Mechanism of anodic cleavage of benzyl ethers

Boyd, Jean W.; Schmalzl, Paul W.; Miller, Larry L.

doi:10.1021/ja00531a030

Cited by 30 publications

(12 citation statements)

References 2 publications

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“…19 Ethers 16 and 17 were prepared by the literature methods. 20 Chemical shifts are relative to the residual solvent signal. Coupling constants are in Hz.…”

Section: Methodsmentioning

confidence: 99%

Amination of ethers using chloramine-T hydrate and a copper(i) catalyst

et al. 2005

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Amination of C-H bonds activated by ether oxygen atoms is facile with chloramine-T as nitrene source and copper(I) chloride in acetonitrile as catalyst. For cyclic ethers the hemiaminal products are generally stable and can be isolated pure. For acyclic ethers, the hemiaminal products, as expected, fragment with elimination of alcohol to yield imines. When activation of benzylic positions is remote through a conjugated system, stable benzylamine derivatives are isolated. Mechanistic studies are consistent with concerted insertion of an electrophilic nitrenoid into the C-H bond in the rate-determining step, though in an asynchronous manner with a more activated substrate.

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“…19 Ethers 16 and 17 were prepared by the literature methods. 20 Chemical shifts are relative to the residual solvent signal. Coupling constants are in Hz.…”

Section: Methodsmentioning

confidence: 99%

Amination of ethers using chloramine-T hydrate and a copper(i) catalyst

et al. 2005

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“…[39][40][41][42] Surface degradation on the CAM also makes sense if capacity loss is a result of irreversible oxidation of the polymer electrolyte at the interface with the cathode at high potentials. 35,43 On the other hand, CAM fracture, especially in a solid-state battery (SSB) system where electrolyte cannot flow, ought to result in the opposite distribution -surface grains still connected to electrolyte will remain redox active, while disconnected grains deep in the particle bulk will not. Finally, delamination or corrosion of a current collector, while increasing the impedance of the cell overall, should not alter the redox activity profile within a CAM particle.…”

Section: Bulk Xanes Analysismentioning

confidence: 99%

Mesoscale Chemomechanical Interplay of the LiNi_0.8Co_0.15Al_0.05O₂ Cathode in Solid-State Polymer Batteries

et al. 2018

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Complex chemomechanical interplay exists over a wide range of length scales within the hierarchically structured lithium-ion battery. At the mesoscale, the interdependent structural complexity and chemical heterogeneity collectively govern the local chemistry and, as a result, critically influence the cell level performance. Here we investigate the morphology and state of charge (SOC) inhomogeneity within secondary NCA particles that were cycled in solid polymer batteries. We observe substantial inhomogeneity in the nickel oxidation state (a proxy for SOC) and loss of structural integrity within secondary particles after only 20 cycles due to significant intergranular cracking. The formation of mesoscale cracks causes loss of ionic and electrical contact within cathode particles, triggering increases in local impedance and rearrangement of transport pathways for charge carriers. This can eventually lead to deactivation of sub-particle level domains in solid-state lithium-ion batteries. Our findings highlight the importance of proper mesoscale strain and defect management in polymer lithium-ion batteries.

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“…The answer may lie in a P450-PhIO complex structure (Scheme 2) proposed by Ortiz de Montellano and Groves (87) to account for the rapid incorporation of 18 O from solvent water into products (84,88). A possible explanation is that activation of H 2 O-liganded P450 iron by PhIO may yield a slightly different compound I-like intermediate, already protonated (or possibly incorporating a H 2 O molecule), that is less capable of acting as a base to abstract an 4 A kinetic deuterium isotope of 1.9 has been reported for the electrochemical oxidation of ␣,␣-d 2 -dibenzyl ether (82), which necessarily involves a cation radical. SCHEME 2.…”

Section: Table II Kinetic Hydrogen Isotope Effects For N-demethylatiomentioning

confidence: 99%

Evidence for a 1-Electron Oxidation Mechanism in N-Dealkylation of N,N-Dialkylanilines by Cytochrome P450 2B1

Guengerich

Yun

Macdonald

1996

Journal of Biological Chemistry

157

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Many enzymes catalyze N-dealkylations of alkylamines, including cytochrome P450 (P450) and peroxidase enzymes. Peroxidases, exemplified by horseradish peroxidase (HRP), are generally accepted to catalyze N-dealkylations via 1-electron transfer processes. Several lines of evidence also support a 1-electron mechanism for many P450 reactions, although this view has been questioned in light of reported trends for kinetic hydrogen isotope effects for N-demethylation with a series of 4-substituted N,N-dimethylanilines. No continuous trend for an increase of isotope effects with the electronic parameters of para-substitution was seen for the P450 2B1-catalyzed reactions in this study. The larger value seen with the 4-nitro derivative is consistent with a shift in mechanism due to either a reversible electron transfer step preceding deprotonation or to a hydrogen atom abstraction mechanism. With HRP, the trend is to lower isotope effects with para electronwithdrawing substituents, due to an apparent shift in rate-limiting steps. Biomimetic model high-valent porphyrins showed reduction rates with variously 4-substituted N,N-dialkylanilines that were consistent with a positively charged intermediate; such relationships were not seen for anisole O-demethylation with P450 2B1. In contrast to the case with the NADPH-supported P450 reactions, high deuterium isotope effects (ϳ7) were seen in the N-dealkylations supported by the oxygen surrogate iodosylbenzene. With iodosylbenzene, colored aminium radicals were observed in the oxidations of aminopyrine, N,N-dimethyl-4-aminothioanisole, and 4-methoxy-N,N-dimethylaniline. With the latter compound, a substantial intermolecular deuterium isotope effect was observed for N-demethylation. In the N-dealkylation of N-ethyl,N-methylaniline by P450 2B1 (NADPH-supported), the ratio of N-demethylation to Ndeethylation was 16. Although it is probably possible for P450s to catalyze amine N-dealkylations via hydrogen atom abstraction when such a course is electronically or sterically favored, we interpret the evidence to favor a 1-electron pathway with N,N-dialkylamines with P450 2B1 as well as HRP and several biomimetic models.

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Mechanism of anodic cleavage of benzyl ethers

Cited by 30 publications

References 2 publications

Amination of ethers using chloramine-T hydrate and a copper(i) catalyst

Amination of ethers using chloramine-T hydrate and a copper(i) catalyst

Mesoscale Chemomechanical Interplay of the LiNi_0.8Co_0.15Al_0.05O₂ Cathode in Solid-State Polymer Batteries

Evidence for a 1-Electron Oxidation Mechanism in N-Dealkylation of N,N-Dialkylanilines by Cytochrome P450 2B1

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Mechanism of anodic cleavage of benzyl ethers

Cited by 30 publications

References 2 publications

Amination of ethers using chloramine-T hydrate and a copper(i) catalyst

Amination of ethers using chloramine-T hydrate and a copper(i) catalyst

Mesoscale Chemomechanical Interplay of the LiNi0.8Co0.15Al0.05O2 Cathode in Solid-State Polymer Batteries

Evidence for a 1-Electron Oxidation Mechanism in N-Dealkylation of N,N-Dialkylanilines by Cytochrome P450 2B1

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Mesoscale Chemomechanical Interplay of the LiNi_0.8Co_0.15Al_0.05O₂ Cathode in Solid-State Polymer Batteries