39139-87-2Relevant academic research and scientific papers
CHEMISTRY OF ONIUM CYANATES. COPOLYMERISATION WITH TDI YIELDING ONIUM POLYISOCYANURATES - POLYISOCYANATES
Lambert, P.,Aguirre, I. de,Touillaux, R.
, p. 393 - 404 (2007/10/02)
Owing to the lipophylic 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 to yield quantitetively 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 the formula (IX), or in abbreviated form, (T)a(R)n(NCO)a+2.Experimental values of parameters a, n, and the average number of adjacent heterocyclic anions, , are presented in table 2.It is demonstrated that anionomers of high M.W. (a>10; n>100; ca. 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).
