V/c-Dinitro compounds

Ono and coworkers have extended the radical elimination of v/c-dinitro compounds to P-nitro sulfones151 and P-nitro sulfides.138,152 As P-nitro sulfides are readily prepared by the Michael addition of thiols to nitroalkenes, radical elimination of P-nitrosulfides provides a useful method for olefin synthesis. For example, cyclohexanone is converted into allyl alcohol by the reaction shown in Eq. 7.110. Treatment of cyclohexanone with a mixture of nitromethane, PhSH, 35%-HCHO, TMG (0.1 equiv) in acetonitrile gives ahydroxymethylated-P-nitro sulfide in 68% yield, which is converted into the corresponding allyl alcohol in 86% yield by the reaction with Bu3SnH.138 Nitro-aldol and the Michael addition reactions take place sequentially to give the required P-nitro sulfides in one pot. 

The addition of dinitrogen tetroxide across the double bonds of electron deficient fluorinated alkenes is a particularly useful route to v/c-dinitro compounds where yields are frequently high 8,37 tetrafluoroethylene gives a 53 % yield of l,2-dinitro-l,l,2,2-tetrafluoroethane. ... 

In this example, the rate of a fast cleavage reaction was determined by a combination of low-temperature and fast-scan voltammetry [24]. Upon insertion of an electron into a v/c-dinitro compound, the resulting radical anion undergoes rapid C-N bond cleavage to form nitrite ion and a p-nitroalkyl radical, which in turn undergoes further reduction. 

Data at smaller scan rates and higher temperatures allowed determination of the rate constant for cleavage of nitrite from the radical anion of this and other v/c-dinitro compounds. In addition to the use of microelectrodes to reduce iR drop, another interesting feature of this study was the observation of the effect... 

Radical anions of geminal nitro compounds in DMF cleave rapidly to nitrite and a radical which initiate a free radical chain in which a v/c-dinitro compound is formed [43]. Radical anions of other a-substituted nitroalkanes may cleave either the nitro group or the other substituent 1-cyano-l-nitrocyclohexane thus splits off nitrite whereas 1-nitrocyclo-hexyl p-tolyl sulfone loses p-tolylsulfinate [44]. 

Denitration of ic-dinitro compounds. ra -StiIbene (2) and 9,9 -bifluor-enylidene (4) can be obtained by denitration of (1) and (3), respectively, with anhydrous stannous chloride or the dihydrate (4 eq.). This method fails in the case of aliphatic v/c-dinitro compounds. ... 

With mineral acids, including nitric acid produced by the decomposition of powder, the N-nitroso compound undergoes rearrangement to form p-nitrosodiphenylamine (IV). This substance is readily oxidized to p-nitrodiphenylamine (V). Furthermore, the higher nitrated products, i.e. dinitro derivatives (VI) and (VII) and trinitro derivatives (VIII) may be formed in powder. Davis and Ashdown isolated 2,4,4 -tri-nitrodiphenylamine from American pyrocollodion powder by heating a sample in a closed vessel for 240 days at a temperature of 65°C. At the end of the heating period brown nitric oxides were given off by the powder. 

Dinitrophenyl-hydrazine 2,4-dinitro-phenylhydrazine (0.4%, m/v) in HCI (2moir ) Heated at 105°C for 5 min Ketoses or ketals - orange 1-2 pg for most keto compounds... 

In order to circumvent the problem of the use of selenium, analogous systems based on the use of sulphur compounds have been developed [85-88]. Aromatic nitro compounds can be reduced by CO in water/methanol media at 120-150 °C and 1-1.5 bar pressure [85, 86]. From nitrobenzene, aniline was obtained with selectivity over 97 % at 100 % PhN02 conversion. The reaction proceeds in the presence of a multicomponent catalyst consisting of a base (preferably a strong base such as sodium hydroxide or methoxide) and sulphur compounds. The ratio of catalytic effectiveness of sulphur compounds is as follows S CS2 H2S COS = 1 1.3 10 10. Vanadium(V) compounds can be added to improve selectivity in aniline formation. Aromatic dinitro derivatives undergo this reaction and selectivity to one of the two main products (phenylenediamine and nitroaniline) can be switched by the choice of reaction conditions. The main byproduct of the reaction of nitrobenzene is PhNHCOOMe [85, 86]. It has been shown that, under the catalytic conditions, methyl phenylcarbamate can be hydrolysed to afford aniline. More forcing conditions (up to 300 bar CO) have also been employed in order to increase the activity [87]. The same catalytic system has been used to reduce nitrophenols to the corresponding aminophenols [88]. 

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