Alkoxycarbonyl Radicals Research Articles

ChemInform Abstract: Kinetics of Reactions of Cyclopropylcarbinyl Radicals and Alkoxycarbonyl Radicals Containing Stabilizing Substituents: Implications for Their Use as Radical Clocks.

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Kinetics of Reactions of Cyclopropylcarbinyl Radicals and Alkoxycarbonyl Radicals Containing Stabilizing Substituents: Implications for Their Use as Radical Clocks

Kinetics of Reactions of Cyclopropylcarbinyl Radicals and Alkoxycarbonyl Radicals Containing Stabilizing Substituents: Implications for Their Use as Radical Clocks

Reductive addition to electron-deficient olefins with trivalent iodine compounds

(Diacyloxyiodo)arene was treated with electron-deficient olefins in the presence of hydrogen donor such as 1,4-cyclohexadiene to give the reductive addition products via alkyl radical through the radical decarboxylative pathway in good yields. Moreover, this system was able to generate either alkoxycarbonyl radicals or alkyl radicals with [bis(alkoxyoxalyloxy)iodo]benzene, which was prepared from alcohol, oxalyl chloride, and (diacetoxyiodo)benzene via two steps, depending on reaction conditions. These radicals were also utilized for CC bond formation with electron-deficient olefins.

A New Selective Method for the Homolytic Alkylation and Carboxylation of Quinones by Monoesters of Oxalic Acid

Abstract Alkyl and alkoxycarbonyl radicals were generated by oxidative decarboxylation of oxalic acid monoesters by persulfate; they were then utilized for the selective substitution of quinones.

EPR study of long-range proton couplings in aliphatic acetoxy and alkoxycarbonyl radicals

Earlier EPR studies of radicals of structures •C(X 1(X 2)OC(O)(X 3) ( 1) and •C(X 1)(X 2)C(X 3)(X 4)OC(O)(X 5) ( 2) (where an (X−) group is an H− or a simple substituent such as CH 3−), generated in aqueous solution at approximately 25°C from saturated and unsaturated aliphatic formates and acetates, have shown that the observed long-range formyl- and acetyl-proton couplings were sensitive probes of variations in preferred radical conformations accompanying changes in the degree and nature of X substitution. In the course of this recent work, a few radicals were also observed of structure CH 2(X 1)OC(O)C(X 2)(X 3) ( 3), all of which exhibited δ-CH alkoxyl-proton couplings. By analogy with the acetyl-proton coupling variations in type- 1 and - 2 radicals, it is predicted that the size of the long-range alkoxyl-proton couplings in type- 3 radicals would also depend on the degree and nature of substitution at the α and δ carbons. Results are reported of a successful comprehensive study of many additional type- 3 radicals aimed at establishing this relationship between alkoxyl-proton couplings and substitutional characteristics in, and hence preferred conformations of, type- 3 radicals.

Spin Trapping of Alkoxycarbonyl Radicals from the Photolysis of Alkoxycarbonylmercury Compounds

Abstract Irradiation of alkoxycarbonylmercury compounds in benzene in the presence of nitrone radical traps leads to the scavenging of alkoxycarbonyl radicals.

The electron spin resonance spectra and decarboxylation of alkoxycarbonyl radicals

The e.s.r. spectrum of the t-butoxycarbonyl σ-radical, generated by u.v. irradiation of a liquid mixture of di-t-butyl peroxide and t-butyl formate, has been observed. Decarboxylation of this radical has been monitored by kinetic e.s.r. spectroscopy and the unimolecular rate constant for the reaction But·ĊO → But·+ CO2 is given by log (k/s–1)= 13·4 – 12·1/θ where θ= 2·303 RT/kcal mol–1.These kinetic parameters differ from those reported in an earlier communication because it was assumed that the rate constants for reaction of a t-butyl radical with a t-butyl radical or with a t-butoxycarbonyl radical had the same value. This assumption has been tested experimentally and shown to be incorrect.Abstraction of hydrogen from the alkoxy-groups of alkyl carbonates gives radicals which do not decompose to form alkoxycarbonyl radicals.

Hypoiodite reaction: the decomposition of oxalic acid half-esters

Alkyl half-esters of oxalic acid photolysed with mercury(II) oxide–iodine reagent gave mainly dialkyl oxalates. 1-Apocamphyl hydrogen oxalate gave, in addition to the diester, 1-apocamphyl iodide. 9-Triptycyl hydrogen oxalate gave 9-triptycyl iodoformate, which was thermally decomposed to 9-iodotriptycene and with silver tetrafluoroborate gave 9-triptycyl fluoroformate. We suggest that diester formation occurs by coupling of an intermediate alkoxycarbonyl radical.