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Journal ArticleDOI

A Review of the Selective Catalytic Reduction of Aromatic Nitro Compounds into Aromatic Amines, Isocyanates, Carbamates, and Ureas Using CO.

01 Oct 1996-Chemical Reviews (American Chemical Society)-Vol. 96, Iss: 6, pp 2035-2052
TL;DR: The use of CO as a reductant had been in the past confined to few reactions, but its use in organic synthesis, especially in the reductive carbonylation of nitro aromatics and the oxidative carbonylations of aromatic amines, has increased dramatically as mentioned in this paper.
Abstract: Although the use of CO as a reductant had been in the past confined to few reactions, its use in organic synthesis, especially in the reductive carbonylation of nitro aromatics and the oxidative carbonylation of aromatic amines, has increased dramatically. Since the discovery of CO-induced reduction of nitro groups, there has been a wide spread increase of interest in the application and mechanistic understanding of this reaction. In a major review published in 1988 it was noted, that in practice no studies of the mechanism of N-carbonylation of aromatic nitro compounds with alcohols leading to carbamates have been carried out. This review clearly shows a major change since that publication. Indeed, metal-catalyzed reductive carbonylation of nitro aromatics using CO as reducing agent has been in the past 10 years the subject of intense investigation both in academia and in the chemical industry. Several articles and reviews have covered the subject up to the late 1980s. The authors will concentrate on more recent literature, but sometimes older data will be used to establish an understanding of these reactions. 127 refs.
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Journal ArticleDOI
TL;DR: The synthesis of ionic liquids and their applications in various chemical and biochemical transformations, in ecofriendly-milder conditions have been reviewed in this paper, with metal and enzyme catalyzed as well as non-catalyzed reactions in ionic liquid reactions covered with 354 refs.

679 citations

Journal ArticleDOI
TL;DR: An emerging interest among synthetic chemists is to use C-H functionalization to construct the nitrogen-containing core of these heterocycles with respect to the type of C- H bond functionalized.
Abstract: Nitrogen heterocycles are abundant in natural products and pharmaceuticals. An emerging interest among synthetic chemists is to use C-H functionalization to construct the nitrogen-containing core of these heterocycles. The following article will provide a brief overview of this concept with respect to the type of C-H bond functionalized.

484 citations

Journal ArticleDOI
TL;DR: This review will comprehensively discuss the use of homogeneous and heterogeneous catalysts based on non-noble 3d-metals for the reduction of nitro compounds using various reductants.
Abstract: The reduction of nitro compounds to the corresponding amines is one of the most utilized catalytic processes in the fine and bulk chemical industry. The latest development of catalysts with cheap metals like Fe, Co, Ni, and Cu has led to their tremendous achievements over the last years prompting their greater application as “standard” catalysts. In this review, we will comprehensively discuss the use of homogeneous and heterogeneous catalysts based on non-noble 3d-metals for the reduction of nitro compounds using various reductants. The different systems will be revised considering both the catalytic performances and synthetic aspects highlighting also their advantages and disadvantages.

433 citations

Journal ArticleDOI
TL;DR: In this article, the earth-abundant nanohybrids Co0/Co3O4@N-doped carbon nanotubes were fabricated via an efficient thermal condensation of d-glucosamine hydrochloride, melamine, and Co(NO3)2·6H2O.
Abstract: The earth-abundant nanohybrids Co0/Co3O4@N-doped carbon nanotubes were fabricated via an efficient thermal condensation of d-glucosamine hydrochloride, melamine, and Co(NO3)2·6H2O. The hybrids furnish excellent catalytic activity and perfect chemoselectivity (>99%) for a wide range of substituted nitroarenes (21 examples) under relatively mild conditions. The high catalytic performance and durability is attributed to the synergistic effects between each component, the unique structure of graphene layers-coated Co0, and the electronic activation of doped nitrogen. Density functional calculations indicate that the inner Co0 core and N species on the carbon shell can significantly decrease the dissociation energies of H2, giving evidence of the ability of carbon shell in the hybrids to enable H2 activation. These results open up an avenue to design more powerful low-cost catalysts for industrial applications.

341 citations

References
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Journal ArticleDOI
TL;DR: Water-soluble catalysts as mentioned in this paper combine the advantages of homogeneous and heterogeneous catalysis: simple and complete separation of the product from the catalyst, high activity, and high selectivity.
Abstract: Rapid developments in the field of catalysis are leading to an increased demand for tailor-made catalysts. Water-soluble complex catalysts, which are being intensively investigated at the present time, combine the advantages of homogeneous and heterogeneous catalysis: simple and complete separation of the product from the catalyst, high activity, and high selectivity. From the large number of available water-soluble ligands, the appropriate catalysts can be developed for many reactions. The industrial applications in the fields of hydrogenation and hydroformylation have already indicated the wide scope of this type of catalyst. In addition, the annual production of 300 000 tons of butyraldehyde through application of water-soluble rhodium complexes at Hoechst AG in Oberhausen, Germany, has demonstrated the industrial importance of the concept of complex-catalyzed reactions in aqueous two-phase systems. The efficient operation of catalytic processes increasingly requires the loss-free recycling of the noble metal catalyst, and this can be simply and economically realized in two-phase systems. Special applications in biochemical problems open up developments in the field of water-soluble transition metal complexes that far transcend the familiar kinds of homogeneous catalysis. In the near future, the investigation and application of metal complex catalysts that are compatible with the physiological, cheap, and environmentally friendly solvent, water, is likely to become a high priority in catalysis research.

624 citations

Book
13 Nov 2012

592 citations

Journal ArticleDOI
TL;DR: In this article, the synthesis of well-defined Pd(II) catalysts that operate in aprotic solvents to yield living alternating copolymers of olefins and CO was reported.
Abstract: Several Pd(II) catalyst systems have been reported which effect prefectly alternating copolymerization of olefins with carbon monoxide to yield polyketones [C(O)CH(R)CH{sub 2}]{sub n}. There has been increasing interest in these polymers, particularly the C{sub 2}H{sub 4}/CO copolymer (T{sub m} = 257{degree}C), due to their unusual properties, the low cost of monomers, the present of the carbonyl functionality, and the potential for further functionalization. The catalyst systems used have typically employed Pd(II) salts in methanol or chloroform. We report here the synthesis of well-defined Pd(II) catalysts that operate in aprotic solvents to yield living alternating copolymers of olefins and CO. In situ spectroscopic studies have established mechanistic details including the identity of the catalyst resting state.

264 citations

Journal ArticleDOI
TL;DR: The dichlorobis(triphenylphosphine)palladium (PdCl 2 (PPh 3 ) 1 )-tin(II) chloride (SnCl 2 ) system showed high catalytic activity for the reductive N-heterocyclization of various 2-nitrostyrene and N-(2-nitrobenzylidene)amine derivatives when employed at 100 o C for 16 h under 20 kg cm -2 of initial carbon monoxide pressure, to give the corresponding indole and 2H-indazole derivatives in
Abstract: The dichlorobis(triphenylphosphine)palladium (PdCl 2 (PPh 3 ) 1 )-tin(II) chloride (SnCl 2 ) system shows high catalytic activity for the reductive N-heterocyclization of various 2-nitrostyrene and N-(2-nitrobenzylidene)amine derivatives when employed at 100 o C for 16 h under 20 kg cm -2 of initial carbon monoxide pressure, to give the corresponding indole and 2H-indazole derivatives in good yield. For example, 2-phenylindole was obtained in 75% yield from the reductive N-heterocyclization of 2-nitrostilbene

143 citations