The influence of the nitro-group upon side-chain reactivity. Part IV. The inhibition of α-proton extraction from 4-nitrobenzyl chloride by the steric effect of methyl groups in the 3- and 5-positions
作者:D. M. Doleib、Y. Iskander
DOI:10.1039/j29670001154
日期:——
The fast α-proton extraction from 4-nitrobenzyl chloride by alkali in dioxan, leading to the formation of 4,4′-dinitrostilbene by the α-E1cB mechanism (the rate-determining step is formation of a carbene intermediate), is greatly retarded by one methyl group in the 3-position and completely inhibited by two methyl groups in the 3- and 5-positions; instead, alcohols and ethers are formed by the SN2
由4-硝基苄基氯的快速α-质子萃取通过在二恶烷碱,导致由α-形成4,4'-二硝基二的ë 1的cB机构(速率决定步骤是形成卡宾中间的),是在3-位被一个甲基极大地阻滞,而在3-和5-位被两个甲基完全抑制;而是由S N形成醇和醚2通过碱和所形成的醇盐置换卤素。动力学研究以及对Arrhenius参数的评估,无论是单独还是在添加的醇盐存在下,在二恶烷中用碱将氯化物与氯化物一起使用,都清楚地表明了甲基的空间效应。氯化物和相关结构的红外和紫外光谱对结果产生了很大的影响。