2,2-Dimethoxy-2-phenylacetophenone → Phenyl(2-phenyl-4,7-dihydro-2H-1,3-dioxepin-2-yl)methanone

Participants

Reaction Steps

1 g of p-toluene sulphonic acid was added to a suspension of 77 g (0.3 mols) of benzil dimethyl ketal in 160 g (~1.8 mols) of cis-2-butene-1,4-diol, and heated to from 50° to 60° C. under a pressure of from 10 to 15 torr. After 45 minutes, a clear solution was obtained, the temperature of which rose to from 65° to 70° C. After a further 45 minutes, the reaction mixture had solidified into a crystal mass. After a total of 4 hours, the material was recrystallized from isopropanol, and 80 g (96%) of 2-benzoyl-2-phenyl-4,7-dihydro-1,3-dioxepin were obtained as colourless crystals having a melting point of from 118° to 119° C.

Provenance & Evidence