Nitric Acid → 2,6-Difluoro-3-nitrobenzoic acid

HRID 1759209Notes

Reaction equation

HRID 1759209 reaction equation
[N+:1]([O-:4])(O)=[O:2].S(=O)(=O)(O)O.[F:10][C:11]1[CH:19]=[CH:18][CH:17]=[C:16]([F:20])[C:12]=1[C:13]([OH:15])=[O:14]>>[F:10][C:11]1[C:19]([N+:1]([O-:4])=[O:2])=[CH:18][CH:17]=[C:16]([F:20])[C:12]=1[C:13]([OH:15])=[O:14]

Participants

4

Reactant 3

HCID 944Nitric AcidHCID 1118Sulfuric AcidHCID 97962,6-Difluorobenzoic acid

Product 1

HCID 3026292,6-Difluoro-3-nitrobenzoic acidYield 20.2%

Conditions

Temperature
10 °C

Procedure

A mixture of 31.4 grams (0.498 mole) of 70% nitric acid and 107.1 grams (1.092 moles) of concentrated sulfuric acid was cooled to 10° C. and added dropwise to 75.0 grams (0.474 mole) of stirred 2,6-difluorobenzoic acid. The complete addition required 25 minutes during which time the resultant reaction caused the reaction mixture temperature to rise to 50° C. Upon complete addition the reaction mixture temperature was maintained at 50° C. for one hour, then allowed to cool to ambient temperature where it stirred for 16 hours. The reaction mixture was poured into 250 ml of ice-water and stirred until the ice melted. The mixture was poured into a separatory funnel and extracted with three portions of diethyl ether. The combined extracts were washed with three portions of 400 ml of an aqueous solution saturated with sodium chloride. The organic layer was filtered through phase separation paper and the filtrate concentrated under reduced pressure to a residual solid. The solid was recrystallized from heptane-ethyl acetate to give 19.4 grams of 2,6-difluoro-3-nitrobenzoic acid. The mother liquor was concentrated under reduced pressure to give an additional 56.5 grams of this product.

Workup

  1. additionThe complete addition required 25 minutes during which time the resultant
  2. customreaction
  3. customto rise to 50° C
  4. additionUpon complete addition the reaction mixture temperature
  5. temperaturewas maintained at 50° C. for one hour
  6. temperatureto cool to ambient temperature where it
  7. additionThe mixture was poured into a separatory funnel
  8. extractionextracted with three portions of diethyl ether
  9. washThe combined extracts were washed with three portions of 400 ml of an aqueous solution saturated with sodium chloride
  10. filtrationThe organic layer was filtered through phase separation paper
  11. concentrationthe filtrate concentrated under reduced pressure to a residual solid
  12. customThe solid was recrystallized from heptane-ethyl acetate

Sources & evidence

ORD record
ord-d23dd7017cf34f5bb39050f4f28c6c9f
Source dataset
uspto-grants-1982_07
Patent number
US04339457

Reaction notes

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