烯酰胺聚合,说明在反应中没有自由基产生.提出了催化剂、底物和氧化剂间生成双核加合物的反应机理.通过kobs与HSO-4的依赖关系,并结合Ce(IV)在溶液中的平衡,找到了本反应体系的动力学活性物种是Ce(SO4)2.还计算出一些速率常数及相应的活化参数.
The kinetics of the oxidation of tetrahydrofurfuryl alcohol with cerium (IV) ions at 25 ~ 40 ℃ under the catalysis of chromium (III) ion was studied by means of redox titration in acid medium. The results showed that the reaction kinetics of the reaction of cerium (IV) Tetrahydrofurfuryl alcohol were all level 1. The quasi-first-order rate constant kobs increased with the increase of catalyst [Cr (III)] and also increased with the increase of [H +] and decreased with the increase of [HSO-4] Under the protection of nitrogen, the reaction can not initiate the polymerization of acrylamide, indicating that there is no free radical generation in the reaction.The reaction mechanism between the binuclear adduct formed by the catalyst, the substrate and the oxidant is proposed.Through the relationship between kobs and HSO-4, The equilibrium of Ce (IV) in solution was found to be Ce (SO4) 2, a kinetic active species of the present reaction system. Some rate constants and corresponding activation parameters were also calculated.