Liquid phase oxidations of cyclic alkenes. II

Sickle, Dale E. Van; Mayo, Frank R.; Arluck, Richard M.

doi:10.1021/jo01286a090

Cited by 16 publications

(14 citation statements)

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“…After 6 h, ∼20% of cyclohexene was oxidized and the major product was cyclohexene hydroperoixde (∼60%), with minor amounts of 2-cyclohexen-1-ol, 2-cyclohexen-1-none, and cyclohexane epoxide, a distribution similar to that from auto-oxidation2223. Without the Au-derived filtrate, there was no reaction.…”

Section: Resultsmentioning

confidence: 96%

Stable and solubilized active Au atom clusters for selective epoxidation of cis-cyclooctene with molecular oxygen

et al. 2017

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The ability of Au catalysts to effect the challenging task of utilizing molecular oxygen for the selective epoxidation of cyclooctene is fascinating. Although supported nanometre-size Au particles are poorly active, here we show that solubilized atomic Au clusters, present in ng ml−1 concentrations and stabilized by ligands derived from the oxidized hydrocarbon products, are active. They can be formed from various Au sources. They generate initiators and propagators to trigger the onset of the auto-oxidation reaction with an apparent turnover frequency of 440 s−1, and continue to generate additional initiators throughout the auto-oxidation cycle without direct participation in the cycle. Spectroscopic characterization suggests that 7–8 atom clusters are effective catalytically. Extension of work based on these understandings leads to the demonstration that these Au clusters are also effective in selective oxidation of cyclohexene, and that solubilized Pt clusters are also capable of generating initiators for cyclooctene epoxidation.

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Section: Resultsmentioning

confidence: 96%

Stable and solubilized active Au atom clusters for selective epoxidation of cis-cyclooctene with molecular oxygen

et al. 2017

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“…The barrier to the second step in the epoxidation mechanism, is computed to be 5.5 kcal mol À1 , leading to a transition state theory (TST) calculated rate constant of k 10 (363 K) = 2 10 9 m À1 s À1 . This reaction stands in competition with the addition of O 2 to the radical adduct (Scheme 5), [30] a reaction that is probably diffusion-controlled, (k 11 (363 K) % 2 10 9 m À1 s À1 ).…”

Section: Addition Of Peroxyl Radicals To the Unsaturated C=c Bondmentioning

confidence: 99%

Mechanism of the Aerobic Oxidation of α‐Pinene

2010

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A combined experimental and theoretical approach is used to study the thermal autoxidation of α‐pinene. Four different types of peroxyl radicals are generated; the verbenyl peroxyl radical being the most abundant one. The peroxyl radicals propagate a long radical chain, implying that chain termination does not play an important role in the production of the products. Two distinct types of propagation steps are active in parallel: the abstraction of allylic H atoms and the addition to the unsaturated CC bond. The efficiency for both pathways appears to depend on the structure of the peroxyl radical. The latter step yields the corresponding epoxide product, as well as alkoxyl radicals. Under the investigated reaction conditions the alkoxyl radicals seem to produce both the alcohol and ketone products, the ketone presumably being formed upon the abstraction of the weakly bonded αH atom by O2. This mechanism explains the predominantly primary nature of all quantified products. At higher conversion, co‐oxidation of the hydroperoxide products constitutes an additional, albeit small, source of alcohol and ketone products.

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“…In this context, the following facet of the oxidation mechanism is noteworthy. Under conditions appropriate for our chemiluminescence studies, cyclohexene is oxidized predominantly through the abstraction of the H atom at the a position to the double bond of this olefin (19,20). Thus, for cyclohexene one may expect the chemiluminescence mechanism similar to that is normally observed for well-studied cases of alkyl aromatic hydrocarbons (6).…”

Section: Introductionmentioning

confidence: 68%

Updating the Chemiluminescence Oxygen‐Aftereffect Method for Determining the Rate Constant of the Peroxy‐Radical Self‐Reaction: Oxidation of Cyclohexene

Fedorova

Lapina

Menshov

et al. 2018

Photochem & Photobiology

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Updating the facile chemiluminescence oxygen‐aftereffect method, most suitable for determining the rate constant (kt) of the peroxy‐radical self‐reaction (main chemiluminescence channel), pertained to considering the sensitivity of such a method toward a disturbing influence of the peroxy radicals of the initiator of the chain oxidation process. Such a disturbance may derive from the side chemiluminescent reaction, which involves peroxy radicals of both hydrocarbon and initiator. To examine the applicability and limitations of the chemiluminescence method under present scrutiny, cyclohexene was used as the model oxidizable hydrocarbon substrate. Computer simulations of the reaction and chemiluminescence kinetics have demonstrated the validity of the considered methodology at the value of the rate constant of the propagation of the overall chain process by peroxy radicals of the initiator higher than 1 m−1 s−1. Despite that the chemiluminescence time profile and the stationary level of the total chemiluminescence intensity depend on the kinetics of the side chemiluminescence channel and on the ratio of the excited‐state generation yields in the mentioned reaction channel and in the main chemiluminescence process, the value of kt assessed by the oxygen‐aftereffect method has been found independent of variation of these characteristics.

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Liquid phase oxidations of cyclic alkenes. II

Cited by 16 publications

References 0 publications

Stable and solubilized active Au atom clusters for selective epoxidation of cis-cyclooctene with molecular oxygen

Stable and solubilized active Au atom clusters for selective epoxidation of cis-cyclooctene with molecular oxygen

Mechanism of the Aerobic Oxidation of α‐Pinene

Updating the Chemiluminescence Oxygen‐Aftereffect Method for Determining the Rate Constant of the Peroxy‐Radical Self‐Reaction: Oxidation of Cyclohexene

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