Trinitromethane

Trinitromethane[1]
IUPAC name Trinitromethane
Other names Nitroform
Identifiers
CAS number	517-25-9 Y
ChemSpider	10157 Y
EC-number	208-236-8
Jmol-3D images	Image 1
SMILES C([N+](=O)[O-])([N+](=O)[O-])[N+](=O)[O-]
InChI InChI=1S/CHN3O6/c5-2(6)1(3(7)8)4(9)10/h1H Y Key: LZGVDNRJCGPNDS-UHFFFAOYSA-N Y InChI=1/CHN3O6/c5-2(6)1(3(7)8)4(9)10/h1H
Properties
Molecular formula	CHN3O6
Molar mass	151.04 g/mol
Appearance	Pale yellow crystals
Density	1.469 g/cm3
Melting point	15 °C, 288 K, 59 °F
Solubility in water	44g/100ml at 20°C
Acidity (pKa)	0.25 (see text)
Hazards
Main hazards	Oxidant, Explosive (esp. in contact with metals), Corrosive.
NFPA 704	1 3 4 OX
Related compounds
Related compounds	Hexanitroethane Octanitropentane Tetranitromethane
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Trinitromethane, also referred to as nitroform, is a nitroalkane and oxidizer with chemical formula HC(NO₂)₃. It was first obtained as the ammonium salt by Shiskov in 1857. In 1900, it was discovered that nitroform can be produced by the reaction of acetylene with anhydrous nitric acid. This method went on to become the industrial process of choice during the 20^th century. In the laboratory, nitroform can also be produced by hydrolysis of tetranitromethane under mild basic conditions.^[2]

Acidity

Trinitromethane exists in two forms, a colorless molecular form, HC(NO₂)₃, and an intensely yellow anion, (NO₂)₃C^-. Nitroform is highly soluble in water, and the stable solution is yellow due to the presence of the anion. The pK_a of trinitromethane has been measured at 0.17 ± 0.02 at 20°C, which is remarkably acidic for a methane derivative.^[3] There is some evidence that the anion (which obeys the 4n+2 Hückel rule) is aromatic.^[4]

Nitroform salts

Trinitromethane forms a series of bright yellow ionic salts. Many of these salts tend to be unstable and can be easily detonated by heat or impact. Because aqueous solutions of trinitromethane are quite acidic, this poses a handling danger similar to that of picric acid due to corrosion of iron or aluminum surfaces.

The potassium salt of nitroform, KC(NO₂)₃ is a lemon yellow crystalline solid that decomposes slowly at room temperatures and explodes above 95 °C. The ammonium salt is somewhat more stable, and deflagrates or explodes above 200 °C. The hydrazine salt, hydrazinium nitroformate is thermally stable to above 125 °C and is being investigated as an ecologically friendly oxidizer for use in solid fuels for rockets.

References

1. ^ Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (12th ed.), Merck, ISBN 0911910123 , 9859.
2. ^ Gakh, A. A.; Bryan, J. C.; Burnett, M. N.; Bonnesen, P. V. (2000), "Synthesis and structural analysis of some trinitromethanide salts", J. Mol. Struct. 520 (1-3): 221–28, doi:10.1016/S0022-2860(99)00333-6 .
3. ^ Novikov, S. S.; Slovetskii, V. I.; Shevelev, S. A.; Fainzilberg, A. A. (1962), "Spectrophotometric Determination of the Dissociation Constants of Aliphatic Nitro Compounds", Russ. Chem. Bull. 11 (4): 552–59, doi:10.1007/BF00904751 .
4. ^ Cioslowski, Jerzy; Mixon, Stacey T.; Fleischmann, Eugene D. (1991), "Electronic structures of trifluoro-, tricyano-, and trinitromethane and their conjugate bases", J. Am. Chem. Soc. 113 (13): 4751–55, doi:10.1021/ja00013a007 .