Primary alkyl chlorides are quantitatively converted to their corresponding bromides in the presence of ethyl bromide, N-methyl-2-pyrrolidinone, and a catalytic amount of metal bromide. A variety of chlorides can be converted. Selective functionalization at bromine of several primary bromochloroalkanes was studied in conjunction with the chloride-bromide conversion for multistep syntheses. Methods for halogen exchange between chloride, ...