1,1′,1-(2,4,6-Trihydroxybenzene-1,3,5-triyl)triethanone tautomerism revisited

It has recently been suggested that 1,1',1 ''-(2,4,6-trihydroxybenzene-1,3,5-triyl)triethanone may be tautomeric. Using C-13 NMR chemical shifts and deuterium isotope effects on C-13 chemical shifts, it is demonstrated that this is not the case. This compound occurs as a strongly hydrogen bonded benzene structure with hydrogen bonds between OH groups and the acetyl groups in both non-polar and hydrogen donating solvents. Quantum-chemical calculations using MP2 and M06-2X methods show substantial preference for the phenol structure in both the gas phase, and in cyclohexane and methanol. In addition, conventional UV-vis spectroscopy data suggest not tautomeric, but aggregation behaviour of the molecule in methanol and acetonitrile. (C) 2013 Elsevier Ltd. All rights reserved.