Syntheses and crystal structures of 2,2,5-trimethyl-1,3-dioxane-5-carboxylic acid and 2,2,5-trimethyl-1,3-dioxane-5-carboxylic anhydride

Abstract

In 2,2,5-trimethyl-1,3-dioxane-5-carboxylic acid, C8H14O4, the carboxyl group occupies an equatorial position on the 1,3-dioxane ring. In the crystal, O—H...O hydrogen bonds form chains of molecules, which are linked into a three-dimensional network by C—H...O hydrogen bonds. The asymmetric unit of 2,2,5-trimethyl-1,3-dioxane-5-carboxylic anhydride, C16H26O7, consists of two independent molecules, which are linked by C—H...O hydrogen bonds. In the crystal, these units are connected into corrugated layers two molecules thick and parallel to the ab plane by additional C—H...O hydrogen bonds.