Chimie Des Cyanates D'onium Copolymérisation Avec Le Toluène Diisocyanate Et Formation De Polyisocyanates - Polyisocyanurates D'onium: Chemistry of Onium Cyanates Copolymerisation with Toi Yielding Onium Polyisocyanurates - Polyisocyanates.

Owing to the lipophilic character of the tetraalkylonium cations many onium cyanates are soluble in aprotic organic solvents in which they show a high reactivity. In this paper we examine the reactions of onium cyanates (QNCO) with aromatic mono- and diisocyanates. Aromatic isocyanates react very rapidly with QNCO (co-trimerization) at room temperature and yield quantitatively onium diarylisocyanurates (IV) (S: Ac, DME). In some solvents (e.g. DCM) co-trimerization and trimerization to triarylisocyanurate (II) are observed (fig. 1). Onium polyisocyanurates polyisocyanates (scheme 1) are prepared from QNCO and diisocyanates (e.g. TDI), the first and rapid step being the co-trimerization to compound (V). In the absence of QNCO, (V) undergoes slow trimerization to (VII) (fig. 2), but in the presence of QNCO co-trimerization to onium polyisocyanurate (VIII) occurs. However, the ionic heterocyclization is not perfectly selective, but is accompanied by the trimerization to triarylisocyanurates. The polymers synthesized from the TDI-QNCO systems are represented by formula (IX) or, in abbreviated form, (T)8 (R)n (NCO)a+2. Experimental values of parameters a, n, and the average number of adjacent heterocyclic anions, n, are presented in table 2. It is demonstrated that anionomers of high M.W. (a>10; n>100; n°5) and soluble in DCM can be prepared by this method. The important parameters in this polymerization are the nature of Q+ and that of the solvent (table 2).