Physicochemical Properties

N,N-Dimethylaniline (abbreviated as DMA), also known as dimethylphenylamine, has the molecular formula C₆H₅N(CH₃)₂ and a molecular weight of 121. It is a pale yellow oily liquid with a melting point of 2.45 °C, a boiling point of 194 °C, a flash point of 62.8 °C, and a relative density of 0.9557 (20/4 °C). It is sparingly soluble in water but soluble in methanol, ethanol, propanol, chloroform, diethyl ether, and aromatic organic solvents.

Chemical Properties

N,N-Dimethylaniline exhibits weak basicity and reacts with picric acid to form a picrate salt with a melting point of 163–164 °C. It reacts with alkyl halides to yield quaternary ammonium salts. Upon reduction, it can yield dihydro-N,N-dimethylaniline or tetrahydro-N,N-dimethylaniline, depending on the reaction conditions. Hydrogenation using palladium as a catalyst yields cyclohexanone and dimethylamine. N,N-Dimethylaniline is readily oxidized; oxidation with potassium permanganate or with concentrated sulfuric acid at 190–200 °C yields tetramethylbenzidine. Oxidation with manganese dioxide in chloroform yields N-formylmethylaniline. Oxidation with neutral hydrogen peroxide or peracids yields dimethylaniline oxide [C₆H₅N(CH₃)₂O]. When reacted with acylating agents, the methyl groups are substituted by acyl groups. Reaction with tetranitromethane in pyridine results in nitrosation of the methyl group rather than substitution on the benzene ring. Halogenation, nitration, and sulfonation reactions occur at the ortho and para positions, while nitrosation, coupling, and Friedel–Crafts reactions take place at the para position.

Toxicology

N,N-Dimethylaniline is highly toxic, with toxicity similar to that of aniline. It can cause poisoning via inhalation of its vapor or absorption through the skin. It exhibits hematotoxicity, neurotoxicity, and carcinogenic potential. The maximum allowable concentration in air is 5 ppm. Contact with skin should be avoided. Adequate ventilation and closed equipment are required at the worksite, and operators must wear appropriate protective equipment.

Its toxicity resembles that of aniline, suppressing the central nervous and circulatory systems, and causing headaches, weakness, local or systemic hypoxia, cyanosis of the skin and mucous membranes, dizziness, and respiratory distress. It can be absorbed through the skin, causing poisoning. Upon skin contact, immediately wash thoroughly with concentrated soapy water. The odor threshold concentration is 0.024 mg/m³. According to Chinese standard TJ 36-79, the maximum allowable concentration in workshop air is 5 mg/m³.

Stability ：Stable

Incompatible Materials：Acids, acid anhydrides, acyl chlorides, chloroform, halogens

Conditions to Avoid Heat

Hazardous Polymerization ：Will not occur

The physicochemical properties of N,N-dimethylaniline are relatively stable, making it a fundamental organic raw material for the synthesis of fine chemical intermediates used in pharmaceuticals, pesticides, dyes, pigments, and other products.

Main Applications

As a fundamental organic raw material for the synthesis of fine chemical intermediates, N,N-dimethylaniline has a wide range of applications. It serves as a major dye intermediate for manufacturing triphenylmethane (basic) dyes, including Basic Yellow, Basic Violet 5BN, Basic Green, Victoria Blue BB, Basic Brilliant Blue R, Cationic Red BL, Brilliant Red 5GN, Violet 3BL, and Brilliant Blue. In the pharmaceutical industry, it is used in the production of cephalosporin V, sulfamonomethoxine, and sulfadoxine. In the fragrance industry, it is used to produce vanillin and other aromatic aldehydes. Additionally, it is used as a solvent, a rubber vulcanization accelerator, and a stabilizer for explosives.

(1) N,N-Dimethylaniline is one of the basic raw materials for producing basic dyes (triphenylmethane dyes, etc.) and other basic dyes. Major products include Basic Yellow, Basic Violet 5BN, Basic Green, Victoria Blue, Brilliant Red 5GN, and Brilliant Blue. In the pharmaceutical industry, it is used to manufacture cephalosporin V, sulfamonomethoxine, sulfadoxine, and flucytosine. In the fragrance industry, it is used to produce vanillin.

(2) It is employed as a solvent, a metal corrosion inhibitor, an epoxy resin curing agent, a curing accelerator for polyester resins, and a co-catalyst for the polymerization of vinyl compounds. It is also used in the preparation of basic triphenylmethane dyes, azo dyes, and vanillin.

(3) In combination with organotin compounds, it is used as a catalyst for the production of polyurethane foam. It also serves as a rubber vulcanization accelerator and a raw material for explosives and pharmaceuticals. It is one of the basic raw materials for producing basic dyes (triphenylmethane dyes, etc.) and other basic dyes, including Basic Yellow, Basic Violet 5BN, Basic Green, Victoria Blue, Brilliant Red 5GN, and Brilliant Blue. N,N-Dimethylaniline is also a raw material for the manufacture of dozens of pharmaceuticals and pharmaceutical intermediates, including cephalosporin V, sulfadimethoxine, sulfamethoxazole, sulfamonomethoxine, sulfadoxine, and flucytosine.

(4) It is used as a curing accelerator for epoxy resins, polyester resins, and anaerobic adhesives, enabling rapid curing of anaerobic adhesives. It can also be used as a solvent, a co-catalyst for polymerization of vinyl compounds, a metal corrosion inhibitor, a UV absorber for cosmetics, and a photosensitizer. Additionally, it is used as a raw material for manufacturing basic dyes, disperse dyes, acid dyes, oil-soluble dyes, and fragrances (e.g., vanillin).

(5) It is used as a reagent for the spectrophotometric determination of nitrite. It is also employed as a solvent and in organic synthesis.

(6) It is utilized as a dye intermediate, solvent, stabilizer, and analytical reagent.