- Simultaneous Generation of t-BuO(radical) and t-BuOO(radical) from the Decomposition of 2,2-Bis(t-butyldioxy)propane. A New Synthetic Method for Introducing a t-BuOO Group into Organic Molecules
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A free-radical synthetic method for introducing a t-BuOO group into various organic substrates has been developed using 2,2-bis(t-butyldioxy)propane (1a) which can efficiently give two oxygen-centered radicals, t-BuO(radical) and t-BuOO(radical), by thermolysis.The thermal reaction of 1a with cumene afforded the desired dialkyl peroxide, t-butyl 1-methyl-1-phenylethyl peroxide, in good yield (53percent based on 1a reacted) together with an appreciable amount of a dimer, 2,3-dimethyl-2,3-diphenylbutane, as a by-product.The addition of t-BuOOH increased the yield of the dialkyl peroxide to as high as 82percent, by suppressing the dimer formation (10percent).Also, reaction with isobutyronitrile and isopropyl methyl ketone gave good yields of dialkyl peroxides.The present method makes it possible to prepare unsymmetrical dialkyl peroxides containing functional groups, if the substrates are good hydrogen donors.
- Watanabe, Yasumasa,Ohta, Kenjiro,Suyama, Shuji
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- DECOMPOSITION OF ORGANIC PEROXIDES AND HYDROGEN PEROXIDE BY THE IRON THIOLATES AND RELATED COMPLEXES
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Disclosed herein is a method of reducing or disproportionating peroxide, comprising combining an organic chalcogenide, an iron salt, and the peroxide in the presence of an additional reductant, which can be the organic chalcogenide. The method can be used to, e.g., prepare alcohols from peroxides and to disproportionate hydrogen peroxide into water and oxygen.
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Paragraph 0725; 0733
(2020/07/04)
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- Synthesis of Ethers via Reaction of Carbanions and Monoperoxyacetals
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Although transfer of electrophilic alkoxyl ("RO+") from organic peroxides to organometallics offers a complement to traditional methods for etherification, application has been limited by constraints associated with peroxide reactivity and stability. We now demonstrate that readily prepared tetrahydropyranyl monoperoxyacetals react with sp3 and sp2 organolithium and organomagnesium reagents to furnish moderate to high yields of ethers. The method is successfully applied to the synthesis of alkyl, alkenyl, aryl, heteroaryl, and cyclopropyl ethers, mixed O,O-acetals, and S,S,O-orthoesters. In contrast to reactions of dialkyl and alkyl/silyl peroxides, the displacements of monoperoxyacetals provide no evidence for alkoxy radical intermediates. At the same time, the high yields observed for transfer of primary, secondary, or tertiary alkoxides, the latter involving attack on neopentyl oxygen, are inconsistent with an SN2 mechanism. Theoretical studies suggest a mechanism involving Lewis acid promoted insertion of organometallics into the O-O bond.
- Kyasa, ShivaKumar,Meier, Rebecca N.,Pardini, Ruth A.,Truttmann, Tristan K.,Kuwata, Keith T.,Dussault, Patrick H.
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p. 12100 - 12114
(2016/01/09)
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- Model dialkyl peroxides of the fenton mechanistic probe 2-methyl-1-phenyl-2-propyl hydroperoxide (MPPH): Kinetic probes for dissociative electron transfer
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Two dialkyl peroxides, devised as kinetic probes for the heterogeneous electron transfer (ET), are studied using heterogeneous and homogeneous electrochemical techniques. The peroxides react by concerted dissociative ET reduction of the O-O bond. Under heterogeneous conditions, the only products isolated are the corresponding alcohols from a two-electron reduction as has been observed with other dialkyl peroxides studied to date. However, under homogeneous conditions, a generated alkoxyl radical undergoes a rapid β-scission fragmentation in competition with the second ET resulting in formation of acetone and a benzyl radical. With knowledge of the rate constant for fragmentation and accounting for the diffuse double layer at the electrode interface, the heterogeneous ET rate constant to the alkoxyl radicals is estimated to be 1500 cm s-1. The heterogeneous and homogeneous ET kinetics of the O-O bond cleavage have also been measured and examined as a function of the driving force for ET, ΔGET, using dissociative electron transfer theory. From both sets of kinetics, besides the evaluation of thermochemical parameters, it is demonstrated that the heterogeneous and homogeneous reduction of the O-O bond appears to be non-adiabatic.
- Magri, David C.,Workentin, Mark S.
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p. 3418 - 3429
(2007/10/03)
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- Substituent Effects in the Decomposition of t-Alkyl t-Butyl Peroxides
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The decomposition rates and products of various t-alkyl t-butyl peroxides were examined in cumene at several temperatures.The decomposition of these peroxides took place homolytically, depending on the structure of the t-alkoxyl moieties (RC(CH3)2-O), and was retarded in the order: R = (CH3)3CCH2 > (CH3)2CH > CH3CH2CH2 > PhCH2 > CH3CH2 > ClCH2 > CH3.The rate constants for the electron-donating alkyl substituents at 150 deg C are correlated very well to a Taft equation (log kd = -10.93Σ?*-6.61 (correlation coefficient of 0.9501)), which is fairly different from the equation log kd = -0.131Σ?*-3.422 for electron-withdrawing polar substituents.From this correlation and a product analysis, the nature of the polar character at the transition state of the decomposition is discussed.
- Matsuyama, Kazuo,Higuchi, Yoshiki
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p. 259 - 265
(2007/10/02)
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