2,3-Dimethylaniline
[CAS# 87-59-2]

Identification

• Classification: Analytical chemistry >> Standard >> Pharmacopoeia standards and magazine standards
• Name: 2,3-Dimethylaniline
• Synonyms: 2,3-Dimethylphenylamine; 2,3-Xylylamine; 2,3-Xylidine
• Molecular Formula: C₈H₁₁N
• Molecular Weight: 121.18
• CAS Registry Number: 87-59-2
• EC Number: 201-755-0
• SMILES: CC1=C(C(=CC=C1)N)C

Properties

• Density: 1.0±0.1 g/cm³ Calc.^*, 0.993 g/mL (Expl.)
• Melting point: 2.5 °C (Expl.)
• Boiling point: 221.9±9.0 °C 760 mmHg (Calc.)^*, 221 - 222 °C (Expl.)
• Flash point: 96.1 °C (Calc.)^*, 96 °C (Expl.)
• Solubility: water: 30 g/L (20 °C) (Expl.)
• Index of refraction: 1.559 (Calc.)^*, 1.569 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS06;GHS08;GHS09 Danger
• Risk Statements: H301+H311+H331-H301-H311-H331-H373-H411
• Safety Statements: P260-P261-P262-P264-P270-P271-P273-P280-P301+P316-P302+P352-P304+P340-P316-P319-P321-P330-P361+P364-P391-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H311
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Acute toxicity	Acute Tox.	3	H301
Acute toxicity	Acute Tox.	3	H331
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H302
Skin irritation	Skin Irrit.	2	H315

• Transport Information: UN 1711

Discovery and Applications

2,3-Dimethylaniline is an aromatic amine belonging to the class of substituted anilines, characterized by two methyl groups attached to the benzene ring in the ortho (2-) and meta (3-) positions relative to the amino group. Its molecular formula is C₈H₁₁N, and it appears as a colorless to pale yellow liquid with a characteristic amine odor. Like other aniline derivatives, it exhibits basic properties due to the lone pair of electrons on the nitrogen atom, which can engage in protonation and electrophilic substitution reactions.

The compound was first synthesized in the late 19th century during the expansion of aromatic amine chemistry that accompanied the development of the synthetic dye industry. Early studies of 2,3-dimethylaniline were related to investigations into the structure-reactivity relationships of substituted anilines, as scientists sought to understand how alkyl substituents influence electron density and reactivity on the aromatic ring. The methyl groups in the ortho and meta positions increase the electron density of the ring through inductive effects, enhancing its reactivity toward electrophilic substitution and modifying its physical properties compared to unsubstituted aniline.

Industrial production of 2,3-dimethylaniline typically involves the reduction of the corresponding nitro compound, 2,3-dimethylnitrobenzene, using catalytic hydrogenation or chemical reducing agents such as iron and hydrochloric acid. This process yields high-purity amine suitable for subsequent transformations. Another route involves direct amination of dimethylbenzene derivatives under controlled conditions, although this method is less common due to selectivity challenges.

2,3-Dimethylaniline serves as an important intermediate in the synthesis of various fine chemicals, dyes, and pharmaceuticals. In the dye industry, it functions as a precursor for azo and anthraquinone dyes, where it reacts with diazonium salts to produce vivid pigments with strong affinity for textiles. These dyes are used in applications requiring durable coloration and chemical resistance. In organic synthesis, it is utilized as a building block for heterocyclic compounds, including benzimidazoles and quinazolines, which are frameworks found in numerous biologically active molecules.

In the pharmaceutical sector, derivatives of 2,3-dimethylaniline are incorporated into the design of anesthetics, analgesics, and antimicrobial agents. The dimethyl substitution pattern provides specific steric and electronic characteristics that influence binding affinity and metabolic stability. It has been used as an intermediate in the production of certain herbicides and agrochemicals as well, contributing to its commercial significance beyond laboratory research.

From a chemical reactivity standpoint, 2,3-dimethylaniline undergoes typical aromatic amine transformations such as acylation, sulfonation, and diazotization. The steric hindrance introduced by the ortho-methyl group, however, affects substitution patterns and reaction rates. This property has made it a useful compound in mechanistic studies of electrophilic substitution and in research focused on steric effects in aromatic systems.

Environmental and safety considerations are essential when handling 2,3-dimethylaniline. Like many aromatic amines, it exhibits moderate toxicity and may cause irritation upon skin contact or inhalation. Prolonged exposure has potential health risks, and strict workplace regulations govern its use and disposal. It is not highly persistent in the environment but can undergo degradation via photochemical or microbial processes under suitable conditions.

In contemporary research, interest in substituted anilines like 2,3-dimethylaniline extends to their roles in advanced materials and catalysis. They are used as ligands in coordination chemistry and as monomers in polymer synthesis for electronic and optical materials. The balance between electron-donating methyl groups and the amino functionality offers tunable properties valuable for the design of molecular semiconductors and dyes for organic light-emitting diodes (OLEDs).

Thus, 2,3-dimethylaniline remains a compound of continuing industrial and scientific relevance. Its well-established synthesis, diverse chemical reactivity, and applicability in both traditional and emerging technologies illustrate the enduring importance of substituted anilines in the broader field of organic and materials chemistry.

References

2024. Analysis of Hydrothermal Aging Water of Fire-Protective Fabrics Using GC × GC–TOFMS and FID. Fibers and Polymers, 25(4).
DOI: 10.1007/s12221-024-00540-5

2025. Enzymes and Single-Cell Protein Production via Biorefineries Approach. Biomass Processing for Sustainable Circular Economy.
DOI: 10.1007/978-981-96-6279-1_5

2025. A Comparative Analysis on the Decomposition and Mitigation of Azo Dyes in Industrial Discharge Using Microbes, Nanoparticles and Nanozymes. Sustainable Environmental Remediation: Avenues in Nano and Biotechnology.
DOI: 10.1007/978-3-031-78483-5_7