N,N-二甲基羟基胺与V(Ⅴ)氧化还原反应动力学及机理研究

Kinetics and Mechanism of Redox Reaction Between N,N-Dimethylhydroxylamine and Vanadium(Ⅴ)

在 HNO3溶液中研究了 N ,N -二甲基羟基胺 (DMHA)与 V( )氧化还原反应动力学 .通过考察溶液酸度、还原剂浓度、离子强度和温度等因素对反应过程的影响 ,获得动力学速率方程为 -d[V( ) ]/ dt=k[V( ) ][DMHA],在 2 5.2℃ ,μ=0 .976mol/ L时 ,反应速率常数 k=(9.95± 1 .0 ) L2 / (mol2· s) ;反应活化能 ΔE=2 2 .1 k J/ mol;依据氮氧自由基的

The kinetics and mechanism of the redox reaction between N,N dimethylhydroxylamine(DMHA) and vanadium(Ⅴ) in nitric acid medium at 25 2 ℃ have been studied by spectrophotometry. By investigating the influences of the DMHA concentration, solutio acidity and reaction temperature on the reaction, the reaction rate equation is found to be -d[V(Ⅴ)]/d t = k [V(Ⅴ)][DMHA] where the k is calculated to be (9 95±1 0) L 2/(mol 2·s), Δ E =22 1 kJ/mol under experiment conditions.A single electron transfer mechanism has been suggested based on the ESR results of (CH 3) 2N·O radical. The following reaction is the rate controlling step: [HO—V—O…H…O—N(CH 3) 2] 2+ (CH 3) 2N·O+H 2O+VO 2+