2-Chloro-3-methylbenzoic Acid: Properties & Lab Uses

2-Chloro-3-methylbenzoic Acid is a halogenated aromatic carboxylic acid widely used as a versatile building block in pharmaceutical synthesis, agrochemical research, and fine-chemical manufacturing.

IUPAC Name

2-Chloro-3-methylbenzoic acid

Molecular Formula

C₈H₇ClO₂

Molecular Weight

170.59 g/mol

CAS Number

7499-11-8

Functional Groups

Carboxylic acid (–COOH), aryl chloride (Ar–Cl), methyl substituent (–CH₃)

Appearance

White to off-white crystalline solid

SKU

C132145

Chemical Identity and Structural Features

2-Chloro-3-methylbenzoic acid (CAS 7499-11-8; MW 170.59 g/mol; molecular formula C₈H₇ClO₂) is an ortho-chloro, meta-methyl substituted derivative of benzoic acid. The compound features three distinct functional moieties on a benzene ring: a carboxylic acid group at the 1-position, a chlorine atom at the 2-position (ortho), and a methyl group at the 3-position (meta relative to the carboxylate). This specific substitution pattern creates a sterically congested environment around the carboxylic acid group, which influences its reactivity in esterification, amidation, and metal-catalyzed cross-coupling reactions. The presence of the electron-withdrawing chlorine atom slightly increases the acidity of the carboxylic acid relative to unsubstituted benzoic acid (pKa ~2.94 for benzoic acid; the pKa of 2-Chloro-3-methylbenzoic acid should be confirmed experimentally), while the methyl group provides a mild electron-donating effect. The compound typically appears as a white to off-white crystalline solid at room temperature.

Synthesis Pathways and Synthetic Utility

2-Chloro-3-methylbenzoic acid serves as a valuable intermediate in multi-step organic synthesis. Its carboxylic acid group can be readily converted to acid chlorides, esters, amides, or reduced to the corresponding alcohol, giving synthetic chemists multiple handles for downstream elaboration. The aryl chloride bond at the 2-position is particularly useful for palladium-catalyzed cross-coupling reactions—such as Suzuki-Miyaura, Heck, and Buchwald-Hartwig couplings—enabling the introduction of diverse aryl, vinyl, or amino substituents. The ortho relationship between the chloro and carboxylate groups can also facilitate intramolecular cyclization reactions, making this compound a useful precursor for the construction of lactone, isocoumarin, or indanone-type scaffolds common in medicinal chemistry. Because of the steric influence of the 2-chloro substituent, selective functionalization requires careful optimization of reaction conditions, including base choice, solvent, and catalyst loading.

Research and Pharmaceutical Applications

Halogenated aromatic carboxylic acids, including 2-Chloro-3-methylbenzoic acid, are widely employed in the pharmaceutical and agrochemical industries as building blocks for active pharmaceutical ingredients (APIs) and crop-protection agents. The compound's bifunctional nature—combining an aryl halide with a carboxylic acid—makes it attractive for library synthesis in medicinal chemistry programs targeting a range of biological endpoints, including anti-inflammatory, antimicrobial, and kinase-inhibitory activities. In agrochemical research, chlorinated benzoic acid derivatives have been investigated as herbicide intermediates and growth-regulator scaffolds. The compound is also of interest in materials science as a ligand precursor for metal-organic frameworks (MOFs) and coordination polymers, where controlled substitution patterns influence pore geometry and binding selectivity. Research laboratories use it as a reference standard for analytical method development, including HPLC and NMR characterization of structurally related compound families.

Handling, Storage, and Safety Considerations

When handling 2-Chloro-3-methylbenzoic acid, standard laboratory safety precautions for aromatic carboxylic acids should be observed. Personnel should wear appropriate personal protective equipment (PPE), including nitrile gloves, a laboratory coat, and safety glasses or goggles, to avoid skin and eye contact. The compound should be handled in a well-ventilated area or a chemical fume hood to minimize inhalation of dust or vapors. As with most halogenated organic compounds, it should be kept away from strong oxidizers, strong bases, and reactive metals. For storage, the compound should be kept in a tightly sealed container in a cool, dry, and well-ventilated location away from direct sunlight and incompatible materials. Always consult the current Safety Data Sheet (SDS) provided by Aladdin Scientific before use, as it contains the most up-to-date hazard classifications, first-aid measures, and disposal guidelines applicable to your jurisdiction. Waste disposal must comply with local, national, and institutional regulations governing halogenated organic waste.

Purity, Specification, and Quality Assurance

Aladdin Scientific supplies 2-Chloro-3-methylbenzoic acid (SKU: C132145) with defined purity specifications suitable for research and development applications. Purity is typically assessed by high-performance liquid chromatography (HPLC) or gas chromatography (GC), with identity confirmed by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). Researchers requiring high-purity material for sensitive biological assays or reference standard applications should consult the product's Certificate of Analysis (CoA), which provides lot-specific purity data and analytical results. When selecting reagent grade versus higher purity options, consider the sensitivity of the intended application: synthetic chemistry typically tolerates ≥97% purity, whereas analytical reference and biological assay work may require ≥99% material. Contact Aladdin Scientific's technical support team for custom quantities, bulk pricing, or application-specific purity requirements.

Frequently asked questions

What is 2-Chloro-3-methylbenzoic Acid used for in organic synthesis?

2-Chloro-3-methylbenzoic acid functions as a bifunctional building block, offering both an aryl chloride for palladium-catalyzed cross-coupling reactions and a carboxylic acid for conversion to esters, amides, or acid chlorides. It is commonly used in the preparation of pharmaceutical intermediates, agrochemical scaffolds, and heterocyclic compounds via cyclization strategies.

How should 2-Chloro-3-methylbenzoic Acid be stored to maintain stability?

The compound should be stored in a tightly sealed container in a cool, dry, and well-ventilated location, away from direct sunlight, moisture, strong oxidizers, and strong bases. Under these conditions, it is expected to remain stable for an extended period. Always refer to the current SDS and Certificate of Analysis for lot-specific storage recommendations.

What purity grade of 2-Chloro-3-methylbenzoic Acid (C132145) is suitable for pharmaceutical intermediate synthesis?

For most pharmaceutical intermediate and medicinal chemistry applications, a purity of ≥97% (as determined by HPLC or GC) is generally acceptable. However, if the compound is to be used as an analytical reference standard or in sensitive bioassays, ≥99% purity material is recommended. Please review the lot-specific Certificate of Analysis available from Aladdin Scientific for exact purity data.

Is 2-Chloro-3-methylbenzoic Acid compatible with Suzuki-Miyaura cross-coupling conditions?

The aryl chloride functionality in 2-Chloro-3-methylbenzoic acid is in principle amenable to palladium-catalyzed Suzuki-Miyaura coupling, though aryl chlorides generally require more active catalyst systems (e.g., bulky phosphine or N-heterocyclic carbene ligands) compared to aryl bromides or iodides. The ortho-positioned carboxylic acid and the adjacent methyl group may introduce steric effects that necessitate optimization of catalyst, base, solvent, and temperature. Empirical optimization is recommended for each specific coupling partner.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. Wiley-Interscience. (General reference for carboxylic acid and aryl halide reactivity.)
2. Miyaura, N.; Suzuki, A. Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chemical Reviews, 1995, 95(7), 2457–2483. doi:10.1021/cr00039a007
3. Aladdin Scientific. Certificate of Analysis for 2-Chloro-3-methylbenzoic Acid, SKU C132145. (Lot-specific purity and analytical data available upon request.)

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.