Nitric Acid → HCID 178526877, compound

HRID 386415Notes

Reaction equation

HRID 386415 reaction equation
[F:1][C:2]([F:12])([F:11])[C:3]1[N:8]=[C:7]([OH:9])[CH:6]=[C:5]([OH:10])[CH:4]=1.[N+:13]([O-])([OH:15])=[O:14]>S(=O)(=O)(O)O>[N+:13]([C:6]1[C:7]([OH:9])=[N:8][C:3]([C:2]([F:1])([F:11])[F:12])=[CH:4][C:5]=1[OH:10])([O-:15])=[O:14]

Participants

4

Reactant 2

HCID 944Nitric Acid2×HCID 178516647HCID 178516647, compound

Product 1

HCID 178526877HCID 178526877, compoundYield 71%

Reagents, catalysts & solvents 1

HCID 1118Sulfuric AcidSolvent

Conditions

Temperature
-50 °C

Procedure

6-Trifluoromethyl-pyridine-2,4-diol (56 g, 310 mmol) was added in 3-5 gm portions to concentrated sulphuric acid (140 mL) with stirring to give a pale brown solution. The temperature increased to −50° C. during the addition. Nitric acid (21.1 mL 328 mmol, 70% HNO3 d=1.4 gm/ml) was added drop wise at such a rate as to maintain a reaction temperature of between 45° and 50° C. which took approximately 90 minutes. Once all the nitric acid had been added the reaction was allowed to cool to ambient temperature over 3 hours. Poured into ice/water (˜1.3 kg) with stirring, after a few minutes a pale yellow precipitate formed which was filtered off, dissolved in ethyl acetate and dried over sodium sulphate, filtered and evaporated. A second crop of material was obtained by extraction of the aqueous filtrate with ethyl acetate. Combined batches and purified by crystallization from ethyl acetate/n-heptane gave 3-nitro-6-trifluoromethyl-pyridine-2,4-diol as a white ‘fluffy’ solid (49.5 gm 71% yield).

Workup

  1. customto give a pale brown solution
  2. temperatureto maintain a reaction temperature of between 45° and 50° C. which
  3. temperatureto cool to ambient temperature over 3 hours
  4. stirringwith stirring, after a few minutes a pale yellow precipitate
  5. customformed which
  6. filtrationwas filtered off
  7. dissolutiondissolved in ethyl acetate
  8. dry with materialdried over sodium sulphate
  9. filtrationfiltered
  10. customevaporated
  11. customA second crop of material was obtained by extraction of the aqueous filtrate with ethyl acetate
  12. customCombined batches and purified by crystallization from ethyl acetate/n-heptane

Sources & evidence

ORD record
ord-65dd6dcef75147f59ac5b8c5a99b3688
Source dataset
uspto-grants-2013_02
Patent number
US08372836B2

Reaction notes

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