Olefin Structure Research Articles

Ionization Potential and Structure of Olefins

The method of photoionization has been used to measure the ionization potential of a number of simple, cyclic, exocyclic, bicyclic mono- and diolefins. These data are compiled with others from the literature of related systems, and the results are compared. In mono-olefins, the ionization potential of the olefinic π electron is found to decrease as the size of the molecule increases, the change being largest with the first methyl substitution to ethylene. As the size of the σ system of a monofolefin increases, the energy of both the neutral molecule and the ion decreases by the extra bonds formed as well as by strengthening the π system as a result of mixing it with the ionic form due to hyperconjugation. Both factors stabilize the ion more than they do the neutral molecule. The fact that cyclic and exocyclic olefins have ionization potential comparable to that observed for straight chain olefins of comparable size again strongly indicates that the stabilization of the ion by the electrons in the σ bonds (rather than by hyperconjugation) is an important factor in determining the ionization energy of π electrons in olefins. The effect of a second olefinic group greatly depends on whether or not strong interaction between the two groups occurs, but is independent of whether a chain or cyclic system is studied. Conjugation is found to decrease the I.P. values by ∼0.5 eV. Due to the increase in the effective nuclear charges of the atoms in the ion, resonance and Coulombic-type interactions stabilize the ion upon conjugation more than they do the neutral species. Nonconjugated dienes have slightly lower I.P. than the corresponding monofolefins by an amount that depends on the separation and geometry of the diene. The effect of a second olefinic system in a bicyclic diene can be as great as that produced by the classic type of conjugation in favorable cases, such as in norbornadiene. In these systems, increasing the ring size increases the number of bonds, thus lowering the value of the I.P., but also increases the separation between the double bonds, which raises the value of the I.P. 1,4,7-cyclononatriene (crown) has an I.P. value which is 0.6 eV lower than that in benzene, but higher than trimethyl-substituted benzene. This result is explained by the fact that strong conjugation is present in the crown but is not as effective as it is in the phenyl ring.

Structure of olefins and rate of their hydrogenation in the presence of a ruthenium catalyst

1. The liquid-phase hydrogenation of C5-C7 olefins on a ruthenium catalyst was investigated. 2. Under the conditions of hydrogenation, the shift of the double bond is slightly accelerated. The rate of cis-trans-conversion is commensurate with the rate of hydrogenation. 3. The dependence of the rate of hydrogenation of theα-olefins studied upon their structure is correlated with the Taft equation.

Relative rates of reaction of olefins with the ground and the first excited electronic states of methylene

Relative rates of reaction of a number of olefins with the ground state triplet and the first excited electronic state (the lowest singlet) of methylene have been determined at room temperature. The rates depend relatively little on olefin structure. Triplet methylene is somewhat more discriminating and, in particular, reacts considerably more rapidly with 1,3-butadiene than with monoolefins.

Catalytic hydrogenation—I: The reaction of platinum metal salts with sodium borohydride—new active platinum metal catalysts for hydrogenation

The treatment of Pt metal salt solutions with sodium borohydride results in the formation of finely divided black precipitates. Certain of these precipitates ar active catalysts for the hydrolysis of sodium borohydride. SomePt, Pd and Rhare active catalysts for the hydrogenation of olefins. If the precipitation is carried out in the presence of high surface area supports such as activated carbon, these materials show even greater activity. The Pt catalyst is remarkably active as a catalyst for the hydrogenation of a large variety of olefins; Pd, on the other hand, shows a marked sensitivity toward olefin structure. Rates of reaction were followed in a novel way, using a standard solution of sodium borohydride added to acid to supply pure hydrogen as required to maintain the pressure.

Kinetics of the Thallic Ion Oxidation of Olefins. II. Effect of Olefin Structure on Rate and Product Distribution

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of the Thallic Ion Oxidation of Olefins. II. Effect of Olefin Structure on Rate and Product DistributionPatrick M. HenryCite this: J. Am. Chem. Soc. 1965, 87, 20, 4423–4428Publication Date (Print):October 1, 1965Publication History Published online1 May 2002Published inissue 1 October 1965https://doi.org/10.1021/ja00948a003RIGHTS & PERMISSIONSArticle Views58Altmetric-Citations26LEARN 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 (729 KB) Get e-Alerts Get e-Alerts

Gas chromatography with stationary phases containing silver nitrate: VI. The methylcycloheptenes and methylenecycloheptane

The gas chromatographic behavior of the isomeric methylcycloheptenes and methylenecycloheptane was investigated using: (a) packed tubes containing conventional non-complex forming phases; (b) capillary tubes coated with squalane and polypropylene glycol; (c) packed columns containing complex forming silver nitrateglycol solutions as the stationary liquid. Smooth separation of a mixture of the isomers is achieved on a silver nitrate-triethylene glycol column; by proper choice of salt concentration and working temperature the components can be quantitatively determined with an accuracy of ±1%. On a preparative scale, the method was conveniently employed for the isolation of the previously unknown 4-methylcycloheptene. By compring the relative retention volumes of the isomers, correlations between complex stability and olefin structure were deduced, taking into consideration the peculiar conformations of the seven-membered ring system.

