Yield Of Aniline Research Articles

Methylviologen-pendant iron porphyrins as models of a reduction enzyme: six-electron reduction of nitrobenzene to anilineElectronic supplementary information (ESI) available: time-courses of reduction, UV-VIS spectral changes, cyclic voltammograms, EPR spectra, conversion and yield percentages for the reduction of p-nitroanisole. See http://www.rsc.org/suppdata/dt/b2/b211125j/

Methylviologen-pendant iron porphyrins, in which methylviologen was introduced to the meso-phenyl group through an amido-bridge at either the p- or m-position, were newly synthesized, in expectation that these methylviologen-pendant iron porphyrins would be good functional models of a multi-electron reductase such as nitrite reductase since the methylviologen-pendant can play the role of an electron-trapping and storage unit like the iron–sulfur cluster of the nitrite reductase. These iron porphyrins were successfully applied to the six-electron reduction of nitrobenzene to aniline, which is a model reaction of nitrite reduction to ammonia catalyzed by nitrite reductase. Both p- and m-methylviologen-pendant iron porphyrins give somewhat larger yields of aniline in the reduction of nitrobenzene and much larger yields of p-methoxyaniline in the reduction of p-nitroanisole than does normal iron tetraphenylporphyrin. Though normal iron tetraphenylporphyrin can not catalyze well the reduction of p-nitroanisole in the presence of the dioxygen molecule, these methylviologen-pendant iron porphyrins can catalyze well the reduction of p-nitroanisole and give a considerably larger yield of p-methoxyaniline even in the presence of the dioxygen molecule. These methylviologen-pendant iron porphyrins give a much larger yield of aniline in the reduction of nitrosobenzene and somewhat larger yield of aniline in the reduction of phenylhydroxylamine than does iron tetraphenylporphyrin. m-Methylviologen-pendant iron porphyrin exhibits higher catalytic activity than does the p-pendant one. The role of methylviologen moiety is discussed, based on cyclic voltammograms and UV-VIS spectra of these iron porphyrins.

Water-induced fluorescence quenching of aniline and its derivatives in aqueous solution

Nonradiative deactivation processes of excited aniline and its derivatives in aqueous solution were investigated by steady-state and time-resolved fluorescence measurements to reveal characteristic solvent effects of water on the relaxation processes of excited organic molecules. The magnitude of nonradiative rate (knr) of excited aniline derivatives increased significantly in water compared to that in organic solvents (cyclohexane, ethanol, and acetonitrile). The fluorescence lifetime measurements in organic solvent/H2O mixed solvents suggested that the fluorescence quenching in water was not due to exciplex formation but due to interactions with a water cluster. From temperature effect experiments on the fluorescence lifetime and quantum yield of aniline, N-methylaniline, and N,N-dimethylaniline, the apparent activation energies for the nonradiative deactivation rate in water were determined as 21, 30, and 41 kJ mol-1, respectively. Upon substitution of hydrogen atoms in the aromatic ring of aniline derivatives for deuterium atoms resulted in normal deuterium isotope effect in cyclohexane, i.e. knr decreased by deuterium substitution, while in water the same deuterium substitution led to an increase in knr (the inverse isotope effect). The inverse isotope effects implied that a direct internal conversion to vibrationally higher excited states in the electronically ground state is not a dominant mechanism but the transition to a close-lying energy level, e.g. the relaxation to charge transfer to solvent (ctts) state, would be associated with the quenching mechanism in water.

