Oxidation of the Perchlorotriphenylmethyl Radical to the Carbocation, and Its Unique Abrupt Reversion

Abstract

A solution of AlCl(3) in CH(2)Cl(2) reacts slowly, at room temperature, with perchlorotriphenylmethyl radical (PTM(*)), an inert carbon free radical, to give perchlorotriphenylmethyl cation (PTM(+)) quantitatively. However, by gradual addition of CH(2)Cl(2) into the resulting solution a point is reached where the PTM(+) reverts to PTM(*) instantaneously and quantitatively. A mechanism for this exceptional phenomenon is suggested. Some PTM(+) reactions, namely hydrolysis yielding quinonoid species and single-electron transfers with hydride ion donors, are reported and discussed.

Novel Antioxidant Reactions of Cinnamates in Wine

“…After the 1-hydroxyethyl radical attaches to the α carbon of the unsaturated side chain, a resonance-stabilized benzyl radical is produced. It has been previously established that a variety of Fe III complexes can oxidize benzyl and tert -butyl radicals to the carbocation form, − and because there is Fe III present during oxidation of wine and here in our study, this mechanism is likely. One electron oxidation of the benzyl radical by Fe III would produce a carbocation β to the carboxyl group, an arrangement that has been previously demonstrated to readily decarboxylate and re-establish the double bond .…”

Perchlorotrityl radical-fluorophore conjugates as dual fluorescence and EPR probes for superoxide radical anion

“…Perchlorotriphenylmethyl radicals are a novel class of trityls whose structures are based on perchlorotriphenyl methyl radical (PTM). Due to the full steric blockage of the central carbon, the PTM radical and its derivatives are highly stable against a variety of reactive chemical agents, and hence are called “inert free radicals” 16,17. The ability of two derivatives, tris(2,3,5,6-tetrachloro-4-carboxylate-phenyl) methyl radical (PTM-TC) and tris(2,3,5,6-tetrachloro-4-ethyloxycarbonyl-phenyl) methyl radical (PTM-TE), to trap O 2 •− have been tested 18,19.…”

A Highly Sensitive Biocompatible Spin Probe for Imaging of Oxygen Concentration in Tissues

“…1 B). The PTM radical and its derivatives are highly stable against a variety of reactive chemical agents, and hence are called ''inert free radicals'' (43,44). They can withstand temperatures as high as 250°C.…”

“…They can withstand temperatures as high as 250°C. Their chemical inertness and thermal stability are due to the full steric blockage of the central carbon, where most of the spin density resides (43). HFB has been well established by Mason et al (19) as a standalone probe for quantitative tumor oximetry using 19 F-NMR relaxometry.…”