Open AccessHomogeneous Catalysis and Heterogeneous Recycling: A Simple Zn(II) Catalyst for Green Fatty Acid Esterification
Author(s) -
Massimo Melchiorre,
Maria Elena Cucciolito,
Martino Di Serio,
Francesco Ruffo,
Oreste Tarallo,
Marco Trifuoggi,
Roberto Esposito
Publication year - 2021
Publication title -
acs sustainable chemistry and engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.878
H-Index - 109
ISSN - 2168-0485
DOI - 10.1021/acssuschemeng.1c01140
Subject(s) - catalysis , chemistry , zinc , homogeneous catalysis , heterogeneous catalysis , organic chemistry , homogeneous , carboxylate , physics , thermodynamics
This work describes the use of simple zinc(II) salts (ZnCl 2 , ZnCO 3 , Zn(OAc) 2 , ZnO, Zn(ClO 4 ) 2 , Zn(TfO) 2 , and Zn(BF 4 ) 2 ) as effective catalysts for the esterification of fatty acids with long-chain alcohols and simple polyols through a homogeneous system that allows the gradual and selective removal of water. The results show that the catalytic activity depends on the nature of the counterion: the most effective are the salts with poorly coordinating anions (perchlorate and triflate) or containing basic Brønsted anions (oxide, acetate, and carbonate). However, only with the latter is it possible to fully recover the catalyst at the end of each run, which is easily filtered in the form of zinc carboxylate, given its insolubility in the ester produced. In this way, it is possible to recycle the catalyst numerous times, without any loss of activity. This beneficial prerogative couples the efficiency of the homogeneous catalysis with the advantage of the heterogeneous catalysis. The process is, therefore, truly sustainable, given its high efficiency, low energy consumption, ease of purification, and the absence of auxiliary substances and byproducts.