- The Ozonolysis of Tetramethylethylene. Concentration and Temperature Effects
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The products of the ozonolysis of tetramethylethylene in hexane or methylene chloride are remarkably dependent on the concentration of tetramethylethylene.Ozonolysis in neat tetramethylethylene gives mostly tetramethylene epoxide as product.As the concentration of tetramethylethylene is reduced, more acetone diperoxide is formed until it becomes the major product.The reaction also produces 3-hydroperoxy-2,3-dimethyl-1-butene.The product distribution is also quite dependent on reaction temperature.At a given concentration of the alkene the epoxide yield decreases as the temperature is lowered.Simultaneously the acetone diperoxide yield increases with lower temperature.The results are explained by postulating that energy-rich acetone oxide can be partially converted to dimethyldioxirane which is primarily responsible for the epoxidation.The proposed reaction scheme also has acetone oxide dimerize in a stepwise manner to give an intermediate which can either close to give diperoxide or lose singlet oxygen.The singlet oxygen would then react with tetramethylethylene to give the hydroperoxide.
- Murray, Robert W.,Kong, Wei,Rajadhyaksha, Shirish N.
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p. 315 - 321
(2007/10/02)
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- Ozonolyses of Olefins with Chloro Substituents in Vinylic Positions on Polyethylene
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Ozonolyses of the chloro-substituted 5- and 6-membered cycloolefins 20a, 20b and 30a-c on polyethylene afforded the corresponding chloro-substituted ozonides.The thermal decomposition of these ozonides is described.Ozonolyses of the same olefins in solution and of the acyclic chloro olefins 5 and 8 both on polyethylene and in solution gave no ozonides.
- Griesbaum, Karl,Greinert, Reinhard
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p. 391 - 397
(2007/10/02)
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- Thromboxane A2 Analogues from 8-Oxabicyclooct-6-en-3-ones
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We describe approaches to thromboxane A2 analogues (3), (4), and (32) which contain 2,6-dioxabicyclooctane and 2,6-dioxatricyclo3,7>nonane ring system.Both were derived from 2-substituted 8-oxabicyclooct-6-en-3-
- Bowers, Kevin G.,Mann, John,Walsh, E. Brian,Howarth, Oliver W.
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p. 1657 - 1666
(2007/10/02)
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- Ozonolysis of Some Tetrasubstituted Ethylenes
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The olefins 1,4-dibromo-2,3-dimethyl-2-butene, 1-bromo-2,3-dimethyl-2-butene, and 2,3-dimethyl-2-butene were ozonized under a variety of conditions.Ozonolysis of 1,4-dibromo-2,3-dimethyl-2-butene in acetone solvent leads to the unexpected products acetone diperoxide and triperoxide.The results are discussed with respect to questions of concertedness in ozonide formation, the need for activating groups in ozonide formation, and the possible intermediacy of dioxiranes.
- Murray, Robert W.,Agarwal, Sudhir K.
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p. 4698 - 4702
(2007/10/02)
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- Synthesis and X-Ray Analysis of 2,3,5,6,11-Pentaoxabicycloundecanes
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The reactions of bicyclic ozonides and aldehyde- or ketone-derived peroxides, performed or generated in situ, in the presence of chlorosulphonic acid afford the corresponding 2,3,5,6,11-pentaoxabicycloundecanes.In addition, 1,2,4,5-tetraoxans are often isolated from the product mixture.Mechanisms are proposed to account for the observed peroxidic products.An X-ray analysis of the crystalline product (4b) confirms the general structure and reveals that it is solely the exo-isomer.
- Miura, Masahiro,Ikegami, Akio,Nojima, Masatomo,Kusabayashi, Shigekazu,McCullough, Kevin J.,Walkinshaw, Malcolm D.
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p. 1657 - 1664
(2007/10/02)
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