物理化学学报 >> 2007, Vol. 23 >> Issue (03): 409-413.doi: 10.3866/PKU.WHXB20070324

研究简报 上一篇    下一篇

二(氢过碘酸)合银(III)配离子氧化愈创甘油醚的反应动力学及机理

申世刚;石红梅;孙汉文   

  1. (河北大学化学与环境科学学院, 河北省分析科学重点实验室, 河北 保定 071000)
  • 收稿日期:2006-09-14 修回日期:2006-09-29 发布日期:2007-03-07
  • 通讯作者: 申世刚 E-mail:shensg@mail.hbu.edu.cn

Mechanism and Kinetics of Guaifenesin Oxidation by Bis(hydrogen periodato)argentate(III) Complex Anion

SHEN Shi-Gang;SHI Hong-Mei;SUN Han-Wen   

  1. (Key Laboratory of Analytical Science and Technology of Hebei Province, College of Chemistry and Environmental Science, Hebei University, Baoding 071000, Hebei Province, P. R. China)
  • Received:2006-09-14 Revised:2006-09-29 Published:2007-03-07
  • Contact: SHEN Shi-Gang E-mail:shensg@mail.hbu.edu.cn

摘要: 在碱性介质中, 用传统的分光光度法研究了Ag(III)配离子, 即[Ag(HIO6)2]5-, 氧化药物分子愈创甘油醚的动力学及其机理. 用质谱鉴定了氧化产物;反应对Ag(III) 和愈创甘油醚均为一级;在温度25.0-40.0 ℃范围内, 通过分析[OH-]和[IO-4]tot对反应速率的影响, 二级速率常数有以下表达式:k′=(ka+kb[OH-])K1/{f([OH-])[IO-4]tot+K1}, 在25.0 ℃及离子强度0.30 mol·L-1时, 对此反应有ka=(2.6±1.2)×10-2 mol-1·L·s-1, kb=(2.8±0.1) mol-2·L2·s-1, 及K1=(4.1±0.4)×10-4 mol·L-1, 求出了涉及ka, kb的活化参数, 并据此推出反应机理为反应体系中的[Ag(HIO6)2]5-配离子在前期平衡后, 反应活性中心与药物分子形成Ag(III)-过碘酸-愈创甘油醚分子三元配合物, 配位甘油醚分子通过两个平行途径将两电子传递给中心原子Ag:一个途径无OH-离子参与, 另一途径有OH-参与完成.

关键词: 愈创甘油醚, Ag(III), 氧化, 动力学, 机理

Abstract: Oxidation of the drug guaifenesin by a Ag(III) complex anion, [Ag(HIO6)2]5-, was studied in aqueous alkaline medium by using spectrophotometry. The major oxidation product of guaifenesin was identified by mass spectrometry. The oxidation reaction displayed an overall second-order kinetics: first-order with respect to both Ag(III) and guaifenesin. Variations of [OH-] and [IO-4]tot had a significant influence on the reaction rates, where [IO-4]tot denotes the total concentration of periodate added externally. An empirical rate expression, k′=(ka+kb[OH-])K1/{f([OH-])[IO-4]tot+K1}, was derived, where ka=(2.6±1.2)×10-2 mol-1·L·s-1, kb=(2.8±0.1) mol-2·L2·s-1, and K1=(4.1±0.4)×10-4 mol·L-1 at 25.0 ℃ and ionic strength of 0.30 mol·L-1. Activation parameters associated with ka and kb were also derived. A mechanism involving the [Ag(HIO6)(OH)(H2O)]2- as the reactive species of the oxidant was proposed. Guaifenesin and the reactive species reversibly formed a complex, which decomposed by two parallel slow steps to give rise to the products: one pathway was spontaneous and the other was assisted by a hydroxide ion.

Key words: Guaifenesin, Ag(III), Oxidation, Kinetics, Mechanism