Benzene → Benzopyran

Participants

Reaction Steps

A mixture of 4-chromanol (30 g; 0.02 mole), benzene (200 ml) and 4-toluenesulfonic acid (200 mg) was refluxed, with a Dean-Stark trap, until separation of water ceased (ca. 3 hrs.). It was then washed successively with saturated NaHCO3 aqueous solution and water, dried over anhydrous MgSO4 and evaporated under reduced pressure to yield an almost colorless liquid which was distilled under vacuum to give benzopyran (20.2 g, 76.4%) b.p. 73°-78°/3 torr.

Provenance & Evidence