| Aromatic amines are prepared generally through the reduction of the corresponding nitroarenes. Although catalytic hydrogenation is an environmentally friendly method for the reduction of aromatic nitro compounds, it suffers from some difficulties such as hydrodehalogenation and higher demands for safety. Recently, catalytic transfer hydrogenation (CTH) of nitroarenes has been developed. In the heterogeneous transfer hydrogenation, catalyst can recover and recycle very easily. So, it is also an eco-friendly method.CTH of nitroarenes is researched in this dissertation. (a) Hydrazine hydrate is used as hydrogen donor. The Ni-Fe mixed oxide, prepared from a Ni-Fe HTLcs precursor, is used as catalyst in the hydrazine hydrate reduction of nitroarenes. The yields of aromatic amines are up to 90%-99% after reduction for 25-142 min over this catalyst. Halogen and ester groups remain intact during the reaction. Aromatic nitro compounds can be reduced to the corresponding aromatic amines in high yields (93%-99%) using macroporous weak acidic ion-exchange resin-bound hydrazine hydrate over ferrihydrite-â… or fen'ihydrite-â…¡catalyst. This approach avoids the release of excess hydrazine hydrate. In addition, the microwave irradiation technique and solid-supported strategy are efficiently combined, which shortens the reaction time (5-8 times) and reduces the amount of solvent (5 times). (b) Propan-2-ol is used as hydrogen donor. The feasibility of the propan-2-ol reduction of aromatic nitro compounds over Fe-MCM-41 catalyst is investigated and the main products of reduction are azoxy compounds.To solve the problem of the reduction of sulphur-containing nitroarenes which may poison the metal used as catalytic hydrogenation catalyst, CTH of sulphur-containing nitroarenes is studied. (a) Hydrazine hydrate is used as hydrogen donor. First, the reduction of sulphur-containing nitroarenes is carried out in the presence of ferrihydrite-â…¡catalyst. The yields reach 97%-99% after 20-50 min. Second, the catalytic activity of Mg-Fe mixed oxide prepared from a Mg-Fe HTLcs precursor is researched. The results demonstrate that 91%-99% yield of aromatic amines is obtained after 1-4 h over Mg-Fe mixed oxide catalyst. Moreover, for this reaction, the catalytic activity of Ni-Fe mixed oxide is also studied. In the presence of Ni-Fe mixed oxide, the reaction gives excellent yields (94%-98%) after 28-66 min. (b) Propan-2-ol is used as hydrogen donor. The feasibility of reduction of sulphur-containing nitroarenes using propan-2-ol as hydrogen donor over Ni-Al or Ni-Mg-Al mixed oxide obtained by calcinations of the corresponding HTLcs precursors is explored. The results indicate that the complete conversion of substrates is achieved and the yield of the corresponding amine compounds, followed by 10%-20% yield of azoxy compounds as by-products, is above 70% (the value of HPLC).Arylhydroxylamines are key intermediates in the synthesis of some important fine chemicals, natural products and biologically active compounds. At present the noble metal catalyst is used generally in the CTH for the preparation of arylhydroxylamines. In this dissertation, arylhydroxylamines are prepared successfully by CTH reaction of the corresponding nitroarenes using the Zn/HCOONH4/CH3CN/ultrasound system. The reaction can be completed within 50-100 rain and gives arylhydroxylamines in 94%-98% yield. Furthermore, many functional groups, such as halogen, nitrile, ester and carbonyl groups, are tolerated. In the case of 1-(4-nitro-phenyl)-ethanone, the effects of various operating parameters on this reaction, such as solvent, presonication time, reaction temperature, amount of catalyst and amount of solvent, have been investigated in detail. The activation energies of the reactions from 1-(4-nitro-phenyl)-ethanone to 1-(4-hydroxyamino-phenyl)-ethanone and from 1-(4-hydroxyamino-phenyl)-ethanone to 1-(4-amino-phenyl)-ethanone under ultrasound are also obtained, which are 37.76 kJ·mol-1 and 130.85 kJ·mol-1 respectively.
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