Organotin carboxylate catalyst in urethane formation in a polar solvent: an experimental and computational study

Abstract

Organotin carboxylates are important catalysts in aliphatic urethane synthesis. They are widely used in two component urethane systems such as casting systems, high performance coatings and in the synthesis of one-component moisture cure urethane pre-polymers for coatings. In most of these systems, a solvent is used to reduce the viscosity to assist application. In general, aromatic hydrocarbon solvents such as xylene, R100 or oxygenated solvents (e.g. esters) are used. In this paper, a detailed investigation of the catalytic mechanism of organotin carboxylate in urethane synthesis in a polar medium is investigated using experimental and computational methods. There is evidence that the dominant catalyst for organotin carboxylate catalysis of aliphatic isocyanate in urethane formation in a polar medium is organotin alkoxide. In this work, DFT studies on B3LYP/LANL2DZ/6-31+G** level of theory with the CPCM solvent model was used to study the reactivity between isocyanate and alcohol in the presence of a selected organotin catalyst in different mediums. The theoretical studies were supported by experimental evidence.

Investigations of catalysis of urethane formation using organotin dicarboxylate

“…NCO depletion with time data for the reaction between isocyanate and alcohol in the presence of different catalyst data were obtained from previous experiments [6,7]. By using this data, reaction rates at selected points for each reaction were calculated to determine the NCO depletion rate with time.…”

“…The product was used without further purification. More details of the preparation of these compounds are given in our previous publication [7]. NMR spectra were recorded on Bruker DRX 400 MHz NMR spectrometer at ambient temperature at 399.89 MHz ( 1 H) with chemical shifts (δ, ppm) reported relative to the solvent peaks of the deuterated solvent.…”

“…However, based on computational and experimental results, we have recently proposed mechanisms for the catalytic processes of the formation of urethanes. Organotin dicarboxylate was used as catalyst in combination with aliphatic and aromatic isocyanates [6,7,8]. In this work, the DFT B3LYP functional was used with LAN2DZ and 6-31G* basis sets for tin and light elements, respectively, and both geometrical and thermodynamic data were used to explain experimental findings.…”

Triorganotin Phosphonates Polymeric Chains - Synthesis, Infrared, Mossbauer and Single Crystal Characterization:the First Organotin(iv) Ph2- Bridged.

“…Metal phosphonate and organotin(IV) classes of compounds aroused and still arouse a great interest because of the wide properties and applications they display in various fields (Bao and Zheng, 2016;Hamchaouiet al, 2013a; Clearfield and Demadis, 2012; Mao, 2007;Fernandez-Armas et al, 2004a,Malllouk et al, 1996Cao et al, 1992;Etaiwet al 2019;Mao et al, 2015;Devendra et al, 2015;Carraher et al, 2019Carraher et al, , 2018Roner et al, 2014). Numerous organic phosphonate compounds were isolated and widely used as anti-HIV, antiviral in AIDS treatment (Troev, 2006).…”

Effect of fluorinated/non‐fluorinated β‐diketones and side‐chain branching of N‐protected amino acids on the antibacterial potential of new heptacoordinated monobutyltin(IV) complexes

“…The biological activity of organotin(IV) complexes may be influenced by the nature and number of donor atoms of organic ligands, presence or absence of fluorine, coordination number of tin and geometry of the resulting complexes. Organotin(IV) complexes exhibit potential relevance in catalysis, organic synthesis, biotechnology and medicinal chemistry . The promising applications and interesting structural chemistry of organotin(IV) complexes provide an impetus to study the structure–activity relationship of some new heptacoordinated organotin(IV) complexes which were generated by the reaction of BuSnCl 3 with sodium salts of flexible ligands AH and BH (B 3 H contains fluorine).…”