Enolization enthalpies for aliphatic carbonyl and thiocarbonyl compounds

Research was conducted to determine the influence of enolization enthalpies at 0 and 298 K for nine aliphatic carbonyl and nine aliphatic thiocarbonyl compounds using ab initio complete basis set fourth-order model calculations. Results reveal lower enolization enthalpies for the thiocarbonyl compounds because of higher thioenol tautomer concentrations compared to the corresponding carbonyl compounds. On the other hand, the enolization enthalpies for the cycloketones and thiocycloketones relied upon the size of the cyclic ring.