5-Methylisoxazole-4-carboxylic acid
Also known as: 5-Methyl-4-isoxazolecarboxylic acid, 5-Methyl-1,2-oxazole-4-carboxylic acid, 4-Carboxy-5-methylisoxazole, Leflunomide Impurity 4, Leflunomide Impurity D, MFCD00955655, T5NOJ C1 DVQ
5-Methylisoxazole-4-carboxylic acid (CAS 42831-50-5) is a compound in the Organic Acids category listed in the Jingsj chemical database. It has the molecular formula C5H5NO3 and a molecular weight of 127.098 g/mol. Key properties include a melting point of 144-148 °C(lit.), a boiling point of 308.3±22.0 °C at 760 mmHg, a density of 1.3±0.1 g/cm3 and a flash point of 140.3±22.3 °C. No supplier offers are currently listed; request a quote. Record last updated Aug 21, 2026.
- CAS No.
- 42831-50-5
- Jingsj CID
- J-3524-5
- Molecular Formula
- C5H5NO3
- Molecular Weight
- 127.098 g/mol
- Category
- Organic Acids
- Last updated
- 8/21/2026
No offers for this compound yet.
Request a quotePhysicochemical Properties
| Melting Point | 144-148 °C(lit.) |
|---|---|
| Boiling Point | 308.3±22.0 °C at 760 mmHg |
| Density | 1.3±0.1 g/cm3 |
| Flash Point | 140.3±22.3 °C |
| Exact Mass | 127.026939 |
| PSA | 63.33000 |
| LogP | 0.22 |
| Vapor Pressure | 0.0±0.7 mmHg at 25°C |
| Refractive Index | 1.514 |
Customs & Trade Information
| HS Code | 2934999090 |
|---|---|
| Summary | 2934999090. other heterocyclic compounds. VAT:17.0%. Tax rebate rate:13.0%. . MFN tariff:6.5%. General tariff:20.0% |
Frequently Asked Questions
What is the CAS number of 5-Methylisoxazole-4-carboxylic acid?
The CAS number of 5-Methylisoxazole-4-carboxylic acid is 42831-50-5.
What are the molecular formula and molecular weight of 5-Methylisoxazole-4-carboxylic acid?
5-Methylisoxazole-4-carboxylic acid has molecular formula C5H5NO3 and molecular weight 127.098 g/mol.
What are the upstream and downstream products of 5-Methylisoxazole-4-carboxylic acid?
For 5-Methylisoxazole-4-carboxylic acid, Upstream Products: Ethyl 5-methylisoxazole-4-carboxylate, Ethyl 2-(ethoxymethylene)acetoacetate, Ethyl 2-formyl-3-oxobutanoate; Downstream Products: Leflunomide, 5-methyl-4-isoxazolecarbonyl chloride, Nerbacadol.
Data compiled from public chemical databases such as PubChem and supplier catalogs; supplier offers are provided by suppliers.
Last updated:
How to cite: Jingsj. "5-Methylisoxazole-4-carboxylic acid (CAS 42831-50-5)". Jingsj Chemical Database. https://www.jingsj.com/compound/J-3524-5 (accessed 2026-11-09).
Data for reference only; verify product details with suppliers before purchase.