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NITRO DERIVATIVES OF ANILINE^563

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PHYSICAL PROPERTIES

2,2’,4,4’,6,6’-Hexanitrodiphenylamine forms yellow needles, which decompose

while melting. It is difficult to dissolve in concentrated sulphuric acid and in most

organic solvents. It dissolves more easily in hot acetic acid, nitrobenzene and ace-

tone. The pyridine salt of hexyl is still more readily soluble in acetone.

At room temperature hexyl is only slightly hygroscopic: when exposed to the

air saturated with water vapour it absorbs only 0.09% moisture. The specific gravity

of hexyl crystals is 1.653. Hexyl is rather difficult to press, but when mixed with 1%

stearic acid more satisfactory pressing can be achieved and a uniform material

obtained.

Densities obtainable under various pressures are :

below 330 kg/cm^2 density 1.43 g/cm^3

,, 660 ,, ,, 1.56 ,,

,, l000 ,, ,, 1.59 ,,

,, 1330 ,, ,, 1.60 ,,

CHEMICAL PROPERTIES

The acidic character of hexyl is one of its most important features. It was first

observed by Aleksandrov [24] when preparing ammonium salt of hexyl. Later this

property was investigated by Hantzsch and Opolski [25], who obtained the O-methyl

ether of the aci-form of hexyl, according to Hantzsch’s nomenclature (Ia).

The aci-form of the compound can yield salts and O-ethers (esters). It is

intensely coloured due to the presence of the quinonoid ring.

Ia

The ammonium salt of hexyl known as “Aurantia” had been used for a long time

as a yellow dye for silk and wool.