Hydrogen (H)-complex formation of maleic anhydride-acrylic acid (methyl acrylate) monomer system

The results of the study of complex formation through H-bond between the -C=O group of maleic anhydride (MA, electron-donor monomer) and the carboxyl group of acrylic acid (AA, electron-acceptor monomer) and the charge transfer complex between the double bond of MA and vinyl acetate (VA, electron donor monomer) using ultraviolet-visible spectroscopy (Uv-vis) and nuclear magnetic spectroscopy (¹H NMR) methods are discussed. Maleic anhydride-methyl acrylate (MAc) monomer pair as a model system is also studied. The formation of two types of complexes in the MA-AA monomer system with further determination of their K_H and K_C values were studied using ultraviolet-visible spectroscopy (UV-vis) and ¹H NMR spectroscopy and the following well known equations of Benesi-Hildebrand, Ketelaar and Hanna-Aushbaugh, respectively. The formation of H-complex in the MA-AA system is confirmed by the analysis of electronic spectra of free monomers and their various mixtures (MA≫AA) in dioxane at 25 °C. The equilibrium constant of the MA...AA charge transfer complex (CTC) formation was determined by ¹H NMR in p-dioxane and acetone at 25 °C.