作者:Hilton M. Weiss、Kim M. Touchette
DOI:10.1039/a703570e
日期:——
The addition of 0.1 M quaternary ammonium halide to a solution of 20% trifluoroacetic acid in methylene chloride causes a large rate increase in the reaction of simple alkenes leading to a mixture of alkyl halides and trifluoroacetates. The mechanism is proposed to involve a halide assisted protonation of the alkene which produces a carbocation intermediate sandwiched between the attacking halide ion
向20%三氟乙酸的二氯甲烷溶液中添加0.1 M卤化季铵盐会使简单烯烃的反应速率大大增加,从而导致烷基卤化物和三氟乙酸盐的混合物。建议该机理涉及烯烃的卤化物辅助的质子化,其产生夹在进攻性卤化物离子和三氟乙酸根离子之间的碳正离子中间体。在较高浓度的卤化物离子下,溶液的质子给予能力降低,从而减慢了反应并提高了卤化物离子捕获阳离子的效率。这导致更大比例的未重排卤化物产物。在最高卤离子浓度下,几乎消除了阳离子重排。