Nitrobenzene to aniline

The Faux process is a modification of the Bechamp reaction that was discovered in 1854. It has been used for the reduction of nitrobenzene to aniline using metallic iron ... 

Dehydrogenation processes in particular have been studied, with conversions in most cases well beyond thermodynamic equihbrium Ethane to ethylene, propane to propylene, water-gas shirt reaction CO -I- H9O CO9 + H9, ethylbenzene to styrene, cyclohexane to benzene, and others. Some hydrogenations and oxidations also show improvement in yields in the presence of catalytic membranes, although it is not obvious why the yields should be better since no separation is involved hydrogenation of nitrobenzene to aniline, of cyclopentadiene to cyclopentene, of furfural to furfuryl alcohol, and so on oxidation of ethylene to acetaldehyde, of methanol to formaldehyde, and so on. 

In 1834 Mitscherlich nitrated benzene to nitrobenzene. But it is only since 1842, when Zinin reduced nitrobenzene to aniline, that rapid development of the chemistry of nitro compounds and their application to organic industry has occurred ... 

Figure 4.5. (a) Process flow diagram hydrogenation of nitrobenzene to aniline (b) Information flow diagram... 

Chiral recognition of A-[Co(phen)3]3+ has been observed in a modified /3-cyclodextrin.772 Chiral discrimination has also been seen in photoinduced energy transfer from luminescent chiral lanthanoid complexes773 to [Co(phen)3]3+ and between photoexcited [Ru(bpy)3]2+ and [Co(phen)3]3+ co-adsorbed on smectite clays.774 The [Co(bpy)3]3+ ion has been incorporated into clays to generate ordered assemblies and also functional catalysts. When adsorbed onto hectorite, [Co(bpy)3]3+ catalyzes the reduction of nitrobenzene to aniline.775 The ability of [Co(phen)3]3+ to bind to DNA has been intensively studied, and discussion of this feature is deferred until Section 6.1.3.1.4. 

The reduction of nitrobenzene to aniline is a major industrial process at the heart of the production of polyurethanes, and it is also often used as a marker reaction to compare activities of catalysts [1,2], It can be performed over a variety of catalysts and in a variety of solvents. As well as its main use in polymethanes, aniline is used in a wide range of industries such as dyes, agrochemicals, by further reaction and functionalisation. Reductive alkylation is one such way of functionalising aromatic amines [3, 4], The reaction usually takes place between an amine and a ketone, aldehyde or alcohol. However it is possible to reductively alkylate direct from the nitro precursor to the amine and in this way remove a processing step. In this study we examined the reductive alkylation of nitrobenzene and aniline by 1-hexanol. 

The combination PMHS/Pd/C reduces nitrobenzenes to anilines in high yields (Eq. 329),316 as does Et3SiH/RhCl(PPh3)3 (Eq. 330).554 This latter combination can also reduce both nitro and enone functionalities.554... 

Very interestingly, contrary to the water-gas rates, the most active catalysts for the reduction of nitrobenzene to aniline in water-gas shift conditions were those containing the sterically hindered 2-picoline and 2,6-lutidine. 

Continuous Multicomponent Distillation Column 501 Gas Separation by Membrane Permeation 475 Transport of Heavy Metals in Water and Sediment 565 Residence Time Distribution Studies 381 Nitrification in a Fluidised Bed Reactor 547 Conversion of Nitrobenzene to Aniline 329 Non-Ideal Stirred-Tank Reactor 374 Oscillating Tank Reactor Behaviour 290 Oxidation Reaction in an Aerated Tank 250 Classic Streeter-Phelps Oxygen Sag Curves 569 Auto-Refrigerated Reactor 295 Batch Reactor of Luyben 253 Reversible Reaction with Temperature Effects 305 Reversible Reaction with Variable Heat Capacities 299 Reaction with Integrated Extraction of Inhibitory Product 280... 

Cytosol conversion of styrene 7,8 epoxide to styrene 7,8 glycol Sequential conversion of nitrobenzene to aniline... 

Carbon nanotubes have been decorated with metal nanoparticies of Au, Ag, Pt, Pd and Co employing different procedures such as the click reaction [107], microwave treatment [106], electroless plating [108] and laser irradiation of mixtures of the individual components [109]. Pt-carbon nanotube hybrids have been used as catalysts for the conversion of nitrobenzene to aniline [110]. Tessonier et al. report that MWNTs covered with Pd nanoparticies on the interior walls can be employed for... 

The challenge of monitoring batch processes for deviations was addressed by Gabrielsson et aP" (also taken up by Wong et al. °) with the hydrogenation of nitrobenzene to aniline as a model reaction. The study followed a factorial design of experiments. Process deviations could only be detected when the UV spectroscopic data set and the process data set were used in a combined manner, not seperately. 

