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ALIPHATIC NITRO COMPOUNDS 587

DINITROMETHANE

CH 2 (NO 2 ) 2

Dinitromethane is a volatile liquid with a sharp, acid smell. It was first obtained

by Villiers [41] and Losanitsch [42]:

(17)

Duden [43] improved the last stages of the method:

(18)

It is unstable at room temperature and is readily decomposed with evolution

of nitrogen dioxide. It can be kept for longer periods only at temperature below 0°C

or in solution in benzene or some other solvents.

Dinitromethane can exist in two tautomeric forms:

I II

This was based on examination of the ultra-violet and visible spectra (Hedley

[44], Hantzsch and Voigt [45]) and electroconductivity measurements (Hantzsch

and Veit [46]). The nitro form (I) is colourless, the aci-form (II) is yellow. The aci-form

is a relatively strong mono-acid (Ka = 1.43 x 10

-4

at 0°C and 2.68 x 10

-4

at 25°C).

Dinitromethane reacts with two mol. of formaldehyde to form the diol (III)

[47]

III

Dinitromethane forms salts which are (generally speaking) unstable and decom-

pose at temperatures not very much above 100°C.

TRINITROMETHANE (NITROFORM)

Trinitromethane CH(NO 2 ) 3 forms white crystals (m. p. 25°C). It was first

obtained as its ammonium salt by Shishkov [48], by hydrolysis of trinitroacetonitrile

with water. It was also Shishkov who obtained trinitroacetonitrile (m. p. 41.5°C)

by treating the sodium salt of fulminuric acid with a mixture of nitric and sulphuric

acid. Trinitroacetonitrile also exhibits explosive properties.

Baschieri [49] found that nitroform was produced in the reaction of acetylene

with anhydrous nitric acid (sp. gr. 1.52). Tetranitromethane, when hydrolysed,