Steric effects on rates of dehalogenation of anion radicals derived from substituted nitrobenzyl halides
作者:Robert K. Norris、Steven D. Barker、P. Neta
DOI:10.1021/ja00323a013
日期:1984.5
One-electron reduction of nitrobenzyl halides produces the anion radicals, which subsequently undergo dehalogenation to form nitrobenzyl radicals. The rate constants for these processes have been studied by pulse radiolysis in aqueous alcoholic solutions. ..cap alpha..-Substitution with a methyl group increases the rate of dehalogenation by weakening the C-X bond. On the other hand, substitution with
硝基苄基卤化物的单电子还原产生阴离子自由基,随后进行脱卤以形成硝基苄基自由基。这些过程的速率常数已通过在酒精水溶液中的脉冲辐解进行了研究。..cap alpha..-用甲基取代通过削弱CX键来提高脱卤率。另一方面,发现用叔丁基取代可显着降低脱卤速率。由于预计叔丁基不会增加 CX 键的离解能,因此可以得出结论,它的作用是空间相互作用的结果,它使 CX 键向环平面旋转,从而减少了该键与环之间的重叠。 .pi.. 系统并减慢 tra