Abstract
Sulfonation of maleic acid monoesters of EOAA (ethylene oxide adducts of C1214 s-alcohols) using sodium sulfite or sodium hydrogensulfite were conducted under various reaction conditions. Disodium salts of sulfonatosuccinic acid monoester of EOAA were obtained in high yield and purity by adjusting reaction temperature, atmosphere (N2), molar ratios of reactants and pH at the start of reactions while supressing the oxidation of sulfites and hydrolysis of monoesters of products or/and raw material. Examination was also made of hydrolysis of salts of maleic acid monoesters or salts of sulfonatosuccinic acid monoesters of EOAA at different pH. Molecular orbital calculation indicated the salts of maleic acid monoesters to be hydrolyzed more easily than those of sulfonatosuccinic acid monoesters. Proton NMR analysis and molecular orbital calculation indicated the insersion of the NaSO3- group into the double bonds of salts of maleic acid monoesters to occur mainly at the α-position.