CATALYTIC HYDROGEN TRANSFER OVER MAGNESIA, XVII. a HYDROCARBONS AS HYDROGEN DONORS

Donor activity of cyclohexene and a series of n-alkanes in catalytic hydrogen transfer to various organic groups over magnesia as a catalyst has been determined. Styrene, phenylacetylene, benzaldehyde and acetophenone were not reduced by cyclohexene in the temperature range 523-673 K. Cyclohexene oxide was reduced to cyclohexanol (38%) and nitrobenzene to aniline (56%) by cyclohexene under adopted conditions (673 K). The highest yield of aniline (57%) from nitrobenzene was reached at 673 K in the presence of n-decane from a series of C6 - C16 n-alkanes used as hydrogen

Amination of benzene and toluene with hydroxylamine in the presence of transition metal redox catalysts

The amination of benzene and toluene to aniline and toluidines with hydroxylamine sulfate has been investigated in water–acetic acid and water–acetic acid–sulfuric acid media in the presence of transition metal compounds as catalysts. The process yields are strongly dependent on the temperature, added sulfuric acid and the composition of catalyst. For the amination of benzene, the soluble catalysts, NaVO 3 and Fe(III) salts produce high yields of aniline without addition of H 2SO 4, whereas Na 2MoO 4 and FeSO 4 exhibit substantial activity only in 5 M H 2SO 4. Amination is accompanied by a disproportionation of hydroxylamine catalyzed by the redox active transition metal ions. The favorable effect of H 2SO 4 on the amination is due mostly to the greater stability of hydroxylamine in the strongly acidic medium. Mixed oxides containing V(V) and Mo(VI) are active amination catalysts when suspended in 5 M solution of H 2SO 4 in acetic acid. Introduction of metallic Pd into these oxide catalysts improves performance increasing the yield and selectivity of amination with respect to the aromatic substrate. Toluene exhibited a close to benzene reactivity in amination giving approximately equal yields of o-, m-, p-toluidines. Mechanistic considerations based on literature data and results of ab initio quantum mechanics calculations suggest that the aminating species is the protonated amino radical ⋅NH 3 +, which in the rate-determining step reacts with benzene and toluene to yield the corresponding aminocyclohexadienyl and aminomethylcyclohexadienyl radical intermediates. These are then oxidatively aromatized to give, respectively, aniline and a non-regiospecific mixture of toluidines.

Three-Phase Nitrobenzene Hydrogenation over Supported Glass Fiber Catalysts: Reaction Kinetics Study

The catalytic properties of Pd and Pt supported on woven glass fibers (GF) were investigated in the three-phase hydrogenation of nitrobenzene (NB). Over all catalysts, a 100 % yield of aniline was attained. The catalytic activity for the best catalysts was two times higher than the activity of commercial Pt/C catalyst traditionally used for liquid‐phase hydrogenation. The intrinsic reaction kinetics were studied and a reaction scheme is suggested. The direct formation of aniline from NB was observed over Pd/ GF with traces of intermediates. Four intermediate products were detected during aniline formation over Pt/GF: nitrosobenzene, phenylhydroxylamine, azoxybenzene, and azobenzene. The Eley-Rideal kinetic model fits the experimental data well. The parameters of the model were determined as a function of initial NB concentration and hydrogen pressure. Pt and Pd supported on GF in woven fabrics are suggested as suitable materials for reactors with a structured catalytic bed in multiphase reactor performance.

Selective N-monomethylation of aniline over Zn 1− xNi xFe 2O 4 ( x=0, 0.2, 0.5, 0.8 and 1) type systems

The reaction of aniline with methanol was carried out over Zn 1− x Ni x Fe 2O 4 ( x=0, 0.2, 0.5, 0.8 and 1) type systems in a fixed-bed down-flow reactor. It was observed that systems possessing low “ x” values are highly selective and active for mono N-alkylation of aniline leading to N-methyl aniline. Selectivity for N-methyl aniline over ZnFe 2O 4 was more than 99% under the optimized reaction conditions. Even at methanol to aniline molar ratio of 2, the yield of N-methyl aniline was nearly 55.5%, whereas its yield exceeded 67% at the molar ratio of 7. The Lewis acid sites of the catalysts are mainly responsible for the good catalytic performance. Cation distribution in the spinel lattice influences their acido-basic properties, and hence, these factors have been considered as helpful to evaluate the activity and stability of the systems.

