Olefin Exchange Research Articles

A Novel Cationic Optically Active Complex of Platinum(II) Containing 2-Methyl-2-butene and o-Benzenediamine. The Circular Dichroism Spectrum and Kinetics of Olefin Exchange

Abstract An optically active cationic olefin complex, [PtCl(o-benzenediamine)((S)-2-methyl-2-butene)]B(C6H5)4 was obtained for the first time as crystal stable in air at room temperature. It deteriorates slightly in solution, but is still stable enough to be characterized. Comparison of its CD spectrum with that of related complexes disclosed that the coordinating atoms at the cis sites to the olefin have a dominant influence upon the CD pattern in the region 20000–35000 cm−1, as compared with those at the trans site. Substitution of cis-1,2-dichloroethylene for the coordinated (S)-2-methyl-2-butene (S-mbn) proceeds in accordance with the second order rate law; there is no contribution of the solvent path. The second order rate constant is smaller than that of trans-[PtCl2(pyridine)(S-mbn)]. The steric effect of the o-benzenediamine at the transition state seems responsible for the small rate rather than the basicity of the ligand at the trans site to mbn.

Change from a σ-alkyl intermediate to a carbonium ion intermediate in reactions of olefins on a molybdenum sulphide catalyst

The double bond migration of 2-methylbut-1-ene on MoS2 occurs predominantly by a carbonium ion mechanism, while isomerization and hydrogen exchange of other olefins proceed through σ-alkyl intermediates.

The mechanism of isomerization and exchange of olefins over metal catalysts: IV. Reactions of some C 5, C 6 and C 7 alkenes in the presence of perdeuteropropene on iron films

The exchange and isomerization of pent-1-ene, cis-pentene, cis-hept-2-ene, trans-hept-3-ene, 2-methylbut-2-ene and 2,3-dimethylbut-2-ene have been investigated on iron films in the presence of a large excess of perdeuteropropene. Further evidence has been given for the occurrence of a direct intramolecular hydrogen shift in double bond migration, and, in cis-trans isomerization, for a direct process without the formation or the breaking of any CH bond. The classical Horiuti-Polanyi mechanism seems to be restricted to cis-trans isomerization and involves only two consecutive steps. The pronounced maxima for d 8, d 5 and d 4 deutero-isomers in the distributions of but-1-ene, pent-1-ene and 3-methylbut-1-ene obtained from the corresponding alk-2-enes show that the isomerization mechanisms involve a dissociative adsorption at a vinylic carbon atom, accompanied by a complete exchange of all the adjacent primary allylic hydrogen atoms. It is suggested that interconversions between σ-π-binuclear surface complexes are responsible for this process.

ChemInform Abstract: THE MECHANISMS OF ISOMERIZATION AND EXCHANGE OF OLEFINS OVER METAL CATALYSTS PART 3, ISOMERIZATION OF BUTENES IN THE PRESENCE OF PERDEUTEROPROPENE ON IRON FILMS

Chemischer InformationsdienstVolume 5, Issue 17 Preparative Organic Chemistry ChemInform Abstract: THE MECHANISMS OF ISOMERIZATION AND EXCHANGE OF OLEFINS OVER METAL CATALYSTS PART 3, ISOMERIZATION OF BUTENES IN THE PRESENCE OF PERDEUTEROPROPENE ON IRON FILMS R. TOUROUDE, R. TOUROUDESearch for more papers by this authorF. G. GAULT, F. G. GAULTSearch for more papers by this author R. TOUROUDE, R. TOUROUDESearch for more papers by this authorF. G. GAULT, F. G. GAULTSearch for more papers by this author First published: April 30, 1974 https://doi.org/10.1002/chin.197417161Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume5, Issue17April 30, 1974 RelatedInformation

ChemInform Abstract: THE MECHANISMS OF ISOMERIZATION AND EXCHANGE OF OLEFINS OVER METAL CATALYSTS PART 1, REACTIONS OF DIMETHYLCYCLOPENTENES IN THE PRESENCE OF PERDEUTEROPROPENE ON PALLADIUM FILMS

