Effect of Multiple Field Assistance with Reversed Micelles on the Decarboxylation of 6-Nitro-1,2-benzisoxazole-3-carboxylate
作者:Junzo Sunamoto、Kiyoshi Iwamoto、Shinichi Nagamatsu、Hiroki Kondo
DOI:10.1246/bcsj.56.2469
日期:1983.8
Decarboxylation reaction of 6-nitro-1,2-benzisoxazole-3-carboxylate (1) in cationic and anionic reversed micelles has been investigated with particular attention to the microenvironmental effect, such as microviscosity, micropolarity, and microactivity, in the specific and restricted reaction field as provided by reversed micelles. In 0.20 M CTAC/0.32 M H2O/CHCl3 reversed micelles, the reaction was accelerated about 1300-fold compared with that in bulk aqueous solution. Of various surfactant aggregate systems such as aqueous micelle, bilayer, and reversed micelle, the cationic reversed micelle could provide the most effective reaction field for the present decarboxylation reaction. This reaction is never accelerated in an anionic aqueous micelle. However, in the anionic AOT reversed micelle, the reaction was apparently accelerated by both lowering the micropolarity and increasing the microviscosity around the substrate. The unique rate enhancement for the decarboxylation reaction of 1 provided by reversed micelles was interpreted in terms of the “multiple field assistance.”
研究了 6-硝基-1,2-苯并异噁唑-3-羧酸盐(1)在阳离子和阴离子反向胶束中的脱羧反应,特别关注了反向胶束提供的特定和受限反应场中的微环境效应,如微粘度、微泼度和微活性。在 0.20 M CTAC/0.32 M H2O/CHCl3 反向胶束中,反应速度比在大量水溶液中加快了约 1300 倍。在水胶束、双分子层和反向胶束等各种表面活性剂聚合体系中,阳离子反向胶束可为本脱羧反应提供最有效的反应场所。在阴离子水性胶束中,这一反应永远不会加速。然而,在阴离子 AOT 反向胶束中,通过降低微泼度和增加底物周围的微粘度,反应明显加快。反向胶束独特地提高了 1 的脱羧反应速率,这可以用 "多场辅助 "来解释。