The synthesis of Acrylic anhydride is as follows:
In a 3-liter, four-necked glass reactor provided with a thermometer and a stirrer were placed, in a dry air atmosphere, 1,240 g of methylene chloride, 1.08 g (0.5% by mass) of Sumilizer GM, 0.65 g (0.3% by mass) of Sumilizer TP-D, 0.65 g (0.3% by mass) of Sumilizer WX-R, 216 g (3.0 mol) of acrylic acid and 264 g (1.5 mol) of benzenesulfonyl chloride. The mixture was cooled to 5°C. Then, 304 g (3.0 mol, 1 equivalent relative to the acids generated from benzenesulfonyl chloride) of triethylamine was dropwise added in 2 hours with the temperature of the reaction mixture being controlled at 30°C or lower. After the completion of the dropwise addition, stirring was made for 1 hour with the same temperature being kept. The reaction mixture was analyzed by GC, which indicated that the conversion of acrylic acid was 99%. After the completion of the reaction, 375 g of water was added to the reaction mixture to wash the reaction mixture. The reaction mixture was further washed twice each time with 563 g of water, after which distillation was conducted to remove methylene chloride. The yield of the acrylic acid anhydride obtained was 172 g and 91% and its purity by GC analysis was 99%, and no high-molecular by-product was detected.
