Electron transfer to ozone: outer-sphere reactivities of the ozone/ozonide and related non-metal redox couples

Kinetics of Hydride Transfer from Catalytic Metal-Free Hydride Donors to CO2

“…This value is in excellent agreement with previously reported self-exchange energies of organic hydrides by Kreevoy and co-workers. ,,, Finally, λ and λ RH values were used to derive λ CO 2 , and the value of 49.2 kcal/mol was obtained, which is in reasonable agreement with the DFT-calculated value (λ CO 2 = 56.4 kcal/mol; see section S2.C, Supporting Information). A large λ CO 2 value obtained in our study is consistent with the previously reported self-exchange reorganization energy associated with the electron transfer involving the CO 2 /CO 2 •– couple . In the case of electron transfer, the λ value was found to be 30.5 kcal/mol, and most of the inner-sphere contribution to this energy was assigned to a large change in the O–C–O bond angle upon one-electron reduction.…”

“…A large λ CO 2 value obtained in our study is consistent with the previously reported self-exchange reorganization energy associated with the electron transfer involving the CO 2 /CO 2 •− couple. 51 In the case of electron transfer, the λ value was found to be 30.5 kcal/ mol, and most of the inner-sphere contribution to this energy was assigned to a large change in the O−C−O bond angle upon one-electron reduction. Similar changes are expected to take place in our HT involving the CO 2 /HCOO − couple and are likely the reason for the observed reorganization energy.…”

Acidity enhances the formation of a persistent ozonide at aqueous ascorbate/ozone gas interfaces

“…An alternative mechanism initiated by the one-electron transfer reaction: AH Ϫ ϩ O 3 (g) ϭ AH ϩ O 3 Ϫ ; ⌬G 0 ϭ Ϫ20 kJ mol Ϫ1 (16,17) should make, at most, a minor contribution to AH 2 ozonolysis because the putative source of (16,34), is thermodynamically disallowed and yields OH radicals that should have perceptibly influenced our experiments. O 3 addition to the CAC bond of AH 2 is expected to generate an unstable primary ozonide AH 2 ⅐O 3 (POZ) that will open up to a Criegee diradical intermediate (CI, not shown in Scheme 1), followed by ring reclosure into a secondary ozonide, AOZ, plus typical ozonolysis products resulting from CI fragmentation (19).…”

“…These secondary oxidants need only last the few microseconds required for diffusing through typical Ϸ0.1-m-thick ELF layers (13). The production of O 2 ( 1 ⌬ g ) in high yields (Ͼ90%) during the ozonolysis of AH 2 (pK a ϭ 4.1) in bulk aqueous solution at pH Ϸ7 (14,15) implicates the exoergic two-electron oxidation into dehydroascorbic acid (DHA), reaction 1 (16)(17)(18):…”

Reactive oxygen species: Reactions and detection from photosynthetic tissues

“…The ozonide anion radical is protonated very fast (k  10 10 M -1 s -1 ), reaction (61) and then decomposed to hydroxyl radical and 3 O 2 [487,496].…”