1H and 13C NMR Study of Tautomerism of 9-Hydroxy-3-methylphenalen-1-ones

Tautomeric equilibria in the series of substituted 9-hydroxy-3-melhylphenalen-1-ones involve proton transfer from the hydroxy to the carbonyl group. The state of the equilibria is determined by the position of the methoxy groups. The relations between the heats of formation of tautomers, calculated by the AMI method, are consistent with the 1H and 13C NMR data.