Hydrochloric Acid → 2,3,4,5-Tetrahydro-1-benzoxepin-5-one

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Reaction Steps

A solution of 238 g (1.2 mole) of 4-phenoxybutyryl chloride, dissolved in 350 ml of 1,2-dichloroethane, is added dropwise to a suspension, cooled to 0° C., of 192 g of aluminum trichloride in 1,200 ml of 1,2-dichloroethane within 4.5 hours while passing through nitrogen and stirring vigorously. The mixture is then stirred at 0° C. for 1.5 hours and allowed to warm to room temperature overnight. The mixture is added to a stirred mixture of 2,000 ml of concentrated hydrochloric acid and 2.5 kg of ice and then stirred for 1.5 hours. The aqueous phase is decanted off, and insoluble residue is removed from the organic phase by filtration, washing thoroughly with 1,2-dichloroethane. The aqueous phase is extracted 3-4 times more with methylene chloride, and the combined organic phases are washed with saturated sodium bicarbonate solution, water and saturated sodium chloride solution and dried over sodium sulfate. A yellowish oil is obtained after the solvent has been evaporated off in vacuo and is dissolved in diethyl ether, and the last residues of dyestuff are removed by filtration. Evaporation in vacuo results in a clear oil which distils at 74°-75° C./0.02 torr.

Provenance & Evidence