.alpha.-Deuterium isotope effects in benzyl halides. 2. Reaction of nucleophiles with substituted benzyl bromides. Evidence for a change in transition-state structure with electron-donating substituents
作者:V. P. Vitullo、J. Grabowski、S. Sridharan
DOI:10.1021/ja00541a014
日期:1980.10
the following substrates and nucleophiles: p-methoxybenzyl bromide (Et/sub 3/N, SCN/sup -/, N/sub 3//sup -/, OH/sup -/, S/sub 2/O/sub 3//sup 2 -/), benzyl bromide (Et/sub 3/N, SCN/sup -/, N/sub 3//sup -/, OH/sup -/, S/sub 2/O/sub 3//sup 2 -/), and p-nitrobenzyl bromide (Et/sub 3/N, SCN/sup -/, N/sub 3//sup -/, S/sub 2/O/sub 3//sup 2 -/). In nearly all cases the second-order rate constant for each nucleophile
速率和 ..cap α..-D 同位素效应已确定为以下底物和亲核试剂:对甲氧基苄基溴(Et/sub 3/N、SCN/sup -/、N/sub 3//sup -/、 OH/sup -/, S/sub 2/O/sub 3//sup 2 -/), 溴化苄 (Et/sub 3/N, SCN/sup -/, N/sub 3//sup -/, OH /sup -/, S/sub 2/O/sub 3//sup 2 -/), 和对硝基苄基溴 (Et/sub 3/N, SCN/sup -/, N/sub 3//sup -/ , S/sub 2/O/sub 3//sup 2 -/)。在几乎所有情况下,每个亲核试剂的二级速率常数都经过未取代化合物的最小值,而 ..cap α..-D 同位素在 p-NO/sub 2/ > pH > p-OCH 序列中单调增加/sub 3/。这些结果与 S/sub N/2 过渡态越