The kinetic study on the electrolytic hydrogenation of nitrobenzene on the hydrogen-storage alloy electrode

The electrolytic hydrogenation of nitrobenzene (NB) was studied by means of a hydrogen-storage alloy electrode. It has been found that hydrogen-storage alloy is an effective electrode for the conversion of nitrobenzene to aniline. The aniline yield and average current efficiency can reach 90%. The β hydride phase shows catalytic activity for the electrolytic hydrogenation of nitrobenzene, mainly resulting from its ample absorbed hydrogen atoms and favorable structure.

Formation of aromatic amines from dinitrogen complexes [Cp2TiAr]2N2 (Ar = C6H5, m-CH3C6H4)

It has been shown that the reaction of the dinitrogen complex [Cp2TiC6H5]2N2 with a mixture of C6H5Li and Li in ether results in the formation of ammonia and aniline after hydrolysis. Under optimum conditions, the yield of aniline is 12 mol% per initial complex and the ammonia yield is 36 mol%. In the absence of lithium neither ammonia nor aniline are formed, while in the absence of phenyllithium only ammonia is produced. The interaction of [Cp2TiC6H5]2N2 with p- m- and o-tolyllithium reagents in the presence of lithium also gives aromatic amines and ammonia after hydrolysis. Similar results have been obtained for the dinitrogen complex [Cp2Ti(m-CH3C6H4)]2N2. The mechanism of the reaction found is discussed.

Synthesis of phenyldiazenido, phenylhydrazido and diorganohydrazido complexes of molybdenum and tungsten and their reactions with acids: A comparison with analogous unsubstituted hydrazido (NNH 2) complexes. The crystal structure of [WCl 2(NN(H)Ph)(PMe 2Ph) 3

The phenyldiazenido complexes [MCl(NNPh)(PMe 2Ph) 4] (M = Mo,W) and phenyl- and diorganohydrazido(2-) complexes [WCl 2(NN(H)Ph)(PMe 2Ph) 3], [MCl 2 (NNRR′)(PMe 2Ph) 3]] (M = Mo, W ; R = R′ = Me, R = R′ = Ph ; M = W, R = Me, R′ = Ph), [MCl 2(NNPh 2)(dppe)(PMe 2Ph)] (M = Mo,W; dppe = Ph 2PCH 2CH 2PPh 2), [MCl(NNPh 2)(dppe) 2]Cl (M = Mo,W), and [WCl(NN(Me)Ph)(dppe) 2]Cl were synthesized, characterized and their reactions with acids studied. These complexes were prepared in a series of reactions starting with WCl 6 or (MoCl 5) 2 involving (i) introduction of the organohydrazido(2 -) group (NNRR′) using the corresponding hydrazine (R = R′ = Me) or hydrazine hydrochloride (R = R′ = Ph; R = Ph,R′ = H or Me), and (ii) incorporation of phosphine ligands under reducing conditions. The particular product formed in the last step depended upon the reduction time. In almost all cases reaction of the complexes with acid (1 M HCl in Et 2O or H 2SO 4 in MeOH) resulted in the formation of some amine and a correspondingly smaller amount of ammonia. For example, the yields of aniline and ammonia when [MCl(NNPh)(PMe 2Ph) 4]Cl reacted with H 2SO 4 in MeOH were ca 0.2 mol and ca 0.1 mol per mol of W, and 0.70 mol and 0.65 mol per mol of Mo, respectively. A comparison of acid reactions of organodiazenido and organohydrazido(2- ) is made with those of unsubstituted hydrazido(2 -) complexes prepared from coordinated dinitrogen. The crystal structure of reddish-brown [WCl 2(NN(H)Ph)(PMe 2Ph) 3] revealed a distorted octahedral complex in which the hydrazido(2 -) moiety is trans to a chlorine atom and the hydrazido(2 -) phenyl group is coplanar with the plane containing W, N, N and C(Ph) atoms. The second chlorine atom, cis to the hydrazido(2 -) ligand, has a close intermolecular contact (2.62 Å) with the hydrazido(2 -) hydrogen atom of a neighbouring molecule and close intramolecular contact (2.76 Å) with the endo o-phenyl hydrogen atom of the hydrazido(2 -) ligand. Comparison of structural data with those for [WCl 2(NNR 2)(PMe 2Ph) 3] (R 2 = Me 2 or Ph 2) indicates significant differences in W-N(1) and W-Cl( trans) distances between the dimethyl-, and the phenyl- and diphenyl-hydrazido(2 -) complexes, respectively.

