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94 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

(5) Heterocyclic compounds are more difficult to nitrate. For example, from

quinoline 11% of mononitroquinoline was obtained at 95-100°C, while at 155-160°C

10-12% of dinitroquinoline could be obtained; from pyridine 6% of nitropyridine

was obtained at 115-120°C.

Aqueous solution of N 2 O 4 has both a nitrating and a nitrosating action.

N-nitrosation and simultaneous C-nitration of secondary aromatic amines

by aqueous solution of N 2 O 4 has been studied by Stoermer [61] and Ruff and Stein

[62]. Thus N-methylaniline yielded N-methyl-n-nitroso-p-nitroaniline.

Paraffin hydrocarbons

T. Urbanski and Slori [63] in a series of experiments described in preliminary

notes between 1936 and 1938 found that normal paraffin hydrocarbons from ethane

to n-nonane can be nitrated with nitrogen dioxide in the gaseous phase to give

good yields. The authors have nitrated normal hydrocarbons using nitrogen dioxide

in large excess. They found the temperature necessary for obtaining the best yield

was the lower, the longer the hydrocarbon chain. At the same time they observed

that the reaction yields rise with the chain length. The principal yields obtained

by the above mentioned authors are shown below in Table 12.

TABLE 12

RELATION BETWEENTHE CHAIN LENGTH OF PARAFFIN HYDROCARBONS

AND THE YIELD OF NITRATION PRODUCT

Hydrocarbon

Ethane

Propane

n-Butane

n-Pentane

n-Hexane

n-Heptane

n-Octane

n-Nonane

Temperature

(minimum), °C

250

220

200

200

200

200

200

180

Yield up to %

(by weight)

10

20

25

30

35

40

40

60

Apart from nitration products some oxidation products such as aldehydes
and fatty acids were also obtained. Nitrolic acids were also present in the products.
Detailed experiments on nitration of n-hexane with nitrogen dioxide in the
vapour phase were recently carried out by Slebodzinski, T. Urbanski et al. [64].
They nitrated n-hexane using the molar ratio

At 300°C the yield of a mixture of nitro compounds was 24-42% by weight.

27-39% of this mixture was composed of lower nitroparaffins (nitromethane,