The Addition of Nitrosyl Halides to Olefins. Dependence of Steric Course on Olefin Structure

The Addition of Nitrosyl Halides to Olefins. Dependence of Steric Course on Olefin Structure

Studies of the Organic Reaction of Metal Carbonyl. V. The Reaction of Cobalt Hydrocarbonyl with Olefin—The Effects of the Reaction Conditions and of the Structure of Olefin

Abstract It has been observed that the reaction of 1-olefin with cobalt hydrocarbonyl is remarkably affected by the reaction conditions and by the structure of olefln. Some functional groups, such as the ester, n-butoxy and phenyl groups, adjacent to a C= C bond increase the reactivity of the C=C bond; the order of the reactivity is n-butyl vinyl ether, 103>styrene, 20>ethyl acrylate, 5>pentene-1. (The numbers indicate the relative reactivities, which have been roughly calculated from the gas absorption curve.) At a relatively low temperature (below 0°C), the α-carbon atom of the C=C bond of all these olefins except pentene-1 is selectively carbonylated; the reaction scheme may be considered to be as follows; suggesting that cobalt hydrocarbonyl is acting as an acid: (Remark: Graphics omitted.) However, these acylcobalt carbonyls with the branched structure isomerize to those with the straight one: (Remark: Graphics omitted.) A relatively high temperature (25°C) and a nitrogen atmosphere promote this isomerization considerably. The reverse isomerization seems to occur only with difficulty. On the other hand, these olefins mainly give the β-carbon carbonylated product at 25 °C, the formation of which seems to result from the two successive reactions, the carbonylation of the α-carbon atom and the isomerization of the corresponding acylcobalt carbonyl. However, the distribution of the products from pentene-1 is not affected by the reaction temperature. A relatively high pressure of carbon monoxide is advantageous for this reaction. Under a nitrogen atmosphere, some reaction other than the carbonylation seems to occur very rapidly, consuming a large part of the cobalt hydrocarbonyl used; a nitrogen atmosphere has an inhibitory effect on the carbonylation.

Thermal polymerization of C5 olefins at high pressures

1. The thermal polymerization of C5 olefins occurs at 260–270° and 1000–3000 Kg/sq.cm. The rate of polymerization depends on the structure of the C5 olefin: 1-pentene and 3-methyl-1-butene polymerize most rapidly, 2-methyl-1 -butene polymerizes somewhat more slowly, and 2-methyl-2-butene and 2-pentene polymerize most slowly. The C5 olefins studied fall into an analogous sequence when placed in order of the degree of polymerization attained. 2. With increase in pressure the rate of thermal polymerization of C5 olefins rises; this acceleration depends on the structure of the C5 olefin. The polymerization of 2-methyl-2-butene and 2-methyl-2-butene is accelerated by pressure to a greater extent than the polymerization of 1-pentene and 3-methyl-1-butene; on the basis of this it was concluded that the polymerization of the first two C5 olefins meets greater steric hindrance. 3. It was found that the interconversion of the three isomeric methylbutenes occurs under the conditions studied.

Gas chromatography with stationary phases containing silver nitrate : III. Isomeric C 8 and C 9 cyclohexenes and p-menthenes

Retention volumes of isomeric C 8 and C 9 cyclohexenes and p-menthenes have been determined, using stationary phases containing silver nitrate. As in the case of lower cyclic olefins, it is found that closely boiling isomers can be separated and determined quantitatvely on a 30% silver nitrate-glycol solution at 20–30°. The correlation between olefin structure and retention volume is discussed.

Relation of reactivity to structure for alkenes, acid anhydrides, and acid chlorides

1. The reactivities of alkenes in reactions with monocarboxylic anhydrides and acid chlorides, and acid chlorides of monoethyl esters of dicarboxylic acids in presence of metal halides depend substantially on the structures of the original alkenes. From a comparison of the reactions of 1-hexene and 2,3-dimethyl-2-butene with acetic anhydride and the acid chloride of monoethyl adipate it was shown that the branched alkene had the greater reactivity. 2. In their reactions with alkenes the reactivities of monocarboxylic anhydrides and acid chlorides and dicarboxylic acid chlorides also depend on the structures of the latter. The behavior of 2,3-dimethyl-2-butene with pivalic anhydride and the acid chlorides of the monoethyl esters of dimethyl- and diethyl-malonic acids indicates the inertness of the latter, which is determined by their highly branched structures. 3. In the reaction of a mixed anhydride with an alkene in presence of zinc chloride, the acyl group of the higher acid adds at the double bond with formation of the keto group of the product.

