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5-Methyl-4-isoxazolecarboxylic acid (CAS:42831-50-5)

August 14, 2025

Basic information:

CAS NO

42831-50-5

Product Name

5-Methyl-4-isoxazolecarboxylic acid

Molecular formula

C5H5NO3

Molecular weight

127.10

Structure

5 Methyl 4 isoxazolecarboxylic acid 42831 50 5

Solubility

soluble in organic solvents like ethanol, insoluble in water, depending on specific conditions.

Usage

anti-inflammatory and arthritis treatment effects

Product Specifications

White or pale yellow Crystalline powder, odourless

Reside on Ignition ≤ 0.1%

Heavy Metals ≤ 0.002%

Water≤0.5%

Melting Point:145-149℃

Assay ≥ 98.5%

3-Methyl Isomeric Compound≤ 0.2%

Product Manager E-mail: grace@coreychem.com/Grace Zhang

Application:

  • This compound is an isoxazole carboxylic acid derivative, which contains both an isoxazole

ring and a carboxyl group as important functional groups in its structure.

  • It is used to produce Leflunomide, it is the key intermediate of Leflunomide.
  • It can also be used for many other applications,such as used as intermediate in the synthesis     

of bioactive compounds.

  • It holds significant application value in the synthesis of antibiotics (such as sulfonamide drugs) and anti-inflammatory drugs.
  • Its carboxyl functional group also makes it easy to undergo various derivatization reactions

such as esterification and amidation.

 

About Synthesize method:

  • It can be synthesized through multiple organic reaction ways, such as Cyclization & Functional Group Addition.
  • The isoxazole ring can be formed via cyclization reactions from suitable precursors—such as an alkene, nitrile, and oxygen sources.
  • The methyl group and a carboxylic acid group can be incorporated at the desired positions using conventional synthetic methods, such as alkylation and oxidation.

 

Current Production Scale:

  • Commercial produced, Stock available for hundreds of kilograms.

 

Transportation information:

  • Not Dangerous goods

 

Security risks:

  • may cause eye and skin irritation
  • harmful if inhaled.
  • Relatively low acute toxicity, but long-term exposure may lead to discomfort.
  • Mild toxicity to aquatic organisms.

 

Storage&Package:

Package: 25KG Carton Drum

Storage: Sealed and stored in a cool (15-25℃), dry place.

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