Hydrogen Bromide → 1H-2-Benzopyran-1,4(3H)-dione

HRID 1909489Notes

Reaction equation

HRID 1909489 reaction equation
[C:1]([C:4]1[CH:12]=[CH:11][CH:10]=[CH:9][C:5]=1[C:6]([OH:8])=[O:7])(=[O:3])[CH3:2].ClC1C=CC=CC=1.Br.O>C(O)(=O)C.BrBr>[C:6]1(=[O:8])[C:5]2[CH:9]=[CH:10][CH:11]=[CH:12][C:4]=2[C:1](=[O:3])[CH2:2][O:7]1

Participants

7

Reactant 4

HCID 260Hydrogen BromideHCID 962WaterHCID 7964ChlorobenzeneHCID 684742-Acetylbenzoic acid

Product 1

HCID 126956791H-2-Benzopyran-1,4(3H)-dioneYield 75%

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolventHCID 24408BromineSolvent

Conditions

Temperature
30 °C

Procedure

A stirred mixture of 2-acetylbenzoic acid (compound of formula (XI)) (1.00 Kg, 6.09 mol) and chlorobenzene (10.0 L) was treated with 5.5 molar hydrobromic acid in acetic acid (55 mL) and bromine (310 mL) then warmed to approximately 30° C. After 3 hours water (10.0 L) was added and the reaction heated to reflux. After 3 hours the reaction was cooled to 60° C. and the organic layer removed. The aqueous layer was extracted with chlorobenzene (2.0 L) and the combined organic layers concentrated under reduced pressure to approximately 3.0 L. Propan-2-ol (5.0 L) was charged and the slurry cooled to 0° C. before being filtered and washed with propan-2-ol (2.0 L). The resulting solid was dried in vacuo at 50° C. to give the title compound (736 g, 75%); 1H NMR (400 MHz, CDCl3): δ 5.14 (2H, s, H-9), 7.82-7.91 (2H, m, H-2 and 3), 8.08-8.10 (1H, m, H-1), 8.28-8.30 (1H, m, H-4); 13C NMR (100 MHz, CDCl3) δ 73.4, 125.6, 128.0, 130.9, 131.8, 134.7, 135.9, 161.4 and 189.5.

Workup

  1. temperaturethe reaction heated to reflux
  2. temperatureAfter 3 hours the reaction was cooled to 60° C.
  3. customthe organic layer removed
  4. extractionThe aqueous layer was extracted with chlorobenzene (2.0 L)
  5. concentrationthe combined organic layers concentrated under reduced pressure to approximately 3.0 L
  6. additionPropan-2-ol (5.0 L) was charged
  7. temperaturethe slurry cooled to 0° C.
  8. filtrationbefore being filtered
  9. washwashed with propan-2-ol (2.0 L)
  10. customThe resulting solid was dried in vacuo at 50° C.

Sources & evidence

ORD record
ord-77b7e2eeaf864203a70a243e235d6d92
Source dataset
uspto-grants-2013_12
Patent number
US08598387B2

Reaction notes

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