Molecular rearrangements. III. Thermal decomposition of some selected thioesters

Article abstract of DOI:10.1139/v82-411

Four selected thioesters (1-4) were prepared and pyrolyzed in the absence of promoters either alone or in isoquinoline solvent.These esters include benzyl thiobenzoate (1), phenyl phenylthioacetate (2), benzyl phenylthioacetate (3), and phenyl thiobenzoate (4).Pyrolysis of 1 gave mainly 2,3,4,5-tetraphenylthiophene in addition to benzene, biphenyl, benzyl thiol, and benzoic acid.Thermal decomposition of 1 under nitrogen gave benzaldehyde, benzil, and only a trace of benzoic acid in addition to the former products.Compound 2 afforded essentially toluene and dibenzyl in addition to benzene, biphenyl, phenyl sulphide, thiophenol, and phenylacetic acid.Thermolysis of 3 gave toluene and stilbene beside small quantities of benzyl and phenylacetic acid.Finally, thermal decomposition of 4 in isoquinoline gave benzene, biphenyl, phenyl sulphide, thianthrene, thiophenol, benzoic acid, and 1-phenylisoquinoline.H2S and CO are also produced in all cases.In these rearrangements, the C-S bonds undergo homolytic fission either simultaneously or selectively.No isomer redistribution precedes the coupling reactions.Plausible mechanism for the above facts are proposed.