Phenol → 4-Hydroxy-4'-chlorobenzophenone

Beteiligte Stoffe

Reaktionsschritte

Phenol is reacted with p-chlorobenzoyl chloride in a Friedel-Crafts reaction in the presence of aluminium chloride to give 4-chloro-4'-hydroxybenzophenone, 179°-181° C. (A). To a solution of this (5 g.) in pyridine (6 ml.) was added methanesulphonyl chloride (2.5 g.), at room temperature. The reactants were heated on a steam bath for 11/2 hours and the liquid reaction product poured into dilute hydrochloric acid to give a solid which was filtered and air-dried. This solid was recrystallised from industrial methylated spirits to give 4-chloro-4'-methylsulphonyloxybenzophenone, m.p. 120°-121° C. (B). A solution of 9.4 g. of this product and ethyl carbazate (7.8 g.) in glacial acetic acid (8 ml.) and ethanol (200 ml.) was heated under reflux for 48 hours and then evaporated to dryness in vacuo. The residue was extracted with methylene chloride (250 ml.) and the extract washed with water, aqueous sodium hydroxide (2.5 N) and water and then dried and evaporated to dryness to give 4-chloro-4'-methylsulphonyloxybenzophenone ethoxycarbonylhydrazone, m.p. 132.5°-140° C. (C).

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