Go Nitro: To Stand Divided: 2

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d) R. J. Kalbasi, A. A. Nourbakhsh and F. Babaknezhad, Catal. Commun., 2011, 12, 955 CrossRef CAS PubMed; c) J. W. Larsen, M. Freund, K. Y. Kim, M. Sidovar and J. L. Stuart, Carbon, 2000, 38, 655 CrossRef CAS. newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\) Conversion of nitrobenzene to aniline, a less toxic end product that can easily be mineralized, was carried out in a continuous-flow anaerobic bioreactor using H 2 gas and a microbial consortium by Cao et al. 117 This reduction is sensitive to both pH and temperature. Optimum reduction was obtained at pH 6.5–6.8 and at 30 °C.

Nitro compounds are a very important class of nitrogen derivatives. The nitro group, \(\ce{-NO_2}\), like the carboxylate anion, is a hybrid of two equivalent resonance structures: A magnetically separable gold-nanoparticle catalyst was prepared and it showed excellent activity for chemoselective reduction of nitroarenes with hydrosilanes. 61 Selective reduction of 4-fluoro- and 4-chloronitrobenzene required only 1 mol% Au while 40 mol% was required for complete reduction of 4-bromonitrobenzene, and 4-iodonitrobenzene could not be reduced. Ketone, ester, amide, cyano, alkene, benzyloxy and carbobenzyloxy functional groups survived during nitro reduction. The activity of the catalyst reduced during its reuse but increasing the quantity of reducing agent could compensate for this reduced activity. R. F. D'Vries, M. Iglesias, N. Snejko, S. Alvarez-Garcia, E. Gutierrez-Pueblaa and M. A. Monge, J. Mater. Chem., 2012, 22, 1191 RSC.X. Yuan, N. Yan, C. Xiao, C. Li, Z. Fei, Z. Cai, Y. Kou and P. J. Dyson, Green Chem., 2010, 12, 228 RSC. Niestety zmiany na gorsze w polskim prawie praktycznie uniemożliwiają dalsze prowadzenie serwisu w obecnej formie w tym kraju. A heterogeneous Fe 3O 4–Ni magnetic NP catalyst was demonstrated for hydrogen-transfer reactions by using the environmentally friendly solvent glycerol as a hydrogen donor by Gawande et al. 101

Reduction was achieved in refluxing MeOH–water mixture using FeS and ammonium chloride by Desai et al. 87 Sensitive substituents like chloro, ester, and N-benzyl were unreactive in this reduction and corresponding anilines were obtained in 56 to 81% yields. Te metal was used as a reducing agent for preparation of anilines from nitroaromatics in neat critical water at 275 °C by Wang et al. 88 Electron-donating (Me) and electron-withdrawing (MeCO, Cl) substituents were well tolerated. However, in the case of Br and I derivatives, competitive dehalogenation takes place. Carboxylic acid group also undergoes decarboxylation. This process does not reduce aliphatic nitro and nitrostyrenes. K. Imamura, S. Iwasaki, T. Maeda, K. Hashimoto, B. Ohtani and H. Kominami, Phys. Chem. Chem. Phys., 2011, 13, 5114 RSC.c) V. Mohan, C. V. Pramod, M. Suresh, K. H. P. Reddy, B. David Raju and K. S. Rama Rao, Catal. Commun., 2012, 18, 89 CrossRef CAS PubMed. T. Mitsudome, Y. Mikami, M. Matoba, T. Mizugaki, K. Jitsukawa and K. Kaneda, Angew. Chem., 2012, 51, 136 CrossRef CAS PubMed. Ease of handling NaBH 4 is also an added advantage in this process. The functional groups which get reduced with NaBH 4 are usually not tolerated during usage of this reduction process. Nanocrystalline magnesium oxide-supported gold NPs were used as a recyclable heterogeneous catalyst for reduction of nitroarenes to anilines using sodium borohydride in double distilled water at room temperature by Maheswaran and coworkers. 40 This reduction system could tolerate various substitutions of the aromatic ring, like F, Cl, Br, I, OCH 3, COOMe, vinyl, CN, OH and NH 2. After the reduction the spent catalyst could be recycled by centrifugation and reused. There was a slight loss in recovery, which resulted in a marginal decrease in efficiency.

