2021 journal article

DFT Analysis of Organotin Catalytic Mechanisms in Dehydration Esterification Reactions for Terephthalic Acid and 2,2,4,4-Tetramethyl-1,3-cyclobutanediol

JOURNAL OF PHYSICAL CHEMISTRY A, 125(23), 4943–4956.

By: J. Clark n, P. Thacker n, C. McGill n, J. Miles n, P. Westmoreland n , K. Efimenko n , J. Genzer n , E. Santiso n 

TL;DR: Calculations are used to show that esterification of TMCD and TPA will reduce and subsequently dehydrate a dimethyl tin oxide catalyst, becoming ligands on the now four-coordinate complex, a key first step in understanding polyester synthesis and avoiding undesirable side reactions during production. (via Semantic Scholar)
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Source: Web Of Science
Added: July 12, 2021

Polyesters synthesized from 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) and terephthalic acid (TPA) are improved alternatives to toxic polycarbonates based on bisphenol A. In this work, we use ωB97X-D/LANL2DZdp calculations, in the presence of a benzaldehyde polarizable continuum model solvent, to show that esterification of TMCD and TPA will reduce and subsequently dehydrate a dimethyl tin oxide catalyst, becoming ligands on the now four-coordinate complex. This reaction then proceeds most plausibly by an intramolecular acyl-transfer mechanism from the tin complex, aided by a coordinated proton donor such as hydronium. These findings are a key first step in understanding polyester synthesis and avoiding undesirable side reactions during production.