Abstract
The UV, 1H NMR, and 13C NMR spectra of 2-mercapto-8H-cyclohepta[d]thiazol-8-one (2) are extremely near to those of 3-methyl-8-oxo-3,8-dihydrocyclohepta[d]thiazoline-2-thione (6). These results proved that the thiazoline form 2a predominates in the tautomeric equilibrium of 2.