Reduction Of Benzene Research Articles

Electrochemical reduction of benzene by solvated electrons in HMPA-alcohol solutions

Etudes de la reduction du benzene en cyclohexadiene, cyclohexene et cyclohexane dans des solutions d'ethanol-HMPA et propanol-2-HMPA, (avec HMPA=hexamethylphosphoramide). On montre l'influence de la liaison hydrogene de l'alcool-HMPA sur l'inhibition de la production d'hydrogene via l'alcool

Use of colloidal ruthenium particles in the electrochemical reduction of benzene by solvated electrons

Ruthenium colloidal particles prepared by the decomposition of a ruthenium acid sulfite complex increased the electrochemical reduction of benzene from 45% to 60% at room temperature and 10 psig of hydrogen. The reduction was carried out in a 21 mole % ethanol - 79 mole % hexamethylphosporamide. The significant increase in the percent of benzene reduced was accompanied by an apparent current efficiency of 98%. Comparison with analogous experiments employing colloidal platinum particles indicates that the above increase in benzene reduction can be attributed to direct catalytic hydrogenation by the ruthenium.

The Electrochemical Reduction of Benzene—First Direct Determination of the Reduction Potential

The Electrochemical Reduction of Benzene—First Direct Determination of the Reduction Potential

The selective reduction of benzene to cyclohexene mediated by platinum metal complexes: X-ray crystal structure of [(η5-C5Me5)Ir(η5-C6H6CH2NO2)][BF4

The dicationic η6-benzene complexes [(CnMen)M(C6H6)]2+[M = Rh, n= 5 (2a); M = Ir, n= 5 (2b); M = Ru, n= 6 (2c)] are reduced by tetrahydroborate to the η5-cyclohexadienyl complexes [(CnMen)M(C6H7)]+(3) which are further reduced to the η4-cyclohexadiene complexes [(CnMen)M(C6H8)](4). Reaction of complexes (4) with acid gives cyclohexene with 100% selectivity; when the reaction is carried out with tetrafluoroboric acid in benzene, the initial benzene complexes (2) are regenerated. The overall reaction consists of addition of two hydrides followed by two protons to co-ordinated benzene, and a cycle catalytic in the platinum metal can be constructed. The efficiency of the overall reduction of benzene to cyclohexene decreases in the order Ir > Ru > Rh. The reaction is compared to the reduction of benzene to cyclohexane mediated by rhodium, iridium, and ruthenium trichloride hydrates and tetrahydroborate in ethanol. Other nucleophiles also attack the benzene ring in (2b): these include methyl-lithium (which gives two dimethylcyclohexadiene complexes from which isomeric dimethylcyclohexenes can be obtained with acid), methoxide (which gives the methoxycyclohexadienyl and, with an excess, two dimethoxycyclohexa-1,3-diene complexes), and nitromethane which in the presence of base gives the nitromethylcyclohexadienyl complex [(C5Me5)Ir(C6H6CH2NO2)][BF4](9). The single-crystal X-ray structure determination of (9) shows the C5Me5 and the C6 ring both to be η5-bonded, and the CH2NO2 substituent to, be in the exo position on the η5-cyclohexadienyl ring. Analysis of the high-field1H n.m.r. spectra of the complexes showed that exo attack on the C6 ring occurred with all the nucleophiles. In the presence of base, (9) reacted further with (2b) to give [{(C5Me5)Ir(C6H6)}2CHNO2]2+. These reactions show the versatility of the reduction procedure.

The selective reduction of benzene to cyclohexene

Hydride attack on a dicationic η6-benzene complex gives the η4-cyclohexadiene, which with acid yield cyclohexene; in the presence of benzene the initial η6-benzene complex can be regenerated and a cycle established.

Rhodium cluster ultradispersed catalysts of high and low activity

Catalysts were prepared using RH 6(CO) 16 adsorbed or slurried on a silica substrate. For these catalysts the rate constants for the reduction of benzene and in some cases cyclohexene were determined. The catalyst particle size distributions were determined by electron microscopy. These results were analyzed to provide varying rate constants assigned to catalyst particles of various sizes. Clusters of rhodium atoms of 0.8 to 1.2 nm corresponding to about Rh 6 were found to have very low, possibly zero, activity for hydrogenation reactions. Clusters of atoms above 1.4 nm diameter were found to be active catalysts for hydrogenation under the same conditions. Some evidence indicating a very high activity for catalyst particles between 1.2 and 2.0 nm was obtained. Below 2.0 nm only two-dimensional rafts are found. This high activity is not therefore attributable to terrace edge sites although evidence of such enhanced activity was found at lower dispersions, 2.0 to 3.0 nm diameter.

