4-Chloro-2-methylaniline: Properties, Uses & Safety Guide

4-Chloro-2-methylaniline is a halogenated aromatic amine widely employed as a versatile building block in the synthesis of dyes, agrochemicals, and pharmaceutically relevant intermediates.

CAS Number

615-65-6

Molecular Formula

C₇H₈ClN

Molecular Weight

141.60 g/mol

Appearance

Light yellow to brown crystalline solid or liquid

Key Functional Groups

Primary aromatic amine (–NH₂), chloro substituent (–Cl), methyl substituent (–CH₃)

Primary Applications

Dye intermediates, agrochemical synthesis, pharmaceutical research

SKU

C111299

Chemical Identity and Physical Properties

4-Chloro-2-methylaniline (CAS 615-65-6), also known as 2-methyl-4-chloroaniline or p-chloro-o-toluidine, is a substituted aromatic amine with the molecular formula C₇H₈ClN and a molecular weight of 141.60 g/mol. Its structure features a benzene ring bearing a primary amino group (–NH₂) at position 1, a methyl group (–CH₃) at position 2 (ortho), and a chlorine atom at position 4 (para).

The compound typically presents as a light yellow to brown crystalline solid at room temperature and may liquefy near its reported melting point range. It is sparingly soluble in water but dissolves readily in common organic solvents such as ethanol, diethyl ether, and chloroform. The electron-donating amino group and electron-withdrawing chloro substituent together modulate the ring's reactivity, making this compound a selective and controllable intermediate for further functionalization.

Synthesis Applications and Research Uses

4-Chloro-2-methylaniline serves as a key intermediate across several industrial and research-scale synthetic pathways:

• Dye and Pigment Synthesis: The compound is a classical precursor in azo dye chemistry. Diazotization of the primary amine, followed by coupling with appropriate coupling components, yields azo colorants used in textile and printing applications.
• Agrochemical Intermediates: It is used in the preparation of herbicides and other crop-protection compounds, where the chloro and methyl substituents contribute to the biological activity profile of the final active ingredient.
• Pharmaceutical and Fine Chemical Research: The amine functionality enables amide bond formation, sulfonamide synthesis, and condensation reactions, offering a versatile handle for constructing pharmacophores and screening libraries.
• Materials Science: Aromatic amines such as this compound are explored in the development of polyurethane hardeners and specialty polymers requiring defined substitution patterns for tailored physical properties.

The orthogonal reactivity of the amino group versus the halogen substituent allows sequential, chemoselective transformations, making 4-Chloro-2-methylaniline particularly attractive for multi-step synthesis strategies.

Safety, Handling, and Storage

As a primary aromatic amine, 4-Chloro-2-methylaniline presents notable hazards that require careful risk assessment and appropriate controls before use.

Hazard Classification: Aromatic amines in this structural class are generally classified as harmful by ingestion, skin contact, and inhalation. They may cause methemoglobinemia upon significant exposure. Some chlorinated toluidines have been identified as potential carcinogens in animal studies; users must consult the current Safety Data Sheet (SDS) and relevant regulatory lists (e.g., IARC, REACH) prior to use.

Personal Protective Equipment (PPE): Use chemical-resistant gloves (e.g., nitrile or butyl rubber), safety goggles with side shields, and a laboratory coat. Handle in a well-ventilated fume hood to minimize inhalation exposure.

Storage: Store in a tightly sealed container under cool, dry, and well-ventilated conditions, away from strong oxidizers, acids, and light. Recommended storage temperature is typically 2–8 °C or as specified on the product label.

Disposal: Dispose of in accordance with local, regional, and national regulations governing hazardous aromatic amine waste. Do not pour down drains.

Purity, Specifications, and Quality Considerations

For research applications, reagent purity is critical to reproducibility and data integrity. Aladdin Scientific offers 4-Chloro-2-methylaniline (SKU: C111299) with defined purity specifications suitable for synthetic and analytical workflows.

Analytical Verification: Identity and purity are typically confirmed by techniques including gas chromatography (GC), high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry (MS). Researchers are encouraged to review the certificate of analysis (CoA) provided with each lot before use.

Common Impurities to Monitor: Related chlorinated or methylated aniline isomers may co-occur as process impurities. These can interfere with sensitive coupling reactions or biological assays; therefore, selecting an appropriately specified grade is essential.

Lot-to-Lot Consistency: For longitudinal studies or scale-up experiments, requesting lot-specific CoA data ensures that physical and chemical parameters remain within acceptable ranges across batches.

Frequently asked questions

What is 4-Chloro-2-methylaniline commonly used for in research?

4-Chloro-2-methylaniline is primarily used as an intermediate in the synthesis of azo dyes, agrochemicals such as herbicides, and pharmaceutical building blocks. Its bifunctional substitution pattern allows both the amino group and the chloro substituent to participate in distinct, chemoselective reactions.

How should 4-Chloro-2-methylaniline be stored to maintain stability?

The compound should be stored in a tightly sealed container under cool, dry, and well-ventilated conditions away from strong oxidizers, strong acids, and direct light. A storage temperature of 2–8 °C is generally recommended; refer to the product label and SDS for lot-specific guidance.

What safety precautions are required when handling 4-Chloro-2-methylaniline?

Users should wear chemical-resistant gloves, safety goggles, and a lab coat, and handle the compound exclusively in a well-ventilated fume hood. Because chlorinated aromatic amines can be harmful upon skin absorption or inhalation and may pose carcinogenic risks, it is essential to consult the current SDS and any applicable regulatory guidance before use.

How can I verify the purity and identity of the 4-Chloro-2-methylaniline I receive?

Each lot is accompanied by a certificate of analysis (CoA) from Aladdin Scientific detailing purity and analytical test results. Identity confirmation can be performed using NMR spectroscopy, GC, or mass spectrometry, while purity is routinely assessed by GC or HPLC.

Is 4-Chloro-2-methylaniline the same as p-chloro-o-toluidine?

Yes. 4-Chloro-2-methylaniline, 2-methyl-4-chloroaniline, and p-chloro-o-toluidine are all synonymous names for the same compound with CAS number 615-65-6. The different names reflect various naming conventions (IUPAC versus common nomenclature).

References

1. Royal Society of Chemistry. 4-Chloro-2-methylaniline compound record. ChemSpider.
2. National Center for Biotechnology Information. 4-Chloro-2-methylaniline. PubChem Compound Summary, CID 12100.
3. International Agency for Research on Cancer (IARC). Monographs on the Evaluation of Carcinogenic Risks to Humans. Relevant volume on aromatic amines.
4. Zollinger, H. Color Chemistry: Syntheses, Properties, and Applications of Organic Dyes and Pigments. 3rd ed. Wiley-VCH, 2003.

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