Sulfuric Acid → 2-Bromo-7-methoxy-9H-xanthen-9-one

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Reaction Steps

To 2-(4-bromophenoxy)-5-methoxybenzoic acid (530 g, 1.6401 mol) was added sulfuric acid (1.6 lit, 3 vol.) at RT. The resulting dark mixture was heated to 60 C. TLC showed complete conversion of starting material to product after about 1 hr. The brown solution was cooled to RT and poured onto ice with manual stirring. The resulting tan precipitate was collected by filtration, washed with water, 1N NaOH (2.0 lit) solution and finally with 800 mL of ethanol & stirred in 2 liters of acetone & filtered. The solids were dried under vacuum to afford 1.3 kg (68.85%) of the titled compounds as a white solid. MS m/z=307.0 [M+H]+. Calc'd for C14H9BrO3: 305.1.

Provenance & Evidence