3H-PYRAZOL-3-ONE, 1,2-DIHYDRO-
- CAS No.
- 137-45-1
- Chemical Name:
- 3H-PYRAZOL-3-ONE, 1,2-DIHYDRO-
- Synonyms
- 1,2-Dihydro-3H-pyrazol-3-one;3-Hydroxypyrazole;1,2-dihydropyrazol-3-one;NSC 520837;Pyrazol-3-ol;Pyrazol-5-ol;3-Pyrazolone;3H-pyrazol-3-one;1H-Pyrazol-3-one;4-Pyrazolin-3-one
- CBNumber:
- CB7838723
- Molecular Formula:
- C3H4N2O
- Molecular Weight:
- 84.08
- MDL Number:
- MFCD00629300
- MOL File:
- 137-45-1.mol
- MSDS File:
- SDS
| Product description | Number | Pack Size | Price |
| 1,2-Dihydro-3H-pyrazol-3-one min. 98.0 % | D5840 | 1G | $112 |
| 1,2-Dihydro-3H-pyrazol-3-one min. 98.0 % | D5840 | 5G | $441 |
| 1,2-Dihydro-3H-pyrazol-3-one 97% | AS26562 | 1g | $25 |
| 1,2-Dihydro-3H-pyrazol-3-one 97% | AS26562 | 5g | $39 |
| 1,2-Dihydro-3H-pyrazol-3-one 97% | AS26562 | 25g | $131 |
| More product size | |||
| Melting point | 160-162 °C |
|---|---|
| Density | 1.191±0.06 g/cm3(Predicted) |
| storage temp. | 2-8°C |
| pka | 9.00±0.70(Predicted) |
| form | solid |
| 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 |
| FDA UNII | U35JHQ8347 |
SAFETY
Risk and Safety Statements
| Symbol(GHS) |  GHS07 |
|---|---|
| Signal word | Warning |
| Hazard statements | H302-H315-H319-H332-H335 |
| Precautionary statements | P261-P280-P305+P351+P338 |
| HS Code | 2933199090 |
3H-PYRAZOL-3-ONE, 1,2-DIHYDRO- price More Price(60)
| Manufacturer | Product number | Product description | CAS number | Packaging | Price | Updated | Buy |
|---|---|---|---|---|---|---|---|
| TCI Chemical | D5840 | 1,2-Dihydro-3H-pyrazol-3-one min. 98.0 % | 137-45-1 | 1G | $112 | 2026-04-30 | Buy |
| TCI Chemical | D5840 | 1,2-Dihydro-3H-pyrazol-3-one min. 98.0 % | 137-45-1 | 5G | $441 | 2026-04-30 | Buy |
| Activate Scientific | AS26562 | 1,2-Dihydro-3H-pyrazol-3-one 97% | 137-45-1 | 1g | $25 | 2026-06-04 | Buy |
| Activate Scientific | AS26562 | 1,2-Dihydro-3H-pyrazol-3-one 97% | 137-45-1 | 5g | $39 | 2026-06-04 | Buy |
| Activate Scientific | AS26562 | 1,2-Dihydro-3H-pyrazol-3-one 97% | 137-45-1 | 25g | $131 | 2026-06-04 | Buy |
3H-PYRAZOL-3-ONE, 1,2-DIHYDRO- Chemical Properties,Uses,Production
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.
Synthesis
922-67-8
137-45-1
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
3H-PYRAZOL-3-ONE, 1,2-DIHYDRO- Preparation Products And Raw materials
Raw materials
Preparation Products
| Supplier | Tel | Country | ProdList | Advantage | |
|---|---|---|---|---|---|
| Shaanxi Dideu Medichem Co. Ltd | +86-17392712779 | 1097@dideu.com | China | 3989 | 58 |
| Capot Chemical Co.,Ltd. | +86-（0）57185586718 +86-13336195806 | sales@capot.com | China | 29626 | 60 |
| Henan Tianfu Chemical Co.,Ltd. | +86-0371-55170693 +86-19937530512 | info@tianfuchem.com | China | 21533 | 55 |
| career henan chemical co | +86-0371-86658258 | factory@coreychem.com | China | 29780 | 58 |
| Hefei TNJ Chemical Industry Co.,Ltd. | +86-0551-65418671 +86-189 4982 3763 | sales@tnjchem.com | China | 34526 | 58 |
| Henan Aochuang Chemical Co.,Ltd. | +86-0371-63689365 +8618638391208 | sales@aochuangchem.com | China | 9322 | 58 |
| HANGZHOU LEAP CHEM CO., LTD. | +86-571-87711850 +86-15355479329 | market18@leapchem.com | China | 43303 | 58 |
| Shanghai Acmec Biochemical Technology Co., Ltd. | +86-18621343501 | product@acmec-e.com | China | 33301 | 58 |
| Aladdin Scientific | tp@aladdinsci.com | United States | 54746 | 58 | |
| Suzhou ARTK Medchem Co., Ltd. | +86-18168183658 | sales1@artkmedchem.com | China | 39007 | 58 |
View Lastest Price from 3H-PYRAZOL-3-ONE, 1,2-DIHYDRO- manufacturers
| Image | Update time | Product | Price | Min. Order | Purity | Supply Ability | Manufacturer | |
|---|---|---|---|---|---|---|---|---|
 |
2025-12-24 | 3H-PYRAZOL-3-ONE, 1,2-DIHYDRO-
137-45-1
|
1KG | 99.0% | 1000KG | Shaanxi Dideu Medichem Co. Ltd | ||
 |
2025-04-04 | 3H-PYRAZOL-3-ONE, 1,2-DIHYDRO-
137-45-1
|
1KG | 98% | 1ton | Henan Aochuang Chemical Co.,Ltd. | ||
 |
2020-01-09 | 3H-PYRAZOL-3-ONE, 1,2-DIHYDRO-
137-45-1
|
$1.00 | 1KG | 99.0% | 100kg | Career Henan Chemical Co |
-
- 3H-PYRAZOL-3-ONE, 1,2-DIHYDRO-
137-45-1
- 99.0%
- Shaanxi Dideu Medichem Co. Ltd
-
- 3H-PYRAZOL-3-ONE, 1,2-DIHYDRO-
137-45-1
- 98%
- Henan Aochuang Chemical Co.,Ltd.
-
- 3H-PYRAZOL-3-ONE, 1,2-DIHYDRO-
137-45-1
- $1.00
- 99.0%
- Career Henan Chemical Co
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