Ring–Chain Tautomerism of Hydroxyketones

Abstract

A study of the u.v., i.r., and n.m.r. spectra of 5-hydroxy-2-pentanone and of 6-hydroxy-2-hexanone has shown that in most organic solvents there is a slight preference for the open-chain form of the hydroxyketone over the cyclic hemiketal. Increase in temperature and in polarity of solvent further favors the open-chain tautomer; in water there was no evidence of any cyclic form.