ORGANOSILICON COMPOUNDS .43. PREPARATION OF ARYL SULPHONES BY DESILYLATION OR DESTANNYLATION

Treatment of an aryltrimethylstannane (X·C6H 4·SnMe3) with a preformed arenesulphonyl chloride-aluminium chloride (Y·C6H4·SO 2Cl,AlCl3) complex in methylene chloride has been used to give the diaryl sulphone X·C6H4-SO 2·C6H4·Y in moderately good yield: examples are the sulphones with X and Y as follows: H, H (62%); p-Me, H (62); H, p-Me (61); p-OMe, H (65); p-F, H (58); H, p-Me3Si (57); H, p-Ph (53). The methanesulphonyl chloride-aluminium chloride complex has been used similarly to give the aryl methyl sulphones p-X·C6H 4·SO2Me, with X = H (58%), F (58), or Me (55), and also mesityl methyl sulphone (31%). Aryltrimethylsilanes similarly gave the expected sulphones when treated with Y·C6H4· SO2Cl,AlCl3 complexes, but there was sometimes contamination by isomeric products; e.g. the products from p-tolyl- or p-methoxy-phenyltrimethylsilane and the benzenesulphonyl chloride-aluminium chloride complex included some o-tolyl or o-methoxyphenyl phenyl sulphone. (However, m-tolyltrimethylsilane and benzenesulphonyl chloride in carbon disulphide in presence of aluminium chloride gave phenyl m-tolyl sulphone in 64% yield.) The disulphone 4,4′-bis(phenylsulphonyl)biphenyl was obtained (47%) from 4,4′-bistrimethylsilylbiphenyl and the benzenesulphonyl chloride-aluminium chloride complex, and (63%) from phenyltrimethylsilane and the 4,4′-bis(chloro-sulphonyl)biphenyl-bis(aluminium chloride) complex. Treatment of p-trimethylsilylbenzenesulphonyl chloride with an excess of benzene or toluene in the presence of aluminium chloride gave phenyl p-trimethylsilylphenyl sulphone (87%) and p-tolyl p-trimethylsilylphenyl sulphone (76%), respectively.