Hydrogenation of Other Heteroatom Functional Groups

Aromatic nitriles can give mixtures of the primary amine and dibenzylamines (via the condensation reaction), but this depends on the catalyst. Rhodium hydroxide [Rh(OH)3] is very effective for production 

Hydrogenation of nitro compounds is rather straightforward, and palladium, platinum, and nickel catalysts have been used. Palladium is the most common catalyst for both aromatic and aliphatic nitro compounds. The poor results obtained for reduction of aromatic nitriles with hydride reagents (sec. 4.2.C.iii) make catalytic hydrogenation the preferred method. Reduction of 407 involved conversion of the aromatic nitrile moiety to the benzylamine derivative when palladium and a trace of platinum oxide was used. Hydrogenation using platinum oxide converts aromatic nitro compounds to aniline derivatives, even in the presence of other reducible groups. OS 

Epoxides react with hydrogen and a catalyst by a hydrogenolysis reaction, but it is relatively slow and many functional groups can be reduced preferentially, which means that epoxides can be reduced if there is little or no other functionality. If reduction of the epoxide is to be avoided, rhodium on carbon (Rh/C) or Wilkinson s catalyst is preferred. Predicting the direction of ring opening (regioselectivity in the reduction) 

Reduction of a, 3-epoxyketones is usually accompanied by hydrogenolysis at the a-position, and the product is a p-hydroxy ketone, 14 as in the conversion of 414 to 415.415 if other substituents (electron releasing or withdrawing) are attached to the p-position, the direction of reduction is less predictable. Reduction of aziridines by hydrogenolysis is similar to that of epoxides and usually occurs at the less hindered C—N bond.416-417 

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