Benign approach for methyl-esterification of oxygenated organic compounds using TBHP as methylating and oxidizing agent

Abstract

Methyl-esterification of oxygenates such as alcohols, aldehydes and carboxylic acids were carried out by employing copper and copper/palladium based catalysts using TBHP. In this reaction, TBHP plays dual role as oxidizing and methylating agent. Cu and Cu-Pd based nanoperticles (NPs) were prepared by wet chemical method using CuCl or PdCl2 by engaging “green solvent” water and dextrose as eco-friendly and renewable reagents. The NPs were fully characterized using various physicochemical techniques such as XRD, SEM, TEM and EDAX. XRD spectra of synthesized NPs confirmed the formation of CuO and Pd/Cu2Cl(OH)3. HRTEM analysis of CuO confirmed uniform cube-shaped morphology with particle size of 25–30 nm. Whereas, HRTEM of Pd/Cu2Cl(OH)3 showed 5–10 nm Pd NPs uniformly dispersed over Cu2Cl(OH)3 surface. Excellent catalytic activity was obtained for the conversion of benzaldehyde to methyl benzoate with 92% selectivity using Pd/Cu2Cl(OH)3 nanocatalyst. Other oxygenates such as aldehydes, alcohols and carboxylic acids were also obtained with high conversion and selectivity for desired methyl esters.