18305-60-7

108-31-6

115-11-7

18305-60-7

Maleic anhydride (13.7 g, 140 mmol), toluene (10 mL), diisopropyl ether (30 mL), water (2.78 mL) and p-toluenesulfonic acid monohydrate were added to a 200 mL four-necked flask and stirred at 30 °C. While maintaining the temperature of the reaction suspension at 30°C, isobutylene gas was passed into the reaction system for 4 hours. Upon completion of the reaction, the unreacted isobutene was expelled through a paraffin bubbler. The reaction mixture was washed sequentially with saturated aqueous sodium bicarbonate (3 x 50 mL) and saturated brine (50 mL), and the organic phase was dried with anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure to give di-tert-butyl maleate (23.4 g, 102.5 mmol, 73% yield).