Sodium Hydroxide → 3-Hydroxy-2-methylbenzoic Acid

Participants

Reaction Conditions

Reaction Steps

A solution of 3-benzyloxy-2-methylbenzoic acid (50 g, 0.21 mol) and sodium hydroxide (9 g, 0.225 mol) in 700 g of water and 2 g of 5% Pd/C catalyst (50% water-moist) are added to a 21 steel autoclave with an aerating stirrer. 10 bar of hydrogen are injected at a temperature of 50° C. and a stirring speed of 800 rpm. Consumed hydrogen is replaced by repeated injection. After 20 min, the absorption of hydrogen falls off. The catalyst is filtered off at room temperature by means of a pressure filter. 760.7 g of a crude solution are obtained, from which 7.7 g of toluene are separated off in a separating funnel. A total of 22.2 g of hydrochloric acid (37% strength) are added to the crude solution, then the solution is cooled to 0° C. The precipitated solid is filtered off with suction and washed twice with 50 g of water. After drying, 18.0 g of 3-hydroxy-2-methylbenzoic acid having a melting point of 147° C. are obtained. After concentration of the mother liquor, a further 9.6 g of substance can be obtained, such that the total yield is 27.6 g or 88.1% of theory.

Provenance & Evidence