o-Toluidine
[CAS 95-53-4]

Identification

• Classification: Organic raw materials >> Amino compound >> Cycloalkylamines, aromatic monoamines, aromatic polyamines and derivatives and salts
• Name: o-Toluidine
• Synonyms: 1-Amino-2-methylbenzene; 1-Methyl-2-aminobenzene; 2-Aminotoluene; 2-Methylaniline
• Molecular Formula: C₇H₉N
• Molecular Weight: 107.15
• CAS Registry Number: 95-53-4
• EC Number: 202-429-0
• SMILES: CC1=CC=CC=C1N

Properties

• Density: 1.008
• Melting point: -23 °C
• Boiling point: 199-200 °C
• Refractive index: 1.571-1.573
• Flash point: 85 °C
• Water solubility: 1.5 g/100 mL (25 °C)

Safety Data

• Hazard Symbols: GHS06;GHS08;GHS09 Danger
• Risk Statements: H350-H331-H301-H319-H400
• Safety Statements: P203-P261-P264-P264+P265-P270-P271-P273-P280-P301+P316-P302+P352-P304+P340-P305+P351+P338-P316-P317-P318-P321-P330-P332+P317-P337+P317-P362+P364-P391-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H301
Carcinogenicity	Carc.	1B	H350
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Acute toxicity	Acute Tox.	3	H331
Eye irritation	Eye Irrit.	2	H319
Germ cell mutagenicity	Muta.	2	H341
Skin irritation	Skin Irrit.	2	H315
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Acute toxicity	Acute Tox.	4	H312
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Serious eye damage	Eye Dam.	1	H318
Skin sensitization	Skin Sens.	1	H317
Acute toxicity	Acute Tox.	2	H330
Eye irritation	Eye Irrit.	2A	H319

• Transport Information: UN 1708

Discovery and Applications

o-Toluidine, also known as 2-toluidine, is an aromatic amine that features a methyl group and an amino group attached to a benzene ring. The compound has been of considerable interest in organic chemistry since its discovery in the mid-19th century. It was first isolated in 1842 by the German chemist August Wilhelm von Hofmann through the reduction of o-nitrotoluene, marking the beginning of its exploration and application in various fields.

The primary application of o-toluidine lies in the production of dyes and pigments. It serves as a crucial intermediate in the synthesis of azo dyes, which are characterized by their vibrant colors and wide-ranging applications in textiles, plastics, and food industries. The ability of o-toluidine to participate in diazotization reactions allows for the creation of numerous derivatives, making it an invaluable compound in dye chemistry.

In addition to dye production, o-toluidine has significant applications in the manufacture of rubber and polymers. It is used as a rubber accelerant, enhancing the curing process and improving the performance characteristics of rubber products. The compound’s reactivity allows it to form cross-links with rubber polymers, which is essential for creating durable and resilient materials. This application is particularly important in the automotive and manufacturing industries, where high-performance rubber components are required.

Moreover, o-toluidine is utilized in the pharmaceutical industry, where it serves as an intermediate in the synthesis of various pharmaceutical compounds. Research has shown that derivatives of o-toluidine exhibit potential therapeutic properties, making them candidates for the development of new drugs. The compound's versatility in chemical reactions allows chemists to modify its structure and develop novel compounds with specific biological activities.

While o-toluidine has numerous beneficial applications, it is important to consider the safety and environmental implications associated with its use. As an aromatic amine, o-toluidine has been classified as a potential carcinogen. Therefore, regulatory agencies have established guidelines for its handling and usage to mitigate health risks. Proper safety measures, such as using personal protective equipment and ensuring adequate ventilation, are crucial in industrial settings where o-toluidine is utilized.

Recent studies have focused on the environmental impact of o-toluidine and its derivatives. Researchers are exploring greener synthesis methods and the potential for biodegradable alternatives in dye production and other applications. This shift towards sustainable practices reflects a growing commitment to reducing the environmental footprint of chemical manufacturing.

In summary, o-toluidine is an important compound with significant applications in dye synthesis, rubber production, and pharmaceuticals. Its discovery has played a vital role in various industrial processes, although safety and environmental concerns must be addressed. Ongoing research aims to enhance its applications while promoting sustainable and safe practices in its use.

References

2024. Synthesis and Characterization of Poly(o-anisidine-co-o-toluidine)/PCBM Composites for Optoelectronic Applications. Journal of Inorganic and Organometallic Polymers and Materials, 34(4).
DOI: 10.1007/s10904-024-03090-8