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In industrial chemistry, organic synthesis, reaction solvent manufacturing, and high-performance fuel formulation, Nitromethane, defined by the molecular formula CH₃NO₂, is a highly polar, reactive organic compound belonging to the class of aliphatic nitro compounds.
Nitromethane exists as a colorless, oily liquid with a mild, slightly fruity odor at room temperature and pressure.
Nitromethane is primarily used in the chemical industry as a strategic solvent, a key building block in organic synthesis, a stabilizer for halogenated hydrocarbons, and a specialized fuel component in race engines and model aviation.
Basic Properties, Physicochemistry, and Identifiers
CAS Registry Number: 75-52-5.
EC / EINECS Number: 200-876-6.
PubChem CID: 6375.
UN Dangerous Goods Number: UN 1261 (Class 3 Flammable Liquid).
Molecular Weight: 61.04 g/mol.
Density: Liquid density at 20 °C is 1.137 g/cm³; vapor density (relative to air) is 2.11 (heavier than air).
Melting Point: -29.0 °C.
Boiling Point: 101.2 °C.
Flash Point: 35.0 °C (Closed cup).
Vapor Pressure: 3.71 kPa (37.1 mbar) at 20 °C.
Solubility in Water: Moderately soluble in water (approximately 95 g/L at 20 °C).
Solubility in Organic Solvents: Misible with ethanol, ether, acetone, DMF, and benzene.
Thermal Decomposition: Nitromethane decomposes at high temperatures or under shock confinement to form nitrogen oxides (NOx), carbon monoxide (CO), carbon dioxide (CO2), and water vapor.
Food Additive Status: Nitromethane is strictly unsuitable as a direct food additive or for human consumption (It has no E-number).
Production Processes and Chemical Synthesis
Nitromethane is produced on an industrial scale by the direct gas-phase nitration of propane with nitric acid (HNO₃) at elevated temperatures and pressures.
This exothermic vapor-phase reaction generates a mixture of nitroalkanes including nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane.
Nitromethane is isolated and purified from the crude nitroalkane mixture through multi-stage fractional distillation and washing processes.
Applications and Industrial Uses
The major chemical application of Nitromethane is serving as a reactive intermediate in Henry aldol-type reactions for the synthesis of pharmaceuticals, pesticides, and biological active ingredients.
Nitromethane is widely utilized as a high-polarity solvent for acrylic polymers, cellulose esters, resins, coating formulations, and electronic cleaning solutions.
Nitromethane serves as an essential stabilizer to prevent the decomposition of halogenated solvents such as 1,1,1-trichloroethane and methylene chloride.
Nitromethane is utilized as an oxygenated fuel additive in motorsports and radio-controlled model engines due to its ability to burn with much less atmospheric oxygen than standard hydrocarbons.
Nitromethane acts as a precursor in the industrial synthesis of explosives, energetic materials, and specialty agricultural chemicals.
Safety, Toxicology, and Storage Standards
According to GHS standards, Nitromethane is classified as Flammable Liquid (Category 3), Acute Toxicity Oral (Category 4), Suspected of Causing Cancer (Category 2).
Nitromethane possesses moderate systemic toxicity; inhalation of high concentration vapors causes central nervous system depression, dizziness, nausea, and respiratory track irritation.
Direct contact with liquid Nitromethane causes mild to moderate eye irritation and skin irritation upon prolonged exposure.
Nitromethane can undergo violent thermal explosion or detonation under strong shock waves, heavy confinement, or high temperature conditions when mixed with amines or strong bases.
Nitromethane reacts dangerously with strong alkalis, strong acids, oxidizing agents, metallic powders, and aliphatic amines, forming heat-sensitive explosive salts.
Nitromethane corrodes carbon steel slightly upon prolonged moisture contact, but is generally compatible with stainless steel, aluminum, and PTFE sealing materials.
Nitromethane must be stored in cool, dry, well-ventilated dedicated chemical storage areas away from heat sources, open flames, strong bases, and direct sunlight, kept inside approved steel drums or pressure containers.
