Nitro compounds tests

Reduction of a nitro compound to a hydroxylamine. Dissolve 0-5 g. of the compound in 10 ml. of 50 per cent, alcohol, add 0-5 g. of solid ammonium chloride and about 0 5 g. of zinc powder. Heat to boiling and allow the ensuing chemical reaction to proceed for 5 minutes. Filter from the excess of zinc powder and test the filtrate with ToUen s reagent see Section III,70,(i). An immediate black or grey precipitate or a silver mirror indicates the presence of a hydroxylamine formed by the reduction of the nitro compound. Alternatively, warm the filtrate with Fehling s solution a hydroxylamine will precipitate red cuprous oxide. (A blank test should be performed with the original compound.)... 

Analytical and Test Methods. o-Nitrotoluene can be analyzed for purity and isomer content by infrared spectroscopy with an accuracy of about 1%. -Nitrotoluene content can be estimated by the decomposition of the isomeric toluene diazonium chlorides because the ortho and meta isomers decompose more readily than the para isomer. A colorimetric method for determining the content of the various isomers is based on the color which forms when the mononitrotoluenes are dissolved in sulfuric acid (45). From the absorption of the sulfuric acid solution at 436 and 305 nm, the ortho and para isomer content can be deterrnined, and the meta isomer can be obtained by difference. However, this and other colorimetric methods are subject to possible interferences from other aromatic nitro compounds. A titrimetric method, based on the reduction of the nitro group with titanium(III) sulfate or chloride, can be used to determine mononitrotoluenes (32). Chromatographic methods, eg, gas chromatography or high pressure Hquid chromatography, are well suited for the deterrnination of mononitrotoluenes as well as its individual isomers. Freezing points are used commonly as indicators of purity of the various isomers. 

It is sometimes cliflicult to detect nitrogen by the sodium test. The result should not be regarded as conclusive, especially if the substance is volatile, unless it has been dropped in small quantities at a time into the melted metal, which should be heated in a hard-glas.s tube clamped in a retort-.stand. Special care must be used with nitro compounds, which may explode and shatter the Lube. 

Gilliland H.B. Hass, Synthesis of Certain Aliphatic Nitro Compounds" in ADL Synthesis and Testing of High Explosives , Report C-57625, Contr W-19-020-ORD-6436, 3 Jan 1949 (AD-222018), p i 05 21) N.D. Mason,... 

PA. Rifle bullet impact in welded cans gave 4/4 high order detonations. Thermal stability at 135°, acid in 15—30 minutes at 82.2° heat test, 10 minutes at 82.2°. This material and its homologs from other aliphatic nitro compounds and aldehydes have been suggested as substitutes for NG... 

Glowiak (Ref 5) claims that detonation velocity, heat of combustion and Trauzl Block test all correlate with a true OB for 25 nitro compounds (some containing diazo or azido groups). This writer has not seen his original publication CA does not specify intelligibly what is meant by true OB... 

Experiment.—Dissolve 1 c.c. of nitromethane in water and test the solution with litmus paper. Then add some phenolphthalein and, drop by drop from a burette, OliV-sodium hydroxide solution. Before a permanent pink colour develops about 2 c.c. of the alkali will be added—a sign that an acid, aci-nitromethane, H2C NOOH, has been formed from the neutral nitromethane. A small sample of this solution gives with ferric chloride a blood-red colour, characteristic of aci-nitro-compounds. The salts of the oci-compound undergo extensive hydrolysis. This is shown by further addition of 0-1 N-alkali which produces a deep red colour. If 10 c.c. of alkali were added and 5 c.c. of 0-1 JV-hydrochloric acid are now run in the solution is decolorised because the liberated oci-compound restricts the hydrolysis of its salt. But the conversion of H2C N02H into H3C.N02 proceeds so rapidly that the red colour reappears in a few moments. 

BP (1914) first described a limit test, based upon the production of coloured nitro-compounds by the interaction of traces of nitrates with phenol-2,4-disulphonic acid, and the conversion of these subsequently into dark-yellow ammonium salts. However, this test has a serious disadvantage of correctly matching the yellow colours with great difficulty. 

A semiconductor sensor-based instrument was described for determination of the composition and concentrations of vapors of organic nitro compounds and nitrogen dioxide in the atmosphere. Four organic semiconductor sensors [e.g. aluminum phthalocyanine fluoride (222a)] were tested in conjunction with platinized platinum preconcentrators sensitivity is to ppm levels of nitrobenzene450. 

An example of the application of this test to a compound that nitrates as its free base is provided by pyridine 1-oxide. Under an identical set of conditions, nitration of this N-oxide had a half life of 20 min, whilst 1-methoxypyridinium gave no nitro compound in 144 h. Two further criteria have been used to provide confirmatory evidence, namely comparison of the rate of nitration for the reactive species with the encounter controlled rate, and by determination of the Arrhenius parameters. 

The systematic studies of T. Urbanski, Kwiatkowski and Miladowski [76] proved that the addition of an aromatic nitro compound distinctly enhances the stability of nitrocellulose and nitrocellulose powder. Thus, nitrocellulose containing 13.4% N which on heating for 5 hr at 120°C had pH=2.28 showed pH=2.89 on addition of 9 1% p-nitrotoluene, pH=3.17 on addition of 9.1 % 2,4-dinitrotoluene and pH=3.34 on addition of the same amount of a-trinitrotoluene. The same samples when heated in a constant volume (Tagliani test) gave at 134.5°C a pressure of decomposition... 

Alkyl halides are often used as substrates instead of alcohols. In such cases the salt of the inorganic acid is usually used and the mechanism is nucleophilic substitution at the carbon atom. An important example is the treatment of alkyl halides with silver nitrate to form alkyl nitrates. This is used as a test for alkyl halides. In some cases there is competition from the central atom. Thus nitrite ion is an ambident nucleophile that can give nitrites or nitro compounds (see 0-60).731 Dialkyl or aryl alkyl ethers can be cleaved with anhydrous sulfonic acids.732... 

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