Methylamine
[CAS# 74-89-5]

Identification

• Classification: Organic raw materials >> Amino compound >> Acyclic monoamines, polyamines and their derivatives and salts
• Name: Methylamine
• Synonyms: Monomethylamine
• Molecular Formula: CH₅N
• Molecular Weight: 31.06
• CAS Registry Number: 74-89-5
• EC Number: 200-820-0
• SMILES: CN

Properties

• Density: 0.6±0.1 g/cm³ Calc.^*, 0.7 g/mL (Expl.)
• Melting point: -93 °C (Expl.)
• Boiling point: -21.1±3.0 °C 760 mmHg (Calc.)^*, -6.3 °C (Expl.)
• Flash point: -65.9±13.1 °C (Calc.)^*, -13.9 °C (Expl.)
• Solubility: soluble (Expl.)
• Index of refraction: 1.34 (Calc.)^*, 1.37 (Expl.)

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

Safety Data

• Hazard Symbols: GHS02;GHS04;GHS05;GHS07 Danger
• Risk Statements: H220-H315-H318-H332-H335
• Safety Statements: P203-P210-P222-P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P354+P338-P317-P319-P321-P332+P317-P362+P364-P377-P381-P403-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H332
Specific target organ toxicity - single exposure	STOT SE	3	H335
Serious eye damage	Eye Dam.	1	H318
Skin irritation	Skin Irrit.	2	H315
Flammable gases	Flam. Gas	1	H220
Flammable liquids	Flam. Liq.	1	H224
Acute toxicity	Acute Tox.	4	H302
Skin corrosion	Skin Corr.	1B	H314
Gases under pressure (liquid)	Press. Gas (Liq.)		H280
Gases under pressure (compressed)	Press. Gas (Comp.)		H280
Acute toxicity	Acute Tox.	3	H331
Flammable liquids	Flam. Liq.	2	H225
Acute toxicity	Acute Tox.	3	H301
Specific target organ toxicity - single exposure	STOT SE	1	H370
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	2	H332
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Respiratory sensitization	Resp. Sens.	1	H334
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	2	H300

• Transport Information: UN 1061

Discovery and Applications

Methylamine is the simplest primary aliphatic amine, with the chemical formula CH₃NH₂. It consists of a methyl group (-CH₃) attached to an amino group (-NH₂), making it structurally and chemically intermediate between ammonia and higher amines. At room temperature, it is a colorless gas with a strong, ammonia-like odor, highly soluble in water and commonly handled as a 40% aqueous solution or compressed gas.

Methylamine is industrially synthesized by the reaction of methanol and ammonia over an aluminosilicate catalyst at elevated temperatures and pressures. This process yields a mixture of methylamine, dimethylamine, and trimethylamine. The proportion of each product can be adjusted by controlling the ammonia-to-methanol ratio.

In organic synthesis, methylamine is widely used due to its nucleophilicity and basicity. It undergoes acylation, alkylation, and condensation reactions readily. As a nucleophile, it reacts with electrophilic carbon centers to form C–N bonds, enabling the construction of amides, imines, and various nitrogen-containing heterocycles.

Methylamine has extensive applications across multiple industries. In pharmaceuticals, it is a precursor to various drug molecules, including local anesthetics, bronchodilators, and antihistamines. It also serves as a key intermediate in the synthesis of methamphetamine, which is strictly regulated due to abuse potential.

In agrochemicals, methylamine is involved in producing herbicides, such as atrazine, and insecticides. It is used in tanning agents and surfactants and as a building block for water treatment chemicals. It also finds use in the electronics industry for etching semiconductors and in the manufacture of rocket propellants.

From a safety perspective, methylamine is flammable and toxic. Inhalation can cause respiratory tract irritation, and high concentrations may lead to systemic toxicity. It reacts violently with oxidizing agents and acids. Therefore, it must be handled with appropriate protective measures, including ventilation, gas detection systems, and fire suppression protocols.

Due to its involvement in illicit drug manufacture, methylamine is a controlled substance in several jurisdictions. However, it remains a valuable reagent in legal industrial and laboratory processes, particularly for its simplicity, reactivity, and low molecular weight.

Methylamine plays a pivotal role in both academic research and industrial chemistry. It offers a fundamental example of amine reactivity and continues to be an indispensable tool in synthetic methodologies, from small-scale laboratory procedures to large-scale chemical manufacturing.

References

1991. Effects of cytochalasin D and methylamine on intracellular growth of Legionella pneumophila in amoebae and human monocyte-like cells. Infection and Immunity, 59(3).
DOI: 10.1128/iai.59.3.758-763.1991

1991. Weak base amines can inhibit class I MHC-restricted antigen presentation. Journal of immunology (Baltimore, Md. : 1950), 146(2).
DOI: 10.4049/jimmunol.146.2.449

1984. Methylation of DNA in stomach and small intestine of rats after oral administration of methylamine and nitrite. Carcinogenesis, 5(12).
DOI: 10.1093/carcin/5.12.1729