- Alternative methods for production of alicyclic epoxides
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The salient and peculiar features of the oxidation of dicyclopentene and unsaturated alicyclic hydrocarbons with a medium-sized carbon ring into the corresponding epoxides have been studied. Organic hydroperoxides, aqueous hydrogen peroxide, and peracids have been used as oxidizing agents. The reactivity of the substrates in each of the oxidation processes under consideration has been estimated, and conditions providing a high epoxide yield have been chosen. The advantages and disadvantages of each process taking into account the problems of isolation of the desired product are considered. The results obtained allow the peracid method to be recommended for the synthesis of dicyclopentene epoxide as an effective and conve-nient for practical implementation. Pleiades Publishing, Ltd., 2014.
- Vereshchagina,Antonova,Abramov,Kopushkina, G. Yu.
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p. 207 - 212
(2014/07/22)
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- Structural Effects in Solvolytic Reactions. 50. Steric Retardation in the Solvolysis of Tertiary Endo Bicyclic Derivatives. Evidence That the Exo:Endo Rate/Product Ratios for typical Reactions in Rigid U-Shaped Bicyclics Is a General Steric Phenomenon
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The exo:endo rate ratios for the solvolysis in 80percent acetone at 25 deg C of the p-nitrobenzoates of tertiary bicyclic alcohols of widely varying U-shape character, such as 2-methyl- and 3-methyl-cis-bicyclooctanols, 2-methyl-2-norbornanol, and 2-, 8-, and 9-methyl-endo-5,6-trimethylene-2-, -8-, and -9-norbornanols increase with increasing U-shape character of the bicyclic skeleton.This supports the proposal that steric retardation of ionization of the endo isomer is a major factor in governing the exo:endo rate ratios in these tertiary systems.A comparison of the solvolysis data with those of representative nonsolvolytic reactions in these U-shaped systems indicates that the exo/endo relative reactivities reveal a similar pattern for all of the reactions.The exo:endo ratios (product or rate) increase with increasing U-shape character of the bicyclic skeleton.Thus the large exo:endo rate ratio in the solvolysis of tertiary 2-norbornyl derivatives may as well be due to steric rather than to the long proposed electronic factor.
- Brown, Herbert, C.,Jagt, David L. Vander,Rothberg, Irvin,Hammar, W. James,Kawakami, James H.
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p. 2179 - 2188
(2007/10/02)
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- Dicyclopentadiene Oxidation. IV. Oxidation of 4,5- and 8,9-Dihydro-dicyclopentadiene
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A mixture of exo- and endo-4,5-dihydro-dicyclopentadiene 5 and also pure endo-8,9-dihydro-dicyclopentadiene 7 and pure exo-dicyclopentadiene 10 was oxidized in the absence and in the presence of catalysts.The compounds containing the norbornene structure mainly gave the corresponding exo-epoxides.No catalytic effects were observed in the formation of these norbornene epoxides.Compound 7 containing only the cyclopentene structure mainly yielded the corresponding hydroperoxide 9.In this case a catalytic effect of epoxidation catalysts was observed : in the presence of such catalysts the epoxide was increased. The results obtained prove the mechanism of dicyclopentadiene oxidation proposed by us.
- Schnurpfeil, D.,Lauterbach, G.
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p. 121 - 128
(2007/10/02)
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