Kinetics of Bromine-Exchange Reaction between Antimony Tribromide and p-Xylyl Bromide in Nitrobenzene and in 1, 2, 4-Trichlorobenzene

摘要

The rate of the bromine-exchange reaction of antimony tribromide with p-xylyl bromide in nitrobenzene or 1,2,4-trichlorobenzene has been measured, using antimony tribromide labelled with Br-82. The results of the study reveal that the exchange reaction follows first order kinetics with p-xylyl bromide, and either second order or first order kinetics with antimony tribromide depending on its concentration. The second order kinetics with respect to antimony tribromide have been observed at relatively higher concentrations of SbBr3 and first order kinetics at lower SbBr3 concentrations. At extremely low concentrations of SbBr3 it is difficult to draw clear conclusion regarding the kinetic order with respect to antimony tribromide, although the zero order kinetics seem to be valid. Reaction mechanisms are proposed for the exchange reaction.