Three fundamental mechanisms of base-catalysed reactions of isocyanates with hydrogen-acidic compounds

Efficient organotin catalysts for urethanes: kinetic and mechanistic investigations

“…With these initial concentrations, the reactions of pheny isocyanate with 1 equiv of alcohol or phenol proceeded smoothly in refluxing dichloromethane and were complete within 10 min (inferred via TLC), giving rise to the corresponding N-phenylurethanes in 76-97% yields ( Table 2, entries 1, 2, 4-11). Similar reactions of toluene-2,4-diisocyanate with 2 equiv of alcohols proceeded to completion in 20 min with the formation of the corresponding diurethanes in 80-91% yield ( Table 2, entries 12, [14][15][16][17]. In all the above cases the uncatalysed reactions under similar conditions showed 6-19% conversion.…”

“…16 While the mechanism of the amine-catalysed reaction 17 is well understood, that of the tin-catalysed reaction remains uncertain. We also describe our work towards understanding the isocyanate-alcohol addition reaction mediated by the new group of organotin catalysts.…”

Fluoropolyethers end-capped by polar functional groups. I. Kinetic approach to the reaction of hydroxy-terminated fluoropolyethers with cycloalyphatic and aromatic diisocyanates

“…[23][24][25] The effect of molecular organization of reagents (autoassociation of an alcohol) can also be of great importance for catalytic reactions of urethane formation. 26 -29 Reegen and Frisch 30 found a sharp increase in the rate of reaction between phenyl isocyanate and 1-methoxy-2-propanol in toluene at 30°C with DBTDL (1 ϫ 10 Ϫ4 mol L Ϫ1 ) due to the action of the increasing urethane group concentration.…”

Coatings for Solderable Wires for the Modern Electric Industry

“…One main type of mechanism has been proposed to describe the amine catalyzed urethane formation in the last five decades 45–50. The complexion of isocyanate with the tertiary amine is followed by the attack of the nucleophilic agent and the formation of a hydrogen‐bonded complex between them, which attacks the isocyanate in a second step (Scheme ).…”