Sodium Hydroxide → 6-Chloroflavanone

Participants

Reaction Steps

5'-Chloro-2'-hydroxychalcone (25.0 g) was dissolved in ethanol (125 ml.) and and aqueous solution of 1.5% sodium hydroxide (375 ml.) was added. The mixture was stirred at room temperature for 4 hrs. and the solid filtered off, washed with water and dried to give 6-chloroflavanone (16.65. g), mp. 90°-93° C. A sample recrystallised from 60°-80° C. petroleum ether had m.pt 95°-96° C. The flavanone (4.0 g) was dissolved in acetic acid (160 ml.) and concentrated hydrochloric acid (20 ml.) and added to amalgamated zinc (from zinc dust (40 g.) and mercuric chloride (0.5 g). The mixture was stirred for 1 hr., and allowed to stand overnight. The residual zinc was filtered off, and the filtrate diluted with water. The oily precipitate was extracted into either and the extract washed with water and saturated sodium bicarbonate solution, dried over magnesium sulphate, filtered and evaporated. The residue was chromatographed on alkaline alumina, eluting with 60°-80° C. petroleum either, to give 6-chloroflavan (0.52 g.), m.p. 71°-72° C.

Provenance & Evidence