An additional method for the reduction of nitrobenzene to aniline involves the previously described t-Bu2Te/TiCl4 system (see Section 4.1.1.3). ... 

The reduction of nitrobenzene to aniline in 23% yield, by means of NaHTe has also been reported by Akiba, M. Cava, M. P. Synth. Commun. 1984, 14, 1119. 

Reduction of substituted nitrobenzenes under alkaline conditions, usually with aqueous sodium acetate as electrolyte and a nickel cathode, is the classical method due to Elbs [45] for the formation of azo- and azoxy-compounds. Protons are used in the electrochemical reaction so that the catholyte becomes alkaline and under these conditions, phenylhydroxylamine reacts rapidly with nitrosobenzene to form azoxybenzene. Finely divided copper has long been known to catalyse the reduction of nitrobenzene to aniline in alkaline solution at the expense of azoxybenzene production [46]. Modem work confirms that whereas reduction of nitrobenzene at polycrystalline copper in alkaline solution gives mainly azoxybenzene, if the electrode is pre-oxidised in alkaline solution and then reduced just prior to the addition of nitrobenzene, high yields of aniline are obtained with good current efficiency... 

Both the copper and nickel surfaces are efficient for the electrochemical reduction of nitrobenzene to aniline. With time however, the properties of this surface are transformed to those of the polycrystalline metal and azoxybenzene becomes as major reduction product [49]. 

Nitroaromatic compounds cire useful in synthesis because converting the nitro (-NO2) group to an cimino (-NH2) group is relatively easy. For example, the reaction of nitrobenzene with acidic tin(II) chloride (SnCl2) converts nitrobenzene to aniline, an important industrial chemical used in the production of medicines, plastics, and dyes, to name but a few. 

Reduction of several classes of organics may be achieved using hydrazine and appropriate catalysts. It reduces nitro compounds to corresponding amines e.g., nitrobenzene to aniline ... 

Laux Process. This is a modification of the Bechamp process for the iron reduction of nitrobenzene to aniline which leaves iron oxide as the residue. Incorporation of iron or aluminium chlorides into the reduction process produces high quality yellow and red iron oxide pigments... 

The hydrogenation of nitrobenzene progressed to aniline without any significant by-product formation, only trace amounts of azobenzene were formed (< 1 %) as the reaction went to completion. NMR analysis showed no detectable phenyl hydroxylamine in solution. The hydrogen uptake displayed a smooth curve and the rate of hydrogen consumption coincided with the rate of aniline production. The rate of hydrogenation of nitrobenzene to aniline was 15.5 mmol.mm. g. ... 

In the hydrogenation of azobenzene, the rate of hydrogen consumption followed a smooth curve. The reaction profile showed a direct transformation to aniline with no by-product formation or intermediates detected. The rate of aniline production (8.3 mmol.min. g ) was half the rate of nitrobenzene to aniline. 

The counterpart of anodically electrocatalyzed oxidation by redox oxides, namely the cathodic reduction of organic substrates by surface-coup led redox system with sufficiently negative redox potential, is almost unknown. Beck reports that specially prepared TiO coating on Ti-electrodes can be reduced cathodically and that the electrogenerated Ti(III) and Ti(II) species do in fact reduce nitrobenzene to aniline (207). 

In presence of morpholine, (17) catalyzes the hydrogenation of nitrobenzene to aniline.61 A near twofold excess of the amine relative to (17) was used. At a higher excess, catalysis ceased. This was attributed to formation of a bis-morpholine complex. The hydrogenation proceeds best in solvents such as acetone, ethyl acetate or THF.62 The transfer of the first hydrogen atom to nitrobenzene was found to be rate determining and a dinuclear nitrobenzene complex (18) was postulated. The base (B) is morpholine. 

In presence of pyridine, solutions of [Pd(acac)2] catalyzed the reduction of nitrobenzene to aniline at normal pressure of hydrogen and the complex [PdH(acac)(PhN02)pyj was isolated. The dinuclear complex [Pd2Cl4(PPh3)2] (46) also catalyzes the reduction of nitrobenzene. At normal hydrogen pressure, complete reduction to aniline occurred.196 A nitrobenzene complex, believed to be an intermediate in the reaction, was isolated (equation 48). 

The analogy between the behaviour of these diketonate complexes and benzene derivatives is indeed remarkable, and reaction sequences very reminiscent of those observed in organic aromatic chemistry are common. In Fig. 5-9, the reduction of a nitro to an amino derivative is illustrated, a conversion reminiscent of the reduction of nitrobenzene to aniline. It is usually necessary to use kinetically inert cP or d6 metal complexes in sequences of this type. 

FIGURE 2 Vapor phase reduction of nitrobenzene to aniline. 

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