| IUPAC name
| Other names
Anhydrous nitric acid
|Molar mass||108.01 g/mol|
|Density|| 2.05 g/cm3 (0 °C)|
1.99 g/cm3 (16 °C)
1.642 g/cm3 (18 °C)
|Melting point||41 °C (106 °F; 314 K)|
|Boiling point||47 °C (117 °F; 320 K) (sublimes)|
|Solubility||Soluble in 1,1-dichloroethane, 1,2-dichloroethane, allyl chloride, bromine, chloroform, CCl4, dinitrogen tetroxide, nitric acid, nitromethane, pentachloroethane, POCl3, liq. SO2|
|Solubility in carbon tetrachloride||51.6288 g/100 ml (15 °C)|
|Solubility in nitric acid||9 g/100 ml|
|Solubility in nitromethane||47.3084 g/100 ml (15 °C)|
|Vapor pressure||279 mmHg at 20 °C|
| 178.2 J·mol-1·K-1 (s)|
355.6 J·mol-1·K-1 (g)
Std enthalpy of
| −43.1 kJ/mol (s)|
+11.3 kJ/mol (g)
|Safety data sheet||None|
| Nitrogen dioxide|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Dinitrogen pentoxide is the chemical compound with the formula N2O5, an unstable nitrogen oxide, used as oxidizer in various chemical reactions, though now largely replaced by nitronium tetrafluoroborate.
Dinitrogen pentoxide can nitrate organic compounds, similar to the nitrating mixture.
- N2O5 + Ar–H → HNO3 + Ar–NO2
While not explosive on its own, N2O5 can form explosive mixtures with various organic compounds.
Dinitrogen pentoxide is not sold by any supplier and has to be made.
Dinitrogen pentoxide can be obtained via dehydration of conc. nitric acid with conc. sulfuric acid or oleum, though phosphorus pentoxide gives better results. The N2O5 obtained this way however, is difficult to separate from the reaction product.
A very simple way of obtaining nitrogen pentoxide involves the reaction of nitrogen dioxide or dinitrogen tetroxide with ozone, reaction which takes place at low temperatures (-11 °C). A good solvent for the reaction is trifluoroacetic acid.
- Synthesis of various energetic materials
Dinitrogen pentoxide is a very poweful oxidizer and must be kept away from any combustible material.
Dinitrogen pentoxide should be used as soon as possible. At room temp it has a half-life of about 9 h, at 0 °C 2 weeks and at -60 °C around one year.
Dissolution in large amounts of water will give nitric acid. Addition of a base will convert the acid to nitrate salt, which is easy to safely dispose of.
- Eyring, H.; Daniels, F.; J. Am. Chem. Soc., 1930, 52 (4), pp 1472–1486
- Jochims, H.-W.; Denzer, W.; Baumgaertel, H.; Loesking, O.; Willner, H.; Berichte der Bunsen-Gesellschaft; vol. 96; nb. 4; (1992); p. 573 - 578