4-Acetylbenzoic acid: hydrogen bonding and packing in a simple aromatic ∊-keto acid

Abstract

Key indicators: single-crystal X-ray study; T = 100 K; mean (C-C) = 0.003 Å; R factor = 0.051; wR factor = 0.156; data-to-parameter ratio = 11.0.The title compound, C 9 H 8 O 3 , adopts a conformation in which both substituents lie nearly coplanar with the ring. Asymmetric units aggregate by centrosymmetric carboxyl pairing. Close offset stacking of rings in parallel planes creates intermolecular CÁ Á ÁCcontacts of 3.322 (3) and 3.352 (3) Å , with an accompanying CÁ Á ÁOcontact of 3.147 (3) Å and similarly close interactions between O atoms and aromatic systems. One close intermolecular C-HÁ Á ÁO contact is also present. CommentOur study of solid-state H-bonding patterns in ketocarboxylic acids has employed several examples of fundamentally simple systems to explore the minimum requirements for various H-bonding modes. Among such compounds is the title aromatic.