Carbon Dioxide → Benzo(b)thiophene-3-carboxylic acid

HRID 464749

Reaction equation

HRID 464749 reaction equation
Br[C:2]1[C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][C:5]=2[S:4][CH:3]=1.CI.[Mg].[C:14](=[O:16])=[O:15].Cl>CCOCC.C1(C)C=CC=CC=1>[S:4]1[C:5]2[CH:10]=[CH:9][CH:8]=[CH:7][C:6]=2[C:2]([C:14]([OH:16])=[O:15])=[CH:3]1

Participants

8

Reactant 5

HCID 280Carbon DioxideHCID 313Hydrochloric AcidHCID 6328Methyl iodideHCID 123250Benzo(b)thiophene, 3-bromo-HCID 5462224Magnesium

Product 1

HCID 601280Benzo(b)thiophene-3-carboxylic acidYield 44%

Reagents, catalysts & solvents 2

HCID 1140TolueneSolventHCID 3283Diethyl EtherSolvent2×

Procedure

A solution of 3-bromobenzothiophene (0.40 mole, (D15)) and methyl iodide (25 ml, 0.40 mole) in dry ether (400 ml) was added to a stirred mixture of magnesium turnings (24 g, 1.0 mole) and dry ether (100 ml) under nitrogen, at such a rate as to maintain a steady reflux. After the addition was complete, the reaction mixture was heated under reflux for 30 minutes and then allowed to cool to room temperature. The solution was diluted with dry toluene (500 ml) and stirred vigorously as dry carbon dioxide was bubbled through over 3 hours. The thick precipitate which formed was dissolved by the addition of dilute hydrochloric acid and the organic layer was then separated. The aqueous solution was extracted with ethyl acetate (2×300 ml) and all the organic solutions were then combined and extracted with 10% sodium carbonate solution (4×300 ml). The aqueous extracts were combined, washed with ether (2×200 ml) and then acidified with dilute hydrochloric acid. The precipitate was filtered off, washed with water and then dried under vacuum to give the title compound as a white solid (31.2 g, 44%) m.p. 171°-173°.

Workup

  1. temperatureat such a rate as to maintain a steady reflux
  2. additionAfter the addition
  3. temperaturethe reaction mixture was heated
  4. temperatureunder reflux for 30 minutes
  5. customwas bubbled through over 3 hours
  6. customThe thick precipitate which formed
  7. customthe organic layer was then separated
  8. extractionThe aqueous solution was extracted with ethyl acetate (2×300 ml) and all the organic solutions
  9. extractionextracted with 10% sodium carbonate solution (4×300 ml)
  10. washwashed with ether (2×200 ml)
  11. filtrationThe precipitate was filtered off
  12. washwashed with water
  13. customdried under vacuum

Sources & evidence

ORD record
ord-61428b7594504909ae8ab63384ed4ea3
Source dataset
uspto-grants-1985_10
Patent number
US04548948

Linked notes

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