Nitrobenzene, reaction with unsaturated compounds

The photochemical action of nitrobenzene on unsaturated compounds in sunlight is a field already investigated by Vechiotti and Zanetti.295 Recently, Buchi and Ayer32 have evaluated the reaction of nitrobenzene with olefins as a possible synthetic route to the heterocyclic class of compounds, 1,3,2-dioxazolidines (CXLVI). Photoexcited... 

Carbon dioxide radical anions, C02 , are commonly used in aqueous chemistry as a reducing agent for metalloporphyrins or as intermediate in the formation of superoxide anion. COf has been reported to undergo efficient electron transfer reactions with methyl violo-gen, quinones, alkyl halides, fumarates, nitro and nitrosobenzenes and chlorinated benzaldehydes. With nitrobenzenes and chlorinated benzaldehydes, electron attachment occurs on the nitro and aldehyde groups, respectively. CO2 radicals have also been reported to add to some unsaturated compounds such as acrylamide and pyridin-3-ol. Efficient hydrogen abstraction from mercaptobenzenes have also been reported. 

The chemistry of indium metal is the subject of current investigation, especially since the reactions induced by it can be performed in aqueous solution.15 The selective reductions of ethyl 4-nitrobenzoate (entry 1), 2-nitrobenzyl alcohol (entry 2), l-bromo-4-nitrobenzene (entry 3), 4-nitrocinnamyl alcohol (entry 4), 4-nitrobenzonitrile (entry 5), 4-nitrobenzamide (entry 6), 4-nitroanisole (entry 7), and 2-nitrofluorenone (entry 8) with indium metal in the presence of ammonium chloride using aqueous ethanol were performed and the corresponding amines were produced in good yield. These results indicate a useful selectivity in the reduction procedure. For example, ester, nitrile, bromo, amide, benzylic ketone, benzylic alcohol, aromatic ether, and unsaturated bonds remained unaffected during this transformation. Many of the previous methods produce a mixture of compounds. Other metals like zinc, tin, and iron usually require acid-catalysts for the activation process, with resultant problems of waste disposal. 

It has been stated that the aromatic compounds differ markedly from the paraffins and the unsaturated hydrocarbons related to ethylene and acetylene. The reactions which take place when benzene and its derivatives are treated with nitric acid, sulphuric acid, or oxidizing agents are characteristic of this group of compounds. Only the higher paraffins react with nitric acid, and in the case of these compounds reaction results to but a slight degree and only after heating for many hours (26). The aromatic hydrocarbons and their substitution-products form well characterized compounds when treated with nitric acid. When benzene is warmed with concentrated nitric acid nitrobenzene is formed —... 

This reaction was initially reported by Doebner and von Miller in 1881 as a modification of the original Skraup Reaction, and it was subsequently modified by Beyer in 1886 It is an acidic condensation between primary aromatic amines (e.g., anilines) and Q ,j8-unsaturated carbonyl compounds (mostly o ,y3-unsaturated aldehydes) to give 2,3-disubstituted quinolines. Therefore, this reaction is generally known as the Doebner-Miller reaction, or Doebner-Miller synthesis." In addition, this reaction is also referred to as the Doebner-von Miller quinoline synthesis, Skraup-Doebner-von Miller reaction, Skraup-Doebner-von Miller quinoline synthesis, Doebner-Miller condensation, and Doebner-Miller Quinaldine Synthesis. For comparison, the modification from Beyer, known as the Beyer method for quinoline, is an acidic condensation between anilines and Q ,j8-unsaturated carbonyl compounds generated in situ from aldehyde or aldehyde and methyl ketone to afford 2,4-disubstituted quinolines." The optimal condition of this reaction is to heat the mixture of aniline/aldehyde (1 2) at 100°C for 6 h with hydrochloric acid and zinc chloride in addition, an oxidizing reagent is also needed in this reaction, such as nitrobenzene. However, it has been reported that A -alkylanilines are also formed in this reaction. The nature and... 

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