| 氢过碘酸）合银（III）配离子氧化L-脯氨酸的反应动力学及机理 |
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| 引用本文： | 孙汉文,石红梅,申世刚,康维钧,郭志峰.氢过碘酸）合银（III）配离子氧化L-脯氨酸的反应动力学及机理[J].中国化学,2008,26(4):615-620. |
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| 作者姓名： | 孙汉文 石红梅 申世刚 康维钧 郭志峰 |
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| 作者单位： | 河北大学化学与环境科学学院，河北保定，071002 河北医科大学公共卫生学院，河北石家庄，050017 |
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| 摘 要： | L-脯氨酸独有的亚胺基使其在生物医药领域具有许多独特的功能，并广泛用作不对称有机化合物合成的有效催化剂。本文在碱性介质中研究了二（氢过碘酸）合银（III）配离子氧化 L-脯氨酸的反应。经质谱鉴定，脯氨酸氧化后的产物为脯氨酸脱羧生成的 γ-氨基丁酸盐；氧化反应对脯氨酸及Ag(III) 均为一级；二级速率常数 k′ 随 IO4-] 浓度增加而减小，而与 OHˉ] 的浓度几乎无关；推测反应机理应包括 Ag(HIO6)2]5-与 Ag(HIO6)(H2O)(OH)]2-之间的前期平衡，两种Ag（III）配离子均作为反应的活性组分，在速控步被完全去质子化的脯氨酸平行地还原，两速控步对应的活化参数为： k1 (25 oC)＝1.87±0.04（mol·L-1)-1s-1,∆ H1≠＝45±4 kJ · mol-1, ∆ S1≠＝-90±13 J· K-1·mol-1 and k2 (25 oC) ＝3.2±0.5（mol·L-1)-1s-1, ∆ H2≠＝34±2 kJ · mol-1, ∆ S2≠＝-122 ±10 J· K-1·mol-1。本文第一次发现 Ag(HIO6)2]5-配离子也具有氧化反应活性。
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| 关 键 词： | L-脯氨酸 氧化 动力学及机理 Ag(III) |
| 收稿时间： | 2007-8-27 |
| 修稿时间： | 2007-11-28 |
Kinetics and Mechanism for Oxidation of L‐Proline by Bis(hydrogen periodato)argentate(III) Complex Anion |
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| Han‐Wen SUN,Hong‐Mei SHI,Shi‐Gang SHEN,Wei‐Jun KANG,Zhi‐Feng GUO.Kinetics and Mechanism for Oxidation of L‐Proline by Bis(hydrogen periodato)argentate(III) Complex Anion[J].Chinese Journal of Chemistry,2008,26(4):615-620. |
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| Authors: | Han‐Wen SUN Hong‐Mei SHI Shi‐Gang SHEN Wei‐Jun KANG Zhi‐Feng GUO |
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| Institution: | 1. College of Chemistry and Environmental Science, Hebei University, Baoding, Hebei 071002, China;2. School of Public Health, Hebei Medical University, Shijiazhuang, Hebei 050017, China |
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| Abstract: | Oxidation of L‐proline by bis(hydrogen periodato)argentate(III) complex anion, Ag(HIO6)2]5?, has been studied in aqueous alkaline medium in the temperature range of 25–40 °C by use of conventional spectrophotometry. Under the conditions for kinetic measurements, the oxidation results in decarboxylation of proline, giving rise to γ‐aminobutyrate as identified by mass spectrometry. The oxidation kinetics is first order with respect to the silver(III) and proline concentrations; the second‐order rate constants, decreasing with increasing periodate], are essentially independent of OH?]. The kinetic results were interpreted in terms of a reaction mechanism which involves a pre‐equilibrium between Ag(HIO6)2]5? and Ag(HIO6)(H2O)(OH)]2?, a mono‐periodate coordinated silver(III) complex. Both Ag(III) complexes are reduced parallelly by the fully deprotonated form of proline in rate‐determining steps (described by k1 for the former Ag(III) and k2 for the latter one). The determined rate constants and their associated activation parameters are k1(25 °C) = (1.87±0.04) L·mol?1·s?1, ΔH1≠= (45±4) kJ· mol?1, ΔS1≠= (?90±13) J·K?1·mol?1 and k2(25 °C) = (3.2±0.5) L·mol?1·s?1, ΔH2≠= (34±2) kJ·mol?1, ΔS2≠= (?122±10) J·K?1·mol?1. This is also the first time to find that Ag(HIO6)2]5? is also reactive toward a particular reductant and shows a lower reactivity than Ag(HIO6)(OH)(H2O)]2?. |
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| Keywords: | L‐proline oxidation kinetics and mechanism Ag(III) |
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