Investigations of catalysis of urethane formation using organotin dicarboxylate

Ransi Devendra; Neil R Edmonds; Tilo Söhnel

doi:10.1016/j.heliyon.2020.e04074

Investigations of catalysis of urethane formation using organotin dicarboxylate

Heliyon. 2020 May 28;6(5):e04074. doi: 10.1016/j.heliyon.2020.e04074. eCollection 2020 May.

Authors

Ransi Devendra^{1

2}, Neil R Edmonds^{1

3}, Tilo Söhnel^{1

4}

Affiliations

¹ School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
² Uroxsys Ltd., P.O. Box 58333, Botany, Auckland, New Zealand.
³ Department of Mechanical Engineering & Centre of Advanced, Composite Materials, University of Auckland, Private Bag 92019, Auckland, New Zealand.
⁴ MacDiarmid Institute of Advanced Materials and Nanotechnology, Victoria University of Wellington, P.O. Box 600, Wellington, New Zealand.

Abstract

The reaction mechanism of the urethane formation for both aliphatic and aromatic isocyanates in the presence of organotin dicarboxylate as a catalyst is investigated theoretically and experimentally. Modelling on a dispersion corrected DFT level of theory (B3LYP-D3) shows that an alkoxide complex is formed between organotin dicarboxylate and alcohol. This complex is the dominant catalyst for the urethane formation reaction. In this study, the interaction between the alkoxide complex and isocyanate through N-coordination is considered. By using thermochemical data, it is possible to show that aliphatic isocyanates can be more sensitive to the carboxylic ligand content of the organotin compound as a catalyst in urethane formation in non-polar solvents compared to aromatic isocyanates. The interactions of carboxylic acid, which is formed as an intermediate in the catalysis process, with isocyanate and the effects on the catalytic process are also discussed.

Keywords: Catalysis; Computational; DFT B3LYP-D3; Inorganic chemistry; Organic chemistry; Organotin dicarboxylate; Urethane.