POLYMORPHISM AND THERMAL-BEHAVIOR OF 3-PARA-TOLUYL-1,2,2-TRIMETHYL CYCLOPENTANE CARBOXYLIC-ACID

The polymorphism of 3-para-toluyl-1,2,2-trimethyl cyclopentane carboxy lic acid was investigated by differential scanning calorimetry, X-ray diffractometry and infrared spectroscopy. Three types of intermolecula r hydrogen bonds can occur. In the first two, cyclic dimers are formed by intermolecular associations between carboxylic groups whose C-O bo nd lengths either differ or are almost equal, while the ketone carbony ls remain uninvolved. The third type is an intermolecular carboxyl-to- ketone hydrogen bond repeated infinitely to yield a chain.