Absolute Rate Constants for Hydrogen Atom Transfer from Tertiary Amides to the Cumyloxyl Radical: Evaluating the Role of Stereoelectronic Effects

Salamone, Michela; Milan, Michela; DiLabio, Gino A.; Bietti, Massimo

doi:10.1021/jo5013459

Cited by 29 publications

(55 citation statements)

References 64 publications

(82 reference statements)

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“…This may, for example, include the water‐mediated isomerization of the benzyloxyl radical ( 4 ) to the hydroxybenzyl radical through a formal 1,2‐hydrogen shift (not shown) . The relevance of this pathway will, among other things, depend on the polarity of the surrounding solvent and its ability to engage in hydrogen‐bonding interactions with the radical 4 . For the sake of completeness, it should also be mentioned that the toluene shown in Figure as an active reaction partner can potentially also “solvate” the hydroperoxide 3 while it undergoes O−O bond homolysis and then react with the generated HO .…”

Section: Resultsmentioning

confidence: 99%

“…[43][44][45] The relevance of this pathway will, among other things,d epend on the polarity of the surrounding solventa nd its ability to engage in hydrogen-bonding interactions with the radical 4. [46][47][48][49][50] For the sake of completeness, it should also be mentioned that the toluenes hown in Figure 3a sa na ctive reaction partner can potentially also "solvate" the hydroperoxide 3 while it undergoes OÀOb ond homolysis and then react with the generated HOC radicali nas econd step along the lines shown in Figure 2. This pathway has been studied by using the same theoretical approach as above and shown to be enthalpically inferior to the sequence shown in Figure 3( see the Supporting Information for furtherd etails).…”

Section: Reaction Of Benzylhydroperoxide With Toluenementioning

confidence: 99%

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Radical‐Pair Formation in Hydrocarbon (Aut)Oxidation

Sandhiya

Zipse

2019

Chemistry A European J

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The reaction profiles for the uni‐ and bimolecular decomposition of benzyl hydroperoxide have been studied in the context of initiation reactions for the (aut)oxidation of hydrocarbons. The unimolecular dissociation of benzyl hydroperoxide was found to proceed through the formation of a hydrogen‐bonded radical‐pair minimum located +181 kJ mol−1 above the hydroperoxide substrate and around 15 kJ mol−1 below the separated radical products. The reaction of toluene with benzyl hydroperoxide proceeds such that O−O bond homolysis is coupled with a C−H bond abstraction event in a single kinetic step. The enthalpic barrier of this molecule‐induced radical formation (MIRF) process is significantly lower than that of the unimolecular O−O bond cleavage. The same type of reaction is also possible in the self‐reaction between two benzyl hydroperoxide molecules forming benzyloxyl and hydroxyl radical pairs along with benzaldehyde and water as co‐products. In the product complexes formed in these MIRF reactions, both radicals connect to a centrally placed water molecule through hydrogen‐bonding interactions.

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Section: Resultsmentioning

confidence: 99%

Section: Reaction Of Benzylhydroperoxide With Toluenementioning

confidence: 99%

Radical‐Pair Formation in Hydrocarbon (Aut)Oxidation

Sandhiya

Zipse

2019

Chemistry A European J

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“…[35] Niu, Li and co-workers [36] were the first to demonstrate the significance of this for alcohol oxidation. Using model FeO/Pt (111) and Cu 2 O/Ag (111) catalysts, the authors demonstrated with STM and DFT measurements that activated oxygen, originating from facile O 2 dissociation at interfacial sites, promoted alcohol adsorption and OÀ H bond activation. Furthermore, the authors elegantly demonstrated that these interfacial effects were independent of particle size (Figure 2-B).…”

Section: Mark Douthwaite Is a Postdoctoral Research Associate At The Cardiff Catalysis Institute Under The Supervision Of Professors Grahmentioning

confidence: 99%

A Perspective on Heterogeneous Catalysts for the Selective Oxidation of Alcohols

Najafishirtari

Ortega

Douthwaite

et al. 2021

Chemistry A European J

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Selective oxidation of higher alcohols using heterogeneous catalysts is an important reaction in the synthesis of fine chemicals with added value. Though the process for primary alcohol oxidation is industrially established, there is still a lack of fundamental understanding considering the complexity of the catalysts and their dynamics under reaction conditions, especially when higher alcohols and liquid-phase reaction media are involved. Additionally, new materials should be developed offering higher activity, selectivity, and stability. This can be achieved by unraveling the structure-performance correlations of these catalysts under reaction conditions. In this regard, researchers are encouraged to develop more advanced characterization techniques to address the complex interplay between the solid surface, the dissolved reactants, and the solvent. In this mini-review, we report some of the most important approaches taken in the field and give a perspective on how to tackle the complex challenges for different approaches in alcohol oxidation while providing insight into the remaining challenges.

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“…The mechanism of HAT processes was investigated in many works (43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54). Of special interest are the studies by Mayer and co-authors (43-47) with a systematic analysis of these processes in terms of the BEP relationship.…”

Section: Hydrogen Atom Transfer In Oxidation Reactions On Metal Complmentioning

confidence: 99%

The Brønsted−Evans−Polanyi Correlations in Oxidation Catalysis

2015

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The experimental Brønsted-Evans-Polanyi (BEP) correlations in the field of oxidation catalysis, describing both the liquid-phase reactions on metal complexes and especially the gas-phase oxidations on metal oxides including the O 2 isotopic exchange, were analyzed. It was shown that the rate of deep oxidations on metal oxides is determined by two thermodynamic parameters of a catalytic system: the heat of oxygen adsorption, Q O2 , and the heat of reaction, Q r , which constitute a unified BEP descriptive parameter Q uni = (Q r -Q O2 ). The correlations based on the energy of chemical bonds that are cleaved or formed in the course of reaction are more limited and less predictive.Special attention was paid to the numerical value of the Brønsted coefficient β. It was found that for all oxidations, in both the liquid and gas phases, β ≈ 0.5. Using the unified BEP descriptor Q uni with β = 0.5, a universal correlation was plotted describing the rates of all reactions over all catalysts under consideration.An idea of considering the kinetic compensation effect as a part of an extended BEP correlation is suggested. One may think that this long-debated phenomenon may relate primarily to mechanistic features of the reaction rather than to the nature of catalyst.In conclusion, difficult questions arising from analysis of the BEP correlations are summarized.

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Absolute Rate Constants for Hydrogen Atom Transfer from Tertiary Amides to the Cumyloxyl Radical: Evaluating the Role of Stereoelectronic Effects

Cited by 29 publications

References 64 publications

Radical‐Pair Formation in Hydrocarbon (Aut)Oxidation

Radical‐Pair Formation in Hydrocarbon (Aut)Oxidation

A Perspective on Heterogeneous Catalysts for the Selective Oxidation of Alcohols

The Brønsted−Evans−Polanyi Correlations in Oxidation Catalysis

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