The enol content and equilibrium free energies for the keto-enol tautomerism have been determined for a series of 1, 3-diketones, at 40° C, in deuterochloroform and dimethylsulfoxide-d6 (DMSO), by1H nmr. Compounds containing methyl, phenyl, t-butyl, 2- thienyl, trifluoromethyl and ethoxy groups have been examined. The equilibrium free energies in DMSO are characterized by a linear additivity effect, and substituent ...
