4-Hydroxybenzoic Acid → Benzoic acid, 4-(benzoyloxy)-

Participants

Reaction Conditions

Reaction Steps

138.1 g (1.0 mol) of para-hydroxybenzoic acid were first dissolved in 400 ml of water and 600 ml of isopropanol and this solution was admixed at 0 to 5° C. with 235.7 g of KOH solution (50% strength by weight aqueous solution, 2.1 mol). The resulting pH was 14. Metered into this solution over the course of one hour, then, at 0 to 5° C., were 140.4 g (1.0 mol) of benzoyl chloride, and the batch was stirred for 30 minutes at 0 to 5° C. thereafter. At the end of the after-stirring, the pH of the reaction mixture was 9.3. The reaction mixture was subsequently adjusted to a pH of 8 at 0 to 5° C. using 25.0 g of HCl solution (32% strength by weight aqueous solution), and the complete solution was heated to 55 to 60° C. and then adjusted to a pH of 1.5 to 3 using 100 g of HCl solution (32% strength by weight aqueous solution). The reaction mixture was cooled to 20 to 25° C. and the solid was filtered off on a suction filter and washed ten times with 150 ml of water. The yield after drying under reduced pressure at 100° C. was 220.5 g (91.0% of theory). According to HPLC and NMR measurement, the product was free from benzoic acid and from unreacted para-hydroxybenzoic acid. The purity of the product is >99.9% by weight.

Provenance & Evidence