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.

N,N-Dimethylaniline (chemical formula: C₈H₁₁N) is an important organic chemical raw material belonging to the class of aromatic amine compounds. It is the product of substituting both hydrogen atoms on the amino group of aniline with methyl groups. At room temperature, N,N-dimethylaniline appears as a pale yellow to light brown oily liquid with a characteristic pungent, irritating odor. It is sparingly soluble in water but miscible with ethanol, diethyl ether, chloroform, and aromatic organic solvents.   As a key intermediate, N,N-dimethylaniline finds extensive applications in the dye, pharmaceutical, pesticide, fragrance, and rubber industries. In the dye industry, it serves as a crucial raw material for synthesizing triphenylmethane dyes (e.g., Basic Green, Victoria Blue) and azo dyes. In the pharmaceutical industry, it is used in the synthesis of various drugs, including cephalosporin V and sulfonamides. Additionally, it is utilized as a solvent, an epoxy resin curing agent, and a rubber vulcanization accelerator. Due to its high toxicity and classification as a suspected carcinogen, strict adherence to safety protection protocols is mandatory during its production and use.   Basic Information Chemical Name N,N-Dimethylaniline CAS NO. 121-69-7 Synonyms Dimethylaniline, Dimethylaminobenzene, N,N-Xylidine Application  Fields Dyes, Pharmaceuticals, Pesticides, Rubber     Discovery Background and Evolution The discovery of N,N-dimethylaniline is closely tied to the dye industry revolution of the late 19th and early 20th centuries. In 1876, while working at BASF, German chemist Heinrich Caro investigated the synthesis of Methylene Blue, which involved reactions with N,N-dimethylaniline and its derivatives. Methylene Blue was the world's first synthetic phenothiazine dye, and its synthesis utilized 4-aminodimethylaniline, marking the beginning of N,N-dimethylaniline's role as a vital chemical raw material. With the vigorous growth of the dye industry, the demand for N,N-dimethylaniline increased dramatically. Early synthesis methods primarily involved the high-temperature, high-pressure condensation reaction of aniline with methanol in the presence of sulfuric acid. With technological advancements, gas-phase catalytic methods and continuous production processes using solid acid catalysts have gradually replaced traditional batch-wise liquid-phase methods, improving production efficiency and product purity. Currently, China has made significant progress in the production technology of N,N-dimethylaniline, though continuous improvements in product quality and environmental standards are still ongoing.   Physical and Chemical Properties N,N-Dimethylaniline is a colorless to pale yellow transparent oily liquid at room temperature; it can oxidize and turn reddish-brown upon prolonged exposure or under light. Its melting point ranges from 1.5 to 2.5 °C, and its boiling point is 193.1 °C. The substance has a density of approximately 0.96 g/cm³, making it lighter than water. It is sparingly soluble in water (solubility approx. 1 g/L at 20 °C) but miscible with many organic solvents such as ethanol, diethyl ether, chloroform, and benzene. It exhibits weak basicity; the pH of a 10% aqueous solution is approximately 7.49. N,N-Dimethylaniline displays typical aromatic amine properties. Due to the two methyl groups attached to the nitrogen atom, its basicity is stronger than that of aniline but weaker than that of aliphatic amines. It is readily oxidized and gradually darkens in color upon exposure to air or sunlight. As a nucleophile, it can undergo N-methylation or C-methylation reactions. Although its basicity is weak, making diazotization difficult, it can proceed under strongly acidic conditions; reaction with sodium nitrite in acidic media yields nitroso compounds, which turn emerald green under alkaline conditions. Furthermore, it serves as an excellent coupling component, reacting with diazonium salts to form azo dyes. It can also undergo substitution reactions such as halogenation, nitration, and sulfonation, typically occurring at the para position relative to the amino group.   Preparation Methods Industrially, N,N-dimethylaniline is primarily produced via the methylation of aniline. The most common method involves reacting aniline and methanol in the presence of a catalyst, such as sulfuric acid or solid acids (e.g., SO₄²⁻/ZrO₂). The reaction is typically carried out at high temperature and pressure, yielding a mixture of N-methylaniline and N,N-dimethylaniline, from which the high-purity product is obtained through distillation separation. Additionally, continuous methylation of methanol and aniline can be achieved using a fixed-bed reactor with a copper-zinc-based catalyst, a method characterized by high conversion rates and good selectivity.   Application Areas Dye IndustryN,N-Dimethylaniline is a vital intermediate in the dye industry. It is widely used to synthesize triphenylmethane basic dyes such as Basic Green, Victoria Blue, Basic Yellow, and Basic Violet 5BN. These dyes are extensively used for dyeing cotton, linen, and viscose fibers, as well as for coloring paper and leather. It is also used in the synthesis of azo dyes and indicators like Methyl Orange. In the fragrance industry, it is an important raw material for producing vanillin and other aroma compounds.   Pharmaceutical IndustryIn the pharmaceutical field, N,N-dimethylaniline is used to synthesize various drugs. It is a key raw material for the synthesis of the antibiotic cephalosporin V. Additionally, it is used in the synthesis of sulfonamide drugs, such as sulfadoxine and sulfadimethoxine. Beyond the mentioned drugs, it is also used in the synthesis of other pharmaceuticals like flucytosine.   Materials and Other ApplicationsIn the pesticide sector, N,N-dimethylaniline is used to synthesize key intermediates for sulfonylurea herbicides. In the rubber industry, it serves as a vulcanization accelerator, helping to improve vulcanization speed and rubber properties. In the materials industry, it can be used as a curing accelerator for epoxy resins and unsaturated polyester resins, as well as a catalyst for polyurethane foam.   Safety Information Toxicological DataN,N-Dimethylaniline is highly toxic, with toxicity similar to but slightly weaker than that of aniline. The oral LD₅₀ in rats is 1410 mg/kg, and the dermal LD₅₀ in rabbits is 1770 mg/kg. Inhalation of its vapor or absorption through the skin can cause poisoning. Its primary targets are the blood and nervous systems, leading to methemoglobinemia, which manifests as cyanosis (bluish discoloration of skin and mucous membranes), headache, dizziness, nausea, and other symptoms. In 2017, the International Agency for Research on Cancer (IARC) of the World Health Organization classified it as Group 3 carcinogen, indicating inadequate evidence for carcinogenicity in humans but sufficient evidence in experimental animals. First Aid and ProtectionUpon skin contact with N,N-dimethylaniline, immediately remove contaminated clothing and wash the skin thoroughly with soap and water. In case of eye contact, rinse immediately with plenty of flowing water or saline for several minutes, lifting the eyelids occasionally. If inhaled, move the affected person to fresh air immediately, keep the airway open, and administer oxygen if breathing is difficult. If swallowed, rinse the mouth, drink plenty of warm water, induce vomiting, perform gastric lavage, administer activated charcoal, and seek immediate medical attention. During handling, wear self-priming filter-type respirators (half-face masks), chemical safety goggles, impervious work clothing, and rubber oil-resistant gloves. Maintain adequate ventilation in the workplace and keep equipment closed. Environmental HazardsN,N-Dimethylaniline is toxic to aquatic life and may cause long-term adverse effects in the aquatic environment. Its vapor can form explosive mixtures with air and is highly flammable upon exposure to open flames or high heat. Therefore, its release into the environment must be strictly controlled. In case of a spill, absorb the material with sand or inert material and dispose of it in a harmless manner.