urbaf2

218 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

phenolic group in o- nitrophenol is not capable of molecular association, unlike

m- and p- nitrophenols.

The nitro group also strongly influences the amino group present in the ring,

reducing its basic properties. This influence is strongest when it is in the ortho

or para position to the amino group. The reactivity of the amino group is so en-

hanced that o- or p- nitroaniline, when boiled in a aqueous solution of sodium

hydroxide, are hydrolysed to form o- or p- nitrophenol. m- Nitroaniline is not subject

to this reaction.

This specific property of o- and p- nitroaniline may be explained by assuming

the structure of an amphoteric ion:

However, this formula for m- nitroaniline cannot be accepted as it requires the

assumption of the m- quinone structure which is unknown at present.

To confirm the formula II, reference is made to the fact that the dipole moment

of p- nitroaniline (μ = 6.45) is much higher than that which would be deduced

from the total of the dipole moments of aniline (μ = 1.52) and nitrobenzene

(μ = 3.96).

The nitro group may, in some cases, form a hydrogen bond with a primary

or secondary amine group in the ortho position to the nitro group. Thus, Hathway

and Flett [98], on the basis of their investigations of the infra-red absorption

spectra of 1,2- and 2,1-nitronaphthylamines, inferred that such a bond might exist.

However, more recent studies by Dyall and Hambly [99] as well as by T. Urban-

ski and Dabrowska [100] with nitro derivatives of aniline have shown that in

o- nitroaniline such a bond cannot be confirmed so that for the time being we can

go no farther than speaking of an ion bond.

BEHAVIOUR OF NITRO COMPOUNDS IN

CONCENTRATED ACIDS

As stated by Hantzsch [101] on the basis of cryometric measurements, the

nitro group itself could be of a basic character. The author had studied the behaviour
of nitromethane, p- nitrotoluene, m- dinitrobenzene and 2,4,6-trinitrotoluene in

oleum solutions. Among all the compounds investigated, only p- nitrotoluene be-