4-Chlorobenzyl bromide undergoes carbonylation in the presence of dimer of chloro(1,5-cyclooctadiene)rhodium(I) to yield the corresponding phenylacetic acid. It can be synthesized by reacting 4-chlorobenzyl alcohol with bromodimethylsulfonium bromide (BDMS) It can also be synthesized by refluxing a mixture of 4-chlorobenzaldehyde, chlorotrimethylsilane, 1,1,3,3-tetramethyldisiloxane and lithium bromide.