Nitro derivatives of aromatic hydrocarbons

Diamines.—Derivatives of aromatic hydrocarbons which contain two or more amino groups are known. They are prepared by reducing nitro compounds which contain two or more nitro groups. The diamines are colorless compounds which rapidly turn brown in the air, and are oxidized readily. When they are treated with an aqueous solution of ferric chloride characteristic colors are formed. 

In order to eliminate the muzzle flame and reduce erosion, usually hydrocarbons, resins, fatty acids and their esters, and nitro derivatives of aromatics esters with low nitration level are added into the explosive. 

These reactions are typical also of many derivatives of aromatic hydrocarbons in fact, the presence of certain substituents, like the amine and phenolic groups, may facilitate substitution into the benzene nucleus on the other hand, certain other substituents, like the nitro and sulfonic acid groups, will cause sub-... 

Gibson, T. L., Nitro Derivatives of Polynuclear Aromatic Hydrocarbons in Airborne and Source Particulate Matter, Atmos. Environ., 16, 2037-2040(1982). 

Jager, J., Detection and Characterization of Nitro Derivatives of Some Polycyclic Aromatic Hydrocarbons by Fluorescence Quenching after Thin-Layer Chromatography Application to Air Pollution Analysis, J. Chromatogr., 152, 575-578 (1978). 

Fiedler, H., and W. Miicke, Nitro derivatives of polycyclic aromatic hydrocarbons . In The Handbook of Environmental Chemistry, Vol. 3, Part G, O. Hutzinger, Ed., Springer, Berlin, 1991, pp. 97-137. 

Aromatic nitro compounds that contain a side chain (e.g. nitro derivatives of alkylbenzenes) may be oxidised to the corresponding acids either by alkaline potassium permanganate (Aromatic hydrocarbons, Section 9.6.3, p. 1238) or, preferably, with a sodium dichromate-sulphuric acid mixture in which medium the nitro compound is more soluble. 

Three patents issued in 1924 and 1925 are conspicuous as placing special emphasis upon the preparation of particular catalysts as suitable for reactions involving the partial oxidation of side chains present in aromatic nuclei. The first00 of these relates to the oxidation of aromatic hydrocarbons and their derivatives, viz., toluene, xylene, cymene, cumene, mesitylene, cresols, etc., together with their derivatives including nitro-... 

The nitro derivatives of the aromatic compounds are prepared by the action of nitric acid on the hydrocarbons or their substitution-products. The process is called nitration. The ease with which reaction takes place is determined by the nature of the element or group in combination with the benzene ring. In general, it is more diflScult to nitrate a compound which contains a strongly negative substituent than one which contains alkyl, hydroxyl, or amino groups. For example, benzoic acid,... 

Nitro derivatives of certain aromatic hydrocarbons are manufactured commercially in large quantities, and are used in the preparation of amines which are converted into a great variety of dyes. 

Nitro Compounds as Explosives.—Nitro compounds prepared from aromatic hydrocarbons and certain of their derivatives were very important explosives used in the recent war. The compounds differ markedly in the properties which are characteristic of explosives namely, (1) sensitiveness to shock, (2) explosive force, and (3) the velocity of the explosion through the substance. If (1) is very high the explosive can not be transported very safely (2) determines the amount of the explosive to be used if (3) is very high the pressure is developed to its maximum so suddenly that rupture of the gun in which it is used may take place. Substances which are very sensitive to shock are used as detonators or boosters a small amount of the material is exploded by the trigger and the explosive wave set up causes the explosion of the less sensitive material. Mercury fulminate, lead azide, Pb(Ns)2, and several nitro derivatives of aniline (see below) are used for this purpose. 

Laurent summarised the experiments which had been made on the action of nitric acid on aromatic hydrocarbons, and prepared nitro-derivatives of naphthalene, anthracene, chrysene and pyrene. In a table he arranged them in decreasing order of the numbers of equivalents of carbon, beginning with anthracene and ending with phene (benzene) He continued to... 

Nitro-substituted polycyclic aromatic hydrocarbons (nitro-PAHs) are formed during the combustion of fossil fuels at high temperatures with a vast supply of combustion air. In this reaction, conversion of nitrite (NO2) to nitric acid is an important intermediate step. Another source of nitro-PAHs is the photochemical radical-mediated conversions of parent PAHs to nitro-derivatives. Combustion at high temperatures with a vast supply of combustion air may lead to the formation of 1-nitropyrene (1-NP), whereas photochemical conversion of pyrene gives rise to 2- and 4-nitropyrene [24,25]. 

Except for artificial alizarin, made from coal tar anthracene, practically all the early synthetic dyes were derived from, coal tar benzene and toluene. From the mid-1870s, however, interest turned to amino and nitro derivatives of the more abundant coal tar hydrocarbon naphthalene. These endeavours were assisted by the large body of theoretical, synthetic and analytical knowledge about aromatic chemistry that had become available during the decade following the announcement of Kekule s benzene ring theory (1865). Roussin s azo dyes were naphthalene derivatives. 

Sometimes it is advantageous to prepare a trinitro derivative [m, p-xylene (36)]. The preparation of mononitroderivatives, which are usually liquid, is generally combined with reduction and the acetylation of the amine formed (37, 38). Nitration is often utilized for the detection and the determination of small amounts of aromatic hydrocarbons, for example, in air. After nitration the nitro derivatives fimmed can be detected by a sensitive color reaction or polarographically. 

Paper chromatography of nitrated aromatic hydrocarbons is usually carried out on papers impregnated with a 5% paraffin oil solution with ethanol-water-acetic acid mixture (20 14 1) as solvent (27, 28), or on formamide-impregnated papers with hexane as the mobile phase. Nitro derivatives of hydrocarbons appear under UV light as dark spots. 

Solvents can be classified into three categories according to their polarity namely, polar protic, dipolar aprotic and non-polar. Most of the common solvents fall under one of following chemical classes Aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, phenols, ethers, aldehydes, ketones, carboxylic acids, esters, halogen-substituted hydrocarbons, amines, nitriles, nitro-derivatives, amides and sulfur-containing solvents (Marcus, 1998). In certain cases a mixture of two or more solvents would perform better than a single solvent. 

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