氮氧自由基研究(ⅩⅩⅢ)——哌啶氮氧自由基及其氧铵盐与N,N,N′,N′-四甲基对苯二胺在水溶液中的单电子转移反应  

Studies on Nitroxides(XXIII) The Single Electron Transfer Reaction Between Piperidine Nitroxide, Its Oxoammonium salt and N.N.N' ,N'-Tetramethyl p.Phenylenediamine in Aqueous Solution

作　　者：高忠理[1] 张发[1] 刘有成[1] 

机构地区：[1]兰州大学化学系

出　　处：《高等学校化学学报》1989年第7期718-723,共6页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金

摘　　要：ESR波谱和流动-停止UV动力学研究表明,水溶液中2,2,6,6-四甲基-4-羟基哌啶-1-氧自由基1和相应氧铵澳盐2均可将N,N,N′,N′-四甲基对苯二胺(TMPD)氧化为相应自由基正离子TMPD+,2还能将TMPD+进一步氧化为二价正离子TMPD^(2+).TMPD+可发生可逆歧化,其稳定性强烈受介质酸碱性的影响。利用计算机对动力学曲线的模拟测得上述有关反应的速率常数,并讨论了反应机理。The investigation by ESR spectroscopic and flow-stop kinetics UV methods shows that in aqueous solution. 2.2.6 . 6-tetramethyl 4- hydroxylpiperidinyl- 1-oxy radical (1 ) and the corresponding oxoammonium bromide (2) can oxidize N ,N .N'N'-tetramethyl-p-phenylenediamine (TMPD) to its radical cation TMPD+ . which can further be oxidi/ed to the quinonediimine (TMPD2- ). The sta-billity of the radical cation TMPD+ is strongly influenced by the acidity of the medium. The radical ation TMPD+ can undergo a reversible disproportionation teactionwhere TMPD can undergo protonation in two steps and TMPD2+ can further react with hydroxyl an -ion in the medium. The rate constants of the above reaction, k1 and k-1, have also been determined tc be 2 × 103 mol -1 . L . s-1 and 4 × 105 mol-1. L . s-1, respectively by computer simulation on the kinetic curves. The rate constant (k2) for the reaction between 1 and TMPD is determined to be 4. 9× 10-2 mol-1. L . s-1. The related experimental results are discussed and a mechanism of the reaction A proposed.

关 键 词：哌啶氮氧自由基 氧铵盐 动力学 单电子转移反应 N N N′ N′-四甲基对苯二胺 

分 类 号：O621.446[理学—有机化学] O625.631[理学—化学]