Mechanism of tin(IV) -catalysed urethane formation

Article abstract of DOI:10.1016/0022-328X(96)06223-7

It has been found that dibutyltin dilaurate and dibutyltin dibutanethiolate are almost equally effective as catalysts in the formation of a urethane from phenyl isocyanate and butanol, and that the catalytic activity of both compounds is inhibited by thiols. These results are consistent with a mechanism which involves the N-coordination of the isocyanate with a tin alkoxide that is formed by alcoholysis of the starting tin compound.