The hydrogenation of nitrobenzene to aniline: a new mechanism

Gelder, Elaine A.; Jackson, S. David; Lok, Chun‐Nam

doi:10.1039/b411603h

Cited by 202 publications

(165 citation statements)

References 8 publications

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“…The mechanism [27] has been generally accepted for long time but recently several authors have criticized some aspects, which do not explain the reactivity of the intermediates and of the specificity of different type of catalyst [31,32,[34][35][36][37][38]. In particular, Jackson and co-workers showed that the hydrogenation rate of nitrobenzene is higher than that of nitrosobenzene, and no nitrosobenzene accumulation is observed.…”

Section: Discussion On the Reaction Mechanismmentioning

confidence: 99%

New insight on the mechanism of the catalytic hydrogenation of nitrobenzene to 4-aminophenol in CH3CN–H2O–CF3COOH as a reusable solvent system. Hydrogenation of nitrobenzene catalyzed by precious metals supported on carbon

Quartarone

Ronchin

Tosetto

et al. 2014

Applied Catalysis A: General

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a b s t r a c tThe preparation of 4-aminophenol via hydrogenation of nitrobenzene in a single liquid phase has been carried in the presence of different precious metal catalysts. The liquid phase is composed of CH 3 CN-H 2 O-CF 3 COOH, which can be easily distilled at low temperature, thus avoiding work-up operation. The yield of 4-aminophenol is in the range 45% and in the presence of sulfolane as promoter reaches almost 50%. The best result has been obtained in the presence of Pt/C as hydrogenation catalyst. The role of the solvent is strictly related to the selectivity to 4-aminophenol, since CH 3 CN decreases the hydrogenation activity compared to other solvent, CF 3 COOH promotes the formation of the desired product both via Bamberger rearrangement in solution as well by a surface catalyzed reaction, while H 2 O is responsible for 4-aminophenol formation in both reactions. Even though, nitrosobenzene and phenylhydroxylamine have not been observed, their reactivity suggest a complex pattern of reactions occurring either on the catalyst surface or in the solution. Indeed, formation of 4-aminophenol may occur both in solution, via acid catalyzed Bamberger rearrangement and on the catalyst surface by the formation of a surface Pt-nitrenium complex, which undergoes surface nucleophilic attack by H 2 O.

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Section: Discussion On the Reaction Mechanismmentioning

confidence: 99%

New insight on the mechanism of the catalytic hydrogenation of nitrobenzene to 4-aminophenol in CH3CN–H2O–CF3COOH as a reusable solvent system. Hydrogenation of nitrobenzene catalyzed by precious metals supported on carbon

Quartarone

Ronchin

Tosetto

et al. 2014

Applied Catalysis A: General

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“…For example, the majority of the globally consumed aniline is produced by catalytic routs, which is used for the synthesis of methylene diphenyl diisocyanate and rubber processing [4]. The mechanism for the hydrogenation of nitrobenzene was proposed by Haber in 1898 [5]. The transformation to aniline occurs in a three-step process involving nitrosobenzene and phenylhydroxylamine (Scheme 1).…”

Section: Open Accessmentioning

confidence: 99%

Magnetically Separable and Sustainable Nanostructured Catalysts for Heterogeneous Reduction of Nitroaromatics

Shokouhimehr

2015

Catalysts

176

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This review is focused on the strategies and designs of magnetic nanostructured catalysts showing the enhanced and sustainable catalytic performances for the heterogeneous reduction of nitoaromatics. Magnetic catalysts have the benefits of easy recovery and reuse after the completion of the reactions and green chemical processes. Magnetic separation, among the various procedures for removing catalysts, not only obviates the requirement of catalyst filtration or centrifugation after the completion of reactions, but also provides a practical technique for recycling the magnetized nanostructured catalysts. Consequently, discussions will address the methodologies and exemplars for the reusable magnetic composite catalysts. Because the synthesis of ideal magnetic nanostructured catalysts is of primary importance in the development of high-quality sustainable processes, the designs, preparation methods and recyclability of various recoverable magnetic nanostructured catalysts are emphasized. The representative methods and strategies for the synthesis of durable and reusable magnetic nanostructured catalysts are highlighted. The advantages, disadvantages, recyclability and the efficiency of the introduced heterogeneous systems have been explored in the reduction of nitrobenzene derivatives.

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“…8.5 nm, much smaller than that of the IM sample. and at any initial NB concentration used (entries 9-13); in contrast, the selectivity in ethanol changed between 62 and 81% with H 2 pressure (entries [4][5][6][7][8]. Moreover, while the selectivity to AN was similar in scCO 2 and in apolar n-hexane (>98%), the conversion in the former (68%) was larger than that in the latter (53%) even though the NB initial concentration in scCO 2 was 1/5 of that in hexane (entries 12 and 14).…”

Section: Properties Of Ni Catalystsmentioning

confidence: 99%

Selective hydrogenation of nitrobenzene to aniline in dense phase carbon dioxide over Ni/γ-Al2O3: Significance of molecular interactions

Meng

Cheng

Akiyama

et al. 2009

Journal of Catalysis

139

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The selective hydrogenation of nitrobenzene (NB) over Ni/γ-Al 2 O 3 catalysts was investigated using different media of dense phase CO 2 , ethanol, and n-hexane. In dense phase CO 2 , the total rate of NB hydrogenation was larger than that in organic solvents under similar reaction conditions; the selectivity to the desired product, aniline, was almost 100% over the whole conversion range of 0-100%. The phase behavior of the reactant mixture in/under dense phase CO 2 was examined at reaction conditions. In situ high-pressure Fourier transform infrared measurements were made to study the molecular interactions of CO 2 with the following reactant and reaction intermediates: NB, nitrosobenzene (NSB), and N-phenylhydroxylamine (PHA). Dense phase CO 2 strongly interacts with NB, NSB, and PHA, modifying the reactivity of each species and contributing to positive effects on the reaction rate and the selectivity to aniline. A possible reaction pathway for the hydrogenation of NB in/under dense phase CO 2 over Ni/γ-Al 2 O 3 is also proposed.

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The hydrogenation of nitrobenzene to aniline: a new mechanism

Abstract: The Haber mechanism describing the process of hydrogenating nitrobenzene to aniline is shown to be incorrect and a new mechanism is proposed.

Cited by 202 publications

References 8 publications

New insight on the mechanism of the catalytic hydrogenation of nitrobenzene to 4-aminophenol in CH3CN–H2O–CF3COOH as a reusable solvent system. Hydrogenation of nitrobenzene catalyzed by precious metals supported on carbon

New insight on the mechanism of the catalytic hydrogenation of nitrobenzene to 4-aminophenol in CH3CN–H2O–CF3COOH as a reusable solvent system. Hydrogenation of nitrobenzene catalyzed by precious metals supported on carbon

Magnetically Separable and Sustainable Nanostructured Catalysts for Heterogeneous Reduction of Nitroaromatics

Selective hydrogenation of nitrobenzene to aniline in dense phase carbon dioxide over Ni/γ-Al2O3: Significance of molecular interactions

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