Urethane/urea chemistry functional groups

Can be synthetic polymers or natural-based polymers XH = -OH or -NH2 Figure 4.12 Application of urethane/urea chemistry in polymer functionalization and cross-linking (a) introduction of functional groups using functionalized monoisocyanates (b) introduction of isocyanates as functional groups (c) application of urethane/urea reaction as a cross-linking method. 

Preparation of Amines. Of the many ways of converting azides to amines, the direct hydrolysis of the intermediate isocyanates would appear to be the most efficient, since the reaction is much more rapid than the hydrolysis of either urethans or ureas. Nevertheless, this route to the amine has seen relatively little use, partly because isocyanates are converted by water quite easily to sym-ureas. It is wise not to risk valuable compounds, available in small amount only, with this method. No one method for converting azides to amines can be said to be the best, and the method must be chosen with due r ard for the chemistry of the other functional groups in the molecule. 

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