Sulphines. Part V. Configurational assignment and interconversion barriers for syn- and anti-isomers of aromatic sulphines

Unambiguous Configurational assignment of syn and anti-isomers of methyl-substituted aromatic Sulphines has been achieved by means of: (a) intermolecular hydrogen bonding with weak acids; (b) intramolecular association in 2-hydroxy-(2′-methyl)thiobenzophenone S-oxide; (c) aromatic solvent induced shift measurements; and (d) carbon-13 n.m.r. spectra. The thermodynamic and kinetic parameters for the thermal interconversion of the isomers have also been determined. These values are discussed in terms of possible isomerisation mechanisms.