+/- 0.4. Oxidation of HOAr-NH2 with [N(C6H4Br)3]*+ is faster, with k congruent with 4 x 107 M-1 s-1. The isotope effect, thermochemical arguments, and the dependence of the rate on driving force (DeltaDeltaG/DeltaDeltaG degrees = 0.53) all indicate that electron transfer from HOAr-NH2 must occur concerted with intramolecular proton transfer from the phenol to the amine (proton-coupled electron transfer
制备氢键
苯酚 2-(
氨基二苯基甲基)-4,6-二叔
丁基苯酚 (HOAr-NH2) 并通过一系列单电子氧化剂在 MeCN 中氧化。产物是
苯氧基自由基,其中
酚质子转移到胺,*OAr-NH3+。HOAr-NH2 和三(
对甲苯基)胺 ([N(tol)3]*+) 生成 *OAr-NH3+ + N(tol)3 的反应具有 Keq = 2.0 +/- 0.5,遵循二阶动力学 k = (1.1 +/- 0.2) x 105 M-1 s-1 (DeltaG = 11 kcal mol-1),主要同位素效应 kH/kD = 2.4 +/- 0.4。HOAr-NH2 与 [N(
C6H4Br)3]*+ 的氧化速度更快,k 与 4 x 107 M-1 s-1 一致。同位素效应、热
化学参数以及速率对驱动力的依赖性(DeltaDeltaG/DeltaDeltaG 度数 = 0。53) 都表明 HOAr-NH2 的电子转