Cationic Arylation. I. Phenylation of Substituted Benzenes with Benzenediazonium Tetrafluoroborate in Homogeneous Solution

Substituted benzenes were phenylated with benzenediazonium tetrafluoroborate in homogeneous solutions with DMSO or acetonitrile. The distribution of substituted biphenyls and the partial rate factors indicated that this phenylation was an electrophilic substitution, but the selectivity was much smaller than those of nitration or sulfonylation. Experiments with chlorobenzene-4d, anisole-4d and chlorobenzene-d5 showed that both the orientation and partial rate factors did not change with deuterated compounds. Therefore, it was established that the rate-determining step was the addition of phenyl cation to an aromatic nucleus, and not the abstraction of proton from the phenylated intermediate.