Copper-catalyzed hydrocyanation of olefins. Kinetic and mechanistic aspects

The CuBr-, CuBr2-catalyzed hydrocyanation of conjugated olefins has been investigated by kinetic methods. The reaction appears to depend on the presence of halogenated species as shown by the effect of additives such as BrCN and crotyl bromide (a possible intermediate in the reaction). Evidence for a mechanism proceeding through protonation of the diolefin by an acidic bromine-containing copper species of the type (HCu(CN)Br) is presented. From a preparative point of view, the reaction gives an excellent yield of pentenenitrile from butadiene, but a poor yield of nitriles from substituted dienes. © 1983.