| Identification | Back Directory | [Name]
3H-PYRAZOL-3-ONE, 1,2-DIHYDRO- | [CAS]
137-45-1 | [Synonyms]
NSC 520837
3-Pyrazolone
Pyrazol-5-ol
Pyrazol-3-ol
3H-pyrazol-3-one
1H-Pyrazol-3-one
3-Hydroxypyrazole
4-Pyrazolin-3-one
1,2-dihydropyrazol-3-on
1,2-dihydropyrazol-3-one
1H pyrazole-3 (2H) - ketone
1,2-Dihydro-3H-pyrazol-3-one
3H-PYRAZOL-3-ONE, 1,2-DIHYDRO- | [Molecular Formula]
C3H4N2O | [MDL Number]
MFCD00629300 | [MOL File]
137-45-1.mol | [Molecular Weight]
84.08 |
| Chemical Properties | Back Directory | [Melting point ]
160-162 °C | [density ]
1.191±0.06 g/cm3(Predicted) | [storage temp. ]
Sealed in dry,2-8°C | [form ]
solid | [pka]
9.00±0.70(Predicted) | [color ]
Pale yellow | [InChI]
InChI=1S/C3H4N2O/c6-3-1-2-4-5-3/h1-2H,(H2,4,5,6) | [InChIKey]
XBYRMPXUBGMOJC-UHFFFAOYSA-N | [SMILES]
N1C=CC(=O)N1 |
| Questions And Answer | Back Directory | [Uses]
1,2-Dihydro-3H-pyrazole-3-one, also known as 1H-pyrazole-3(2H)-one, is an organic intermediate that can be prepared by one-step cyclization from methyl propargylate, ethyl acrylate, or (2E)-3-methoxyacrylate. |
| Hazard Information | Back Directory | [Synthesis]
General procedure for the synthesis of 1,2-dihydro-3H-pyrazol-3-one from methyl propargylate: Hydrazine hydrate (3.62 mL, 48.53 mmol) was slowly added dropwise to a solution of methyl propargylate (4.23 mL, 47.58 mmol) dissolved in methanol (40 mL) under cooling conditions in an ice bath. The reaction mixture was stirred at room temperature for 30 min. Subsequently, brine (10 mL) was added and methanol was removed by distillation under reduced pressure. The remaining aqueous layer was extracted with ethyl acetate (4 × 75 mL), the organic layers were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give 1,2-dihydro-3H-pyrazol-3-one (3.82 g, 95% yield) as a milky white solid. Nuclear magnetic resonance hydrogen spectrum (400 MHz, DMSO-d6): δ 5.44 (1H, d, J = 2.27 Hz), 7.35 (1H, d, J = 2.23 Hz), 9.50 (1H, br s, NH), 11.45 (1H, br s, NH); nuclear magnetic resonance carbon spectrum (101 MHz, DMSO-d6): δ 89.25, 129.71, 160.73; MS (electrospray positive ionization mode): m/z 85.04 (100, [M+H]+); high-resolution MS (electrospray ionization): measured value of [M+H]+ 85.03951, calculated value of C3H5N2O 85.03964. | [References]
[1] Tetrahedron, 2012, vol. 68, # 27-28, p. 5434 - 5444
[2] Patent: US2016/376287, 2016, A1. Location in patent: Paragraph 0634
[3] Patent: WO2017/117708, 2017, A1. Location in patent: Paragraph 54 |
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