Nitromethane
Nitrocarbol
Colorless liquid with a fruity odor
Liquid
1.14 g · cm -3
-29 ° C
100.8 ° C
36.4 hPa (20 ° C)
10.2
3.1 D
1.38056
Attention
940 mg · kg -1 ( LD50, rat, oral)
Template: Infobox chemical / molecular formula search available
11.3 MJ · kg -1
36 ° C.
Nitromethane CH3NO2, the simplest organic nitro compound. The connection is simply substituted members of the series of Nitromethane with nitromethane, dinitromethane, trinitromethane and tetranitromethane. It is a nitroalkane and a constitutional isomer of carbamic acid.
- 3.1 Historical Use
- 3.2 Current Use
Representation and extraction
In the laboratory, the reaction of sodium chloroacetate with sodium nitrite or methyl bromide and silver nitrite nitro methane supplies. The technical production is carried out by nitration of methane or by a gas-phase nitration of propane, where it is contained at about 25 % in the resulting nitro alkane mixture.
Properties
Nitro Methane is a colorless, slightly smelling, flammable liquid with a melting point of -29 ° C and atmospheric pressure boiling point of 100.8 ° C. Nitromethane is only partially miscible in water. With increasing temperature the solubility of nitromethane in water increases and increases the solubility of water in nitromethane.
The 1H NMR spectrum shows only a single peak at 4.28 ppm for the CH function. This is a significant shift from the methane at 0.23 ppm. For connecting two tautomeric structures can be formulated. In addition to the Nitrotautomer still exists a Nitronsäuretautomer. The balance, however, lies practically on the side of Nitrotautomers. Quantum chemical calculations show a difference in free energy of 59.8 kJ · mol -1 to the nitro acid structure. The salt formation in the presence of alkali bases such as sodium hydroxide leads to the corresponding Nitro acid salts.
The vapors act on the central nervous system, prolonged exposure or ingestion cause liver and kidney damage.
Thermodynamic properties
The vapor pressure function is given by Antoine corresponding log10 (P) = A- ( B / ( T C )) ( P in bar, T in K) with A = 4.11350, B = 1229.574 and C = -76.221 in temperature range from 404.9 to 476 K and with A = 4.40542 B = C = -45.633 1,446.196 and in the temperature range from 328.86 to 409.5 K.
The temperature dependence of the enthalpy of vaporization can be determined according to equation ΔVH0 = A exp ( - βTr ) (1- Tr) β ( ΔVH0 in kJ / mol, Tr = (T / Tc) reduced temperature ) with A = 53.33 kJ / mol, β = 0.2732 and Tc = 588 K describe the temperature range between 318 K and 374 K.
Explosion characteristics
When handling safety rules must be observed, since nitromethane is able to detonate. Although the mechanical sensitivity is very low, in the impure state or as a mixture with other substances, such as amines, however, the sensitivity can be increased. Important explosion indicators are:
- Heat of explosion: 1026 kJ · kg -1 (H2O ( g)).
- Detonation velocity: 6210 m · s-1 at the density of 1.14 g · cm -3
- Normal gas volume: 1102 l · kg -1.
- Specific energy: 1245 kJ · kg -1
- Lead block expansion: 430 ml/10 g
Mixtures of nitromethane with methanol are also able to detonate. The detonation velocity decreases with increasing methanol fraction from linear and decreases with a share of 35 % methanol to 5.08 km / s
Use
Nitromethane is used as a solvent for spectroscopy and high performance liquid chromatography for the production of rocket fuels, explosives ( PLX, ANNM ), insecticides and as an additive for gasolines.
In organic chemistry, it is a useful reagent, because it can be easily deprotonated and named in this form reactions such as the nitro - aldol reaction, Henry reaction, received, can be produced by the slightly aliphatic nitro compounds
The use as a racing fuel is both historically and currently the most important use.
Historical Usage
First documented use as a performance-enhancing fuel additive for internal combustion engines is nitromethane in 1950 when Rodger Ward, an American race car driver, a number of surprising wins race wins. Vic Edelbrock, responsible for engine tuning, had achieved a significant performance increase in gasoline in test series with different nitromethane shares. However, the engines still required lengthy adjustments in order to survive on this fuel race distance.
Today's use
When Model Nitro engines are used with methanol / nitromethane mixture for RC Cars and Airplanes usually. Nitromethane improves the performance of model engines, but affects the same time cooling off, and the cooling system of the engine is weaker than the heating by the increase in performance.
In motor sport, a mixture of methanol with up to 85% nitromethane for the Top Fuel dragster vehicle class is used as fuel. It come of it passenger car gasoline engines used, whereby the cost of the modification is relatively low. Further changes of the characteristic, such as in pure methanol - firing, are not necessary here. Pure nitromethane about twice the performance of a gasoline-fueled engine is possible with a correspondingly higher thermal and mechanical stress.