Nitromethane
Properties
| State | Liquid (colorless oily liquid with slightly fruity odor) |
| Color | Colorless |
| Solubility | Slightly soluble in water (111 g/L at 20°C); miscible with most organic solvents |
| Melting Point | -29°C |
| Boiling Point | 101°C |
About Nitromethane
Nitromethane is the simplest nitroalkane (formula CH3NO2, molar mass 61.040 g/mol), a colorless oily liquid with a slightly sweet, fruity odor that boils at 101°C. It's best known to the public as the fuel that lets Top Fuel dragsters and nitro-burning model airplane engines deliver power densities you cannot get from gasoline — the nitro group provides internal oxygen, so a nitromethane-fueled engine can inject roughly 8.7 times more fuel per intake stroke than a comparable gasoline engine breathing the same mass of atmospheric air, producing far more power per cycle even though nitromethane has lower energy density per unit mass. A Top Fuel dragster running on nitromethane generates over 11,000 horsepower from a 500-cubic-inch supercharged V8 and accelerates from 0 to 330+ mph in under 4 seconds. In organic chemistry, nitromethane is a useful C1 nucleophile because its α-hydrogens are unusually acidic (pKa 10.2 — comparable to phenol) — the nitro group stabilizes the conjugate base through delocalization onto both oxygens, so mild bases like piperidine or tetramethylguanidine fully deprotonate it. The Henry reaction (nitroaldol) couples a deprotonated nitromethane to an aldehyde to give a β-nitro alcohol, a classic disconnection for amino-alcohol pharmaceuticals. The Nef reaction converts the nitronate salt back to a carbonyl, effectively turning the nitro group into a ketone or aldehyde. Industrially, nitromethane is also the precursor to chloropicrin (Cl3CNO2), a soil fumigant used in strawberry and tomato production.
Where you'll encounter it
If you've ever stood in the staging lanes at an NHRA race weekend and inhaled the sharp, slightly sweet fumes drifting back from the nitro classes, that's vaporized nitromethane bypassing combustion — Top Fuel teams burn 12 to 14 gallons in a 4-second pass, and the engines run rich enough that the unburnt exhaust is what irritates spectator eyes and noses. In an undergraduate organic chem teaching lab, the Henry reaction with benzaldehyde and nitromethane (catalyzed by triethylamine or KF on alumina) is a classic synthesis exercise — the student isolates a 2-nitro-1-phenylethanol crystal product within an afternoon, then reduces it to the corresponding β-amino alcohol in a follow-up week. The dark side: nitromethane has been weaponized as an explosive when sensitized by amines, and the Oklahoma City bombing in 1995 used a nitromethane-fertilizer mixture, leading to U.S. regulatory restrictions on bulk sales above 5 gallons.
Common Uses
- Primary fuel in Top Fuel and Funny Car drag racing engines (over 11,000 hp on a 500-ci supercharged V8)
- Performance fuel in glow-plug model aircraft and RC car engines (5-30% nitromethane in methanol)
- C1 building block in the Henry (nitroaldol) reaction for β-nitro alcohol and amino alcohol synthesis
- Carbonyl precursor via the Nef reaction (nitronate → ketone or aldehyde)
- High-dielectric polar aprotic solvent for cyanide displacement reactions and SnCl4-catalyzed Diels-Alder
- Precursor to chloropicrin (Cl3CNO2) soil fumigant for strawberry and tomato fields
- Stripper additive for industrial paint and varnish removers (replaces methylene chloride in some formulations)
Safety Information
GHS classifications: H226 (flammable liquid, flash point 35°C closed cup), H302 + H332 (harmful if swallowed or inhaled), H319 (causes serious eye irritation), H351 (suspected carcinogen). OSHA PEL is 100 ppm (250 mg/m3) as 8-hour TWA; ACGIH TLV is 20 ppm (52 mg/m3). The detonation hazard is real — pure nitromethane can detonate from confined heating or from contamination with bases (amines, NaOH) that form sensitive nitronate salts; bulk storage requires inhibitors and explosion-resistant containers. The 1958 Tesoro pipeline disaster killed two workers when nitromethane being pumped underwent shock detonation. U.S. DOT regulates as a Class 3 flammable liquid; quantities over 5 gallons require ATF reporting. Store away from amines, strong bases, oxidizers, and metal oxides. Use butyl rubber gloves; nitrile fails after extended contact. Always work in a fume hood with eye protection.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.