作者:Hilton M. Weiss、Kim M. Touchette
DOI:10.1039/a703569a
日期:——
The addition of 0.1 M quaternary ammonium bromide to a solution of 20% trifluoroacetic acid in methylene chloride causes a large rate increase in the reaction of non-conjugated alkynes. The initial vinyl bromide product reacts further to provide a mixture of isomeric vinyl bromides and dibromides. At high salt concentrations however, the secondary reactions are prevented and only the initial vinyl
向20%三氟乙酸的二氯甲烷溶液中添加0.1 M溴化季铵盐会使非共轭炔烃的反应速率大大提高。起始的乙烯基溴化物产物进一步反应,以提供异构的乙烯基溴化物和二溴化物的混合物。然而,在高盐浓度下,可以防止副反应,并且仅发现起始的乙烯基溴。与烯烃的相应添加相反,提出的主要机理是通过卤离子对酸性炔烃π络合物进行一步一步,一致的亲核攻击,从而直接生成卤化乙烯。涉及syn的次要路径另外还可以看到。在所有盐浓度下,丙二烯都会产生大量的重排产物,表明阳离子机制的重要参与。