1.4- Dinitrobenzene, synthesis

The synthesis of 1,3,5-trinitrobenzene (TNB) from the direct nitration of m-dinitrobenzene is very difficult. Desvergnes reported a 71 % yield of TNB (2) on treatment of m-dinitrobenzene (32) with a large excess of mixed acid composed of anhydrous nitric acid and 60 % oleum at a reaction temperature of 110 °C for several days. Similar results are also reported from other... 

The effect which amino functionality has on the thermal and impact sensitivity of polyni-troarylenes (Section 4.8.1.4) makes amination by VNS a method with much future potential for energetic materials synthesis. Other carbon, nitrogen, oxygen and sulfur nucleophiles can displace aromatic hydrogen examples with 1,3-dinitrobenzene and 1,3,5-trinitrobenzene are extensive. 

Similar routes have been used for the synthesis of other polynitrophenylenes. 1,3,5-Tris(2,4,6-trinitrophenyl)-2,4,6-trinitrobenzene (160) is synthesized from the reaction of 1,3,5-trichloro-2,4,6-trinitrobenzene with three equivalents of picryl chloride in the presence of activated copper powder in refluxing mesitylene. " 2,2",4,4, 4",6,6, 6"-Octanitro-m-terphenyl (161) has been synthesized from picryl chloride and l,3-dichloro-4,6-dinitrobenzene. ... 

Pagoria and co-workers synthesized a number of thermally stable explosives from the reaction of the sodium salt of ANTA with chloro-substituted arylenes and A-heterocycles. These include the synthesis of (117) from picryl ehloride, PRAN (118) from 2-chloro-3,5-dinitropyridine, IHNX (119) from 2,4-dichloro-5-nitropyrimidine, (120) from 1,5-dichloro-2,4-dinitrobenzene, and (121) from 4-chloro-6-(3-nitro-l,2,4-triazolyl)-5-nitropyrimidine. Coburn and co-workers " reported the synthesis of the tetrazine (122) and the triazine (123) from the reaction of the sodium salt of ANTA with 3,6-dichlorotetrazine and cyanuric chloride respectively. 

DNB is often made first. Both 1,3-DNB and 1,3,5-TNB are formed as by-products when another explosive, trinitrotoluene (TNT), is made. 1,3-DNB is also used to make certain dyes, as an intermediate in the synthesis of organic chemicals, and in the plastics manufacturing industry. 1,3,5-TNB is used in making rubber. Other names for 1,3-DNB include m-dinitrobenzene,... 

Problem 18.35 Using C Hj, C HjCHj, via diazonium salts and any other needed reagents, prepare (a) o-chlorotoluene, (h) m-chlorotoluene, (c) 1,3,5-tribromobenzene, (d) m-bromochlorobenzene, (c) p-iodotoluene, (/) p-dinitrobenzene and (g) p-cyanobenzoic acid. Do not repeat the synthesis of intermediate products. <... 

Trialkylaryltin derivatives 30 are converted into fluoro-substituted derivatives 31. 37-38 (4-Mcth-oxyphenyl)trimethylsilane (32) in acetonitrile gives 4-fluoroanisole and (3-fluoro-4-meth-oxyphenyl)trimethylsilane in the ratio 1 2. A -Methyldiethanol esters of arylboronic acids 33 (l-aryl-5-methyl-2,8-dioxa-5-azonia-l-boranuidabicyclo[3.3.0]octanes) are converted into tluoroaromatic compounds with cesium fluoroxysulfate in acetonitrile in the presence of 1,3-dinitrobenzene at room temperature.39-40 Regiospecific synthesis of 2-fluoro-3-0-methyles-trone in 27 % yield occurs upon fluorination of the corresponding arylboronic acid with cesium fluoroxysulfate.41... 

The synthesis of -phenylenediamine [108-45-2] is also straightforward it proceeds via the formation of / -dinitrobenzene [99-65-0] by the nitration of benzene, followed by hydrogenation to the diamine. 

Formation of a symmetrical sulphide (a) (e.g. dipropyl sulphide, Expt 5.204), is conveniently effected by boiling an alkyl halide (the source of carbocations) with sodium sulphide in ethanolic solution. Mixed sulphides (b) are prepared by alkylation of a thiolate salt (a mercaptide) with an alkyl halide (cf. Williamson s ether synthesis, Section 5.6.2, p. 583). In the case of an alkyl aryl sulphide (R-S Ar) where the aromatic ring contains activating nitro groups (see Section 6.5.3, p. 900), the aryl halide is used with the alkyl thiolate salt. The alternative alkylation of a substituted thiophenol is described in Section 8.3.4, p. 1160. The former procedure is illustrated by the preparation of isobutyl 2,4-dinitrophenyl sulphide (Expt 5.205) from l-chloro-2,4-dinitrobenzene and 2-methylpropane-1-thiol. 

The structure elucidation of 34 was based, in principle, on two facts color reactions and hydrolysis. Compound 34 does not react with ninhydrin (therefore, no primary amino group is present) but it does react with l-fluoro-2,4-dinitrobenzene. By exact determination of the absorption ratio E35O/E390 after the reaction with the latter reagent, Tait concluded that 34 contains a secondary amino group (50). Hydrolysis (6 N HC1, 110°C, 24 hr) of the so-called compound II afforded 2,3-dihydroxybenzoic acid and spermidine (50). The presence of two 2,3-dihydroxybenzoyl residues in 34 was demonstrated by its enzymatic (50) and chemical synthesis (51-54). 

The reactions between i-dinitrobenzene or 1,3,5-trinitrobenzene, aryl halides, and copper(I) oxide in quinoline 17-19, 21) provide a simple synthesis of nitrobiphenyls uncontaminated by symmetrical biphenyls. These couplings may be related to the Ullmann reaction, the decarboxylative coupling of benzoic acids with aryl halides, and the preparation of ethers from phenols 165). Although no intermediates... 

The conversion of an amino group into a nitro group can be useful when specific substitution patterns are required. The synthesis of 1,4-dinitrobenzene from 4-nitroaniline is illustrative (Scheme 7.5). Oxidation can be accomplished directly using peroxytrifluoroacetic acid or in two steps using H2SO5 (monoperoxysulfuric acid) and oxidation of the resulting nitroso compound with hydrogen peroxide. Alternatively, the amine can be diazotized in fluoroboric acid and then reacted with sodium nitrite in the presence of copper powder. 

The diaminobenzenes (phenylenediamines) are prepared by reduction of 1,3-dinitrobenzene and 2- and 4-nitroanilines. o-Phenylenediamine is of value in the synthesis of a range of nitrogen heterocycles. Thus reaction with organic acids produces benzimidazoles (8). With 1,2-dicarbonyl compounds, quinoxalines (9) are produced. Treatment with nitrous acid results in diazotization of one amino group followed by immediate cyclization to give benzotriazole (10). 

Aromatic diazonium salts on treatment with sodium nitrite decompose to form nitro compounds. This method represents a good procedure for obtaining o- and p-dinitrobenzenes, in 70% and 76% yield, respectively, from the corresponding diazonium sulfates. Improved yields in the preparation of dinitronaphthalenes are obtained when the decomposition of the diazonium sulfates is catalyzed by a cupro-cupri sulfite prepared by the interaction of copper sulfate and sodium nitrite. The procedure is illustrated by the synthesis of 1,4-dinitronaphthalene (60%). Occasionally, diazonium fluoborates are first formed, and these compounds are treated with sodium nitrite in the presence of copper powder, viz.,... 

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