Crystal structures of 2-acetyl-4-ethynylphenol and 2-acetyl-4-(3-hy-droxy-3-methylbut-1-yn-1-yl)phenol.

In the title compounds, CHO, (I), and CHO, (II), the 2-acetyl-4-ethynylphenol unit displays a planar geometry, which is stabilized by an intra-molecular O-H⋯O hydrogen bond. The crystal structure of (I) is constructed of infinite strands, along [101], of C-H⋯O=C hydrogen-bonded mol-ecules, which in turn are linked by C-H⋯π inter-actions. In the crystal of (II), which crystallized with three independent mol-ecules per asymmetric unit, the non-polar parts of the mol-ecules form hydro-phobic layered domains, parallel to (10-1), which are separated by the polar groups. While the 2-acetyl-phenol part of the mol-ecules are involved in O-H⋯O=C hydrogen bonding, the ternary OH groups creates a cyclic pattern of O-H⋯O hydrogen bonds.