Acid−Base Properties of Arylnitrenium Ions

This study uses a combination of laser flash photolysis (LFP) and product analysis to show that singlet nitrenes from the irradiation of phenyl, 4-biphenylyl, and 2-fluorenyl azide can be trapped by protonation in aqueous solutions forming nitrenium ions. With phenyl azide, the phenylnitrenium ion is indicated by the formation of ring-substituted anilines in yields of up to 50% in 1 M acids. The acidity dependence furnishes the ratio kH:kexp = 1.1, where kH refers to H+-trapping of singlet phenylnitrene and kexp to ring expansion of this species. With kH expected to be 2−4 × 1010 M-1 s-1, kexp is therefore estimated as 2−4 × 1010 s-1. Protonation by solvent water also occurs, but even though the rate constant is of the order of 109 s-1, it constitutes a minor pathway in competition with the ring expansion. LFP studies in acids reveal a transient that is assigned the structure of N-protonated 4-hydroxy-2,5-cyclohexadienone imine, the intermediate formed by water addition to the para position of the phenyln...

Influence of oxidative treatment of copper grid electrodes on the efficiency of conversion to aniline in the electroreduction of nitrobenzene and azobenzene in basic aqueous methanol

The influence of preoxidizing the surface of polycrystalline copper electrodes on the efficiency of the controlled potential electrochemical reduction of nitrobenzene and azobenzene to aniline in basic aqueous methanol has been investigated. Electrodes electrochemically preoxidized to Cu(OH)2 or to Cu2O gave high yields of aniline (90–100%) with high current efficiencies (88–99%) for the electrohydrogenation of nitrobenzene compared to electrodes preoxidized by air (7–29% of aniline, 64–74% current efficiency). For the electrohydrogenation of azobenzene, copper electrodes preoxidized to Cu2O were found to be more active (average yield of aniline of 28%, average current efficiency of 55%) than electrodes preoxidized to Cu(OH)2 (3–11% of aniline, 42–53% current efficiency), and electrodes preoxidized by air were inactive (the electrohydrogenation stopped at hydrazobenzene). The improvement of activity induced by preoxidation of the copper surface is linked to the increase of the surface area.

Reduction of nitrobenzene by dodecacarbonyl tri-iron under triphase conditions

Reduction of nitrobenzene to aniline by Fe 3(CO) 12 under triphase conditions has been investigated and the efficiency of the polymer-supported phase transfer agents compared. Reduction occurs under mild conditions and the isolation of the product is easier than in the homogeneous system. The yield of aniline is similar to that obtained in the Fe 3(CO) 12/Al 2O 3 system.

Further differential-pulse polarographic and visible spectrophotometric studies of the degradation of permitted synthetic food colouring matters with and without the addition of ascorbic acid: accelerated heat degradation studies

