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- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)/Radical_Reactions_of_Carbohydrates_II%3A_Radical_Reactions_of_Carbohydrates/04%3A_Selenides_and_Tellurides/II._Selenides2 A way for making this choice begins with the observation that the absolute rate constant for reaction of 1 with cyclohexyl phenyl selenide to give cyclohexane (k Se ) is 9.6 x 10 7 M -1 s -1 and th...2 A way for making this choice begins with the observation that the absolute rate constant for reaction of 1 with cyclohexyl phenyl selenide to give cyclohexane (k Se ) is 9.6 x 10 7 M -1 s -1 and the rate constant for reaction of 1-bromooctane to give octane (k Br ) is 2.0 x 10 7 M -1 s -1 . If every cyclohexyl and 1-octyl radical is formed irreversibly and abstracts a hydrogen atom from (CH 3 Si) 3 SiH (Scheme 3), then the ratio k Se /k Br should be equal to the ratio of cyclohexane to oc…
- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)/Radical_Reactions_of_Carbohydrates_I%3A_Structure_and_Reactivity_of_Carbohydrate_Radicals/05%3A_Sequential_Reactions1,2 Since all participants in a sequential reaction, including the intermediate radicals, are present in the reaction mixture at the same time, achieving the selectivity necessary to have each radica...1,2 Since all participants in a sequential reaction, including the intermediate radicals, are present in the reaction mixture at the same time, achieving the selectivity necessary to have each radical react in the desired manner at the correct time is a challenging task, one that is critical to the success of the overall process.
- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)/Radical_Reactions_of_Carbohydrates_I%3A_Structure_and_Reactivity_of_Carbohydrate_Radicals/00%3A_Front_Matter/PrefaceIt provides the information needed for an individual to start with a basic understanding of organic chemistry and reach the current level of understanding of the radical chemistry important in the stu...It provides the information needed for an individual to start with a basic understanding of organic chemistry and reach the current level of understanding of the radical chemistry important in the study of carbohydrates.
- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)/Radical_Reactions_of_Carbohydrates_II%3A_Radical_Reactions_of_Carbohydrates/05%3A_Acetals_and_Ethers/VII._Silyl_Ether_Rearrangement36,37 This concentration dependence can be explained by the more rapidly formed, but less stable, radical 46 having sufficient time and energy, when the concentration of Bu 3 SnH is low, to be conve...36,37 This concentration dependence can be explained by the more rapidly formed, but less stable, radical 46 having sufficient time and energy, when the concentration of Bu 3 SnH is low, to be converted into the more stable radical 47, either by a rearrangement that involves a cyclic transition state or by a fragmentation-addition sequence (Scheme 18).
- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)/Radical_Reactions_of_Carbohydrates_II%3A_Radical_Reactions_of_Carbohydrates/23%3A_Organocobalt_and_Organomercury_Compounds/III._SummaryOrganocobalt complexes are sources of free radicals because heating, photolysis, or enzymatic reaction cleaves a carbon–cobalt bond homolytically to produce carbon-centered and cobalt-centered...Organocobalt complexes are sources of free radicals because heating, photolysis, or enzymatic reaction cleaves a carbon–cobalt bond homolytically to produce carbon-centered and cobalt-centered radicals. Carbon-centered radicals produced from organocobalt complexes also undergo the characteristic radical reactions of addition and cyclization.
- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)Volume I: "Structure and Reactivity of Carbohydrate Radicals", is concerned with the basic structure of carbohydrate radicals and the reactivity that can be expected from these intermediates. "Volume ...Volume I: "Structure and Reactivity of Carbohydrate Radicals", is concerned with the basic structure of carbohydrate radicals and the reactivity that can be expected from these intermediates. "Volume II: Radical Reactions in Carbohydrate Synthesis" contains discussion and analysis of the radical reactions that have been used in carbohydrate synthesis.
- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)/Radical_Reactions_of_Carbohydrates_I%3A_Structure_and_Reactivity_of_Carbohydrate_Radicals/04%3A_Elementary_Reactions/05._Fragmentation_ReactionsHomolytic β-fragmentation of a radical is an elementary reaction that cleaves a bond to one of the atoms adjacent to a radical center. (Other names for β-fragmentation are β-cleavage and β-scission.) ...Homolytic β-fragmentation of a radical is an elementary reaction that cleaves a bond to one of the atoms adjacent to a radical center. (Other names for β-fragmentation are β-cleavage and β-scission.) This type of reaction sometimes produces an unsaturated carbohydrate by expelling a noncarbohydrate radical (eq 27), and other times it gives a carbohydrate radical and an unsaturated noncarbohydrate (eq 28).
- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)/Radical_Reactions_of_Carbohydrates_I%3A_Structure_and_Reactivity_of_Carbohydrate_Radicals/04%3A_Elementary_Reactions/07._Radical_CombinationThe basic requirement in most instances is that the noncarbohydrate radical be sufficiently stable that its concentration in solution builds to the point that it will combine quickly with the more rea...The basic requirement in most instances is that the noncarbohydrate radical be sufficiently stable that its concentration in solution builds to the point that it will combine quickly with the more reactive carbohydrate radicals as they are produced. [Radicals with considerable stability are described as being either persistent or stable (Chapter 2, Section I).
- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)/Radical_Reactions_of_Carbohydrates_II%3A_Radical_Reactions_of_Carbohydrates/07%3A_Unprotected_CarbohydratesRadical reactions of unprotected carbohydrates begin with hydrogen-atom abstraction from a carbon–hydrogen bond in the carbohydrate structure. A hydrogen atom usually is abstracted from an unprotecte...Radical reactions of unprotected carbohydrates begin with hydrogen-atom abstraction from a carbon–hydrogen bond in the carbohydrate structure. A hydrogen atom usually is abstracted from an unprotected carbohydrate by a hydroxyl radical (HO·), but sometimes the sulfate radical anion (SO 4 · - ) is the abstracting agent. A beginning point for discussing radical reactions of unprotected carbohydrates is to examine how the abstracting radicals HO· and SO 4 · - are formed.
- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)/Radical_Reactions_of_Carbohydrates_II%3A_Radical_Reactions_of_Carbohydrates/12%3A_Reactions_of_O-Thiocarbonyl_Compounds/V._Comparing_the_Reactivity_of_O-Thiocarbonyl_and_O-Carbonyl_Carbohydrates223–225 According to this explanation, the equilibrium involving addition of Bu 3 Sn· to a compound with an O-thiocarbonyl group produces a far greater concentration of the adduct radical 77 than the...223–225 According to this explanation, the equilibrium involving addition of Bu 3 Sn· to a compound with an O-thiocarbonyl group produces a far greater concentration of the adduct radical 77 than the concentration of the radical 76 produced by addition of Bu 3 Sn· to the corresponding O-carbonyl carbohydrate.
- https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Radical_Reactions_of_Carbohydrates_(Binkley)/Radical_Reactions_of_Carbohydrates_I%3A_Structure_and_Reactivity_of_Carbohydrate_Radicals/11%3A_Stereoselectivity/VI._SummaryA primary factor in determining this pathway is the way in which various groups shield a radical center. As the steric size of a molecule reacting with a carbohydrate radical increases, the extent to...A primary factor in determining this pathway is the way in which various groups shield a radical center. As the steric size of a molecule reacting with a carbohydrate radical increases, the extent to which the least-hindered pathway is followed also increases. The critical factor in forming a particular stereoisomer in a reaction is the ability of the reactants to maintain in the transition state a stabilizing interaction between orbitals on C-1 and the ring oxygen atom.
