Highly Efficient SO3H-Carbon Catalysed Solvent-Free Synthetic Protocol for Wax Esters Via Esterification of Long Chain Fatty Acids and Alcohols

Solvent-free synthesis of saturated and monounsaturated wax esters (WEs), 3a-j with carbon chain ranging from C26 to C38 was successfully demonstrated through esterification of long chain fatty acids (LCFAs), 1a-g (C10:0, C12:0, C16:0, C18:0, C18:1, C18:1,12-OH, C22:0, and C22:1 acids) with long chain fatty alcohols (LCFAlc), 2a-d (cetyl (C16), stearyl (C18), behenyl (C22) and erucyl (C22:1) alcohols) by SO3H-carbon catalyst derived from glycerol. The optimized reaction conditions for the efficient synthesis of WEs with excellent conversion and selectivity recorded in solvent free system are: 20 wt.% of SO3H-carbon catalyst, reaction time of 6-10 h, temperature of 90 °C and substrate (LCFA:LCFAlc) molar ratio of 1:1. All the synthesized WEs were purified by silica gel column chromatography and characterized by FTIR, 1H-NMR, and GC-MS spectral studies. In addition, this methodology involves simple workup protocol, without use of dean stark or dehydrating agents compared to the reported homogeneous/heterogeneous catalysed methods. Furthermore, the resulting synthetic WEs can play a potential alternates for the commercial products extracted from natural sources of lesser availability, thus making this SO3H-carbon catalysed route very promising for further potential industrial implementation.