What Is Nitromethane?
Nitromethane, an organic compound, is represented by the chemical formula CH3NO2. As the simplest form of nitro compound, it holds a CAS registration number of 75-52-5. This compound is extensively utilized across various industries, serving roles in extraction, as a reaction and cleaning solvent. A notable historical event highlighted nitromethane’s explosive nature when a freight train carrying it exploded in 1950. Nowadays, it is transported with added stabilizers due to its higher explosive energy compared to TNT, a well-known explosive.
Uses of Nitromethane
Nitromethane finds its primary use as a raw material for solvents, combustion improvers, surfactants, explosives, pharmaceuticals, insecticides, and fungicides. Beyond its role as a raw material, it sees widespread industrial use as an extraction, reaction, and cleaning solvent. In organic synthesis, it functions as a one-carbon carburizing reagent and an organic solvent. Noteworthy reactions utilizing nitromethane include the nitroaldol (Henry) reaction, which condenses nitroalkanes with aldehydes and ketones to yield β-nitroalcohols, and the Michael reaction, facilitating nucleophile addition to unsaturated carbonyl compounds. Additionally, its capability to generate greater power with less oxygen than gasoline makes it a preferred fuel in motorsports, such as drag racing.
Properties of Nitromethane
With a molecular weight of 61.04, nitromethane is a colorless, viscous liquid at room temperature, featuring a melting point of -28℃ and a boiling point of 101℃. It possesses a distinct odor, a density of 1.13g/mL, and shows solubility in alcohol, ether, and dimethylformamide, though it is insoluble in water. Its acid dissociation constant (pKa) is 10.2, indicating the presence of a weakly acidic proton.
Types of Nitromethane
Primarily marketed as a research and development reagent, nitromethane is available in various capacities including 25 mL, 100 mL, 500 mL, and 500 g. These small-volume products are designed for easy laboratory handling. Given its potential hazards, nitromethane is a regulated compound, necessitating lawful and safe handling.
Other Information about Nitromethane
1. Synthesis of Nitromethane
Industrial production of nitromethane involves reacting propane with nitric acid at temperatures between 350-400°C. This process also yields nitroethane, 1-nitropropane, and 2-nitropropane. The reaction mechanism includes the formation of free radicals, such as alkoxy radicals (CH3CH2CH2O), from the homolysis of the corresponding nitrate ester. Laboratory synthesis commonly employs sodium chloroacetate and sodium nitrite.
2. Chemical Reaction of Nitromethane
The nitroaldol (Henry) reaction is a notable chemical reaction involving nitromethane. This process deprotonates nitromethane using a base, followed by condensation with an aldehyde or ketone to produce β-nitroalcohol. This reaction mechanism extends from the aldol reaction, where a carbanion stabilized by a nitro group nucleophilically adds to a carbonyl group. The resulting β-alcohol undergoes dehydration to create a nitroalkene, serving as a valuable substrate for further reactions such as Michael addition and Neff reactions.
3. Nitromethane Safety Information
A combination of nitromethane and ammonium nitrate forms an explosive mixture. While pure nitromethane is less shock-sensitive, stabilizers are incorporated to minimize risk. It is classified as a flammable liquid and vapor and poses various health risks, including mild skin irritation, severe eye irritation, potential carcinogenic effects, and potential damage to the liver, kidneys, and respiratory system.