β-DIKETONE INTERACTIONS Part 12. The structure and properties of 3-(3',4',5'-trimethylphenyl)-pentane-2,4-dione, C14H18O2; the hydrogen-bond energy of the enol tautomers of β-diketones

Article abstract of DOI:10.1016/0022-2860(90)80496-7

The X-ray crystal structure of 3-(3',4',5'-trimethylphenyl)pentane-2,4-dione shows it to be the enol tautomer, with a hydrogen bond length R_o...o of 2.460 Angstroem, and the enol ring remarkably symmetrical indicating a strong hydrogen bond.The hydrogen-bond energy is estimated to be 110+/-10 kJ mol^-1, a value derived from the infra-red spectrum.In CDCl3 solution 8percent of the keto tautomer is present.