Sulfuric Acid → 2-Benzoylcyclohexanone

Participants

Reaction Steps

1-Methoxy-2-propanol (61.3 g; 0.68 mol), sodium hydroxide (16.0 g; 0.40 mol), and xylenes (300 mL) were placed into a four-necked, round bottom, half-liter flask equipped with a stirrer, a thermometer, and an Oldershaw column with a Dean-Stark trap and a condenser. The mixture was heated to boiling with stirring under a blanket of nitrogen and the water was azeotroped out (temperature of reflux 106-116° C.). When no more water was collected (23 mL of lower phase) some solvent was distilled off (215 mL), while xylenes (432.2 g, dry) were replaced, until no more alcohol was detected in the distillate (temperature of reflux 137° C.). The mixture in the flask was cooled down to and kept at 80° C. and the fractionation column and trap were replaced with a reflux condenser while maintaining the nitrogen stream. Methyl benzoate (68.1 g; 0.50 mol) was added, and slow addition over a period of 10 minutes of cyclohexanone (24.5 g, 0.250 mol) by means of a syringe pump was begun. After 19 minutes from the beginning of the addition of the ketone, the mixture was cooled down (an ice bath was used), and acidified by slow addition of 98% sulfuric acid (slightly over 24.5 g) with stirring. The mixture was transferred to a 1 L separatory funnel, washed with aqueous sodium bicarbonate, and then with water. Evaporation of the organic layer under vacuum and recrystallization from heptane afforded 32.86 g of BCH (65% yield based on cyclohexanone), with a purity of 99% (GC).

Provenance & Evidence