Benzene nitration test

C) Nitration Test. Place in a 30 or 50 ml Erlenmeyer flask 6 ml of a mixture of equal volumes of concentrated nitric acid and concentrated sulfuric acid. Add 2 ml of benzene and shake for a minute. In another flask treat in the same manner 2 g of naphthalene. Place flasks in a water bath and warm at 50° for 10 minutes. Shake the mixture frequently, using care that no acid is splattered. TFeor your goggles. After the mixtures are heated pour each into 50 ml of water and note whether any yellow oil or solid separates out. The nitro compound is separated and handed to the instructor. Compare the nitronaphthalene with the original compound. Record in your note book the observations and explanation. 

The dimerization of ethylene into n-butenes by means of tetrachlo-robis(ethylene)palladium in nonhydroxylic media (benzene or dioxane) has been attempted [246]. Other palladium salts (fluoride, bromide, iodide, nitrate) tested in the dimerization of olefins do not form complexes of the type (C2H4),Pd2X4. Palladium cyanide dimerizes ethylene twice as slowly as PdCL, probably on account of deactivation of the catalyst by a polyethylene deposit formed along with the dimer. 

Rapid, simple, quaUtative methods suitable for determining the presence of benzene in the workplace or surroundings have been utilized since the 1930s. Many early tests offered methods for detection of aromatics but were not specific for benzene. A straightforward test allowing selective detection of benzene involves nitration of a sample to y -dinitrobenzene and reaction of the resultant ether extract with an ethanoHc solution of sodium hydroxide and methyl ethyl ketone (2-butanone), followed by the addition of acetic acid to eliminate interferences from toluene and xylenes. Benzene imparts a persistent red color to the solution (87). The method is claimed to be sensitive to concentrations as low as 0.27 ppm benzene from 10 mL air samples. 

The two key isocyanates that are used in the greatest volumes for polyurethane polymers are toluene diisocyanate (TDl) and methylene diphenyl diisocyanate (MDl). Both isocyanates are produced first by nitration of aromatics (toluene and benzene, respectively), followed by hydrogenation of the nitro aromatics to provide aromatic amines. In the case of MDl, the aniline intermediate is then condensed with formaldehyde to produce methylene dianiline (MDA), which is a mixture of monomeric MDA and an oligomeric form that is typical of aniline/formaldehyde condensation products [2]. The subsequent reaction of phosgene with the aromatic amines provides the isocyanate products. Isocyanates can also be prepared by the reaction of aromatic amines with dimethylcarbonate [3, 4]. This technology has been tested at the industrial pilot scale, but is not believed to be practiced commercially at this time. 

In this method, an ale soln of benzene-sulfonic acid(previously standardized with phosgene by weighing the pptd diphenyl-carbamide) is added from a burette to a sample of aniline(or its nitrated compd not jiighvr thsji tctrsnitro-) until the 3ppcufuptcc of a dirty-bluish coloration, when a drop of the reaction mist is placed on a filter paper previously impregnated with amino-/3-naphthol indicator(spot test). This method is not applicable for analysis of penta-nitroani ine(Ref 15)... 

Benzin is a mixture of various hydrocarbons. It has, therefore, no sharp boiling point, but distils within rather wide limits. The testing of benzin for benzene by nitrating the latter with nitro-sulphuric acid was not adopted here, because it is impossible to obtain a benzin that will stand this test. 

The high, values for the lead block expansion test given by mixtures of tetranitro-methane with higher nitrated aromatic compounds are striking. On the other hand, the rates of detonation of these mixture are lower than those of mixtures containing lower nitrated compounds or benzene. 

An interesting application of the color reaction of nitrotoluene with sodium hydroxide is made in detecting traces of nitrotoluene in nitrobenzene. The latter substance will not give a red color with sodium hydroxide, and by standardizing the colors, the test may be made roughly quantitative. This reaction may, of course, be applied to the detection of toluene in benzene by first nitrating. (8)... 

Di-phenyl amine crystallizes from ligroin in white leaflets with faint odor melting point 54°, boiling point 302 . It is soluble in alcohol, ether and benzene and slightly soluble in water. A solution of diphenyl amine in sulphuric acid, i.e., di-phenyl amine sulphate, is colored blue by a trace of nitric acid, and is used as a test for nitrates. In the color industry di-phenyl amine makes azo dyes. 

Metallic picrates and oxalates should be absent, and other nitrocompounds should be present only in traces, The melting point or setting point carried out on a well-dried sample should be at least 20. The moisture content is generally limited to o i-o 3S per cent., and the ash to o-oS-o t per cent. this should not be of a gritty nature. Impurities insoluble in water should not exceed the uh content by more than 0 05 per cent. The picric acid should be almost completely soluble in benzene. Sulphates are restricted to 0 05 0 i per cent, as SO,). Chlorides and nitrates are sometimes tested for. Absence of lead in any form which might give rise to the formation of lead picrate is of special importance. Lead sulphate is, however, comparatively harmless. 

Balxistic pendulum test for explosives, 68 Ballistite, stability tesu for, 73 Barium nitrate, for use in explosives, examination of, 4 for use in match compo tiocu, toj Benzene, for use in explosives, 34 in ethyl alcohol, sej radon of, 39 Bergmann and Junx test, for stability of explosives, 83... 

---