...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Indian Journal of Chemistry, Section A. Inorganic, Physical, Theoretical & Analytical >Substituent effects on the spontaneous cleavage of benzyl-gem-dibromides in aqueous solution
【24h】

Substituent effects on the spontaneous cleavage of benzyl-gem-dibromides in aqueous solution

机译：取代基对水溶液中苄基-宝石-二溴化物自发裂解的影响

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The alpha-bromobenzyl cations have been produced in aqueous solution by chemical initiation (solvolysis) of benzyl alpha-gem-dibromides. The solvolysis reactions of benzyl-gem-dibromides in water proceed by a stepwise mechanism through alpha-bromobenzyl carbocation intermediates, which are captured by water to give the corresponding benzaldehydes as the sole detectable products. Rate constant ratios kappa_(Br)/kappa_s (M~(-1)) for partitioning of the carbocation between reaction with bromide ion and reaction with water have been determined by analysis of bromide common ion inhibition of the solvolysis reaction. The rate constants kappa_s (s~(-1)) for the reaction of the cation with solvent water were determined from the experimental values of kappa_(Br)/kappa_(solv), for the solvolysis of the benzyl-gem-dibromides, using kappa_(Br) = 5 X 10~9 M~(-1) s~(-1) for diffusionlimited reaction of bromide ion with benzyl carbocations. Calculation and discussion of selectivities, kappa_(Br)/kappa_s, of the alpha-bromobenzyl cations, activation parameters for solvolysis step and for addition of water to the cation are some of the salient features not reported earlier. Effect of substituents is also discussed in terms of Hammett equation for both the steps.
机译：α-溴苄基阳离子已经在水溶液中通过化学引发（溶剂分解）苄基α-宝石-二溴化物产生。苄基-二溴化物在水中的溶剂分解反应通过α-溴苄基碳正离子中间体的逐步机理进行，该中间体被水捕获，得到相应的苯甲醛作为唯一可检测的产物。通过分析溶剂分解反应中溴离子对离子的抑制作用，确定了碳负离子在与溴离子的反应与与水的反应之间的分配时的速率常数比kappa_（Br）/ kappa_s（M〜（-1））。阳离子与溶剂水反应的速率常数kappa_s（s〜（-1））由kappa_（Br）/ kappa_（solv）的实验值确定，用于溶剂化苄基-锗-二溴化物，方法是kappa_（Br）= 5 X 10〜9 M〜（-1）s〜（-1），用于溴离子与苄基碳阳离子的扩散受限反应。 α-溴苄基阳离子选择性，kappa_（Br）/ kappa_s的计算和讨论，溶剂分解步骤的活化参数以及向阳离子加水的活化参数是先前未报道的一些显着特征。对于两个步骤，还根据Hammett方程讨论了取代基的作用。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号