Autoxidation of Hydrocarbons: From Chemistry to Catalysis

Hermans, Ive; Peeters, Jozef; Jacobs, Pierre

doi:10.1007/s11244-008-9099-7

Cited by 99 publications

(73 citation statements)

References 46 publications

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“…[44] However, for activated substrates, such as ethylbenzene [17] and a-pinene, [10,11] and hence, also b-pinene, the importance of this alcohol production channel can be neglected in first approximation.…”

Section: Over-oxidation Of the Hydroperoxidesmentioning

confidence: 99%

Peculiarities of β‐Pinene Autoxidation

2011

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The thermal oxidation of the renewable olefin β-pinene with molecular oxygen was experimentally and computationally investigated. Peroxyl radicals abstract weakly bonded allylic hydrogen atoms from the substrate, yielding allylic hydroperoxides (i.e., myrtenyl and pinocarvyl hydroperoxide). In addition, peroxyl radicals add to the C=C bond of the substrate to form an epoxide. It was found that a relatively high peroxyl radical concentration, together with the high rate of peroxyl cross-reactions, make radical-radical reactions surprisingly important for this particular substrate. Approximately 60 % of these peroxyl cross-reactions lead to termination (radical destruction), keeping a radical chain length of approximately 4 at 10 % conversion. Numerical simulation of the reaction-based on the proposed reaction mechanism and known or predicted rate constants-demonstrate the importance of peroxyl cross-reactions for the formation of alkoxyl radicals, which are the precursor of alcohol and ketone products.

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Section: Over-oxidation Of the Hydroperoxidesmentioning

confidence: 99%

Peculiarities of β‐Pinene Autoxidation

2011

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“…Ab initio calculations demonstrated that the resulting R ÀaH · OOH radical does not exist and spontaneously dissociates to Q=O and · OH. [9,10] This implies that the abstraction of the aH atom of the hydroperoxide is a fast and straightforward source of the ketone. The · OH radical will rapidly abstract an H atom of A combined experimental and theoretical approach is used to study the thermal autoxidation of a-pinene.…”

Section: Introductionmentioning

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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“…Therefore, many attempts are made to develop methods that use cheap catalysts, benign conditions and oxygen or air as terminal oxidant 10 . Many organic compounds react slowly with oxygen from air in autoxidation reactions which can functionalize C-H bonds by effectively inserting O 2 , forming a hydroperoxide moiety 11,12 . Autoxidation processes are used on industrial scale to generated oxygenated compounds from hydrocarbon feedstocks, but autoxidation is also an unwanted process if it leads to decomposition of valuable compounds or materials.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)

Gulzar

Klußmann

2014

JoVE

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The direct functionalization of C-H bonds is an important and long standing goal in organic chemistry. Such transformations can be very powerful in order to streamline synthesis by saving steps, time and material compared to conventional methods that require the introduction and removal of activating or directing groups. Therefore, the functionalization of C-H bonds is also attractive for green chemistry. Under oxidative conditions, two C-H bonds or one C-H and one heteroatom-H bond can be transformed to C-C and C-heteroatom bonds, respectively. Often these oxidative coupling reactions require synthetic oxidants, expensive catalysts or high temperatures. Here, we describe a two-step procedure to functionalize indole derivatives, more specifically tetrahydrocarbazoles, by C-H amination using only elemental oxygen as oxidant. The reaction uses the principle of C-H functionalization via Intermediate PeroxideS (CHIPS). In the first step, a hydroperoxide is generated oxidatively using visible light, a photosensitizer and elemental oxygen. In the second step, the N-nucleophile, an aniline, is introduced by Brønsted-acid catalyzed activation of the hydroperoxide leaving group. The products of the first and second step often precipitate and can be conveniently filtered off. The synthesis of a biologically active compound is shown

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Autoxidation of Hydrocarbons: From Chemistry to Catalysis

Cited by 99 publications

References 46 publications

Peculiarities of β‐Pinene Autoxidation

Peculiarities of β‐Pinene Autoxidation

Mechanism of the Aerobic Oxidation of α‐Pinene

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)

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