تسجيل الدخول

تسجيل

Chemical Reactions of the Isocyanates

المؤلف:  A. Ravve

المصدر:  Principles of Polymer Chemistry

الجزء والصفحة:  p470-471

2026-02-09

426

Chemical Reactions of the Isocyanates

These reactions can be divided into two categories. They are additions to compounds with active hydrogens and self-condensation. The reactions are well described in organic chemistry textbooks, so there is little reason to describe them here. It is noteworthy, though, that the uncatalyzed reactions of isocyanates with various active hydrogen compounds are probably broadly similar. Among them, the most investigated reactions are the ones of alcohols with isocyanates :

Electron withdrawing substituents increase the positive charge on the isocyanate carbon and move the negative charge further away from the site for the reaction:

This makes an attack by an electron donor easier and yields a faster reaction. Electron donating groups, therefore, have an opposite effect.

Table7.7 Relative effects of catalysts on reactivity ofphenylisocyanate .