Polyisocyanurates as Catalyst Support Systems

Significance

N-heterocyclic carbenes (NHCs) are known to catalyze the cyclotrimerization of isocyanates (1 → 2). The authors used this reaction to develop the synthesis of a microporous covalent network (4) from a diisocyanate (3). By absorbing FeCl₂ onto 4 a heterogeneous oxidation catalyst was formed, which could be recycled numerous times without loss of activity, and was generally a superior oxidant of benzyl alcohol than FeCl₂ by itself. The absorption of benzyl alcohol by the porous framework, thereby increasing the exposure of the reagent to the catalyst, was offered as an explanation for the increased catalyst activity.