2.2- Dinitrostilbene

A mixture of 27 g. (0.15 mole) of 2,4-dinitrotoluene and 17.9 g. (17.2 ml. or 0.17 mole) of freshly distilled benzaldehyde is heated to boiling, and 30 drops of piperidine is added. The mixture is heated in an oil bath at 140° for 2 hours. After cooling, the solid is broken up and washed with cold methanol and benzene. The material is then recrystallized from glacial acetic acid to yield 29 g. (73%) of 2,4-dinitrostilbene as yellow needles, m.p. 140°. 

A mixture of 20 g. (0.093 mole) of hydrobenzoin (p. 174) and 100 g. of crystalline oxalic acid is heated in an oil bath to a bath temperature of 156° and held at this point for 4 hours. The resulting product is extracted with ether, and the ethereal solution is washed with aqueous sodium carbonate solution, dried over anhydrous sodium sulfate, and distilled. The fraction boiling at 184-186°/20 mm. is redistilled to give 10.5 g. (60%) of diphenylacetaldehyde boiling at l88-188.5°/24 mm., ng 1.5937. 

A mixture of 39.2 g. (0.20 mole) of benzophenone hydrazone fOrg. Syntheses Coll. Vol. 2, 497 (1943)], 44 g. (0.20 mole) of yellow mercuric oxide, and 200 ml. of petroleum ether (b.p. 30-40°) is agitated with moderate external cooling for 9 hours. The deep red petroleum ether solution is filtered, and the solvent is removed from the filtrate under vacuum without heating the mixture. The resulting deep red crystals of diphenyldiazomethane, m.p. 29-30°, weigh between 33 and 

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Being involved in a charge-transfer complex with A/,A-dimethylaniline, d5 -a,p-dinitrostilbene undergoes a conversion into its trans form with no changes in the nitro group (Todres et al. 1986 Scheme 2.11). 

In contrast, one-electron polarographic redaction of a,p-dinitrostilbene yields an anion-radical, wMch is stabilized in a nitronic form with a carboradical center. These radicals possess an enhanced electron affinity and are prone to the capture of the second electron at the first wave potential, with the formation of a stable dinitronic dianion. In the case of a,p-dinitrostilbene, the cathodic reduction cannot be stopped at the one-electron step (Todres 1991 see Scheme 2.12). 

Now let us compare 4,4 - and 2,4-dinitrostilbenes with respect to their relative capabilities to rotate around the C=C bond on electron transfer. The difference between them is shown in Scheme 3.46 (Todres et al. 1980). 

Nelsen et al. (2007) have revealed one more aspect of solvent control over charge localization. Solvents with marked electron-donor properties contribute to charge localization in cation-radicals, whereas anion-radicals experience the same changes in better electron-accepting solvents. Thus, naked (non-ion-paired) anion-radicals of 4,4 -dinitrostilbene and 4,4 -dinitrotolane show the spectra of delocalized species in HMPA and THF, but essentially spectra of localized species in DMF, DMSO, and MeCN. 

Dinitrostilbene, C6H5.CH, CH.C0H3(NO2)2, exists in high- St low- melting forms (Ref 1)... 

Dinitrostilbene, trans, yel ndls (from glac acet ac), mp 240—42°, bp — sublimes at 175° under 0.001mm press (Ref 4)... 

Dinitro-a,a -diphenyl-ethylene Ether or Dinitrostilbene Oxide,... 

The starting compound for all triazinylaminostilbenes is 4,4 -dinitrostilbene-2,2 -disulfonic acid [128-42-7], which is obtained by oxidizing 4-nitrotoluene-2-sulfonic acid with aqueous sodium hypochlorite in the presence of sodium hydroxide or, more recently, by atmospheric oxidation in an aqueous ammoniacal medium [39], The Bechamps reduction using iron filings etched with hydrochloric acid yields 4,4 -diaminostilbene-2,2 -disulfonic acid [81-11-8] (DAS). 

Extensive research work on the action of N203, N204 and N205 on olefins was carried out by Demyanov [76, 77, 78], He found that both glycol esters and nitro compounds were obtained in these reactions. According to Wieland [13,55], the reaction of N204 with stilbene results in the formation of dinitrostilbene (VIII) ... 

The nitration of acetylene hydrocarbons proceeds in a more complex way than that of olefins. The first member of the series-acetylene-undergoes various reactions, for example, with nitric acid (see p. 82 and p. 599) Tolane (diphenylacety-lene) is nitrated with N204 to form dinitrostilbene. Two products are formed which are presumably a- and p- stereoisomers ... 

Trinitrotoluene gives analogously trinitrobenzoic acid. p-Dinitrostilbene. While carrying out some experiments on the dye sun yellow/ which is obtained by warming p-nitro-toluenesulplxonic acid with sodium hydroxide, Elbs and Kre-mann3 worked on the electrochemical reduction of several stilbene derivatives. 

They obtained the following results p-Dinitrostilbene, reduced in alkaline solution, gives p-azoxystilbene in hydrochloric-acid solution with addition of stannous chloride (method of C. F. Boehringer Sohne), p-diaminostilbene. 

In addition to the complexes of platinum(II), a number of olefin complexes of platinum(O) have been prepared. Chatt, Shaw, and Williams (103) have described the complex (olefin)bis(triphenylphosphine)-platinum(O) prepared by reaction of the olefin at 60°C with cis-dichloro-bis(triphenylphosphine)platinum(Il) in ethyl alcohol containing hydrazine hydrate. The complex was formed only with ethylene complex (C2H4)Pt[P(CgH5)3]2 has been prepared (121) by reduction of the corresponding oxygen complex with sodium borohydride in the presence of the olefin. 

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