Aminolysis of PU Polymer

Urethane groups react with primary and secondary amines leading to a disubstituted urea and an alcohol (reaction 20.8). 

The disadvantage of hydroxyalkyl urea formation is an intramolecular reaction which leads to an oxazolidone, a cyclic urethane (reaction 20.10) [33]. 

The oxazolidone formed is not an interesting component in PU chemistry because it does not have reactive groups such as hydroxyl or amino groups to enter into the PU structure (just the low reactivity -NH-COO- urethane group which leads to an allophanate). 

By using sodium or potassium hydroxides as catalysts of aminolysis, it is possible to regenerate the initial monoethanolamine (a bifunctional compound in the conditions of PU chemistry and to destroy the oxazolidone formed (reaction 20.11) [33]  

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