SyntheticPage 428
Published Jul 05, 2010
Powdered phthalic anhydride (74 g, 0.5 mol) and methanol (100 cm3, 2.47 mol) were heated under reflux with magnetic stirring on an oil bath for 8 h. The clear solution was distilled to remove most of the methanol. Toluene (100 cm3) was added to the residue and distillation was continued until the still-head temperature reached 110 ºC. After cooling to 30 ºC, the resulting thick white precipitate was filtered and the residue washed with toluene (50 cm3). Petroleum ether (30/40, 100 cm3) was added to the combined filtrates to give a dense oil which crystallised as long white needles after standing overnight. Filtration and washing with petroleum ether (60/80, 50 cm3) gave the product, 44.5 g, 49% yield.