Nanosecond flash studies of reduction of benzophenone by aliphatic amines. Quantum yields and kinetic isotope effects

Nanosecond flash photolysis, steady irradiation, and deuterium substitution studies have been carried out on solutions of benzophenone with added reductants. Quantum yields (phi/sub ketyl/) for reduction in benzene of benzophenone triplet to ketyl radical, based on phi = 2 for benzhydrol (I), were approx. 1 for cyclohexane (II), tert-butylamine (III), 2-aminobutane (IV), cyclohexylamine (V), di-n-propylamine (VI), and triethylamine (VII), approx. 0.7 for 1,4-diazabicyclo(2.2.2)octane (VIII), and approx. 0 for tert-butyl alcohol (IX). Thus, quenching, without radical formation by H abstraction from N and/or ..cap alpha..-C, does not occur with common aliphatic amines but does with Dabco (VIII). The latter quenching is markedly increased by small additions of acetonitrile; the flash spectrum from this compound indicates formation of a triplet amine CT complex or radical ion pair. Triplet-reductant interaction rate constants, k/sur ir/, are high for the amines (approx. 10/sup 8/-10/sup 9/ M/sup -1/ s/sup -1/) but also show significant deuterium kinetic isotope effects: 1.9 with III-N-d/sub 2/; 1.4 with IV-N-d/sub 2/; 1.2-1.3 with IV-..cap alpha..-C-d. It is proposed that k/sub ir/ measures H atom abstraction, favored in the transition state by an initial charge-transfer interaction. Overall steady irradiation quantum yields of reduction by amines, phi/sub Red/, are much lower than phi/submore » ketyl/. This is attributed to disproportionationreactions of ketyl and alkylaminyl radicals for primary and secondary amines, and, possibly, aminoalkyl radicals for tertiary amines. In the case of tert-butylamine, the rate constant for disproportionation is obtained from the decay kinetics of ketyl radical and leads to phi/sub Red/ in agreement with that directly measured.« less

Reduction of Benzene and Related Compounds in Aqueous Solution and Undivided Cells

Benzene and other aromatic compounds may be reduced to the 1,4‐dihydro‐derivatives in an undivided cell using a dispersion of hydrocarbon and aqueous quaternary ammonium hydroxide. At optimum conditions benzene is converted to 1,4‐cyclohexadiene at 90% selectivity with nearly quantitative current efficiency. A continuous reaction scheme for the benzene reduction is described.

Electrogenerative chemical reactors

Electrogenerative processes are electrochemical ones in which the exothermic energy of chemical reaction is converted to direct electric current while a desired chemical product is produced. Fuel cells processes actually are related but differ in that they normally involve complete fuel combustion. Conventional electrochemical processes differ from electrogenerative processes in that they consume power although they may give similar desired products. Furthermore, electrogenerative electrodes may operate in different potential regions determined by potentials produced by the chemical reactions taking place. For example, the electrogenerative reduction of benzene takes place with energy production in acid solution and can be represented by Anode(−) 3 H 2 → 6 H + + 6 e, (1) Cathode (+) C 6 H 6 + 6 H + + 6 e → C 6 H 12. (2) In contrast, the electrochemical reduction of benzene by conventional means requires the supply of a negative potential of several volts and special solvents. Here, several electrogenerative processes are reviewed as well as the design and operation of electrogenerative reactors. The importance of electrocatalysis is illustrated. Possibilities for incorporating electrogenerative and related processes into existing chemical processing technology are discussed from the standpoint of conserving and recovering energy that is presently lost as heat.

ｇｅｍ‐ジクロロシクロプロパンの水素化アルミニウムリチウムによる還元

gem-Dichlorocyclopropanes were reduced easily by lithium aluminium hydride in boiling tetrahydrofuran to afford cis-trans mixtures of the corresponding monochlorocyclopropanes. The cistrans ratios were determined by GLC. The relatively high isomer ratios were obtained for the reduction of (2, 2-dichloro-cyclopropyl)benzene and 7, 7-dichloronorcarane in both of which a hydrogen atom in the substituent is close to the cis-chlorine atom. The reduction proceeds presumably via a synfacial mechanism in which the attacking hydride and the chlorine atom attacked are on the same side of the cyclopropane plane.

A study of thermal stability in a number of aromatic and nitrogen containing polycyclic compounds

Abstract A comparative study has been made by pyrolytic gas chromatography of the thermal stability of a number of aromatic and nitrogen containing polycyclic compounds modelling the units and individual fragments of the chain of heat resistant polymers. It is shown that introduction of various bridging groups between the benzene rings and reduction of the aromaticity of the cyclic systems bring about a decrease in thermal stability. It was found that the substances with greatest thermal stability are fully aromatic ring compounds and heterocyclic ring systems condensed with the benzene nucleus.

