Novel Copolymers of Styrene. 8. Ring-Trisubstituted 2-Cyano-3-phenyl-2-propenamides

Abstract

Novel trisubstituted ethylenes, ring-trisubstituted 2-cyano-3-phenyl-2-propenamides, RC 6 H 2 CHHC(CN)CONH 2 (where R is 2,4, 6-trimethyl, 2,3-dimethyl-4-methoxy, 2,3,4-trimethoxy, 2,4,5-trimethoxy, 2,4,6-trimethoxy, and 3,4,5-trimethoxy) were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-trisubstituted benzaldehydes and cyanoacetamide and characterized by CHN elemental analysis, IR, 1 H-and 13 C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution in the presence of a radical initiation (AIBN) at 70 C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1 H-and 13 C-NMR, GPC, DSC, and TGA. Thus, the order of relative reactivity (1/r1) and the tendency toward alternation of monomer units in the copolymer for the monomers is 2,4,6-(CH 3 ) 3 (0.71) > 2,3-(CH 3 ) 2 -4-CH 3 O (0.52) > 2,3,4-(CH 3 O) 3 (0.34) > 2,4,5-(CH 3 O) 3 (0.30) > 3,4,5-(CH 3 O) 3 (0.15) > 2,4,6-(CH 3 O) 3 (0.12). High T g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200-500 C range with residue (2.9-9.9 wt%), which then decomposed in the 500-800 C range.