1.5- Dinitronaphthalene preparation

Under spectroscopic conditions, a 100% conversion is easily reached and the reaction is reported to be remarkably clean. High 5delds are obtained in preparative runs. In the same way both nitro groups are exchanged for chlorine in 1,5-dinitronaphthalene, whereas 1,8-dinitronaphthalene gives rise to a tiichloro-naphthalene. 2-Nitronaphthalene was unreactive. 

Nitration via diazotisation has been extensively used for the synthesis of isomeric dinitronaphthalenes. Ward and co-workers used nitration via diazotisation to prepare 3,3, 4,4 -tetranitrobiphenyl from 3,3 -dinitrobenzidine, and 3,4,5-trinitrotoluene from 3,5-dinitro-4-toluidine. Ward and Hardy " prepared 1,4,6-trinitronaphthalene from 4,7-dinitro-1-naphthylamine. Korner and Contardi used the nitrate salts of aryldiazonium compounds for the synthesis of polynitro derivatives of benzene " and toluene. " " Accordingly,... 

Naphthoxidine is a very useful intermediate for dyes of this group, and it can be prepared conveniently by treating 1,5-dinitronaphthalene with sulfur in oleum [27], [28], A solution of sulfur in 20 % oleum is added slowly over 35 min to a slurry of 1,6-dinitronaphthalene in concentrated sulfuric acid, maintaining the temperature at 50-55 °C. The dark brown mixture is stirred for a further 10 min at this temperature and then for 30 min at 20 °C. The mixture is then poured onto ice and the suspension filtered. The blue filtrate is made alkaline with sodium hydroxide solution, employing efficient external cooling in order to keep the temperature below 40 °C. The resultant blue precipitate of the sodium salt of naphthoxidine is filtered off and washed with a little water. The solid is extracted with boiling acetic acid, and concentration of the extracts gives lustrous red needles of naphthoxidine. 

The mixture is prepared from 600 kg of the spent acid from the dinitronaph-thalene manufacture and 550 kg of the spent acid from mononitration, which has been re-used for washing dinitronaphthalene. In consequence the spent acid contains some of the HN03 adsorbed by dinitronaphthalene. The composition and the quantity of the mixture should be so calculated as to contain 128 kg of HN03, required for complete nitration of 300 kg of naphthalene. 

The product is washed as described below (see preparation of dinitronaphthalene from nitronaphthalene). 

Dinitrobenzoic acid has been prepared by nitration of benzoic acid with sulfuric acid and fuming nitric acid 1 by nitration of 3-nitrobenzoic acid 2 and by oxidation of 3,5-dinitrotol-uene.1, 3 It has been obtained along with other products by the action of nitric acid upon 1,5-dinitronaphthalene.4... 

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.,... 

Dinitronaphthalene may be obtained similarly from 2-nitro-l-naphthylamine, or less satisfactorily from l-nitro-2-naph-thylamine 1,6- and 2,6-dinitronaphthalenes can be prepared from the 5-nitro- and 6-nitro-2-naphthylamines, respectively, by a modification of the process. Since the solubility of these amines in glacial acetic acid is slight, it is preferable to prepare the diazonium sulfate as follows Ten grams of the amine is dissolved in 50 ml. of sulfuric acid (sp. gr. 1.84), and the solution is mixed with one of 10 g. of sodium nitrite in 50 ml. of sulfuric acid (sp. gr. 1.84). This mixture is stirred into 200 ml. of gladal acetic acid. The temperature is maintained below 20° throughout these operations. After 30 minutes, the diazonium sulfate is precipitated at 0° by the addition of 200-500 ml. of ether as previously described. 

Dinitronaphthalene has been prepared previously from diazotized 4-nitro-l-naphthylamine by a modified Sandmeyer procedure, - from 5,8-dinitrotetralin by dehydrogenation, by the deamination of l,4-dinitro-2-naphthylamine, and by the decomposition of 4-nitro-l-naphthalenediazonium cobaltinitrite. The method described above has been published. ... 

Some kinds of proton sponges are best prepared starting from accessible l,8-bis(methyl-amino)naphthalene (4) or its derivatives2,40-43. For example, the optimal synthesis of l,8-bis(dimethylamino)-4,5-dinitronaphthalene (51) consists in methylation of compound 50, which in turn can be prepared from perimidone 49 (Scheme 2)44,45. 

Sulfur sesquioxide, SjOs- The preparation of this reagent and its use for the conversion of 1,5-dinitronaphthalene into naphthazarin is described in the patent literature and in papers by Charrieri and by one of us. In our procedure 25 g. of sulfur is dissolved in 375 ml. of 18% fuming sulfuric acid and the solution is added to a suspension of 50 g. of 1,5-dinitronaphthalene in 230 ml. of coned, sulfuric acid and... 

A number of dinitronaphthalenes have also been prepared similarly, but in less good yields.1172... 

A chromatogram is run in a preparative chromatographic system to separate acetonaphthalene (AN) from dinitronaphthalene (DN). The results are shown in Figure 18-22. Find K dn> N and the... 

Zeng SM, Maeda T, Mondori J, Tokumitsu K, Mochida I, Preparation of isotropic pitch precursors for general purpose carbon fibers (GPCF) by air blowing. 3. Air blowing of isotropic naphthalene and hydrogenated coal tar pitches with addition of 1,8-dinitronaphthalene, Carbon, 31(3), 421-426, 1993. 

Arylations are commoner than alkylations. Ullmann and Nadai s preparation of dinitrochlorobenzenes, and its extension to that of diphenyl ethers—reactions in which the nucleophiles are chloride ions and phenols, respectively—have been mentioned already (p. 268). Applied to l-(2,4-dinitronaphthyl)pyridinium chloride, the reaction gives l-chloro-2,4-dinitronaphthalene, and the same salt reacts with water to give the naphthol, with hydrogen sulphide to yield the thionaphthol, and with carboxylic acids to form dinitronaphthyl esters . Amines , alcohols , mercaptans and thiophenols have been dinitrophenylated with pyridinium salts. Styrylpyridinium salts give N-styrylpiperidine with piperidine . 

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