4259-00-1Relevant articles and documents
Rate Constants and Arrhenius Parameters for the Reactions of Some Carbon-Centered Radicals with Tris(trimethylsilyl)silane
Chatgilialoglu, C.,Dickhaut, J.,Giese, B.
, p. 6399 - 6403 (2007/10/02)
Rate constants for the reactions of some carbon-centered radicals with (Me3Si)3SiH have been measured over a range of temperatures by using competing unimolecular radical reactions as timing devices.For example, the rate constants (at 298 K) are 3.7, 1.4, and 2.6 x 1E5 M-1 s-1 from primary, secondary, and tertiary alkyl radicals, respectively.Comparison of the radical trapping abilities of tri-n-butylstannane and tris(trimethylsilyl)silane is discussed.The use of 1,1-dimethyl-5-hexenyl cyclization as a radical clock has been recalibrated by using new data and data from the literature.
Organometallic Reaction Mechanisms. 17. Nature of Alkyl Transfer in Reactions of Grignard Reagents with Ketones. Evidence for Radical Intermediates in the Formation of 1,2-Addition Product Involving Tertiary and Primary Grignard Reagents
Ashby, E. C.,Bowers, Joseph R.
, p. 2242 - 2250 (2007/10/02)
When a Grignard reagent reacts with an aromatic ketone, a radical anion-radical cation pair is formed which can collapse to give 1,2-addition product or dissociate to form a radical anion and a free radical within the solvent cage which in turn can collapse to 1,2-addition product or a conjugate addition product or escape the solvent cage to form pinacol.The 1,2-addition products, which form after dissociation of the radical anion-radical cation pair, show free-radical character as indicated by the cyclized 1,2-addition products formed from the reaction of a tertiary Grignard reagent probe with benzophenone in THF and from the reaction of a primary Grignard reagent probe (neooctenyl Grignard reagent) with benzophenone in ether.The 1,6-addition products, which come about after dissociation of the radical anion-radical cation pair, show free-radical character as evidenced by the cyclized 1,6-addition products formed in all of the reactions which involve the tertiary probe Grignard reagent (in all solvents studied) with benzophenone and 2-MBP and also in the reaction of the neooctenyl probe Grignard reagent with 2-MBP.
