17072-58-1Relevant articles and documents
Catalyzed Radical Termination in the Presence of Tellanyl Radicals
Ribelli, Thomas G.,Rahaman, S. M. Wahidur,Matyjaszewski, Krzysztof,Poli, Rinaldo
supporting information, p. 13879 - 13882 (2017/10/13)
The decomposition of the diazo initiator dimethyl 2,2′-azobis(isobutyrate) (V-601), generating the Me2C.(CO2Me) radical, affords essentially the same fraction of disproportionation and combination in media with a large range of viscosity (C6D6, [D6]DMSO, and PEG 200) in the 25–100 °C range. This is in stark contrast to recent results by Yamago et al. on the same radical generated from Me2C(TeMe)(CO2Me) and on other X-TeR systems (X=polymer chain or unimer model; R=Me, Ph). The discrepancy is rationalized on the basis of an unprecedented RTe.-catalyzed radical disproportionation, with support from DFT calculations and photochemicaL V-601 decomposition in the presence of Te2Ph2.
Dissociation and Aromatization of a Semibenzene. Reactions of Triphenylmethyl and Methyl Isobutyryl Radicals
Engel, Paul S.,Chen, Yanqiu,Wang, Chengrong
, p. 3073 - 3079 (2007/10/02)
Semibenzene 4, which can be regarded as the recombination product of triphenylmethyl and methyl isobutyryl radicals (5), affords exactly these intermediates on thermolysis or inefficiently on direct photolysis.Recombination and disproportionation of these dissimilar radicals proceeds with a much lower barrier than the dimerization of triphenylmethyl.Whereas thiophenol or triplet 9-fluorenone aromatize 4, thermolysis in the presence of 1,4-cyclohexadiene allows trapping of 5 and oligomeric radical 13.From the measured heat of aromatization (22.0 kcal/mol), the C-H bond dissociation enthalpy of 4 and its analogue lacking the side chain ("p-isotriphenylmethane") is calculated to be 54 kcal/mol, the lowest value known for any closed-shell, neutral hydrocarbon.Exposure of 4 to the atmosphere causes rapid autoxidation to hydroperoxide 19, which thermolyzes in the GC to aromatic ketones and phenols instead of undergoing a 1,2-aryl shift.
Photochemical Reactions of Arenecarboxylic Acid Esters with Electron-Rich Alkenes: 2 + 2 Cycloaddition, Hydrogen Abstraction, and Cycloreversion
Cantrell, Thomas S.,Allen, Andrew C.
, p. 135 - 139 (2007/10/02)
The photochemical reaction of arenecarboxylic acid methyl esters and isopropyl esters with alkenes has been examined and found to afford three types of products: (a) 2-alkoxyoxetanes 3 via a direct 2 + 2 cycloaddition to the substrate alkenes; (b) β,γ-unsaturated ketones 5 via hydrogen abstraction by the carbonyl oxygen of the photoexcited ester from an allylic position of the substrate alkene; and (c) alkoxyalkenes 4, which arise via 2 + 2 cycloreversion of the oxetanes 3.The quantum yields for the formation of the various products generally fell in the range 0.005-0.03, approximately 1 order of magnitude less than those of aryl ketones and aldehydes undergoing similar reactions.