Differential-pulse polarography (DPP) has been used to monitor solutions at pH 5.5 in acetate buffer of permitted synthetic food colouring matters containing azo groups during accelerated heat degradation studies carried out at 130 °C in sealed vials. Complete visible loss was effected in 0.5–28 d, depending on the food colour. The yields of simple amines (aniline, sulphanilic acid and naphthionic acid) were determined by visible spectrophotometry. The relatively high yields of aniline and sulphanilic acid obtained after complete visible loss of food colour were independent of further heating time; the stability of these two amines under the experimental conditions was verified separately. The ammonia formed in these experiments was determined by visible spectrophotometry and clearly was not formed from the simple amines, which are stable. The molar yields of simple amines and ammonia from the food colour solutions were concentration dependent; in general, the molar yields were lower at higher concentrations, presumably owing to the formation of stable nitrogen compounds of higher relative molecular mass. Red 10B was observed as an intermediate in the degradation of Red 2G at higher concentrations, and a stable yellow compound was formed in the degradation of Ponceau 4R also at higher concentrations.The length of time required for complete visible loss of food colour was increased considerably by the addition of EDTA, whereas in the presence of 1 000 p.p.m. of ascorbic acid without the addition of EDTA degradation occurred within a few hours. In the latter instance relatively high yields of simple amines were again observed, but the amines were degraded further to ammonia by ascorbic acid. At higher concentrations of the food colours degradation of ascorbic acid was complete before that of the food colour and the simple amines formed remained undegraded. The ascorbic acid was determined by DPP and by this means the stoicheiometry of the reaction of ascrobic acid with the food colours was found to be 2.3, 2.3, 2.4, 3.0 and 3.9:1 for Sunset Yellow FCF, Ponceau 4R, Carmoisine, Brown FK and Chocolate Brown HT, respectively.

Emission and intersystem crossing quantum yields of aniline solutions: photostationary state diagram

We measured the emission quantum yields of aniline in various solvents. For phosphorescence (in either—isopentane—ethanol at 77 K) a photoionization by a biphotonic process occurred for exciting wavelengths below 290 nm. Using tris(dibenzoylmethano)europium as the acceptor in a triplet—triplet energy transfer the intersystem crossing quantum yeilds of aniline in liquid solutions at 20°C were measured. We also calculated the quantum yields of aniline transitions and constructed state diagrams.

Mass Spectral and Pyrolytic Behavior of the Two Main Products of Phenylbutazone Degradation

AbstractThe two major routes of degradation of phenylbutazone (I) are oxidation and hydrolysis. Hydrolysis gives rise to n‐butylmalonic acid mono‐(N, N′‐diphenyl)hydrazide (II). Oxidation at the C‐4 position yields 1,2‐diphenyl‐4‐n‐butyl‐4‐hydroxypyrazolidine‐3,5‐dione (III), which is readily hydrolyzed to n‐butyltartronic acid mono‐(N, N′‐diphenyl)hydrazide (IV). Whereas the mass spectra of I, III, and the methyl esters of carboxylic acids II and IV all demonstrate major peaks corresponding to their respective molecular ions, the mass spectrum of II is essentially identical with that of I, suggesting facile dehydration. In the mass spectrum of IV, the peak of highest mass is found at m/e 205; no peak could be perceived corresponding to the molecular ion or to loss of water, carbon dioxide, or both of these elements from the molecular ion. Under normal pyrolytic conditions, II is decarboxylated to N‐caproylhydrazobenzene (V) and IV is readily dehydrated to yield III. The mass spectral fragmentation of IV was successfully simulated in the laboratory to give an excellent yield of aniline and α‐keto‐N‐caproylaniline (VI) (mol. wt. 205). The probable course of this unusual transformation was elucidated from studies of the accelerated decomposition of IV and derivatives considered as possible intermediates in the degradation process.

The photolysis of Schneider's 1-phenyliminopyridinium ylides

Photolysis of the pyridinium ylides (4) and (5) produces, besides high yields of aniline and (8) and (9) respectively, the additional products (10)[from (4) in benzene] and (12)[from (5) in diethylamine] which suggest a phenyl nitrene intermediate in these reactions.

The Photochemical Reduction of Hydrazobenzene

Abstract Hydrazobenzene was irradiated with an ultraviolet light in n-hexane under a nitrogen atmosphere. The products were azobenzene, aniline, and a trace of semidines. The yield of azobenzene was usually larger than that calculated on the basis of the disproportionation of hydrazobenzene, while the yield of aniline was less. The reactions were followed by the determination of the disappearance of hydrazobenzene and that of the formation of azobenzene. On the basis of the available data, in the photochemical reaction of hydrazobenzene it was assumed that the formation of azobenzene was not due to the disproportionation, but to the oxidation of hydrazobenzene, and that no fission of the N–N bond of hydrazobenzene occurred to give azobenzene.