Chemischer InformationsdienstVolume 5, Issue 17 Preparative Organic Chemistry ChemInform Abstract: THE MECHANISMS OF ISOMERIZATION AND EXCHANGE OF OLEFINS OVER METAL CATALYSTS PART 1, REACTIONS OF DIMETHYLCYCLOPENTENES IN THE PRESENCE OF PERDEUTEROPROPENE ON PALLADIUM FILMS R. TOUROUDE, R. TOUROUDESearch for more papers by this authorL. HILAIRE, L. HILAIRESearch for more papers by this authorF. G. GAULT, F. G. GAULTSearch for more papers by this author R. TOUROUDE, R. TOUROUDESearch for more papers by this authorL. HILAIRE, L. HILAIRESearch for more papers by this authorF. G. GAULT, F. G. GAULTSearch for more papers by this author First published: April 30, 1974 https://doi.org/10.1002/chin.197417160Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume5, Issue17April 30, 1974 RelatedInformation

The mechanisms of isomerization and exchange of olefins over metal catalysts: II. Exchange of olefins in the presence of perdeuteropropene on iron films

The exchange of α-olefins (ethylene, propene, but-1-ene and pent-1-ene) and of β-olefins ( cis-butene and cis-pentene) has been studied on iron films at −37 and 0 °C in the presence of an excess of perdeuteropropene or perdeuteroethylene. While the exchange of the α-olefins is very fast, about 20 times faster than their isomerization, the exchange of the β-olefins may be considered as negligible. Whereas the exchange of the simplest molecules, ethylene propylene, may be considered as a simple exchange of all four and three vinylic hydrogens, respectively, in the case of but-1-ene and pent-1-ene the internal and terminal vinylic hydrogens seem to be differentiated and a multiple exchange takes place.

The mechanisms of isomerization and exchange of olefins over metal catalysts: III. Isomerization of butenes in the presence of perdeuteropropene on iron films

The initial deuterium distributions of the reaction products obtained by isomerization of but-1-enes, cis- and trans-butenes in the presence of perdeuteropropene on iron films at −37 °C are examined in this paper, together with the product distributions obtained by co-isomerization of cis-d 0- and d 8-butenes. While but-1-ene yields poorly exchanged cis and trans isomers, best interpreted by assuming an intramolecular hydrogen shift, highly deuterated but-1-enes with a maximum in d 8 are obtained from cis- and trans-butenes. This result can only be explained if two different types of site for double bond migration are present on the surface and α- and β-olefins are adsorbed on each type of site with very different strengths. Cis-trans isomerization, on the other hand, occurs mostly by a Horiuti-Polanyi mechanism restricted to a single interconversion between mono- and diadsorbed species (formation of the d 1 isomer), but also by a direct process which does not involve the breaking or the formation of any CH bond and leads to d 0 -butenes. The results obtained in the co-isomerization experiment confirm these views and suggest moreover that the replacement of the hydrogen atoms of an olefin during the exchange reaction is fast when compared with the mobility of the adsorbed hydrogen or deuterium atoms.

The mechanisms of isomerization and exchange of olefins over metal catalysts: I. Reactions of dimethylcyclopentenes in the presence of perdeuteropropene on palladium films

The isomerization and exchange of 1,2-dimethyl- and 2,3-dimethylcyclopentenes have been effected on palladium films at 150–200 °C in presence of a large excess of perdeuteropropene. As far as isomerization is concerned, the results are substantially the same as the ones obtained when these molecules are reacting in presence of deuterium. The comparison between the deuterium distributions of the exchanged and the isomerized hydrocarbons suggests that double bond migration takes place by a direct hydrogen intramolecular shift. Exchange by dissociative adsorption of the olefin at an allylic position is also suggested.

