Synthesis of methylthio- and methylsulfonyl-polychlorobiphenyls via nucleophilic aromatic substitution of certain types of polychlorobiphenyls

A one-step preparation of some methylthiopolychlorobiphenyls from methanethiolate in methanol and certain chlorinated biphenyls is described. Two of the methyl sulfides and one bis(methyl-thio)tetrachlorobiphenyl are characterized in some detail. The methylthiopolychlorobiphenyls were oxidized by use of hydrogen peroxide in acetic acid to give five methylsulfonylpolychlorobiphenyls which are characterized by melting point, elemental analysis, UV-absorption (Table 1), ¹H NMR (Table 2) and mass spectrometry (Table 3). By use of the method presented a mixture of methyl sulfides derived from a technical mixture of polychlorinated biphenyls (PCB) were prepared as well as the corresponding mixture of methyl sulfones. Additionally the same synthetic method was used for the preparation of methyl sulfides and methyl sulfones derived from two ¹⁴C-labelled polychlorobiphenyls.