物理化学学报 >> 2005, Vol. 21 >> Issue (08): 929-933.doi: 10.3866/PKU.WHXB20050821

研究简报 上一篇    下一篇

铱(III)离子催化铈(IV)离子氧化四氢糠醇的动力学及机理

宋文玉; 赵荣慧; 降青梅   

  1. 河北大学化学与环境科学学院,河北 保定 071002
  • 收稿日期:2004-12-13 修回日期:2005-03-07 发布日期:2005-08-15
  • 通讯作者: 宋文玉 E-mail:songwenyu@126.com

Catalyzed Oxidation of Tetrahydrofurfuryl Alcohol by Cerium(Ⅳ) in Aqueous Sulphuric Acid Medium

SONG Wen-yu; ZHAO Rong-hui; JIANG Qing-mei   

  1. College of Chemistry and Environmental Science, Hebei University, Baoding 071002
  • Received:2004-12-13 Revised:2005-03-07 Published:2005-08-15
  • Contact: SONG Wen-yu E-mail:songwenyu@126.com

摘要: 在酸性介质中用氧化还原滴定法研究了铈(IV)离子在痕量铱(III)离子催化作用下,于298~313 K区间氧化四氢糠醇(THFA)的反应动力学. 结果表明,反应对铈(IV)离子为一级,对铱(III)离子也为一级,对四氢糠醇的表观反应级数为正分数. 准一级速率常数kobs随[H+]增加而增大,而随[HSO4-]增加而减小. 在氮气保护下,反应能引发丙烯腈聚合,说明在反应中有自由基产生. 通过kobs与[HSO4-]的依赖关系,找到本反应体系的动力学活性物种是Ce(SO4)2,并计算出平衡常数,速控步骤的速率常数及相应的活化参数.

关键词: 铱(III)离子, 铈(IV)离子, 四氢糠醇, 催化剂, 动力学, 机理

Abstract: The kinetics of trace Ir(III) catalyzed oxidation of tetrahydrofurfuryl alcohol(THFA) by Ce(IV) in aqueous sulphuric acid medium was studied by titrimetric technique of redox in the temperature range of 298~313 K. The order was found to be unity with respect to both Ce(IV) and Ir(III), and for tetrahydrofurfuryl alcohol the apparent reaction order was a positive fraction. It was found that the pseudo first order ([THFA]>>[Ce(IV)]) rate constant, kobs, increased with the increase of [H+] but decreased with the increase of [HSO4-]. Under the protection of nitrogen, however, the reaction system could induce polymerization of acrylonitrile, indicating the generation of free radicals. A reasonable mechanism involving a preequilibrium was proposed. From the relation between kobs and [HSO4-], Ce(SO4)2 was found to be the kinetically active species. The equilibrium constants and rate constants of the rate-determining step along with the activation parameters were evaluated.

Key words: Iridium(III) ion, Cerium(IV) ion, Tetrahydrofurfuryl alcohol, Catalyst, Kinetics, Mechanism