@article{clark_thacker_mcgill_miles_westmoreland_efimenko_genzer_santiso_2021, title={DFT Analysis of Organotin Catalytic Mechanisms in Dehydration Esterification Reactions for Terephthalic Acid and 2,2,4,4-Tetramethyl-1,3-cyclobutanediol}, volume={125}, ISSN={["1520-5215"]}, url={https://doi.org/10.1021/acs.jpca.1c00850}, DOI={10.1021/acs.jpca.1c00850}, abstractNote={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.}, number={23}, journal={JOURNAL OF PHYSICAL CHEMISTRY A}, publisher={American Chemical Society (ACS)}, author={Clark, Jennifer A. and Thacker, Pranav J. and McGill, Charles J. and Miles, Jason R. and Westmoreland, Phillip R. and Efimenko, Kirill and Genzer, Jan and Santiso, Erik E.}, year={2021}, month={Jun}, pages={4943–4956} }
 @article{mcgill_westmoreland_2021, title={Molecular Carbonyl Insertion as the Homogeneous Catalysis Mechanism for Transesterification of Dimethyl Terephthalate with Ethylene Glycol}, volume={60}, ISSN={["0888-5885"]}, url={https://doi.org/10.1021/acs.iecr.0c05188}, DOI={10.1021/acs.iecr.0c05188}, abstractNote={Carbonyl insertion is identified and computationally quantified as a mechanism for homogeneous organotin catalysis of transesterification. Organotin species are widely used catalysts for reactions ...}, number={14}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, publisher={American Chemical Society (ACS)}, author={McGill, Charles J. and Westmoreland, Phillip R.}, year={2021}, month={Apr}, pages={5090–5101} }
 @article{mcgill_westmoreland_2018, title={Monosaccharide Isomer Interconversions Become Significant at High Temperatures}, volume={123}, ISSN={1089-5639 1520-5215}, url={http://dx.doi.org/10.1021/acs.jpca.8b07217}, DOI={10.1021/acs.jpca.8b07217}, abstractNote={Quantum-chemical calculations show how low barriers to anomerization and shifting equilibria cause a significant presence of different monosaccharide isomers in high-temperature processes such as pyrolysis. The transition between isomeric forms of monosaccharides is long-studied, but examination has typically been limited to the solution phase and to pyranose isomers. Processes and rates of anomerization by reversible, gas-phase ring-opening and -closing reactions were predicted for the monosaccharides d-glucose, d-mannose, d-galactose, d-xylose, l-arabinose, and d-glucuronic acid. Structures and thermochemistry were computed for stable species and pericyclic transition states using CBS-QB3, and high-pressure-limit Arrhenius reaction parameters were predicted and fitted from 300 to 1000 K. Activation energies for the ring-opening reactions were 162-217 kJ/mol for four-center pericyclic separation of the lactol group but were reduced by catalytic participation of a hydroxyl group within the monosaccharide or an external R-OH group represented by an explicit water molecule, reaching activation energies as low as 97 and 67 kJ/mol, respectively. Equilibrium constants implied increasing fractions of furanose and linear aldehyde anomers with increasing temperature.}, number={1}, journal={The Journal of Physical Chemistry A}, publisher={American Chemical Society (ACS)}, author={McGill, Charles J. and Westmoreland, Phillip R.}, year={2018}, month={Nov}, pages={120–131} }