Reactions of α-Hydroxybenzyl Free Radicals. III.¹ Processes for α-Hydroxycyclopropylcarbinyl Radical Formation

Kinetics of the gas‐phase reaction of cyclopropylcarbinyl iodide and hydrogen iodide. Heat of formation and stabilization energy of the cyclopropylcarbinyl radical

“…10-14 kcal/mole in the liquid phase [ l ] and probably greater in the gas phase [1-3]) of a cyclopropyl group on an adjacent carbonium ion center has been well documented, but the question as to whether similar stabilization is provided in the case of radicals has not been completely settled. Application of molecular orbital theory [4] suggests that the radical is significantly less stabilized, and indeed substitution of a cyclopropylcarbinyl group for structurally similar groups increases the rate of various radical-forming reactions by only factors of from 1 to 55 [5][6][7][8][9][10]191. These various accelerations imply a stabilization of from 0 to 5 kcal/mole but have not unambiguously supplied a more precise value.…”

Photochemistry of epoxyquinones. 1. Photochemical reactions of 2-alkyl-2,3-epoxy-2,3-dihydro-1,4-naphthoquinones with hydrogen donors

“…Such a phenomenon was also observed in the reaction of cyclopropylphenylcarbinol with di-ferf-butyl peroxide previously reported. 13 Therefore, these data suggest the intermediacy of -hydroxyalkyl radical 8 generated via hydrogen atom abstraction from 18 in the photochemical reaction. At higher concentrations of DBPO the oxidation process via 8 will mainly proceed to give lb, the starting epoxyquinone.…”

A Quaternary Nitronyl Nitroxide α‐Amino Acid: Synthesis, Configurational and Conformational Assignments, and Physicochemical Properties

“…radicals;21 meanwhile, α‐hydroxyalkyl radicals could be generated via reaction of the corresponding alcohols with alkoxyl radicals such as t‐ BuO . ,22 and might be oxidized to α‐hydroxyalkyl cations in the presence of oxidants via a single‐electron transfer (SET) process 23. As such, it could be speculated that TBAB/TBHP might work as an efficient catalytic system for alcoholic hydroxy group transformations as well.…”

“…could be generated from TBHP with the assistance of TBAB 21. This radical subsequently abstracts an α‐hydrogen atom from benzylic alcohol,22 and the resulting key intermediate α‐hydroxybenzyl radical A is then further oxidized to the corresponding carbonyl product. The oxidation of A might occur through a SET process forming the intermediate α‐hydroxybenzyl cation B directly23 (the oxidation of A with TBHP to α‐hydroxybenzyl cation B or the deprotonation of A with TBHP to radical anion could not be ruled out).…”