SYNOPSISSide reactions of isocyanate groups in N,N-dimethylacetamide ( DMAC ) were studied. Although 4,4'-diphenylmethane diisocyanate (MDI) in DMAC was stable and no changes occurred at 3"C, the isocyanate content decreased and a gel was finally formed a t 40°C. Using phenyl isocyanate ( P I ) as a model compound of MDI, the identification of PI sidereaction products in DMAC were studied. From these experiments, the following five products were identified; ( 1 ) 1,3-diphenylurea (DPU ), ( 2 ) 1,3-diphenyl-5-phenylcarbamyl-6-dimethylaminouracil ( P U R ) , (3) 1,3,5-triphenylbiuret ( T P B ) , ( 4 ) triphenyl-s-triazine-2,4,6-trione (TTT), and ( 5 ) l,l-dimethyl-3-phenylurea (DMPU) . Among these identified products, the novel side reaction product PUR, which was formed between P I and DMAC as solvent, was found along with T P B and TTT, which were already known to cause threedimensional network formation.
A quantitative analytical method for a small amount of aromatic amino groups derived from some side reactions in segmented polyurethaneurea (SPU) was established. The amount of aromatic amino qroups in SPU was proportional to water content in the raw materials. The aromatic amine content in SPU in creased by hydrolysis of SPU. The reactions with various model compounds were investigated in order to clarify which chemical bonds in SPU gave aromatic amino grops. The results suggested that the amino groups were derived from the hydrolysis of biuret bonds in SPU analogous to that in 1, 3, 5-triphenylbiuret.
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