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42 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

of nitric and sulphuric acids. Thus, phenol undergoes violent reaction and carboni-

zation with HNO 3 +SO 2. According to these workers aniline, methyl- and dimethyl-

aniline also react with the mixture with an almost explosive violence to yield carbon-

ized products. Because of the vigour of the reaction there are hardly any prospects

of the practical use of the mixture. On the contrary, it seems that in many cases

(nitration of phenols and aromatic amines) the presence of SO 2 in nitrating mix-

tures may be undesirable and even dangerous.

Nitric acid and fluorine compounds

It has been shown that the addition of sulphuric acid to nitric acid is not the

sole method of producing an intensification of the nitrating properties of nitric

acid. The addition of such substances as boron fluoride (R. T. Thomas et al. [46])

or hydrofluoride (Simons at al. [47]) to nitric acid produces a similar effect.

These phenomena can also be explained by the formation of the nitronium ion,

according to eqns. (28) and (29) (p. 16).

Nitric acid and perchloric acid

Nitration can also be carried out by solutions of nitric acid with perchloric

acid [99a].

Bonner and Frizel [99b] describe O-nitration of isoamyl alcohol with a solu-

tion composed of fuming nitric acid (or N 2 O 4 ) and perchloric acid of 55-62%

HClO 4.

Nitric acid and acetic acid or anhydride

Acetic anhydride creates dehydrating conditions, therefore a mixture of nitric

acid with acetic anhydride has strong nitrating properties. Moreover in esterifi-

cation with nitric acid, the acetic acid present in the mixture or formed in the reaction

does not hydrolyse the nitric acid ester formed.

Nitric and acetic acids. According to A. Pictet and Genequand [100], acetic

acid combines with nitric acid (d = 1.52) to give a kind of mixed orthonitric

and acetic anhydride, the so-called diacetylorthonitric acid (b. p. 127.7°C):

(47)

The same compound is formed when acetic anhydride and nitric acid (d = 1.4)
are mixed.
However, no research work on the structure of the compound has been carried
out yet. In particular there is no evidence to decide whether diacetylorthonitric

acid is a true chemical compound or only an azeotrope.