N-Methylaniline
[CAS# 100-61-8]

Identification

• Classification: Organic raw materials >> Amino compound >> Cycloalkylamines, aromatic monoamines, aromatic polyamines and derivatives and salts
• Name: N-Methylaniline
• Synonyms: Monomethylaniline
• Molecular Formula: C₇H₉N
• Molecular Weight: 107.15
• CAS Registry Number: 100-61-8
• EC Number: 202-870-9
• SMILES: CNC1=CC=CC=C1

Properties

• Density: 0.989 g/mL
• Melting point: -57 °C
• Boiling point: 196 °C
• Refractive index: 1.5694-1.5714
• Flash point: 85 °C
• Water solubility: 30 g/L

Safety Data

• Hazard Symbols: GHS06;GHS07;GHS08;GHS09 Danger
• Risk Statements: H301-H311-H319-H331-H373-H400-H410
• Safety Statements: P260-P261-P262-P264-P264+P265-P270-P271-P273-P280-P301+P316-P302+P352-P304+P340-P305+P351+P338-P316-P319-P321-P330-P337+P317-P361+P364-P391-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H301
Acute toxicity	Acute Tox.	3	H331
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Acute toxicity	Acute Tox.	3	H311
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - repeated exposure	STOT RE	1	H373
Eye irritation	Eye Irrit.	2A	H319

• Transport Information: UN 2294

Discovery and Applications

N-Methylaniline, also known as N-methylphenylamine or monomethylaniline, is an aromatic amine with the molecular formula C₆H₅NHCH₃. It consists of a phenyl group attached to a secondary amine, with one hydrogen on the nitrogen atom replaced by a methyl group. This simple structural modification of aniline gives N-methylaniline unique chemical properties, which have been explored since its initial discovery in the late 19th century. N-Methylaniline has found widespread application in several industrial and chemical processes due to its reactivity and role as a versatile intermediate.

The discovery of N-methylaniline dates back to early research in organic chemistry when chemists were investigating derivatives of aniline. Aniline, derived from coal tar and used in dye production, was of considerable interest during the development of synthetic dyes and related chemicals. In the search for modified anilines with different chemical reactivities, N-methylaniline was synthesized by reacting aniline with methylating agents such as methyl iodide or dimethyl sulfate. This reaction leads to the substitution of one of the hydrogen atoms on the nitrogen by a methyl group, forming the N-methylaniline molecule.

N-Methylaniline’s role as a chemical intermediate has made it a valuable compound in the production of a variety of materials and chemicals. One of its primary applications is in the synthesis of dyes. As a component in the manufacture of azo dyes, N-methylaniline participates in coupling reactions that lead to the formation of complex, color-rich compounds used in textiles, inks, and pigments. Its reactivity in electrophilic substitution reactions allows it to form diazonium salts, which are key intermediates in azo dye synthesis.

In addition to its use in dye production, N-methylaniline is also a significant intermediate in the pharmaceutical and agrochemical industries. It is employed in the synthesis of certain drugs, where its amine functionality is crucial for creating bioactive compounds. N-Methylaniline is also used in the production of herbicides and pesticides, serving as a building block for chemicals that target unwanted plant growth and pests. Its presence in these industries highlights its versatility as a chemical that can be readily modified to produce a wide range of biologically active molecules.

N-Methylaniline is also utilized in the rubber industry, where it is used as an antioxidant and stabilizer. Rubber materials exposed to oxidative conditions can degrade over time, leading to reduced performance and durability. N-Methylaniline helps prevent this degradation by inhibiting the oxidation processes that cause the rubber to deteriorate. This application extends the lifespan of rubber products, making them more durable in demanding environments.

Despite its utility, N-methylaniline poses some challenges in terms of safety and environmental impact. The compound is toxic and potentially harmful if inhaled or ingested, and it can cause skin and eye irritation upon contact. In industrial settings, proper precautions must be taken to handle N-methylaniline safely, including the use of protective equipment and proper ventilation. Additionally, N-methylaniline can be harmful to aquatic life if released into water systems, raising concerns about its environmental impact. Regulatory agencies monitor its use and disposal to minimize risks associated with its toxicity.

In terms of research, N-methylaniline has served as a model compound for studying the behavior of aromatic amines. Its relatively simple structure makes it an ideal candidate for investigating the mechanisms of electrophilic substitution reactions and the effects of methyl substitution on aniline derivatives. These studies have contributed to a deeper understanding of aromatic chemistry and have informed the development of new synthetic methods for amines and related compounds.

Overall, N-methylaniline is a chemically significant substance with a range of industrial applications. Its discovery in the context of aniline derivatives opened the door to its use in dye synthesis, pharmaceuticals, agrochemicals, and the rubber industry. Despite the challenges associated with its toxicity, its value as a versatile chemical intermediate continues to make it a key compound in many industrial processes.

References

1979. Chloroperoxidase-catalyzed oxidation of N-methyl-4-chloroaniline. Cellular and Molecular Life Sciences, 35(9).
DOI: 10.1007/bf01963254

2024. Highly Effective Zirconia/γ-Alumina for Continuous Vapor Phase N-methylation of Aniline. Catalysis Letters, 154(6).
DOI: 10.1007/s10562-023-04568-9

2012. Potassium iodide catalyzed simultaneous C3-formylation and N-aminomethylation of indoles with 4-substituted-N,N-dimethylanilines. Organic & Biomolecular Chemistry, 11(1).
DOI: 10.1039/c2ob26636a