In-Water and Neat Batch and Continuous-Flow Direct Esterification and Transesterification by a Porous Polymeric Acid Catalyst.

Heeyoel Baek,Maki Minakawa,Yasuhiro Uozumi,Jin Wook Han,Yoichi M A Yamada

doi:10.1038/srep25925

Abstract

A porous phenolsulphonic acid—formaldehyde resin (PAFR) was developed. The heterogeneous catalyst PAFR was applied to the esterification of carboxylic acids and alcohols, affording the carboxylic acid esters in a yield of up to 95% where water was not removed from the reaction mixture. Surprisingly, the esterification in water as a solvent proceeded to afford the desired esters in high yield. PAFR provided the corresponding esters in higher yield than other homogeneous and heterogeneous catalysts. The transesterification of alcohols and esters was also investigated by using PAFR, giving the corresponding esters. PAFR was applied to the batch-wise and continuous-flow production of biodiesel fuel FAME. The PAFR-packed flow reactor that was developed for the synthesis of carboxylic acids and FAME worked for four days without loss of its catalytic activity.

Highlights

Nonequilibration of these equilibrium reactions should overcome the issue
High-resolution Scanning Electron Microscope (SEM) observation revealed that phenolsulphonic acid—formaldehyde resin (PAFR) 1a was an aggregated macroporous solid with a pore size of [1,2,3,4,5] μm wide, in which sulfur moiety from the SO3H unit in 1a was readily detected (Energy Dispersive x-ray Spectroscopy, EDS) (Fig. 1(a–c))
The heterogeneous catalyst PAFR 1a with less than 1 mol% promoted the esterification of carboxylic acids and alcohols, where the resulting water was not removed from the reaction vessel during the reaction

Summary

Introduction

Nonequilibration of these equilibrium reactions should overcome the issue. For example, some enzymes mediate the dehydrative reaction in water for the synthesis of nucleic acids and proteins with the assistance of phase separation[8]. Transesterification of various esters with alcohols using heterogeneous and homogeneous acidic catalysts has been reported[28,29,30,31,32,33,34,35,36,37,38]. 0.7 mol% of the macroporous PAFR 1a promoted the esterification of carboxylic acids and alcohols under neat conditions without removal of water more efficiently than the nonporous PAFR 1b and general homogeneous/heterogeneous acid catalysts, affording the corresponding esters with up to a quantitative yield. We show the full details of the preparation of PAFR 1a and its application to the esterification of carboxylic acids and alcohols under neat conditions without www.nature.com/scientificreports/.

Methods

Results

Conclusion