5-Methyl-4-isoxazolecarboxylic acid

Product Name: 5-Methyl-4-isoxazolecarboxylic acid
CAS No.: 42831-50-5
Chemical Name: 5-Methyl-4-isoxazolecarboxylic acid
Synonyms: 5-METHYLISOXAZOLE-4-CARBOXYLIC ACID;TIMTEC-BB SBB005909;Leflunomide Impurity D;Lefluonamide Impurity D;LeflunoMide EP IMpurity D;Leflunomide impurities1343;Methylisoxazole-4-carboxylic;5-Methyl-4-isoxazolecarboxyl;5-METHYLISOXAZOLE-4-CARBOXYLIC;5-methylisoxazole-4-formic acid
CBNumber: CB8342928
Molecular Formula: C5H5NO3
Formula Weight: 127.1
MOL File: 42831-50-5.mol

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5-Methyl-4-isoxazolecarboxylic acid Property

Melting point:: 144-148 °C(lit.)
Boiling point:: 308.3±22.0 °C(Predicted)
Density: 1.348±0.06 g/cm3(Predicted)
storage temp.: Sealed in dry,Room Temperature
solubility: DMSO (Slightly), Methanol (Slightly)
form: Solid
pka: 2.85±0.25(Predicted)
color: White to Pale Brown
BRN: 116000
CAS DataBase Reference: 42831-50-5(CAS DataBase Reference)

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Safety

Hazard Codes: Xi,F
Risk Statements: 36/37/38-37/38-36-10
Safety Statements: 22-26-36/37/39-36-16
WGK Germany: 3
HazardClass: IRRITANT
HS Code: 29349990

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Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H315Causes skin irritation

H319Causes serious eye irritation

H335May cause respiratory irritation

Precautionary statements

P261Avoid breathing dust/fume/gas/mist/vapours/spray.

P304+P340IF INHALED: Remove victim to fresh air and Keep at rest in a position comfortable for breathing.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

P405Store locked up.

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N-Bromosuccinimide Price

Sigma-Aldrich

Product number: 633771
Product name: 5-Methylisoxazole-4-carboxylic acid
Purity: 97%
Packaging: 10g
Price: $232
Updated: 2025/07/31

Sigma-Aldrich

Product number: 633771
Product name: 5-Methylisoxazole-4-carboxylic acid
Purity: 97%
Packaging: 1g
Price: $34.7
Updated: 2023/06/20

TCI Chemical

Product number: M1740
Product name: 5-Methylisoxazole-4-carboxylic Acid
Purity: >98.0%(T)(HPLC)
Packaging: 5g
Price: $17
Updated: 2025/07/31

TCI Chemical

Product number: M1740
Product name: 5-Methylisoxazole-4-carboxylic Acid
Purity: >98.0%(T)(HPLC)
Packaging: 25g
Price: $56
Updated: 2025/07/31

TRC

Product number: M315000
Product name: 5-Methylisoxazole-4-carboxylic acid
Packaging: 1g
Price: $50
Updated: 2021/12/16

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5-Methyl-4-isoxazolecarboxylic acid Chemical Properties,Usage,Production

Chemical Properties

Cream to brown Solid

Uses

5-Methylisoxazole-4-carboxylic Acid (Leflunomide EP Impurity D) is an intermediate for synthesis of Leflunomide (L322750). Herbicidal activities towards Digitaria ciliaris.

Flammability and Explosibility

Non flammable

Synthesis

51135-73-0

42831-50-5

Example 4 Preparation of 5-methylisoxazole-4-carboxylic acid To a two-necked flask equipped with a mechanical stirrer and a horizontal condenser for distillation were added 40.0 g of crude ethyl 5-methyl-4-isoxazolecarboxylate and 44 g of 60% sulfuric acid solution. The mixture was heated to 85°C while the ethanol generated from the reaction was continuously distilled. After 4 hours of reaction, thin layer chromatography (TLC) analysis showed complete disappearance of spots of ester compounds. After cooling the reaction mixture to room temperature, the solid product (16.5 g) was collected by filtration. The filtrate was retained for a second product collection at room temperature. The resulting crude acid was dissolved in 60 mL of 2% acetic acid-toluene mixed solvent and crystallized to give 5-methylisoxazole-4-carboxylic acid (9.5 g) of about 99.9% purity. The crystallized mother liquor was retained for subsequent batch processing. The crystallization process was performed as follows: the crude acid was added to 2% acetic acid-toluene solvent mixture and heated for 30 minutes until dissolved. Separate and remove the brown oil from the bottom of the flask. The upper clear organic phase was carefully transferred to another container and left to crystallize.

