THE SPECTROSCOPY AND PHOTOCHEMISTRY OF ENAMINONITRILES INCLUDING THE SYNTHESIS AND IDENTIFICATION OF CIS‐β‐AMINOACRYLONITRILE

Abstract— The absorption spectral and photochemical properties of β‐aminoacrylonitrile (AAN), β‐aminocrotonitrile (ACN) and three other enaminonitriles have been studied. The synthesis and identification of cis‐β‐aminoacrylonitrile are also included. Each enaminonitrile has one intense absorption band (1–2 × 10⁴M^‐1cm^‐1) in the 254–273 nm region. Photoisomerization and photocyclization to imidazoles are observed. Imidazole formation is quite strongly inhibited by oxygen and the presence of oxygen can cause wavelength dependent photochemistry, other reactions and destruction of the reactant. The quantum yield of formation of imidazoles is low (<10^‐4) for β‐aminoacrylonitrile and β‐aminocrotonitrile and photoisomerization dominates in those four cases where it can occur. Imidazole formation from a dimethylamino compound proves that the presence of H atoms on the amino group is not a prerequisite for photocyclization.