Methyl Benzoate → Dibenzoylmethane

Participants

Reaction Steps

Methylbenzoate (136.0 grams; 1.0 mol), acetophenone (30.0 grams; 0.25 mol), sodium methoxide (17.3 grams; 0.3 mol) and xylene (300 ml) were placed into a four-necked, round bottom, one liter flask equipped with stirrer, nitrogen addition adapter, thermometer and Oldershaw column connected with distillation head and a trap. The mixture was heated with stirring to 135°-140° C. and maintained there for 6 hours while under a blanket of nitrogen. At 110°-120° C. methanol started to evolve and the reaction mixture became semi-solid. After two hours of heating the contents of the flask somewhat liquified. Towards the end of the reaction, nearly 25 ml of liquid consisting of methanol and xylene had been collected in the trap. The reaction mixture was cooled to room temperature and acidified with hydrochloric acid (500 ml of 6N). Stirring was continued for about 30 minutes until all the solid was dissolved. The xylene layer was separated and washed twice with water, then twice with aqueous sodium carbonate and then twice again with water. The xylene layer was removed by evaporation from the dibenzoylmethane (53.1 grams; 95% yield). Analysis by GLC showed the product to be 95% pure. This product after recrystallized from methanol had a melting point of 77°-78° C. The distillate (347.0 grams) containing xylene, methylbenzoate and water was subjected to azeotropic distillation.

Provenance & Evidence