Nickel 1,3-dinitrobenzenes

For the test of the various modifiers the following conditions were used 300 ml stainless steel autoclave 40.8 g (0.2 mole) l-chloro-2,4-dinitrobenzene 2.0 g Raney nickel (60% in water) 0.012 moles of modifier 120 ml methanol temperature 60°C H2 pressure 10 bar 1100 rpm. 

Influence of the modifier structure on reaction time and chemoselectivity of the hydrogenation of l-chloro-2,4-dinitrobenzene (Raney nickel methanol 60°C 10 bar). 

Yang and Burton studied reductive radical additions of iododifluoroacetate 37 to olefins 38 and dienes catalyzed by 6-17 mol% of a catalyst generated from NiCl2 and stoichiometric amounts of zinc in the presence of water (Fig. 8) [90, 91]. Olefins gave the reductive addition products 40a in 60-83% yield, while 1,5-hexadiene or 1,8-nonadiene provided double addition products exclusively in 55% and 73% yield. 1,7-Hexadiene gave an inseparable mixture of the expected acyclic double addition product and a tandem addition/cyclization product, in which the former dominated. The radical nature of the addition is supported by inhibition of the reaction by para-dinitrobenzene. The reaction proceeds probably via initially formed atom transfer product 39, which is subsequently reduced by nickel(0) and zinc. This is supported by deuterium incorporation, when D20 was used instead of water. No deuterium incorporation was observed with THF-dg, thus ruling out hydrogen transfer from the solvent. 

Raney copper is another Raney type catalyst that is prepared from a copper-aluminum alloy. This catalyst has been used infrequently but does show some reaction selectivity not possible with other catalysts. Of particular interest is its use for the selective hydrogenation of substituted dinitrobenzenes (Eqn. 11.6).2 This catalyst, as well as Raney cobalt, generally promotes fewer side reactions than does Raney nickel. 25... 

The traditional treatment of nitrobenzene (1) with iron and acid, called Bechamp reduction, was employed almost exclusively in the production of aniline (2) and many aromatic amines until the 1960s1,2 (Scheme 1). The reduction is straightforward, and can also be achieved by catalytic hydrogenation, sodium sulfide reduction and zinc reduction with caustic soda. Nitrotoluenes and nitroxylenes are hydrogenated under pressure over a nickel catalyst supported on kieselguhr. The sulfide reduction is useful in selective reduction, such as of m-dinitrobenzene to m-nitroaniline. 

Since the dinitro compounds are rather insoluble in water and the diamines are quite soluble, Benner and Stevenson have developed a method involving reduction of a dispersion of dinitro compound in water, effected by very rapid agitation, using noble-metal catalysts. This process can be run continuously by using a series of vessels to carry out the reduction. Similar reductions of w-dinitrobenzene, in water dispersion, using nickel and copper catalysts were also carried out in the laboratories of I. G. Far-benindustrie.2... 

Nickel halides catalyze the conversion of unreactive aryl chlorides into aryl iodides by Nal in DMF at 140 °C. In the presence of a palladium catalyst and an activated olefin, the aryl iodide is transformed into the Heck coupling product. Nickel(O) complexes are poor catalysts for the coupling step. The halide exchange is thought to be a radical reaction since it is suppressed by the addition of 5% p-dinitrobenzene as radical scavenger. While nickel catalysts do not perform... 

There are various specific colour tests for special classes of organophosphorus compounds. Tertiary phosphines, R3P, for example, produce a rose red colour in a carbon tetrachloride solution of m-dinitrobenzene. Trialkylphosphine oxides, R3PO, and dialkylphosphinic acids, RjPfOlOH produce a blue colour in a toluene solution of nickel bromide. A chloroform solution of PhjPO reacts with a chloroform solution of iodine to form an insoluble yellow compound and so forth. 

Monomers. m-Phenylene diamine (MPD) can be prepared by the continuous liquid phase hydrogenation of m-dinitrobenzene at moderate temperatiu-es (7). One process employs a dispersion of the m-dinitrobenzene in water (8) another uses a solvent, such as DMF, which dissolves both the reactant and the MPD product (9). Catalysts for the hydrogenation include platinum, palladium, and nickel that must be recovered by filtration. Purification steps include vacuum distillation. 

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