496. Beta energy recoil effects of carbon-14 in toluene and ethylbenzene

Recoil energy from Ci4 beta particles in STAMe-C/sup 14/! toluene was found to cause negligible bond rupture, as judged by the yield of aniline, while with STA alpha -O/sup 14/! ethylbenzene about 15 to 20% bond rupture occurred. This was in line with a concept of rupture being caused by electronic excitation. (auth)

Chemistry of acetylenic ethers. XVIII: Reactions of ethoxyethynylcarbinols with amines

AbstractEthoxyethynylcarbinols, which can be prepared from carbonyl compounds and metallic derivatives of ethoxyacetylene, react with amines in three different ways.Strongly basic amines like diethylamine mainly cause reaction A, dissociation of the carbinol into the carbonyl compound from which the carbinol was derived, and ethoxyacetylene (which reacts further with the amine used). Very weakly basic aromatic amines like p‐nitroaniline catalyze the rearrangement into α,β‐unsaturated esters (reaction B), whereas aromatic amines like aniline yield amides of β‐hydroxy‐acids with evolution of ethylene (reaction C).

Societies and Academies

PARIS. Academy of Sciences, August 5.—M. Fouqué in the chair.—On Poisson's theorem and on a recent theorem of M. Buhl, by M. Paul Appell. The theorem of Buhl is a particular case of Poisson's theorem.—The law of pressures in cannon, by M. Vallier.—New method of preparing aniline and its analogues, by MM. Paul Sabatier and J. B. Senderens. A mixture of hydrogen and nitrobenzene vapour is passed over reduced copper kept at a temperature of from 300°–400° C., the yield of aniline being nearly theoretical. If nickel is employed instead of the copper, the reaction goes farther even at 200°, benzene and ammonia being produced-On the luminous variation of the planet Eros; curves of light; amplitude of the variation, by M. Ch. André.—On the infinitely small deformation of a spherical elastic envelope, by MM. Eug`ene and Francois Cosserat.—On a relation which probably exists between the characteristic angle of deformation of metals and the Newtonian coefficient of restitution, by M. G. Gravaris. The characteristic angle of deformation (a), and the Newtonian constant of restitution (e), appear to be related according to the equation πe=2a.—Critical study of the general theory of mechanisms, by M. G. Kœnigs.—On disruptive discharge in electrolytes, by M. K. R. J ohnson.—Remarks on a communication of MM. A. Broca and Turchini.—The electric capacity of the human body, by M. G. de Metz. It follows from the experiments described that it is illusory to compare the electric capacity of the human body with that of an ellipsoidal conductor. The same person may possess several capacities according to the conditions under which he is placed. The average figure found is about 0.00011 microfarad.—The difference of potential and the deadening of the electric spark with oscillatory character, by M. F. Beaulard.—On the transmission of Hertzian waves through conducting liquids, by M. Charles Nordmann. For the liquids studied (solutions of sulphuric acid, common salt, potassium chloride and magnesium sulphate), the maximum thickness which could be traversed by the waves employed, that is to say, the transparencies for the waves, varies in the same sense as the resistances, but not in proportion.—The vapour tension of solutions. The hypothesis of Arrhenius, by M. A. Ponsot.—An attempt at an immediate analysis of nervous tissue, by M. N. Alberto Barbieri.—On the cycloplasmic maturation, by M. Yves Delage.—Carboniferous goniatites in the Sahara, by M. Collot. The discovery of goniatites in the carboniferous layers of the Sahara points to an age a little more recent than that deduced by M. Ficheur, and it shows further that there were several levels, amongst which that which furnished the goniatites may be contemporaneous with the layers observed by Foureau in the Tassli Adzjer.—A physiological photometer, by M. G. M. Stanoïévitch.