For best experience please turn on javascript and use a modern browser!
You are using a browser that is no longer supported by Microsoft. Please upgrade your browser. The site may not present itself correctly if you continue browsing.
uva.nl
Van 't Hoff Institute for Molecular Sciences null

Mechanistic elucidation of monoalkyltin(iv)-catalyzed esterification

24 February 2021

In a paper just accepted by the RSC journal Catalysis Science & Technology, HIMS researchers report on the mechanistic investigation of esterification catalyzed by mono-n-butyltin(iv) species, a class of catalysts that has been used since decades by the chemical industry to make polyesters. The researchers analysed the working of these catalysts under catalytically relevant conditions with a variety of spectroscopic techniques complemented with DFT calculations. They propose a mononuclear mechanism where carbon–oxygen bond breaking is the rate-determining step.
Image: HIMS.

Abstract

Monoalkyltin(IV) complexes are well-known catalysts for esterification reactions and polyester formation, yet the mode of operation of these Lewis acidic complexes is still unknown. Here, we report on mechanistic studies of n-butylstannoic acid in stoichiometric and catalytic reactions, analyzed by NMR, IR and MS techniques. While the chemistry of n-butyltin(IV) carboxylates is dominated by formation of multinuclear tin assemblies, we found that under catalytically relevant conditions only monomeric n-BuSn(OAc)3 and dimeric (n-BuSnOAc2OEt)2 are present. Density functional theory (DFT) calculations provide support for a mononuclear mechanism, where n-BuSn(OAc)3 and dimeric (n-BuSnOAc2OEt)2 are regarded as off-cycle species, and suggest that carbon–oxygen bond breaking is the rate-determining step.

Paper

Lukas A. Wolzak, Joen J. Hermans, Folkert de Vries, Keimpe J. van den Berg, Joost N. H. Reek, Moniek Tromp and Ties J. Korstanje: Mechanistic elucidation of monoalkyltin(iv)-catalyzed esterification. Catal. Sci. Technol., 2021, Advance Article. DOI: 10.1039/D1CY00184A