Cobalt, hydrogenation nitro groups

The selective hydrogenation of an aryl nitro group has been accomplished even in the presence of an easily hydrogenated acetylene group. Cobalt polysulfide and ruthenium sulfide have been reported to be effective for the selective hydrogenation of the nitro group in m-nitrophenyl acetylenes giving the amino-acetylenes in 75-85% yields (Eqn. 19.2). Ruthenium catalysts were also effective for this reaction but since the order of reactivity over these catalysts was found to be ... 

Reduction of Nitro- to Amino-groups. - Sulphide catalysts continue to find application in selective hydrogenation of nitro-groups. Aromatic nitro-groups in the presence of acetylenes were selectively hydrogenated (373 K, 25-70 atm, in isopropanol) to amino-groups over cobalt polysulphide and RUS2 catalysts, for example (3-nitrophenyl)acetylene to (3-aminophenyl)acetylene in 75-85% yield. ... 

Primary Amines.—Cobalt polysulphide and ruthenium(iv) sulphide catalysts have been found to be selective for the preferential hydrogenation of aromatic nitro-groups in the presence of acetylenes/ Formamidinesulphinic acid/ phenylselenol in the presence of DABCO/ and sodium borohydride in the presence of [Cu(acac)2r also effect the aromatic nitro-to-amine conversion. 

Hydrogenation Catalysts. The key to catalytic hydrogenation is the catalyst, which promotes a reaction which otherwise would occur too slowly to be useful. Catalysts for the hydrogenation of nitro compounds and nitriles are generally based on one or more of the group VIII metals. The metals most commonly used are cobalt, nickel, palladium, platinum, rhodium, and mthenium, but others, including copper (16), iron (17), and tellurium... 

Various other reducing methods are employed for the conversion of (3-nitro alcohols to amino alcohols, namely, electrochemical reduction.107 The selective electrohydrogenation of ni-troaliphatic and nitroaromatic groups in molecules containing other groups that are easy to hydrogenate (triple bond, nitrile, C-I) are carried out in methanol-water solutions at Devarda copper and Raney cobalt electrodes (Eq. 6.55).107... 

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