Preparation of Ethyl 4-Nitrobenzoate Using Ultradispersed Natural Zeolite Catalysts, Ultrasound and Microwave Irradiation

Abstract

The new possibilities of preparing the ethyl 4-nitrobenzoate by esterification of 4-nitrobenzoic acid (4-NBA) with ethanol under argon at 80˚C are shown; particularly, over catalysts: on micrometric (4.8 -7.0 μm) or ultradispersed crystallites (290 -480 nm) of hydrogen forms of nanoporous natural zeolites H-CL, H-MOR, H-HEU-M, H-PHI and under irradiation of the reaction mixture with ultrasound (US, 37 kHz, 330 W, 2 h) or microwaves (MW, 2450 MHz, 300 W, 2 h). Ultradispersed crystallites of zeolite catalysts were prepared from hydrogen forms of parent natural zeolites by their treatment with US or MW. In the esterification, the synergism of the actions of catalysts and MW or US was revealed; wherein on the ultradispersed best catalysts H-HEU-M and H-MOR conversion of 4-NBA and yield of ethyl 4-nitrobenzoate reached up to 70% and 67%, respectively. GC/MS, FTIR, NMR methods were used in the study.