Solvent effects on an organotin-catalyzed alcohol-isocyanate reaction

The pseudo-first order kinetics of the reaction of cyclopentanol with pheny lisocyanate, catalyzed by dibutyltin di(2-ethylhexanoate) (DBTDEH), was stu died by means of UV and IR spectrophotometry. Reaction orders with respect to catalyst and to monomeric alcohol [1] were considered in toluene (Tol), di(n-butyl)ether (DBE) and acetonitrile (ACN). The results, which were inte rpreted with the aid of rate equations previously derived [2-4] on the basi s of a reaction scheme involving an alkoxytin(IV) intermediate, indicate th at pre-reaction complexes of solvent-dependent composition are formed in th e rate determining step of both catalyzed and uncatalyzed mechanisms [5].