Isomerization of Certain Olefins by Silica Gel at Room Temperature

Gallaway, W. S.; Murray, M.

doi:10.1021/ja01187a086

Cited by 13 publications

(4 citation statements)

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“…The formation of 2,4,4-trimethyl pentenes in an acid-catalyzed dimerization of isobutene has been reported to produce TMP1 and TMP2 in a ratio of 4:1. ,− It has been explained that, when a protonated isobutene reacts with an isobutene molecule, a C 8 carbocation is formed, where the tertiary carbon has a positive charge. Now, TMP1 is formed in larger amounts because the elimination of a proton takes place more readily from the methyl groups adjacent to the electron-deficient carbon atom than from the neopentyl group.…”

Section: Discussionmentioning

confidence: 99%

“…It has been reported that the acid-catalyzed polymerization of isobutene produces TMP1 and TMP2 in a ratio of about 4:1 ,− , but the thermodynamics for the isomers has not been discussed in detail. Some thermodynamic data have been presented for the enthalpy of formation − and the standard entropy ,− of trimethyl pentene molecules, and for the isomerization reaction enthalpy, but the variation within these values is extremely large, e.g., the reaction enthalpy is exothermic in some references and endothermic in others, and the equilibrium data obtained from the literature values are inconsistent.…”

Section: Introductionmentioning

confidence: 99%

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Reaction Equilibrium in the Isomerization of 2,4,4-Trimethyl Pentenes

Karinen¹,

Lylykangas²,

Krause³

2001

Ind. Eng. Chem. Res.

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The isomerization reaction of 2,4,4-trimethyl-1-pentene to 2,4,4-trimethyl-2-pentene was studied. In contrast to the general rule for alkene stability, an excess of the R-alkene (2,4,4-trimethyl-1-pentene) was observed in the thermodynamic equilibrium. The result is explained in terms of the molecular structure: the large and bulky substituents in 2,4,4-trimethyl-2-pentene cause steric tension and make the molecule less stable. A reaction enthalpy of 3.51 ( 0.03 kJ mol -1 , i.e., endothermic reaction, and a reaction entropy of -0.47 ( 0.10 J mol -1 K -1 were determined from the experimental data of the isomerization reaction.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reaction Equilibrium in the Isomerization of 2,4,4-Trimethyl Pentenes

Karinen¹,

Lylykangas²,

Krause³

2001

Ind. Eng. Chem. Res.

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“…This is a hint that the isomerization of 1-dodecene to isododecene in silica-stabilized PEs is affected by the silica particles during the preparation process. Gallaway and Murray 53 showed that olefins can isomerize by the passage of olefins through a silica gel column. This isomerization might be affected by the silanol groups of the fumed silica particles (HDK N20).…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

Synergistic Effects of a Rhodium Catalyst on Particle-Stabilized Pickering Emulsions for the Hydroformylation of a Long-Chain Olefin

Stehl

Milojević

Stock

et al. 2018

Ind. Eng. Chem. Res.

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Hydrophilic silica nanoparticles (100 nm in length and of 20 nm diameter) and larger hollow Halloysite nanotubes (HNTs; 800 nm in length with an outer diameter of 50 nm and an inner diameter of 15 nm) are used to stabilize an oil-in-water emulsion. These particle-stabilized Pickering emulsions (PEs) are used for the hydroformylation of a long-chain olefin (1-dodecene). Rhodium (Rh) and the water-soluble ligand sulfonated 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene are used as catalyst. The emulsions are prepared by sonication and Ultra-Turrax in a specially designed vessel to protect the catalyst from oxygenation and to control the temperature of each sample during the preparation process. The Rh catalyst shows interfacial active behavior and strongly influences the mean droplet size of the emulsions, stability, wettability, and energy of detachment. Further, the Rh catalyst stabilizes an emulsion even in the absence of particles. In a mixture of Rh catalyst and particles, both attach at the interface if the droplet size is in a magnitude of micrometers. These PEs show a monotonous droplet decrease with increasing particle concentration. It is shown that hydroformylation is possible in all emulsions stabilized by the Rh catalyst, silica nanoparticles, or HNTs. However, the conversions in the emulsions are different. The highest conversion is observed in silica-stabilized emulsions with above 40 wt % after a reaction time of only 5 h. Further, high selectivity for aldehyde was observed for all emulsions. A model for the behavior of the emulsions in the reactor is postulated. Interestingly, the emulsions stabilized by the Rh catalyst and silica nanoparticles are destroyed after the reaction, but the HNTs-stabilized PEs remained stable.

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“…The thermodynamic relations between this pair of olefins has received considerable previous attention. Equilibrium has been observed with acid (K = 5.3 at 25 "C) (7), base (K = 5.6 at 55 "C) (4), and silica gel (K = 5 at 25 "C) (8). Heats of combustion, hydrogenation, and free energies have been obtained by several workers (9).…”

Section: Introductionmentioning

confidence: 99%

2,4,4-Trimethylpentenyl anions

Hunter¹,

Mair²

1969

Can. J. Chem.

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The allylic anions derived by proton abstraction from 2,4,4-trimethyl-1-pentene 1 and 2,4,4-trimethyl-2-pentene 2 have been studied as short-lived intermediates. The anions were generated in t-butyl alcohol-0-d-potassium t-butoxide at 21 5 "C and relative rates of hydrogen-deuterium exchange and isomerization were compared. The isomerization of the thermodynamically less stable 2 to 1 occurs through the cisallylic anion with a low 10% intramolecular component. The intermediate anion preferentially collapses to give 2 (3 to 1). Treatment. of 1 leads more frequently into the less substituted allylic anion.

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Isomerization of Certain Olefins by Silica Gel at Room Temperature

Cited by 13 publications

References 0 publications

Reaction Equilibrium in the Isomerization of 2,4,4-Trimethyl Pentenes

Reaction Equilibrium in the Isomerization of 2,4,4-Trimethyl Pentenes

Synergistic Effects of a Rhodium Catalyst on Particle-Stabilized Pickering Emulsions for the Hydroformylation of a Long-Chain Olefin

2,4,4-Trimethylpentenyl anions

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