Trichloromethanesulfonyl chloride is an efficient free radical chlorinating agent. It reacts with pent-4-enylcobaloximes in inert solvent under tugsten lamp irradiation to yield 2-(β,β,β- trichloroethyl)sulfolanes. It also reacts with trimethylsilyl enol ethers of acetophenones in the presence of a ruthenium (II) phosphine complex to yield 1-aryl-3,3-dichloropropen-1-one and α-chloroacetophenones.