Reaction of Isocyanates with Carboxylic Acids

The reactivity of isocyanates toward carboxylic acids is much lower than the one with amines, alcohols and water. The final product is an amide and gaseous carbon dioxide [1-3, 13]  

A special case is the reaction of an isocyanate group with formic acid. One mol of formic acid generates two mols of gases one mol of carbon dioxide and one mol of carbon monoxide. Formic acid is considered, like water, to be a reactive blowing agent (see Equations 2.1 and 2.2). 

Isocyanates have some important reactions without the participation of active hydrogen compounds. These reactions, of real importance in polyurethane chemistry are dimerisation, trimerisation, formation of carbodiimides and reaction with epoxides and cyclic anhydrides. 

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A Tracer Study of the Reaction of Isocyanates with Carboxylic Acids. J. 

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