Special reactions for formation of polyamides

There are occasional reports in the literature on use of special reactions to form polyamides. One is a synthesis via enamines. In this case, diisocyanates are condensed with cyclopentanone enamines of morpholine or of piperidine [77]  

7 Step-Growth Polymerization and Step-Growth Polymers 

The molecular weights of the polymers decrease when the ring sizes of the ketone components increase. Excess diisocyanate yields branched and cross-linked polymers. The enamine units in the polymers can be hydrolyzed with formic acid to the corresponding ketones [77]. 

A similar reaction was reported from aromatic isocyanates and imidazoles, where 1,4 tetramethylene-A,A -di imidazoles were reacted with aromatic polyisocyanates to form thermoset polyamides [45]  

When aromatic di nitriles are used, high melting polymers with good thermal stability form [78]. 

Direct polycondensation of various dicarboxylic acids with diamines is possible under mild conditions by using a catalytic system of an enol phosphite in the presence of imidazole. One such enol phosphite is diethyl, l-methyl-3-oxo-l-butenyl phosphite  

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