Hydrochloric Acid → 3-Isobutyl-1H-pyrazole-5-carboxylic acid

HRID 1063805Notes

Reaction equation

HRID 1063805 reaction equation
C([O:3][C:4]([C:6]1[CH:10]=[C:9]([CH2:11][CH:12]([CH3:14])[CH3:13])[NH:8][N:7]=1)=[O:5])C.[OH-].[Na+].Cl>O1CCOCC1>[CH2:11]([C:9]1[NH:8][N:7]=[C:6]([C:4]([OH:5])=[O:3])[CH:10]=1)[CH:12]([CH3:14])[CH3:13]

Participants

5

Reactant 3

HCID 313Hydrochloric AcidHCID 14798Sodium HydroxideHCID 3804408ethyl 5-(2-methylpropyl)-1H-pyrazole-3-carboxylate

Product 1

HCID 6541713-Isobutyl-1H-pyrazole-5-carboxylic acidYield 71.6%

Reagents, catalysts & solvents 1

HCID 312751,4-DioxaneSolvent

Procedure

5-Isobutyl-1H-pyrazol-3-carboxylic acid ethyl ester (16.2 g, 83 mmol) and 1M NaOH solution (173 ml, 173 mmol) were dissolved in 1,4-dioxan (260 ml) and the reaction was stirred at room temperature under nitrogen for 64 hours. The reaction mixture was adjusted to pH 7 using concentrated hydrochloric acid, and concentrated under reduced pressure. Water (500 ml) was added, the slurry was adjusted to pH 1 with concentrated hydrochloric acid and the aqueous phase was extracted with ethyl acetate (5×300 ml). The combined organic extracts were dried over MgSO4 and the solvent was removed under reduced pressure to give 5-isobutyl-1H-pyrazol-3-carboxylic acid (10 g) as a white solid. 1H NMR (400 MHz, DMSO-D6): δ=12.72-12.90 (1H, brs), 6.39 (1H, s), 2.39-2.43 (2H, d), 1.77-1.86 (1H, m), 0.78-0.83 (6H, d) ppm. LRMS (electrospray): m/z [M+Na]+ 191, [2M+Na]+ 359, [M−H]+ 167, [2M−H]+ 335.

Workup

  1. concentrationconcentrated under reduced pressure
  2. additionWater (500 ml) was added
  3. extractionthe aqueous phase was extracted with ethyl acetate (5×300 ml)
  4. dry with materialThe combined organic extracts were dried over MgSO4
  5. customthe solvent was removed under reduced pressure

Sources & evidence

ORD record
ord-b3b05df0f36549c48de548b7d4af4098
Source dataset
uspto-grants-2005_11
Patent number
US06967204B2

Reaction notes

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