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NITRO DERIVATIVES OF NAPHTHALENE^423

Derivatives with β− nitro groups are more readily nitrated than the others. This

Hodgson attributed to a higher electronegativity of β− nitro groups, particularly

in the presence of vacant α− positions which are easy to substitute.
Hodgson has summarized the results of the nitration of dinitronaphthalenes

(Table 94).

TABLE 94

starting Trinitro derivatives Tetranitro derivatives

material

1,3- 1,3,8- 1,3,6,8-

1,4- 1,4,5- 1,3,5,8- and 1,4,5,8-

1,5- 1,4,5- and 1,3,5- 1,3,5,8- and 1,4,5,8-

1,6- 1,3,8- 1,3,6,8-

1,8-

2,6-

1,3,8- 1,3,6,8-

none 1,3,5,7-

2,7- 1,3,6- 1,3,6,8-

On reduction, acid reducing agents attack the α− nitro group preferentially,

while sodium and ammonium sulphides reduce the β− nitro group.

Until the end of World War I and some years after, nitro derivatives of naph-

thalene were fairly widely used in mixtures with other explosives, for example

with ammonium nitrate (e.g. Schneiderite) or with various other nitro compounds

such as picric acid, as well as with potassium chlorate (cheddit) (Vol. III).

During World War II these compositions did not play any significant role. Used

mostly in France, they dropped out of use from 1940 onwards.

At present nitronaphthalenes are scarcely used in the manufacture of explosives,

mainly because of the shortage of naphthalene. The latter is used in large quantities

in the manufacture of phthalic acid and of valuable dye intermediates. The large

demand for phthalic acid and the lack of adequate supplies of naphthalene for

its production have led to extensive research into the isolation of o- xylene and its

oxidation to phthalic acid.

Nitronaphthalene is not an explosive. Dinitronaphthalene shows weak explosive

properties and only trinitronaphthalene may be regarded as a true explosive. Tetrani-

tronaphthalene is about as powerful an explosive as TNT (Lenze [4]).

Nitro derivatives of naphthalene have the advantage of being only slightly

toxic. Although the output of nitro derivatives of naphthalene in Germany was

high during World War I, no cases of poisoning were observed. However, eye

irritation on exposure to the vapour or on contact with solutions of α− nitronaph-

thalene have been reported. The irritation is accompanied by eye-sight trouble

(Frank [5]; Hanke [6]; Silex [7]; Caspar [8]).

Nitration of naphthalene was first mentioned in description of experiments

by Laurent [9] between 1835 and 1842. On boiling naphthalene with nitric acid he

obtained a mixture of mono-, di- and tri-nitronaphthalenes.