References

[1] Patent: US2003/139606, 2003, A1
[2] Letters in Drug Design and Discovery, 2016, vol. 13, # 9, p. 912 - 920
[3] Journal of Heterocyclic Chemistry, 1991, vol. 28, # 2, p. 453 - 457
[4] Yakugaku Zasshi, 1959, vol. 79, p. 836
[5] Chem.Abstr., 1960, p. 1493

5-Methyl-4-isoxazolecarboxylic acid Preparation Products And Raw materials

Raw materials

Preparation Products

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5-Methyl-4-isoxazolecarboxylic acid Suppliers

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View Lastest Price from 5-Methyl-4-isoxazolecarboxylic acid manufacturers

WUHAN FORTUNA CHEMICAL CO., LTD

Product: 5-Methyl-4-isoxazolecarboxylic acid 42831-50-5
Price: US $0.00-0.00/Kg/Drum
Min. Order: 1KG
Purity: 99%min
Supply Ability: 1000KGS
Release date: 2021-11-08

Shaanxi Dideu New Materials Co. Ltd

Product: 5-Methyl-4-isoxazolecarboxylic acid 42831-50-5
Price: US $0.00/kg
Min. Order: 1kg
Purity: 99%
Supply Ability: 10000KGS
Release date: 2025-02-20

Shaanxi Dideu New Materials Co. Ltd

Product: 5-Methyl-4-isoxazolecarboxylic acid 42831-50-5
Price: US $0.00/kg
Min. Order: 1kg
Purity: 99%
Supply Ability: 10000KGS
Release date: 2025-02-25

42831-50-5, 5-Methyl-4-isoxazolecarboxylic acidRelated Search:

Methyl acrylate Methyl acetate Bensulfuron methyl 2-(Trifluoromethyl)benzoic acid 4-(Aminomethyl)benzoic acid m-Toluic acid o-Toluic acid 4-(Chloromethyl)benzoic acid Kresoxim-methyl 4-Bromomethylbenzoic acid p-Toluic acid Sulfamethoxazole Methylparaben 5-Methylisoxazole Thiophanate-methyl Methyl A77 1726 Leflunomide 3-Isomer

5-Methyl-4-isoxazolecarboxylic acid, Tech.

5-methylisoxazole-4-carboxylic acid(SALTDATA: FREE)

Methylisoxazole-4-carboxylic

LeflunoMide EP IMpurity D

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5-Methylisoxazole-4-carboxylic acid, 99%, 99%

Leflunomide Impurity D

5-Methyl-isoxazol-4-carboxylic acid

Leflunomide Impurity 4(Leflunomide EP Impurity D)

TIMTEC-BB SBB005909

5-METHYLISOXAZOLE-4-CARBOXYLIC ACID

5-METHYL-4-ISOXASOLECARBOXYLIC ACID

5-METHYL-4-ISOXAZOLECARBOXYLIC ACID

5-Methyl-4-Isooxazolecarboxylic Acid

5-METHYLISOXAZOLE-4-CARBOXYLIC

5-MethylIsoxazole-4-CarboxalicAcid,Leflunomide

4-Isoxazolecarboxylic acid,5-Methyl

5-METHYLISOXAZOLE-4-CARBOXYLIC ACID 98%

5-Methylisoxazole-4-carboxylic acid, 98+%

Imp. D (EP):5-Methylisoxazole-4-carboxylic Acid

5-Methylisoxazole-4-carboxylicAcid&gt

5-Methyl-4-isoxazolecarboxylic acid ISO 9001：2015 REACH

5-Methyl-4-isoxazolecarboxyl

5-methylisoxazole-4-formic acid

Leflunomide EP Impurity D (5-Methylisoxazole-4-carboxylic Acid)

Lefluonamide Impurity D

Leflunomide impurities1343

5-Methyl-4-isoxaze-4-carboxylic AcidQ: What is 5-Methyl-4-isoxaze-4-carboxylic Acid Q: What is the CAS Number of 5-Methyl-4-isoxaze-4-carboxylic Acid Q: What is the storage condition of 5-Methyl-4-isoxaze-4-carboxylic Acid Q: What are the applications of 5-Methyl-4-isoxaze-4-carboxylic Acid

CAS No.42831-50-5 5-Methyl-4-isoxazolecarboxylic acid

MethylisoChemicalbookxazole-4-carboxylic

42831-50-5

42931-50-5

C5H5NO3

C5H4NO3

CARBOXYLIC ACID

Heterocyclic Building Blocks

Isoxazoles

Building Blocks

Intermediates

Intermediates & Fine Chemicals

Pharmaceuticals

Isoxazoles, Oxadiazoles, Oxazoles

Acids and Derivatives

Heterocycles

Carboxylic Acids

Oxazoles, Isoxazoles & Benzoxazoles

Oxazole&Isoxazole

Organic acids

(intermediate of leflunomide)

Heterocyclic Compounds

Carboxylic Acids

Oxazoles, Isoxazoles & Benzoxazoles

Building Blocks

Heterocyclic Building Blocks

Isoxazoles