Ligand dependence in the copper-catalyzed oxidation of hydroquinones.
Ligand dependence in the copper-catalyzed oxidation of hydroquinones.
复制标题
铜催化氢醌氧化中的配体依赖性。
DOI：
10.1016/j.abb.2004.11.025
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Sayre,LawrenceM
中科院分区：
文献类型：
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作者：
Mandal,Subrata;Kazmi,NajamH;Sayre,LawrenceM
过渡金属氧化对苯二酚是一种重要的生理反应，在磷酸盐缓冲液中，铜（II）能有效地催化该反应。本文报道的在单独的磷酸盐缓冲液中的研究表明，在不存在配位配体的情况下，铜（II）是无效的催化剂，但是1，10-菲咯啉和组胺促进铜（II）介导的对苯二酚及其2，5-和2，6-二叔丁基类似物氧化成相应的苯醌。PBS中高浓度的氯化物是使铜（II）在该系统中发挥作用的关键因素。尽管铜（II）的双浴铜灵二磺酸盐配合物（BC）2Cu（II）是一种强化学计量氧化剂，但化学计量量的铜（II）在除BC以外的配体存在下在厌氧条件下氧化对苯二酚非常缓慢。因此，需氧操作的快速铜（II）催化反应不涉及通过对苯二酚将铜（II）简单乒乓还原为铜（I）和通过O2再氧化铜（I）。
Transition metal-mediated oxidation of hydroquinones is an important physiologic reaction, and copper(II) effectively catalyzes the reaction in phosphate-buffered saline (PBS). Studies reported herein in phosphate buffer alone demonstrate that copper(II) is an ineffective catalyst in the absence of coordinating ligands, but that 1,10-phenanthroline and histamine facilitate the copper(II)-mediated oxidation of hydroquinone and its 2,5- and 2,6-di-tert-butyl analogs to the corresponding benzoquinones. The high concentration of chloride in PBS is the key element that allows copper(II) to work in this system. Although the bis-bathocuproine disulfonate complex of Cu(II), (BC)2Cu(II), is a strong stoichiometric oxidant, stoichiometric amounts of copper(II) in the presence of ligands other than BC oxidize hydroquinones very slowly under anaerobic conditions. Thus, the rapid copper(II)-catalyzed reaction operating aerobically does not involve a simple ping-pong reduction of copper(II) to copper(I) by hydroquinone and reoxidation of copper(I) by O2.