4-ethynyl-4-hydroxycyclohexan-1-one and 4-ethynyl-4-hydroxy-2,3,5,6-tetramethylcyclohexa-2,5-dien-1-one

Abstract

The title compounds, C₈H₁₀O₂, (I), and C₁₂H₁₄O₂, (II), occurred as by-products in the controlled synthesis of a series of bis(gem-alkynols), prepared as part of an extensive study of synthon formation in simple gem-alkynol derivatives. The two 4-(gem-alkynol)-1-ones crystallize in space group P2₁/c, (I) with Z' = 1 and (II) with Z' = 2. Both structures are dominated by O-H …O=C hydrogen bonds, which form simple chains in the cyclohexane derivative, (I), and centrosymmetric dimers, of both symmetry-independent molecules, in the cyclohexa-2,5-diene, (II). These strong synthons are further stabilized by CC-H …O=C, C_methylene-H …O(H) and C_methyl-HO(H) interactions. The direct intermolecular interactions between donors and acceptors in the gem-alkynol group, which characterize the bis(gem-alkynol) analogues of (I) and (II), are not present in the ketone derivatives studied here.