QUANTUM-CHEMICAL STUDY OF ENERGIES OF MALEIMIDE AND ITACONIMIDE ISOMERIC DERIVATIVES

For 38 pairs of the isomeric derivatives of maleimide and itaconimide, the Gibbs free energies were calculated using the density functional theory (DFT) and domain-based local pair natural orbital (DLPNO) methods. The effects of the solvent and of substituents in positions 1, 3, and 4 of the maleimide ring on the energy difference of the isomers were studied. Depending on the substituents and conditions, the equilibrium can shift toward the maleimide or itaconimide form. Further migration of the double bond and cis-trans- isomerism were also considered wherever possible.