Kinetic and optical relaxation studies of adsorbed intermediates in some electrochemical reactions

In certain electrocatalytic reactions, co-adsorption of more than one electroactive intermediate may arise. The charge under the overall potentiodynamic current-potential profile for the adsorbed species may not then be used to evaluate coverage by the species. A method is proposed for resolution of processes involving more than one electrochemisorbed species when the electroactivity of, e.g., two species arises over a common potential range. The method is based on the different kinetic relaxation response of “reversibly” electrosorbed species from that for more “irreversibly” electrosorbed species. Applications to the case of reduction of adsorbed nitriles at Pt enables a two-stage mechanism to be formulated and in the reduction of benzene the charges for co-adsorption of H and benzene reduction can be distinguished. In the initial stages of Pt surface oxidation, the method enables the reversibly electrosorbed OH species to be distinguished from more irreversibly reactive rearranged surface oxide.The behaviour of chemisorbed CH3CN and the oxide film on Pt below a monolayer have also been investigated by a.c. modulated reflectance over a range of a.c. frequencies and wavelengths of light.

The Reaction of Metals with Weak Acids in Liquid Ammonia and Methylamine

AbstractKinetic data for the reactions of sodium with water, ethanol, and t‐butyl alcohol in liquid ammonia are consistent with the mechanism: magnified image Analysis of the data for these reactions yields values for k1 and k2/k3. k3 has been measured directly at ‐35°C by reacting solutions of sodium and ammonium bromide in liquid ammonia using the stopped‐flow technique. Rate data for the reaction of cesium with water in ethylenediamine have been analyzed on the assumption that two parallel second‐order reactions are operative. Kinetic data for the reaction of cesium with water in methylamine at ‐70°C could best be explained in terms of Equation (1) and (2) where NH3 is replaced by CH3NH2. The reaction of sodium with water in methylamine was found to be consistent with observed second‐order kinetics. Recent data for the metal‐ammonia‐alcohol reduction of benzene suggest that a steady‐state concentration of ammonium radicals is established.

Reduction of diazonium salts with silyl and stannyl hydrides : A new route for the replacement of amino-groups of aromatic amines by hydrogen

Diazonium salts are reduced by silyl or stannyl hydrides in ethers and acetonitrile to give the corresponding arenes with elimination of the diazonium group, thus providing a new route for replacement by hydrogen of the amino group attached to an aromatic nucleus. The treatment of p-chloro- and p-methoxybenzenediazonium fluoroborates with tri-n-butyltin deuteride resulted in the formation of chlorobenzene and anisole containing only about 40% of deuterium. The reduction of benzene- and p-chlorobenzenediazonium fluoroborates with tri-n-butyltin hydride in a mixture of acetonitrile and benzene (1:2) afforded biphenyl (8·4%), 1,4-dihydrobiphenyl (about 1%), and 4-chlorobiphenyl (16·8%). These findings indicate that aryl radicals are involved as intermediates.

Reduction of benzene by hydrated electrons in .gamma.-ray irradiated alkaline solutions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReduction of benzene by hydrated electrons in .gamma.-ray irradiated alkaline solutionsMartin H. Studier and Edwin J. HartCite this: J. Am. Chem. Soc. 1969, 91, 15, 4068–4072Publication Date (Print):July 1, 1969Publication History Published online1 May 2002Published inissue 1 July 1969https://doi.org/10.1021/ja01043a008RIGHTS & PERMISSIONSArticle Views41Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (549 KB) Get e-Alerts Get e-Alerts

Reduction of benzene by europium and ytterbium

Reduction of benzene by europium and ytterbium

Kinetics of the Lithium-Ammonia-Ethanol Reduction of Benzene. A Fourth-Order Reaction1

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of the Lithium-Ammonia-Ethanol Reduction of Benzene. A Fourth-Order Reaction1O. John Jacobus and Jerome F. EasthamCite this: J. Am. Chem. Soc. 1965, 87, 24, 5799–5800Publication Date (Print):December 1, 1965Publication History Published online1 May 2002Published inissue 1 December 1965https://doi.org/10.1021/ja00952a055RIGHTS & PERMISSIONSArticle Views55Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (283 KB) Get e-Alerts Get e-Alerts

Extensive Reduction of Coal by a New Electrochemical Method

IN recent years electrolytic methods have been used in the reduction and structural elucidation of coal1–2. The usefulness of these methods is limited by the fact that the benzene ring (that is, the isolated benzene ring as in benzene or tetralin), which may represent a large portion of the coal structure, has not previously been reduced electrolytically. Work here has shown that reduction of benzene can be achieved by electrolysis in ethylenediamine saturated with lithium chloride3. The same method has now been successfully applied to the reduction of a high-rank coal and has resulted in the addition of 44 hydrogens per 100 carbon atoms. The best electrochemical reduction achieved2 prior to this was carried out in dimethylformamide and amounted to the addition of 14 hydrogens.

Electrochemical Reduction of the Benzene Ring

Reduction of benzene and tetrahydronaphthalene (tetralin) was achieved by electrolysis in ethylenediamine saturated with lithium chloride. This reduction could also be carried out with tetrabutylammonium iodide as the supporting electrolyte. In the absence of a substrate, electrolysis of a solution of lithium chloride in ethylenediamine produced the blue color of the solvated metal.