Kinetics of synthesis of perfumery grade p-tert-butylcyclohexyl acetate over ion exchange resin catalyst

Abstract

Esterification reactions are conventionally carried out by using homogeneous acids on industrial scale and only a few heterogeneous catalysts are reported. Esters represent an imperative class of aroma compounds. They often possess fruity odors and are widely used by the food and fragrance industries. In view of stringent environmental concern the use of heterogeneous catalysts is now heavily pursued. In order to develop environmentally benign process, the present work hinges on importance of Amberlyst-15 (an ion exchange resin) in the esterification of p-tert-butylcyclohexanol (PTBCH) with acetic acid to get p-tert-butylcyclohexyl acetate (PTBCHA) including kinetics of the reaction. PTBCHA has a sweet, almost creamy-woody odour with a soft-floral undertone. PTBCHA is expensive and is widely used in perfumery industry. The effects of various parameters on rate of reaction were studied in detail and a model was developed for an intrinsically kinetically controlled reaction which is free from either intra-particle diffusion or external mass transfer resistance. The catalyst is reusable without loss of activity. Esterification of PTBCH was also carried with propionic acid, isobutyric acid, pentanoic acid and hexanoic acid to study the effect of chain length and also because of their commercial significance.