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6 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

In aromatic compounds, an amino group may be substituted by the nitro group

by diazotization and reacting with nitric acid in the presence of cuprous salts (the

Sandmeyer reaction). This method is used for laboratory work only and is de-

scribed in textbooks on preparative organic chemistry.

With respect to the chemical structure of compounds resulting from nitration

processes, three types of nitration reactions are distinguished which may be re-

ferred to as:

(1) C-nitration, leading to the formation of “true” nitro compounds, having

the nitro group attached to a carbon atom:

(2) O-nitration, leading to the formation of nitric acid esters, with the nitro

group attached to an oxygen atom:

(3) N-nitration, leading to the formation of nitramines with the nitro group

attached to a nitrogen atom of an amine or amide group:

NITRIC ACID

The physical constants of chemically pure nitric acid are

specific gravity 1.

specific heat 0.5 k&/kg

melting point -41.6°C

boiling point +86°C

heat of formation -41.66 kcal/mole

At the boiling point nitric acid undergoes partial decomposition which pro-
ceeds chiefly according to the equation:

2HNO 3 -> 2NO 2 + H 2 O + ½O 2 (1)

At higher temperatures the degree of decomposition is greater and at 256°C it
is complete.
In conformity with the accepted notation for simplified electronic formulae,

the structural formula of nitric acid according to Sugden is

As this formula indicates in the nitro group one atom of oxygen is linked to the
nitrogen atom by a double bond, the other-by a semipolar linkage (see Chapter V

on the structure of the nitro group, p. 168). Bond distances and bond angles have

been calculated by Maxwell and Mosley [5] (Fig. 1a), using their own experiments