Hydroxymethyl cation/radical

The reactivity of the hydrocarbons increases in the order ortho < meta < para in the liquid-phase catalytic oxidation of methyl derivatives of biphenyl into acids by air. The mechanism of the oxidation of hydroxymethylbiphenyls and hydroxymethyl-benzenes involves the formation of an unstable cation radical, which is then stabilized by emitting a proton, giving hydroxybenzyl radical.243... 

Organometallic radicals are important intermediates in biological and catalytic reactions. The structure and formation mechanism of radicals trapped in y-irradiated molecular sieves exposed to methanol and ethylene have been studied by EPR spectroscopy. It was found that Ag CH2OH+ radical with one-electron bond between Ag and C is formed by the attack of -CH2OH hydroxymethyl radical on Ag+ cation. 

Figure 1. EPR A/CH3OH zeolite A(A ) and atoms at different sites B, CH2OH hydroxymethyl radicals E, Ag CH2OH silver hydroxymethyl radical cation...

Recent studies conducted by the same group revealed that the radical cation of toluene generated by photoinduced electron transfer can be deprotonated in a protic cosolvent and thus efficient trapping by electrophilic alkenes is feasible, yielding benzylation products. Secondary hydrogen abstraction by the benzyl radical from methanol generates hydroxymethyl radicals, which can also be used for preparative hydroxymethylation of alkenes (Scheme 18) [24],... 

Chatgilialoglu C, Castelhano AL, Griller D (1985) Structures and optical absorption spectra of some sulfuranyl radicals in solution. J Org Chem 50 2516-2518 D Alessandro N, Bianchi G, Fang X, Jin F, Schuchmann H-P, von Sonntag C (2000) Reaction of superoxide with phenoxyl-type radicals. J Chem Soc Perkin Trans 2 1862-1867 Das S, von Sonntag C (1986) Oxidation of trimethylamine by OH radicals in aqueous solution, as studied by pulse radiolysis, ESR and product analysis. The reactions of the alkylamine radical cation, the aminoalkyl radical and the protonated aminoalkyl radical. Z Naturforsch 41b 505-513 Das S, Schuchmann MN, Schuchmann H-P, von Sonntag C (1987) The production of the superoxide radical anion by the OH radical-induced oxidation of trimethylamine in oxygenated aqueous solution. The kinetics of the hydrolysis of (hydroxymethyl)dimethylamine. Chem Ber 120 319-323... 

This chapter discusses an entirely different approach to the generation and investigation of highly reactive transient intermediates. The high reactivity is usually due to an unusual electron distribution in the intermediate that was acquired in the course of the chemical reaction. This implies that for an electron rich intermediate there is a corresponding stable cation in which the electron density was lowered by ionization. Likewise, for an electron-deficient intermediate there is a corresponding stable anion in which the electron deficiency was alleviated by electron attachment. Equations (1) and (2) show simple examples of the methoxy and hydroxymethyl radicals, respectively, which are isomeric transient intermediates of hydrogen atom abstraction from methanol ... 

The product (183) is formed on irradiation of acridine (184) phenothiazine (185) crystals in which the ratio of the reactants is 3 4," This reactivity is different from the solution phase (in acetonitrile) process which affords both (183) and the dihydro dimer (186). The photoinduced electron transfer reactions of some a-silyl ethers has been investigated." The sensitizing system uses DCA/ biphenyl and irradiation at A, > 345 nm in acetonitrile/methanol. The irradiation brings about the formation of the radical cation (187) of the ether which undergoes cleavage to yield the radical (188), a hydroxymethyl equivalent. When these are generated in the presence of a,P-unsaturated esters such as (189) addition takes place affording the adducts (190). Additions to dimethyl maleate were also carried out successfully." ... 

Figure 5 FT EPR spectrum of duroquinone radical-anion, durosemiquinone radical as well as triethylamine radical cation and hydroxymethyl radical at a delay time of 100 ns. The simulation of the experimental spectrum is shown in Boltzmann equilibrium. Sample 1 mM DQ with 1 mM TEA in methanol (Reprinted with permission from Ref. 76)...

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