The formation and isomerization of the sodium methoxide adducts of cinnamylidenemalononitrile, followed by IR spectra and ab initio force field calculations

Abstract

The reaction of cinnamylidenemalononitrile with sodium methoxide in dimethyl sulphoxide and the isomerization α,β→α,δ of the adduct formed has been followed by IR spectra and ab initio force field calculations. The formation of the α,β adduct is kinetically controlled, probably due to a steric hindrance at the δ-position. According to the calculations, however, the α,δ adduct is by 28.2kJmol−1 more stable than its α,β-isomer and this result could be used as an explanation of the further conversion: within 24h the α,β-adduct isomerizes spontaneously and practically completely into the α,δ-one. The latter conversion is also well evident from the IR spectra.