Microwave spectroscopic studies of hydrogen exchange, isomerization and hydrogenation of unsaturated hydrocarbons on the stoichiometric electron donor–acceptor complexes of phthalocyanine with alkali metals

Hydrogen exchange, isomerization and hydrogenation of olefins, such as C2H4, C3H6 and C4H8, was studied over the stoichiometric electron donor–acceptor (EDA) complexes of various phthalocyanines with alkali metals (Li, Na, K). The mass and microwave spectroscopic techniques have been shown to be effective for determining not only the deuterium content but also its distribution in the [2H1] and [2H2]-species of the reactant and product molecules. It was accordingly concluded that these three reactions proceed through the same reaction intermediate; the half-hydrogenated state of the olefins, and that the rate-determining step is the process where the π-coordinated olefin becomes the σ-coordinated half-hydrogenated state. The chemisorbed state of the olefins and the mechanisms of these reactions were correlated with the electron configuration of the EDA complexes.

The hydroisomerization of n-butenes : 2. The reaction of 1-butene over mercury-poisoned rhodium-silica catalysts

The influence of adsorbed mercury upon the rates of hydrogenation, isomerization and olefin exchange over silica-supported rhodium catalysts has been studied in the temperature range 0–69 °, using deuterium and radioactive tracer techniques. The results show that whereas the rates of hydrogenation and 1-butene exchange decrease uniformly with increasing mercury coverage, the rate of isomerization is virtually independent of mercury coverage up to θ Hg > 80%. The results are interpreted in terms of a model in which hydrogenation and olefin exchange occur directly on the metal, while isomerization involves the migration of adsorbed 1-butene from the metal to the support followed by isomerization on the silica.

Deuteration isomerization and exchange of cycloolefins over palladium catalysts

The deuteration, exchange, and isomerization of cyclopentene and of several disubstituted cycloolefins with four- and five-membered rings are studied over palladium films and over palladium-pumice catalysts at very low conversions. The cis-trans distribution and the deuterium content of the saturated products depend mostly upon the size of the ring. Cis-dimethylcyclobutanes, poorly exchanged, and trans-dimethylcyclopentanes with a high content of deuterium are the main saturated products obtained from dimethylcyclobutenes and cyclopentenes, respectively. On the other hand, most of the isomerized and exchanged cycloolefins contain no or one deuterium atom. No correlation may be derived then between the deuterium distributions of the olefins and of the saturated hydrocarbons, when the calculations are based on the Horiuti-Polanyi model or any similar model. It is, therefore, believed that the deuteration does not proceed by the same mechanism as the double-bond migration and the olefin exchange. While the interconversion between diadsorbed species and π-allylic species determine the nature of the saturated products, double-bond migration and olefin exchange involve entirely different intermediaries.

Exchange of olefins with oxymercurials

Exchange of olefins with oxymercurials

Tracer studies of acid-catalyzed reactions. Part 10.—Deuterium exchange and isomerization of cyclic olefins over alumina

The mechanisms of double-bond migration and the exchange of D2 with the hydrogen atoms of small cyclic olefins (methylenecyclobutane, methylenecyclopentane, cyclopentene, 3-methylcyclopentene, cyclohexene, and bicyclo-(2,2,1)-hepta-2, 5-diene) were investigated over a pure alumina catalyst. At temperatures below 100°, only those hydrogen atoms which were initially vinyl, or which could become vinyl by isomerization of the olefin, underwent exchange. A primary kinetic isotope effect of about 2.8 was found, indicating that cleavage of the C—H bond was probably the slow step in the exchange reaction. Rapid intermolecular scrambling of all vinyl hydrogen atoms was observed, and the presence of the olefins greatly reduced the usually fast rate of H2+ D2 equilibration. Double-bond migration below 100° was sensitive to the geometry of the olefin. Only molecules having a three carbon chain, including the double bond, which could appear concave when viewed from outside the molecule underwent isomerization; those which did not fulfill this requirement did not isomerize. Nearly pure 1,2-cyclopentene-d2 could be prepared, suggesting a dissociative mechanism for the exchange reaction. Hence, exchange and double-bond migration are independent processes, although both reactions may have involved the same sites and may have had a common intermediate. Poisoning experiments using radioactive CO2 indicated an active site density of about 1.4 × 1013 cm–2 for the exchange reaction after 530° pretreatment.

