Kinetic isotope effects in the Menshutkin-type reaction of benzyl benzenesulfonates with N,N-dimethylanilines. Variation in the transition-state structure
作者:Takashi Ando、Hiroshi Tanabe、Hiroshi Yamataka
DOI:10.1021/ja00319a030
日期:1984.4
secondary ..cap alpha..-tritium isotope effects were measured for the Menschutkin-type reaction of m-bromobenzyl-methylene-/sup 14/C X-substituted benzenesulfonates with Y-substituted N,N-dimethylanilines in acetone at 35/sup 0/C (eq 1; Z = m-Br). The large carbon-14 (/sup 12/k//sup 14/k = 1.117-1.151) and small ..cap alpha..-tritium (/sup H/k//sup T/k = 1.026-1.041) isotope effects were consistent with
对于间溴苄基-亚甲基-/sup 14/C X-取代的苯磺酸盐与 Y-取代的 N,N-二甲基苯胺的 Menschutkin 型反应,测量了初级碳 14 和次级 ..cap α..-氚同位素效应丙酮在 35/sup 0/C (eq 1; Z = m-Br)。大碳 14 (/sup 12/k//sup 14/k = 1.117-1.151) 和小..cap α..-氚 (/sup H/k//sup T/k = 1.026-1.041) 同位素效果与反应的 S/sub N/2 机理一致。当碳同位素效应针对不同 Xs 和固定 Y (p-CH/sub 3/) 的相对速率绘制时,观察到单调趋势,而对于不同 Ys 和固定 X (p-Cl) 观察到钟形)。将结果与未取代的苄基酯的结果进行比较表明,苄基部分上的吸电子 m-Br 基团取代使过渡态更像产物。与未取代系列相比,m-Br 系列的 ..cap α..-