Factors Affecting the Photoaddition of Olefins to Benzene
Author : Hilary Margaret Tyrrell
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Page : pages
File Size : 45,66 MB
Release : 1974
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Author : Hilary Margaret Tyrrell
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Page : pages
File Size : 45,66 MB
Release : 1974
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Author : M. W. Bin Samsudin
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Page : 281 pages
File Size : 17,43 MB
Release : 1977
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Author : Brian Earnest Foulger
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Page : pages
File Size : 12,15 MB
Release : 1971
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Author : Brian Harold Orger
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Page : pages
File Size : 46,30 MB
Release : 1969
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Author : R. Srinivasan
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Page : 20 pages
File Size : 14,41 MB
Release : 1976
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The photochemical 1,3-addition reaction of benzene, several alkyl benzenes, and anisole to a variety of linear, monocyclic, and bicyclic olefins has been studied from both mechanistic and synthetic points of view. The addition takes place with retention of the stereochemistry at the olefin and with a high degree of orientational specificity. The reaction is believed to originate in the lowest singlet excited state of the aromatic and may involve an exciplex as an intermediate. The quantum yields for the addition at the limit of the olefin concentration fall in a range from 0.1 to 0.5. A model for the exciplex which accounts for all of the observations and has considerable predictive value for the reactivity and orientational effects that are observed in different olefins has been proposed. Two classes of reactions of the photochemical adducts have been investigated in detail. These are the thermal rearrangements, particularly of the adducts of benzene to cyclobutene, and the acid catalyzed rearrangements. All of the 1,3-adducts are sensitive to pyrolysis. At about 280 degrees, in the vapor phase in a static system, the reactions that are observed are reversal of the photoaddition, a 1,5-sigmatropic shift of hydrogen, and the vinylcyclopropane rearrangement. The adducts of cyclobutene also undergo a (2'-vinylcyclopropyl) cyclobutane rearrangement, a hitherto unknown 1,5-sigmatropic shift of a C-C bond. The course of this reaction has been studied by deuterium labeling. Acid catalyzed opening of the 1,3-adducts results in the breaking of the cyclopropane ring to give bicyclo 3.2.1 octane-8-01 derivatives. The sterochemistry of this rearrangement was established.
Author : Mohamed Wahid Bin Samsudin
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Page : pages
File Size : 21,30 MB
Release : 1977
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Author : Owain Griffiths
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Page : pages
File Size : 50,17 MB
Release : 1992
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Author : Henry T. Meriwether
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Page : 81 pages
File Size : 32,99 MB
Release : 1947
Category : Catalysis
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Author : Henry Clay Linstid
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Page : 276 pages
File Size : 14,95 MB
Release : 1978
Category : Addition reactions
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Author : Rama Rao Deshpande
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Page : pages
File Size : 33,73 MB
Release : 1971
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