3-Oxo-1-cyclohexene-1-carboxylic Acid: Catemeric Hydrogen Bonding and Flexional Ring Disorder in a γ-Keto Acid

The crystal structure of 3-oxo-1-cyclohexene-1-carboxylic acid, C₇H₈O₃, involves hydrogen-bonding catemers of an unusual type. Hydrogen bonds progress from the carboxyl H atom of one molecule to the ketone O atom of a glide-related molecule [O...O 2.703 (2) Å], resulting in heterochiral chains. Parallel counterdirectional pairs of hydrogen-bonding chains proceed through the chosen cell. There are mutual close contacts of 2.65 Å between the ketone O and vinyl H atoms of centrosymmetrically related chains. Two of the tetrahedral C atoms of the molecule are flexionally disordered, and three of their associated H atoms show attractive inter­molecular close contacts to O atoms.

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