Water → 1-Ethyl-5-methyl-1H-pyrazole-3-carboxylic acid

HRID 1825346Notes

Reaction equation

HRID 1825346 reaction equation
[CH2:1]([N:3]1[C:7]([CH3:8])=[CH:6][C:5]([C:9]([O:11]CC)=[O:10])=[N:4]1)[CH3:2].[OH-].[K+].O>C(O)C>[CH2:1]([N:3]1[C:7]([CH3:8])=[CH:6][C:5]([C:9]([OH:11])=[O:10])=[N:4]1)[CH3:2]

Participants

5

Reactant 3

HCID 962WaterHCID 14797Potassium HydroxideHCID 16394811Ethyl 1-ethyl-5-methyl-1H-pyrazole-3-carboxylate

Product 1

HCID 163948271-Ethyl-5-methyl-1H-pyrazole-3-carboxylic acidYield 61.1%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

Ethyl 1-ethyl-5-methylpyrazole-3-carboxylate (10.93 g) in ethanol (70 ml) was treated with KOH (3.69 g), followed by water (30 ml), and the mixture was stirred and heated under reflux for 6 h. The ethanol was removed using a rotary evaporator and ethyl acetate/water were added. The pH of the mixture was adjusted to 3.0 and the layers were separated. The aqueous layer was re-extracted with ethyl acetate. The combined ethyl acetate layers were extracted with excess aqueous NaHCO3. The NaHCO3 extract was poured into excess acid, and the pH was then adjusted to 3, and NaCl was added to the solution. The mixture was then repeatedly extracted with ethyl acetate, and the combined extracts were dried (MgSO4) and evaporated. The residue was triturated with diethyl ether to give the acid as a solid (5.65 g) υmax (CH2Cl2) 2754, 2598, 1698, 1498, 1464, 1387, and 1233 cm−1; δ(CDCl3) 1.40 (3H, t, J 7.3 Hz), 2.32 (3H,s), 4.19 (2H, q, J 7.3 Hz), 6.61 (1H,s) ppm; (Found m/z 154.0740. C7H10N2O2 requires m/z 154.0742).

Workup

  1. temperatureheated
  2. temperatureunder reflux for 6 h
  3. customThe ethanol was removed
  4. customa rotary evaporator and ethyl acetate/water
  5. additionwere added
  6. customthe layers were separated
  7. extractionThe aqueous layer was re-extracted with ethyl acetate
  8. extractionThe combined ethyl acetate layers were extracted with excess aqueous NaHCO3
  9. extractionThe NaHCO3 extract
  10. additionwas poured into excess acid
  11. additionwas added to the solution
  12. extractionThe mixture was then repeatedly extracted with ethyl acetate
  13. dry with materialthe combined extracts were dried (MgSO4)
  14. customevaporated
  15. customThe residue was triturated with diethyl ether

Sources & evidence

ORD record
ord-b458a2b09e284967929efc84d3e1bd32
Source dataset
uspto-grants-2006_05
Patent number
US07045619B2

Reaction notes

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