M- Dinitrobenzene

CfiHgNj. Colourless crystals m.p. 63 C, b.p. 2%TC. Turns brown in air. Prepared by a one-stage reduction of m-dinitrobenzene with iron and hydrochloric acid. 

Naphthalene, oxalic acid (hydrated), cinnamic acid, acetamide, benzamide, m-dinitrobenzene,/>-nitrophenol, toluene p-sulphon-... 

If an impure and discoloured sample of m-dinitrobenzene is used in the above preparation, add some animal charcoal to the solution immediately prior to the 20 minutes boiling the use of charcoal is to be avoided when possible, however, as it is liable to absorb an appreciable quantity of the /-nitroanilinc. 

Physical Properties. Nitrobenzene, C HjNOj pale yellow liquid, insoluble in and heavier than water, characteristic odour of bitter almonds, (similar to that of benzaldehyde and benzonitrile). /> Nitro toluene, C,H4(CH3)N02, usually pale yellow solid, insoluble in water, m-Dinitrobenzene, C8H4(N02)g, colourless solid when pure, but often pale yellow insoluble in water. 

Yellow. Quinones, m- and p-nitroaniline, o-nitrophenol, and many other nitrO"Compounds. [Note that some nitro-compounds often appear yellow (e.g. m-dinitrobenzene and 3, 5 -dinitro-benzoic acid), but are colourless when absolutely pure.] Iodoform. 

Choice of solvent for recrystallisation. Obtain small samples (about 0 5 g.) of the following compounds from the storeroom (i) salicylic acid, (Li) acetanilide, (iii) m-dinitrobenzene, (iv) naphthalene, and (v) p-toluene-sulphonamide. Use the following solvents distilled water, methylated spirit, rectified spirit, acetone, benzene and glacial acetic acid. 

Benzene. Add 0 5 ml. of benzene slowly and with shaking and cooling to a mixture of 4 ml. each of concentrated sulphuric and nitric acids. Heat the mixture carefully until it just boils, cool and pour into excess of cold water. Filter oflF the precipitate, wash it free from acid and recrystalhse it from dilute alcohol. m-Dinitrobenzene m.p. 90°, is formed. 

Transfer the crude dinitrobenzene to a 250 ml. flask fitted with a reflux condenser, add 80-100 ml. of methylated (or rectified) spirit and heat on a water bath until all the crystalline solid dissolves. If the resulting solution is not quite clear, filter it through a fluted filter paper on a large funnel which has previously been warmed or through a warm Buchner funnel. Colourless crystals of m-dinitrobenzene (15 g.) are deposited on cooling. If the m.p. is below 89-90°, recrystaUisation is necessary. 

In azole chemistry the total effect of the several heteroatoms in one ring approximates the superposition of their separate effects. It is found that pyrazole, imidazole and isoxazole undergo nitration and sulfonation about as readily as nitrobenzene thiazole and isothiazole react less readily ica. equal to m-dinitrobenzene), and oxadiazoles, thiadiazoles, triazoles, etc. with great difficulty. In each case, halogenation is easier than the corresponding nitration or sulfonation. Strong electron-donor substituents help the reaction. 

Only 22-45% yields of m-fluoronitrobenzene are obtained from the fluoro-denitration of m dinitrobenzene by potassium fluoride in Af-methyl-2-pyrrolidone or hexamethylphosphoramide, along with significant amounts of 3,3 dinitro-diphenyl ether [107, 108, 109] (equation 32)... 

Nizol. An expl patented by Schweiz of Spreng-stoff-Fabrik AG, Dottikon (SwissP 226852), contg m-dinitrobenzene made more sensitive to initiation by the addition of 30% PETN. It was... 

PETN with 80% m-dinitrobenzene 82.4 10% PETN with 90% 2,4-dinitrotoluene 67.3 13% PETN with 87% Oi-trinitrotoluene 76.1 30% PETN with 70% Tetryl 111.3... 

The complexes precipitate immediately on mixing 1 1 complexes (n = 1) are prepared from arenes such as benzene, biphenyl, naphthalene, acenaphthalene, fluorene, phenanthrene, anthracene and m-dinitrobenzene. These complexes contain a complex Hg(I) cation with the arene v coordinated to one Hg as in III ... 

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