An improved synthesis of 2-vinyl-4,5-dicyanoimidazole and characterization of its polymers

An efficient synthesis of (1Z)-1-amino-1,2-dicyano-3-aza-1,3,5-hexatriene (acrodamn), via condensation of acrolein and diaminomaleonitrile (DAMN), is described. A larger laboratory-scale synthesis of 4,5-dicyano-2-vinylimidazole (vinazene) is described in detail. The alkylation of vinazene proceeds with strong electrophiles. The compound, 4,5-dicyano-1-methyl-2-vinylimidazole (1-methylvinazene), undergoes Michael addition with pyrrolidine, morpholine, and thiophenol and at higher temperatures with itself, resulting in step-growth oligomerization. Direct measurements of kinetic rates for vinylic radical addition polymerization of vinazene yielded k(app) = kp/2 rootk(t)fk(d) values of (7.2 +/- 0.25) x 10(-3) and (6.6 +/- 0.27) x 10-3 Direct measurements of kinetic rates for 1-methylvinazene yielded k(app) = k(p)/2 rootk(t)fk(d) values of (4.3 +/- 0.31) x 10(-3) and (3.7 +/- 0.06) x 10(-3). Indirect measurements show the polymerization obeys first-order kinetics. The poly(vinazene) is an acidic material with molecular weights ranging from 100 000 to 200 000 and polydispersities between 2.0 and 2.9. The Mark-Houwink constants for poly(vinazene) in 0.05 M LiBr in N-methylpyrrolidinone were K = 3,35 x 10(-5) and a = 0.889. The titration behavior is similar to poly(methacrylic acid).