Fragmentation in Organosulphur Compounds

Carbon-sulphur bond homolysis has been shown to be, in addition to sulphur-sulphur bond homolysis, a primary process in the photolysis of disulphides in solution. Sulphur-sulphur bond homolysis is, however, responsible for the establishment of an equilibrium between various alkyl disulphides on irradiation. Other liquid-phase studies of the photodecomposition of acyclic alkyl disulphides have been reported, -and the quantum yield for the formation of methyl ethyl disulphide from methyl disulphide and ethyl disulphide has been determined.  

The disulphide (175), obtained by photo-oxidation of 6-mercapto-l,3-dimethyl-lumazine, undergoes photorearrangement to the dithiin derivatives (176) and (177) by way of initial sulphur-sulphur bond homolysis. The photodecomposition of 2,2 -dithiodibenzoic acid derivatives has also been examined. Irradiation of 

Competing photodecomposition pathways have been observed in sulpho-namides and sulphonylureas, and the photohydrolysis of sulphonamides, via the formation of donor-acceptor ion pairs with electron-donating aromatic compounds, has been reported.Irradiation of AT-tosylmethylphenethylamine (188) in the presence of veratrol (189) in ethanol, for example, gave methyl-phenethylamine (190) in 66% yield. This procedure has also been employed in the selective detosylation of lysine peptides. 

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