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128 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

An interesting case of introducing the nitro group, accompanied by hydro-

lysis, was reported by Leandri [195] :

(88)

When halogenated phenols or phenolic ethers are nitrated with nitric acid

a halogen o- or p- to hydroxyl or alkoxyl group can also be replaced. The ease of

replacement appears to be in the order Cl< Br<I.

A typical and the oldest example was given by P. W. Robertson [195a]:

(89)

Hodgson and Smith [196] give an example which indicates the mobility of

various halogen atoms:

(90)

Sometimes the free halogen liberated in this displacements itself enters the

aromatic ring, thus giving rise to an apparent substitution. Thus P. W. Robert-

son [196a] and P. W. Robertson and Briscoe [196b] found that 6-bromothymol

on nitration in dilute acetic acid gives 2-bromo-6-nitrothymol:

(91)

Aliphatic nitro compounds may be obtained in the well known Kolbe reaction

[197] by acting with sodium nitrate on α− halogen fatty acids. During the substitution

the carboxyl group splits off.