Transition metal alkyls and hydrides VIII. Nickel chloride catalyzed insertion of ethylene into arylmagnesium halides

Anhydrous nickel chloride catalyses the insertion of ethylene into the CMg-bond of arylmagnesium bromides and also the subsequent alkylolefin exchange reaction of the primary aralkyl metal derivatives. Other transition metal halides are less active. (2-Phenylethyl)magnesium bromide isomerises under these conditions to the 1-isomer, and this isomerization is promoted by olefins. The nickel catalyst complex probably contains both σ-alkyl (aralkyl or aryl) and π-olefin ligands, and direct hydride migration between these ligands is proposed as the mechanism for the exchange and isomerization in the presence of certain olefins.

Homogeneous catalysis with trans-chlorocarbonylbis(triphenylphosphine)iridium(I)

A tetragonal d 8 complex of iridium, trans-[IrCl(CO)(Ph 3P) 2], catalyzes hydrogen-deuterium exchange, and hydrogenation and isomerization of olefins homogeneously in solution under mild conditions. The hydrogen-deuterium exchange appears to proceed via hydrido-deuterio complexes in which the two isotopes are simultaneously bonded to the same metal atom. The isomerization of 1-butene requires the presence of molecular hydrogen as co-catalyst. The hydrogenation of ethylene was studied by tracer techniques in order to gain information on the mechanism of this catalytic conversion. The reaction between C 2H 4 and D 2 yields d 0, d 1, d 2, d 3, and d 4 ethanes, d 1and d 2 ethylenes, as well as HD and H 2. The observed extensive HD exchange suggests that both reactants are activated reversibly on the same metal atom at which the hydrogen transfer to the double bond occurs.

The importance of $pi;-bonded intermediates in hydrocarbon reactions on transition metal catalysts

Abstract The significance of π-bonded intermediates in reactions of hydrocarbons on transition metal catalysts is generally discussed. Mechanisms are briefly reviewed in the light of this theory for the exchange of paraffins, olefins, and aromatics with deuterium, for hydrogenation, dehydrogenation, and isomerization reactions. It is shown that a rational explanation of many apparently unrelated phenomena in these reactions is afforded on the basis of the proposed theory. The close similarity of the reactions of surface intermediates to homogeneous reactions of corresponding π-bonded ligands in transition metal complexes is also emphasized. The surface atoms in metals seem to possess chemical properties which are in many ways identical with those of the free atoms or ions. By analogy with the bond strengths in corresponding compounds, heats of chemisorption of π-bonded intermediates, and thus catalytic activity and selectivity should be a function of the position of the metal in the periodic table. This concept is discussed with reference to the hydrogenation of benzene and the decomposition of formic acid. Some selectivity and activity sequences for the hydrogenation of acetylene, ethylene, and diolefins are also considered.

Olefin Coordination Compounds of Rhodium: The Barrier to Rotation of Coordinated Ethylene and the Mechanism of Olefin Exchange

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOlefin Coordination Compounds of Rhodium: The Barrier to Rotation of Coordinated Ethylene and the Mechanism of Olefin ExchangeRichard. CramerCite this: J. Am. Chem. Soc. 1964, 86, 2, 217–222Publication Date (Print):January 1, 1964Publication History Published online1 May 2002Published inissue 1 January 1964https://doi.org/10.1021/ja01056a022RIGHTS & PERMISSIONSArticle Views769Altmetric-Citations229LEARN 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 (793 KB) Get e-Alerts Get e-Alerts

Synthetic Applications of the Titanium-Catalyzed Exchange of Olefins with Grignard Reagents1a

Synthetic Applications of the Titanium-Catalyzed Exchange of Olefins with Grignard Reagents^1a

Mechanisms of Exchange and Hydrogenation Reactions of Olefins

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