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Acid catalysed transesterification of benzyl acetate in glycerol

ADI WOLFSON*, SHAI NAIM, CHRISTINA DLUGY, DORITH TAVOR
*Corresponding author
Green Processes Centre, Chemical Engineering Department, Sami Shamoon College of Engineering, Bialik/Basel Sts., Beer-Sheva, 84100 Israel

Abstract

The acid catalysed alcoholysis of benzyl acetate was successfully performed in glycerol that was simultaneously used as a green solvent and as the acyl acceptor. Both soluble and solid acid were employed, and it was found that increasing either the reaction temperature and time or substrate concentration and catalyst loading increased the conversion of benzyl alcohol. Using glycerol as the solvent also enabled the separation of product by simple extraction with diethyl ether, catalyst recycling, and microwave-promoted reactions.


INTRODUCTION

Benzyl alcohol, a valuable organic solvent and bacteriostatic preservative agent, is traditionally produced by the hydrolysis of benzyl chloride under alkali conditions (1, 2). As hydrolysis usually requires an excess amount of alkali base that produces a correspondingly large amount of waste, alternative benzyl alcohol production routes have been investigated. One such alternative is the oxyacetoxylation of toluene with acetic acid and oxygen that produces benzyl acetate (3, 4), which can then be hydrolyzed to benzyl alcohol in a more environmentally benign fashion by transesterification (alcoholysis) using homogeneous and heterogeneous catalysts (5-7). Traditionally, the reaction has been performed in an acidic or basic aqueous solution under mild