Chemistry of the ß-thiolactones: substituent and solvent effects on thermal decomposition and comparison with the ß-lactones.

ABSTRACT

The synthesis of a series of di-, tri-, and tetraalkyl ß-thiolactones and ß-lactones is described as well as their thermal decomposition with extrusion of carbon oxysulfide and carbon dioxide in two solvents of opposite polarities. The ß-thiolactones are considerably more thermally stable than the ß-lactones and require higher temperatures for efficient decomposition in both solvents, whatever the degree of substitution. The results are interpreted in terms of a zwitterionic mechanism for fragmentation with a change in the rate-determining step between the two series.