keto-enol tautomerism was investigated for ionized pyruvic acid using the dft(b3lyp) method and the larger basis sets [6-31++g(d,p), 6-311++g(3df, 3pd) and aug-cc-pvdz]. change of the tautomeric preference was observed when going from the neutral to ionized tautomeric mixture. ionization favors the enolization process (ketoenol) of pyruvic acid, whereas the ketonization (ketoenol) is preferred ...