Chemical Identity and Physical Properties

3-Chloro-1-methyl-1H-pyrazole-5-carboxylic acid (SKU C174971) belongs to the pyrazole family of five-membered nitrogen-containing heterocycles. The compound features three key functional handles: (1) a carboxylic acid group at the 5-position, enabling amide coupling, esterification, and decarboxylative reactions; (2) a chlorine substituent at the 3-position, available for nucleophilic aromatic substitution or cross-coupling; and (3) an N-methyl group at N-1, which removes the N–H tautomerism present in unsubstituted pyrazoles and improves metabolic stability in drug candidates.

The molecular formula is C₅H₅ClN₂O₂ with a molecular weight of 160.56 g/mol. The compound typically appears as a white to off-white solid. Its carboxylic acid moiety renders it moderately soluble in polar aprotic solvents such as DMF and DMSO, and in aqueous base. Solubility in diethyl ether and non-polar solvents is limited.

Note: Precise melting point, exact solubility data, and pKa values are not specified in the current source material; consult the certificate of analysis (CoA) supplied with each lot.

Synthesis and Reactivity

Pyrazole-5-carboxylic acids of this type are commonly prepared by cyclization of hydrazine derivatives with 1,3-dicarbonyl equivalents, followed by N-alkylation and halogenation steps. The 3-chloro substituent in this compound can be introduced via electrophilic chlorination or via Sandmeyer-type chemistry on the corresponding 3-amino precursor.

Key reactions exploiting the carboxylic acid group:

• Amide coupling — reaction with primary or secondary amines using standard coupling reagents (e.g., EDC/HOBt, HATU) to deliver pyrazole-5-carboxamides, a privileged scaffold in kinase inhibitor design.
• Esterification — treatment with alcohols under acid catalysis or using coupling agents yields the corresponding esters, useful as protected intermediates.
• Acyl chloride formation — treatment with oxalyl chloride or thionyl chloride provides the reactive acyl chloride for further functionalization.

Key reactions exploiting the C3-chloro group:

• Nucleophilic substitution (S_NAr) — the electron-withdrawing carboxylic acid and ring nitrogens activate the C3 position toward displacement by amines, alkoxides, or thiolates.
• Palladium-catalyzed cross-coupling — Suzuki, Negishi, or Buchwald–Hartwig protocols can install aryl, heteroaryl, or amino groups at C3.

Specific reaction conditions and yields are not cited in the source material; researchers should conduct a primary literature search before designing synthetic routes.

Applications in Drug Discovery and Agrochemistry

The pyrazole ring system is one of the most frequently occurring heterocycles in approved drugs and agrochemical active ingredients. 3-Chloro-1-methyl-1H-pyrazole-5-carboxylic acid is valued as a bifunctional building block that can simultaneously contribute the pyrazole pharmacophore and provide two orthogonal points of diversification (the carboxylic acid and the C3-chloro group).

Pharmaceutical research: Pyrazole-5-carboxamide motifs appear in kinase inhibitors, anti-inflammatory leads, and CNS drug candidates. The N-methyl group eliminates N–H-mediated metabolic liabilities and reduces the risk of reactive metabolite formation compared with NH-pyrazoles. The C3-chloro group may serve as a leaving group for further library synthesis or may be retained as a lipophilicity-modulating halogen substituent.

Agrochemical research: Chlorinated pyrazole carboxylates are recognized pharmacophores in fungicidal and insecticidal leads. The electron-deficient ring system interacts favorably with target enzyme active sites in plant-pathogenic fungi and pest species.

Specific drug names, approved products, or quantitative bioactivity data derived from this specific compound are not cited in the source material and are not claimed here; consult primary medicinal chemistry literature.

Handling, Storage, and Safety

As with all laboratory reagents, appropriate precautions should be taken when handling 3-chloro-1-methyl-1H-pyrazole-5-carboxylic acid. The following general guidelines apply:

• Personal protective equipment (PPE): Wear appropriate laboratory coat, nitrile gloves, and safety goggles when handling the compound. Work in a well-ventilated area or fume hood.
• Storage: Store in a tightly sealed container in a cool, dry, well-ventilated area away from heat sources, moisture, and incompatible materials (strong oxidizers, strong bases). Recommended storage temperature is typically room temperature to slightly below, but confirm with the specific lot CoA.
• Stability: The compound is expected to be stable under recommended storage conditions. The carboxylic acid moiety is susceptible to esterification if stored in protic solvents; the C3-chloro group is stable under ambient conditions but may be labile under strongly nucleophilic or basic conditions.
• Disposal: Dispose of in accordance with applicable local, regional, and national regulations for halogenated organic waste.

Always consult the current Safety Data Sheet (SDS) supplied by Aladdin Scientific before use. Specific GHS hazard classifications, H-statements, and P-statements must be verified from the product SDS, as they are not provided in the current source material.

Quality, Purity, and Ordering Information

Aladdin Scientific supplies 3-chloro-1-methyl-1H-pyrazole-5-carboxylic acid under SKU C174971. Researchers and procurement teams should note the following when ordering:

• Purity: Exact purity specification for each lot is stated on the Certificate of Analysis (CoA). For synthetic applications requiring high-purity material, confirm purity by NMR, HPLC, or other analytical methods upon receipt.
• Available pack sizes: Please consult the Aladdin Scientific product page or contact customer service for current pack size options and pricing.
• Lot-to-lot consistency: Each lot is tested against internal specifications. Request a CoA when placing your order to confirm identity (NMR or IR), purity, and appearance.
• Customs and shipping: The compound contains a halogen substituent; verify import/export regulations applicable in your jurisdiction. Aladdin Scientific ships globally — consult the shipping and delivery policy for lead times and cold-chain options if required.

For technical questions, custom synthesis inquiries, or bulk pricing, contact Aladdin Scientific technical support or your regional sales representative.