9Α-Chloro-16α-methyl-3,11-dioxoandrosta-1,4,6-triene-17β-carboxylic Acid Pinacolone Solvate: Catemeric Hydrogen Bonding and Pinacolone Solvation in a Steroidal Diketo Acid Derived from a Commercial Glucocorticoid

The title ketocarboxylic acid, synthesized from the anti-inflammatory clocortolone pivalate, crystallizes as C21H23ClO4·C6H12O, with one mol­ecule of steroid and one of 3,3-dimethyl­butanone per asymmetric unit. The carboxyl group is highly ordered and the steroid molecules form translational carboxyl-to-ketone hydrogen-bonding catemers [O⋯O = 2.682 (3) A and O—H⋯O = 158°] that utilize the 3-ketone group, with one chain proceeding in the [110] direction and the other in the [\overline{1}10] direction. One close inter­molecular C—H⋯O=C contact is present, which involves the solvent O atom, but neither it nor the Cl atom nor the 11-ketone group play any role in the classical hydrogen bonding.