Kinetics of reductive dehalogenation of bromobenzene derivatives

The catalytic reductive dehalogenation of p-bromoaniline, p-bromobenzonitrile and p-bromobenzene with hydrogen was studied. The decrease of molar ratio bromoderivative/palladium catalyst is shown to change the reaction order from zero to the first. With the decrease of hydrogen pressure the reaction order transition zone shifts towards increased bromoderivative/catalyst ratio. Preliminary saturation of catalyst with hydrogen increases the starting rate of reaction, maximum rate being achieved at saturation during 5-15 minutes. The catalytic reductive dehalogenation with tritium-containing hydrogen shows that the molar activity of the products corresponds to that of the initial gas. Strong adsorption of initial bromoderivatives on catalyst surface is a dominant factor in reaction mechanism