p-Toluenesulfonic acid → p-Methoxyphenylpropionic acid

Participants

Reaction Conditions

Reaction Steps

A mixture of 1-(4'-methoxyphenyl)-2-bromo-1-propanone (24,3 g; 0.1 mole), p-toluenesulphonic acid (1,9 g; 0,01 mole) and ethylene glycol (750 ml) is heated at 115° C. under vacuum (40 mmHg) for three hours, while distilling off a mixture of glycol and water. To the mixture cooled to 60° C., neutralized by means of sodium methoxide (0.6 g; 0.011 mole), potassium acetate (11,77 g; 0,12 mole) is added, and the mixture is heated at 130° C. for 6 hours. The mixture is then cooled to 90° C., to it 40%-concentrated potassium hydroxide (30 ml) is added, and the mixture is kept at the temperature said for 5 hours. After cooling to room temperature, the reaction mixture is poured into water (200 ml) and extracted with methylene chloride (2×250 ml). The aqueous phase is then made acid by means of concentrated hydrochloric acid, and extracted with methylene chloride (4×250 ml). The methylene chloride phase is washed with water (4×500 ml), separated and evaporated under vacuum. The residual oil is dissolved in a 10% solution of sodium bicarbonate (500 g), treated with charcoal (1 g) and filtered on celite. The so-obtained clear solution is cooled to 0° C. and made acid to pH 1 by means of concentrated HCl. 2-(4'-Methoxyphenyl)-propionic acid precipitates (7 g; 0,038 mole). Yield of 38%; melting point 54°-55° C.

Provenance & Evidence