W-Dinitrobenzene

The catalytic effect of aromatic nitro groups in the substrate and product or in an added inert nitro compoimd (e.g., w-dinitrobenzene in 18) has been observed in the reaction of 2,4-dinitrochlorobenzene with an amine in chloroform. Hydrogen bonding to benzil or to dimethyl sulfone and sulfoxide also provided catalysis. It is clear that the type of catalysis of proton transfer shown in structure 18 will be more effective when hydrogen bonding is to an azine-nitrogen. 

The urinary excretion of steroids is closely related to the gonadal and adrenocortical production of hormones. Because they can be determined quantitatively on the basis of color reactions, for example, with /w-dinitrobenzene, a relatively large amount of data is available with respect to the excretion of 17-ketosteroids. Exactly what is included in this group in specific instances must be ascertained by consulting the original publications. 

Fig. 3 Electrochemical and homogeneous standard free energies of activation for self-exchange in the reduction of aromatic hydrocarbons in iV.A -dimethylformamide as a function of their equivalent hard sphere radius, a. 1, Benzonitrile 2, 4-cyanopyridine 3, o-toluonitrile 4, w-toluonitrile 5, p-toluonitrile 6, phthalonitrile 7, terephthalonitrile 8, nitrobenzene 9, w-dinitrobenzene 10, p-dinitrobenzene 11, w-nitrobenzonitrile 12, dibenzofuran 13, dibenzothiophene 14, p-naphthoquinone 15, anthracene 16, perylene 17, naphthalene 18, tra 5-stilbene. Solid lines denote theoretical predictions. (Adapted from Kojima and Bard, 1975.)...

The replacement of one nitro group in w-dinitrobenzene by a chlorine atom by means of partial reduction and diazotization has been described by Griess.4... 

Rapid, simple, qualitative methods suitable for detemiining 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 w-dinitrobenzene and reaction of the resultant ether extract with an ethanolic 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 mT, air samples. 

Transfer the crude dinitrobenzene to a 250-ml flask fitted with a reflux condenser, add 80-100 ml of industrial (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 w-dinitrobenzene (15 g, 73%) are deposited on cooling. If the m.p. is below 89-90 °C, recrystallisation is necessary. 

Some aromatic dinitro compounds, e.g. w-dinitrobenzene, may be characterised by partial reduction to the nitroamine. Experimental details using sodium polysulphide as the reducing agent are to be found in Expt 6.51. 

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 off the precipitate, wash it free from acid and recrystallise it from dilute alcohol. w-Dinitrobenzene, m.p. 90 °C, is formed. 

Pressure. Solubility of w-dinitrobenzene m ethyl acetate at 30 00° (grams of solute in 100 grams of solvent). 

High-boiling alcohols are sometimes better dehydrogenated in the liquid phase in presence of a hydrogen-acceptor such as copper and nitrobenzene or w-dinitrobenzene. The preparation of o-chlorobenzaldehyde in 86% yield from 2-chlorobenzyl alcohol at 205-210° may be cited as example.432... 

Since the dinitro compounds are rather insoluble in water and the diamines are quite soluble, Benner and Stevenson have developed a method involving reduction of a dispersion of dinitro compound in water, effected by very rapid agitation, using noble-metal catalysts. This process can be run continuously by using a series of vessels to carry out the reduction. Similar reductions of w-dinitrobenzene, in water dispersion, using nickel and copper catalysts were also carried out in the laboratories of I. G. Far-benindustrie.2... 

Standard solutions w-dinitrobenzene, fluorenone, acetone-2,4-dinitro-phenyl-hydrazine, benzylidene acetone and azobenzene (all 1% (w/v) in toluene). 

In certain cases, alkanolamines function as reducing agents. For example, monoethanolamine reduces anthraquinone to anthranols, acetone to 2-propanol, and azobenzene to aniline (17). The reduction reaction depends on the decomposition of the alkanolamine into ammonia and an aldehyde. Similarly, diethanolamine converts o-chloronitrobenzene to 2,2 -dichloroazobenzene and w-dinitrobenzene to 3,3 -diaminoazobenzene. 

Prediction of the structures of DHDK w-dinitrobenzene and DHDK PDMB would seem to demand either a clairvoyant structural chemist or an exceptionally powerful computer program. 

In accordance with the radical mechanism, the reaction in benzene yields trinitrobenzene, p- and w-dinitrobenzenes, 2,4-di- and 2,4,6-trinitrophenol and oxalic acid. The formation of w-dinitrobenzenes, and trinitrobenzene is accounted for by the addition of three and five NO radicals to the primary nitrocyclohexadienyl radical followed by an abstraction of two or three nitrous acid (HNO ) molecules from the adducts. For the trinitrobenzene formation, this process can be represented as follows [4] ... 

In the Callow modification of the Zimmermann reaction an ethanolic solution of the urinary extract is treated with w-dinitrobenzene and etha-... 

A homogeneous liquid containing 50 per cent ethjd alcohol and ether together with aniline, methylaniline, nitrobenzene, and w-dinitrobenzene. 

Alkaline dinitrobenzene solution. Mix 1 ml of a 10 per cent aqueous solution of tetramethylammonium hydroxide with 140 ml of dry ethanol, titrate a portion of the solution with 0 01 N hydrochloric acid to methyl red and adjust the remaining solution to a concentration of 0-008N by dilution with dry ethanol. Immediately before use mix 40 ml of this solution with 60 ml of a 5 per cent solution of w-dinitrobenzene in benzene. 

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