Influence of Olefin Structure on Bromine Number as Determined by Various Analytical Methods

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInfluence of Olefin Structure on Bromine Number as Determined by Various Analytical MethodsE. H. UngerCite this: Anal. Chem. 1958, 30, 3, 375–380Publication Date (Print):March 1, 1958Publication History Published online1 May 2002Published inissue 1 March 1958https://doi.org/10.1021/ac60135a019RIGHTS & PERMISSIONSArticle Views142Altmetric-Citations16LEARN 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 (681 KB) Get e-Alerts Get e-Alerts

Effect of olefin structure on the ceiling temperature for olefin polysulfone formation

AbstractCeiling temperatures Tc (at which the free energy change for the reaction is zero) have been determined for the formation of polysulfones from a wide variety of olefins and allyl compounds under standard concentration conditions ([M] [S] = 27 mole2 liter−2, M = unsaturated compound, S = sulfur dioxide). In the 1‐olefin series Tc falls from ethylene to propylene 90°, to 1‐butene 64°, and then remains approximate constant as the chain is lengthened. With 2‐olefins there is a progressive decrease from butene 34°, to pentene 8°, to heptene −38°. Branching invariably lowers Tc and the effect is greatest when the branching is at the double bond; thus isobutene 4°, 3‐methyl‐1‐butene 36°, 4,4‐dimethyl‐1‐pentene 14°. 2‐ethyl substitution of a 1‐olefin, or 2, 3, or 4 branching of a 2‐olefin results in inability to react (Tc < −80°). Cycloolefins have Tc values considerably higher than the corresponding 2‐olefins; thus cyclopentene 102°, cyclohexene 24°. In the allyl compounds a carboxyl group tends to lower Tc but a hydroxyl group raises Tc. An ether group raises Tc slightly. The results are discussed in terms of structural effects on the heat and entropy changes and on the monomer activity coefficients and polymer solubilities. The infrared absorption spectra of 20 polysulfones and 3 aliphatic sulfones are recorded for the sulfone stretching region (7.5–9.5 μ).

Kinetics and Mechanism of the Hydroformylation Reaction. The Effect of Olefin Structure on Rate1

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics and Mechanism of the Hydroformylation Reaction. The Effect of Olefin Structure on Rate1Irving Wender, Sol Metlin, Sabri Ergun, Heinz W. Sternberg, and Harold GreenfieldCite this: J. Am. Chem. Soc. 1956, 78, 20, 5401–5405Publication Date (Print):October 1, 1956Publication History Published online1 May 2002Published inissue 1 October 1956https://doi.org/10.1021/ja01601a064RIGHTS & PERMISSIONSArticle Views943Altmetric-Citations69LEARN 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 (547 KB) Get e-Alerts Get e-Alerts

Kinetic Studies in the Chemistry of Rubber and Related Materials. III. Thermochemistry and Mechanisms of Olefin Oxidation

Abstract A new estimate of the O—O bond strength in hydroperoxides is reported, based on a determination of the heats of oxidation of ethyl linoleate and linolenate. This value is employed, together with other known bond strengths and resonance energies, to estimate the heats of a number of alternative oxidation reactions of olefins. By considering the effects of the olefin structure on these heats of reaction, it is possible to see how structural differences can lead to the formation of different oxidation products. The discussion is confined to primary products of the oxidation chain, but, even so, a considerable diversity of behavior is shown to be possible. The final material may include simple monomeric hydroperoxides, polymers with varying amounts of oxygen incorporated in the chain, cyclic peroxides, and scission products. The very limited experimental evidence available falls generally into line with expectation.

Kinetic studies in the chemistry of rubber and related materials. III. Thermochemistry and mechanisms of olefin oxidation

Abstract A new estimate of the O—O bond strength in hydroperoxides is reported, based on a determination of the heats of oxidation of ethyl linoleate and linolenate. This value is employed, together with other known bond strengths and resonance energies, to estimate the heats of a number of alternative oxidation reactions of olefins. By considering the effects of the olefin structure on these heats of reaction, it is possible to see how structural differences can lead to the formation of different oxidation products. The discussion is confined to primary products of the oxidation chain, but, even so, a considerable diversity of behavior is shown to be possible. The final material may include simple monomeric hydroperoxides, polymers with varying amounts of oxygen incorporated in the chain, cyclic peroxides, and scission products. The very limited experimental evidence available falls generally into line with expectation.