Computational exploration of urethane formation in the presence of amine catalysts

Abstract Polyurethanes are highly versatile polymers widely used in industry to produce a broad range of materials. Their synthesis from diisocyanates and polyols under industrial conditions typically requires a catalyst—or a combination of catalysts—which plays a critical role in determining reaction efficiency and selectivity. In this study, we examined a diverse set of amine catalysts to identify key properties relevant to selecting the most suitable species for specific applications. To this end, we evaluated both structural and energetic descriptors, namely steric parameters (expressed as %Vbur) and proton affinities (PA). The results show that 1-(3-aminopropyl)imidazole (APIM) possesses the lowest calculated proton affinity (905.8 kJ mol − 1 ) among the studied compounds, indicating a greater tendency of its conjugate acid to donate a proton. In contrast, steric analysis revealed that tertiary amines generally exhibit higher buried volumes than primary and secondary amines. Notably, the differences in %VBur values between 2,2’-dimorpholinodiethylether (DMDEE) (67.0%), dimethylaminoethylether (DMAEM-1 N*) (66.4%), and N -Ethylmorpholine (NEM*) (65.8%) are relatively small; these values indicate similar steric environments, rather than a strictly greater steric effect for one catalyst over the others. However, given the small numerical differences, these catalysts can be considered to exhibit comparable steric profiles. Overall, this work provides deeper insight into how electronic and steric factors influence urethane formation and offers a rational basis for selecting appropriate catalysts tailored to specific applications.