2-((2-Cyanoethyl)(4-((4-nitrophenyl)azo)phenyl)amino)ethyl isobutyrate 75908-85-9 EINECS 278-342-7 Propanoic acid, 2-methyl-, 2-((2-cyanoethyl)(4-((4-nitrophenyl)azo)phenyl)amino)ethyl ester