It is used as a raw material for synthetic resins and paints, as well as impregnants, dispersants, lubricants, etc. in the petroleum industry, fabrics, plastics, and paper industries, and can be used as a plasticizer for polyvinyl chloride resins and methacrylic resins. Maleic acid esters are used as intermediates in organic synthesis, mainly for addition reactions on double bonds. Such as Diels-Alder reaction with butadiene, cyclopentadiene, etc., adding hydrogen, nitrile, mercaptan, amine and other compounds containing active hydrogen, the famous surfactant dialkyl succinate sulfonate, It is prepared by the addition of sodium bisulfite.