Sulfuric Acid → 6-bromo-3,4-dihydro-2H-1-benzopyran-4-one

4-Bromophenol (105 g, 0.61 mole) was converted into methyl(4-bromophenoxy)propanoate by the method referred to in Description 11A. This ester (125 g, 0.48 mole) was then added slowly to concentrated sulphuric acid (500 ml) and the resulting yellow solution stirred at room temperature for 30 minutes. This solution was poured slowly into ice/water (5 liters) and the mixture extracted using ethyl acetate (2×700 ml). The organic solution was washed with 10% sodium carbonate solution (2×300 ml) and brine (1×300 ml), dried (Na2SO4) and evaporated to dryness to give a pale yellow solid. This was recrystallised from ethyl acetate/petroleum ether (60°-80° C.) to give the title compound as a white crystalline solid (43.4 g, 31%). M.p. 79°-80°.

1. extractionthe mixture extracted
2. washThe organic solution was washed with 10% sodium carbonate solution (2×300 ml) and brine (1×300 ml)
3. dry with materialdried (Na2SO4)
4. customevaporated to dryness
5. customto give a pale yellow solid
6. customThis was recrystallised from ethyl acetate/petroleum ether (60°-80° C.)

ORD record

ord-e184b36bf7b1438181b2424e88920d9b

Source dataset

uspto-grants-1985_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04548948