Active hydrogen compounds base catalyst condensation

The isocyanate group is very reactive and will condense with other active compounds containing hydrogen, like amines and thiols. Products resulting from such reactions, respectively, are the ureas and thiocarbamates. With amines the rate of reaction is somewhat faster than with hydroxyl compounds, while that with thiols is slower. However, a wide variety of catalyst systems (many based on amines and organometallic compounds) is available for the acceleration of isocyanate reactions. 

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