Journal of Molecular Catalysis B: Enzymatic 30 (2004) 185–188 Short communication Ionic liquids: efficient additives for Candida rugosa lipase-catalysed enantioselective hydrolysis of butyl 2-(4-chlorophenoxy)propionate Swapnil S. Mohile, Mahesh K. Potdar, Jitendra R. Harjani, Susheel J. Nara, Manikrao M. Salunkhe ∗ Department of Chemistry, The Institute of Science, 15-Madam Cama Road, Mumbai 400 032, India Received 5 March 2004; received in revised form 6 May 2004; accepted 7 May 2004 Available online 6 July 2004 Abstract The Candida rugosa lipase-catalysed enantioselective hydrolysis of butyl 2-(4-chlorophenoxy)propionate 1 has been carried out in aqueous buffer with ionic liquid as co-solvent. The influence of ionic liquid on the catalytic efficiency and selectivity has been studied, using both hydrophobic and hydrophilic ionic liquids. The markedly enhanced enantioselectivity towards the R enantiomer of substrate 1 is observed under optimum additive conditions (1:1 composition of ionic liquid and buffer). Hydrophobic ionic liquids offered almost quantitative conversions with ee ≥ 99%. © 2004 Elsevier B.V. All rights reserved. Keywords: Candida rugosa lipase; Butyl 2-(4-chlorophenoxy)propionate; Enantioselective hydrolysis; Ionic liquid; Co-solvent 1. Introduction Enantiopure compounds have undoubtedly gained a vi- tal role in the development of modern chemical technol- ogy. Enzymes as biocatalysts have proved their capability to achieve the speed and co-ordination of multiple trans- formations involved in the preparation of enantiomerically pure compounds such as pharmaceutical and agricultural chemicals [1]. In particular, lipases are a unique class of hy- drolases, which have been exploited the most because they display relatively higher enantioselectivity, possesses broad substrate specificity and are commercially available [2]. Li- pase activity and selectivity are strongly influenced by the medium used for the desired reaction [3,4]. They exhibit high catalytic activity in water and even higher activity in two-phase systems such as water and hydrophobic organic solvents [5–7]. However with all the known advantages of organic solvents as reaction media for biotransformations they suffer from degradation in value when the question of environmental concern arises. ∗ Corresponding author. Tel.: +91 22 22816750; fax: +91 22 22816750. E-mail address: mmsalunkhe@hotmail.com (M.M. Salunkhe). The groundbreaking success of ionic liquids has paved the way for convenient, efficient and environmentally friendly methodologies for a wide array of chemical reactions having significant synthetic value. The negligible vapour pressure of ionic liquids and their recyclability satisfies the safety and financial necessity for any industrial application. The excel- lent reviews by Welton [8], Wasserscheid and Wilhelm [9] and Dupont et al. [10] have benchmarked the advantages as- sociated with the ionic liquid based systems. Enzyme cataly- sis in ionic liquids has established completely green solution towards development of environmentally benign procedures [11–13]. Recently, Candida rugosa lipase-catalysed hydrolysis of butyl 2-(4-chlorophenoxy)propionate in aqueous buffer containing dimethyl sulfoxide (DMSO) as co-solvent was studied by Watanabe and Ueji [14]. Wherein, they reported a markedly enhanced enantioselectivity of lipase in pres- ence of DMSO as compared to no-additive conditions. Here presence of DMSO again poses the question of environ- ment factors as well as recyclability of the solvent. The process lipase-catalysed asymmetric hydrolysis has been judged to be superior from the standpoint of productivity, ease of product separation and the number of steps required for the practical resolution of racemic acids [15]. All these things encouraged us to carry out an applied study on the 1381-1177/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.molcatb.2004.05.002