Structure and reactions of carbon-centered α-oxy(Oxo)Radicals

Multiphase Chemistry of Glyoxal: Revised Kinetics of the Alkyl Radical Reaction with Molecular Oxygen and the Reaction of Glyoxal with OH, NO3, and SO4– in Aqueous Solution

“…Also a quite similar result was measured by comparison of the column “0 Pulses Start” and “0 Pulses End” in Table . The formation of tartaric acid was observed under oxygen-reduced conditions, this can be explained by either acid or base catalyzed dehydration. − Apparently, even when oxygen concentration are nonzero the formation of tartaric can be observed. This effect warrants further study as it might be important in atmospheric aqueous systems.…”

Conductive AFM Patterning on Oligo(ethylene glycol)-Terminated Alkyl Monolayers on Silicon Substrates: Proposed Mechanism and Fabrication of Avidin Patterns

“…Unlike alkyl radicals in which the unpaired electron occupies a nonbonding orbital, the unpaired electron orbital in the R 1 –O– • CH–R 2 radicals has a higher energy due to the two-orbital three-electron interaction with the lone electron pair orbital of the O-atom. 45 Therefore, these α-oxy radicals are easily oxidized by single electron transfer, 45 leading to the carbocations 3 that are quenched by the hydroxyl anion to form the hemiacetals 4 . Further oxidation of 4 in a similar way may generate esters.…”

“…The resultant highly reactive hydroxy radicals will then rapidly abstract a hydride from the adjacent OEG chains 1 , generating the carbon radicals 2 inside the film. Unlike alkyl radicals in which the unpaired electron occupies a nonbonding orbital, the unpaired electron orbital in the R 1 –O– • CH–R 2 radicals has a higher energy due to the two-orbital three-electron interaction with the lone electron pair orbital of the O-atom . Therefore, these α-oxy radicals are easily oxidized by single electron transfer, leading to the carbocations 3 that are quenched by the hydroxyl anion to form the hemiacetals 4 .…”

Reactions of 2-Propanol Radical with Halogenated Organics in Aqueous Solution: Theoretical Evidence for Proton-Coupled Electron Transfer and Competing Mechanisms

“…In the focus of our interest are the α-hydroxyalkyl radicals (α-HAR), represented by the general formula • CR1­(R2)­OH. These radicals are frequently encountered in all of the aforementioned contexts, as is evidenced by the decades of research invested in unraveling their chemistry. − In the atmosphere, for instance, α-HAR usually emerge as products of the hydroxyl ( • OH) radical-induced oxidation of pervasive simple alcohols. , α-HAR commonly react as reducing agents because the donation of the unpaired electron to an electron-accepting species A provides a strong thermodynamic pull due to the formation of a stable carbonyl compound, aldehyde or ketone. The reduction of A is accompanied by the deprotonation of the OH group of α-HAR, which may be optionally promoted and controlled via a suitable basic anion B – − If the electron-accepting species A is a halogenated organic substrate, A–X, the reduction thereof usually leads to the rapid dehalogenation via scission of the susceptible C–X bond and the formation of the daughter radical • A. Because • A may further abstract the hydrogen atom from the alcohol, thus restoring the original α-HAR, such a sequence may instigate a chain reaction that is capable of significantly enhancing the dehalogenation yields. − One of the principal interests in the reaction systems akin to eq draws from the well-founded conjecture that the reduction, that is, the transfer of the electron from the radical to the substrate, could take place concertedly with the transfer of the proton from the OH group to the basic species that acts as a proton acceptor (eq ).…”