esterification: put alkylphenol polyoxyethylene ether (1 mol) into the esterification kettle, and add a small amount of antioxidant catalyst sodium acetate. Under strong stirring, maleic anhydride (1.05 mol) was added in batches, and the temperature was gradually increased to 70 ℃ for 6 h. To obtain alkylphenol polyoxyethylene ether succinate.
The alkylphenol polyoxyethylene ether succinate was put into a sulfonation kettle, and sodium sulfite aqueous solution (NaSO 31.05 mol) was added dropwise under strong stirring. After dropping, stir at about 80 ℃ for 1 h. To get sulfonated products.