80037-95-2Relevant articles and documents
Study of alkyl radicals fragmentation from 2-alkyl-2-propoxyl radicals
Nakamura, Tomoyuki,Watanabe, Yasumasa,Suyama, Shuji,Tezuka, Hiroshi
, p. 1364 - 1369 (2007/10/03)
The reaction of a series of 2-alkyl-2-propoxyl radicals 2 in cumene has been studied. Alkoxyl radicals 2 were generated from the thermolysis of the corresponding tert-alkyl peroxypivalates, and underwent several modes of unimolecular reactions, that is, β-scission to give methyl radical, β-scission to give alkyl radicals and 1,5-H shift, which competed with hydrogen abstraction from cumene. The ratios of the rate constant for alkyl radicals elimination to that for methyl radical elimination, kβ(R)/kβ(Me), were determined by using the radical trapping method employing TEMIO as the scavenger. The logarithm of the relative rate was satisfactorily correlated with the heat of formation of the leaving alkyl radicals containing the steric parameters of neopentyl radical 2d. Then the plot of ln [kβ(R)/kβ(Me)] vs. the SOMO energies of the corresponding alkyl radicals showed a linear relationship with a slope of -7.6 eV-1, which is comparable to that of formolysis of alkyl bromides. The mechanism involving a fairly polar transition state of the alkyl radicals fragmentation from tert-alkoxyl radicals 2 is discussed in terms of the MO diagrams and the solvent effects.
Reaction of acyclic hydrocarbons towards t-butoxy radicals. A study of hydrogen atom abstraction by using the radical trapping technique
Dokolas, Peter,Loffler, Steven M.,Solomon, David H.
, p. 1113 - 1120 (2007/10/03)
The reaction of 3-methylpentane and 2,4-dimethylpentane toward t-butoxy radicals has been investigated, in neat and benzene solutions, by using the radical trapping technique. Abstraction occurs principally from the tertiary and secondary C-H reaction sites of 3-methylpentane and the tertiary position of 2,4-dimethylpentane. The tertiary and in particular secondary C-H reaction sites of 2,4-dimethylpentane are shown to be considerably less susceptible towards t-butoxy radical facilitated abstraction compared with the equivalent reaction sites of 3-methylpentane. As a result, the latter is three times as reactive as 2,4-dimethylpentane as a neat hydrocarbon solution and seven times as reactive in a diluted mixture of benzene. Differences in selectivity and rate of hydrogen abstraction, between the substrates, are interpreted in terms of non-bonding interactions retarding t-butoxy radicals from approaching sterically demanding C-H reaction sites. The selectivity from 3-methylpentane is solvent-insensitive whereas abstraction from 2,4-dimethylpentane is modified in benzene. Further, the rate of hydrogen abstraction, from either substrate, to t-butoxy radical β-scission is considerably smaller in benzene. Both observations are interpreted in terms of t-butoxy radical solvation by the aromatic solvent.
A novel organic peroxyester as an exclusive source of tert-butyl radicals
Nakamura, Tomoyuki,Watanabe, Yasumasa,Tezuka, Hiroshi,Busfield, W. Ken,Jenkins, Ian D.,Rizzardo, Ezio,Thang, San H.,Suyama, Shuji
, p. 1093 - 1094 (2007/10/03)
A novel peroxyester, 1,1,2,2-tetramethylpropyl peroxypivalate 1b, has been synthesized and thermolyzed in cumene. The kinetic data show that the decomposition rate constant of 1b is about three times higher than that of tert-butyl peroxypivalate. The radical trapping technique employing 1,1,3,3-tetramethyl-2,3-dihydro-1H-isoindol-2-yloxyl has been used to study the decomposition mechanism of 1b. The results show that the thermolysis of 1b in cumene generates tert-butyl radicals exclusively.
