Practical methods of organic chemistry by Gattemann Ludwig

Author:Gattemann, Ludwig. [from old catalog]
Language: eng
Format: epub, pdf
Publisher: [n.p.]
Published: 1901-03-25T05:00:00+00:00

gradually added (hood) ; the reaction-mixture is then heated for half an hour on a water-bath, with frequent shaking • after cooling somewhat, it is poured, with stirring, into cold water. The dinitro-benzene which solidifies is filtered off, washed with water, pressed out on a porous plate, and recrystallised from alcohol. Melting-point, 90 0 . Yield, 10-12 grammes.

The property of yielding nitro-derivatives, when treated with nitric acid, is a characteristic of aromatic compounds. According to the conditions under which the nitration is carried out, one or more nitro-groups can be introduced at the same time. The above reactions take place in accordance with the following equations :

C C H 6 + N0 2 . OH = C 6 H-. N0 2 + H 2 0,

C 6 H,. N0 2 + N0 2 . OH = C fi H 4 . (N0 2 ) 2 + H 2 0.

If a saturated aliphatic residue is present in an aromatic compound, the nitration under the above conditions always affects the benzene ring, and not the side-chain. Since the benzene carbon atoms are in combination with only one hydrogen atom, the nitro-compounds obtained on nitration are tertiary ; they therefore do not have the power to form salts, nitrolic acids, or pseudo-nitroles, like the primary and secondary nitro-compounds.

Recently the nitro-group has been introduced directly into the side-chain. 1 If, e.g., toluene or ethyl benzene be heated with weak nitric acid (sp. gr. 1.076) in a bomb up to about ioo°, phenylnitromethane, C 6 H 5 . CH 2 . N0 2 , or phenylnitroethane, C 6 H S . CH . N0 2 . CH 3 is obtained.

Not only can the mother substances, the aromatic hydrocarbons, but all their derivatives, as phenols, amines, aldehydes, acids, etc., undergo similar reactions. But the nitration does not take place in every case with the same ease. In each case, therefore, the most favourable conditions for the experiment must be determined. If a compound is very easily nitrated, the nitration may be effected, according to the conditions, by nitric acid diluted with water, or the substance may be dissolved in a solvent which is not attacked by nitric acid; glacial acetic acid is frequently used for this purpose, and then treated with nitric acid. The reverse process may also be employed, i.e. the substance is added to a mixture of nitric acid and water, or nitric acid and glacial acetic acid. If a substance is moderately difficult to nitrate, it is added

1 B. 27. Ref. 194 and 198.

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