K. A. Reza, Z. Maryam, M. T. Fatemeh and F. M. Mehdi, Iran. J. Chem. Chem. Eng., 2011, 30, 37 Search PubMed. On the desktop or web client (this is not available on mobile), go to User Settings > Subscriptions. Cobalt sulfide, Co 3S 4, was recently reported for such a reduction using NaBH 4 in EtOH under sonication. 56 The halogens were unaffected during this nitroreduction. The chemical community had ignored gold due to its low reactivity, but recently its unique catalytic properties have drawn the attention of numerous research groups, which has been reflected in a number of research publications in the literature.Substituted nitro aromatics were selectively hydrogenated to the corresponding N-aryl hydroxylamines in excellent yields (up to 99%) using supported platinum catalysts such as Pt/SiO 2 under a hydrogen atmosphere (1 bar) at room temperature by Takenaka et al. 25 This reduction was carried out in IPA with DMSO and n-BuNH 2 as additives. Gao L, Ying D, Shen T, Zheng Y, Cai J, Wang D, Zhang L (2020) ACS Sustainable Chem Eng 8:10881–10891 Graphene and graphene oxide materials are studied for various applications in material science and this trend has been followed even in catalysis because of their applications as supports and also their ability to enhance the property exhibited by a catalyst. Tetramethyldisiloxane (TMDS)/Fe(acac) 3 was used for nitro reduction and the product amines were isolated as hydrochloride salts with good to excellent yields by Lemaire and coworkers. 59 Nitrile, acid, ester and bromo groups were well tolerated while p-nitrobenzaldehyde gave p-hydroxymethylaniline. m-Dinitrobenzene was selectively reduced to m-nitroaniline. A. Wang, H. Cheng, B. Liang, N. Ren, D. Cui, N. Lin, B. H. Kim and K. Rabaey, Environ. Sci. Technol., 2011, 45, 10186 CrossRef CAS PubMed.

a) L. He, L. Wang, H. Sun, J. Ni, Y. Cao, H. He and K. Fan, Angew. Chem., 2009, 121, 9702 CrossRef PubMed; Commercial MoS 2 was found to be a highly selective catalyst for the reduction of nitrobenzenes to the corresponding anilines with hydrazine under mild conditions by Huang et al. 74 Very high selectivity is observed in the reduction of halonitrobenzenes and styrylnitro compounds. Polyvinylpyrrolidine-stabilized Ni or Co NPs were used for selective reduction of nitroarenes in the presence of Cl, Br, I, CN. Aliphatic nitro compounds were also reduced using this system. 75a Quantitative conversion of nitroarenes to anilines was obtained with cobalt-modified Mo carbide supported on activated carbon in refluxing hydrazine hydrate. Sensitive reducible groups like Cl, ester, and aldehyde were tolerated during reduction. 75b Reduction of nitroaromatics to anilines by hydrazine was also studied using carbon or graphite as catalysts. 75c Ru dye-sensitized TiO 2 was reported by Konig and coworkers as a catalyst in the presence of green light for this reduction and triethanolamine (TEOA) as reducing agent. 107a Addition of a small amount of transition metals (less than 0.1 mol%) led to significant enhancement of photocatalytic activity. The optimal catalytic amount of the transition metal (Pt, Pd, Au and Ag) required for quantitative reduction depended on the nature of the metal and the method of preparation. Amounts higher than 1 mol% decreased the catalytic activity. The photocatalytic activity also depended upon the oxidation state of the metal source. Critical cluster sizes of 2 nm are required for good photocatalytic activity and the size depended upon the metal loading. Similar morphologies were found for all the transition metals. A quantum efficiency of 8% was determined for the reduction reaction under the optimized reaction conditions. Aldehyde, ketone, ester, cyano and halogen were compatible for this reduction. Dehalogenation occurs with higher loading of platinum. Green light photoreduction of nitrobenzene was also demonstrated on a laboratory preparative scale. Chen et al. 107b have reported reduction of nitro compounds using TiO 2 photocatalyst by UV and visible dye-sensitized systems.Reduction of nitro compounds to anilines was achieved in water using zinc powder and silica gel supported PEG by Reza et al. 94 The products were isolated in 68–92% yield by simple acid–base purification with retention of other substituents like NH 2 and COOH, and also sensitive functionalities like CHO, Cl, and CH 2Br. Readily available and magnetically separable Fe 3O 4 NPs were utilized for recyclable and efficient nitroarene reduction. 64a Reducible functional groups like halogen, ester, benzyloxy ether, amide and benzyl alcohol remained intact while only 45% selectivity was obtained for the reduction of ethyl 4-nitrocinnamate. Aliphatic nitro compounds were reduced less efficiently. e) U. Sharma, P. Kumar, N. Kumar, V. Kumar and B. Singh, Adv. Synth. Catal., 2010, 352, 1834 CrossRef CAS PubMed;