The approaches to 13-methylphenalene system and the studies of aromaticity and antiaromaticity.
Item
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Title
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The approaches to 13-methylphenalene system and the studies of aromaticity and antiaromaticity.
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Identifier
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AAI9108118
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identifier
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9108118
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Creator
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Huang, Wolin.
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Contributor
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Adviser: Klaus G. Grohmann
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Date
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1990
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Organic | Chemistry, Physical
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Abstract
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An important precursor to the long sought 13-methylphenalene system, dihydro-13-methylphenalene (pentaene) 10-4, has been synthesized. Dehydrobromination of the hexabromides gave 10-4 and bromopentaenes, which convert to the 10-4 through a lithium-bromo exchange followed by protonation. 10-4 might undergo an unusual solvent-dependent hydrogen (1,11) {dollar}\sigma{dollar} shift.;10-4 was treated with DDQ at 80{dollar}\sp\circ{dollar}C giving perinaphthenone, and treated with sodium dimsyl at room temperature furnishing phenalenyl anion. In both cases, the stable planar high conjugated phenalene system were formed. As a result, the central methyl has lost.;The interesting known conversion of dione 6-3 into dienedione 6-4 was investigated in detail. The reaction conditions have been optimized, and the yield has been improved to 52%.;The stereochemistry of the tricyclic trione VI was investigated. After a base-catalyzed hydrogen-deuterium exchange, the NOE spectrum undoubtedly points out that VI is cis, cis, trans.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI).;An unusual epoxidation at C1 and C2 in the triene VII has been found, just open to air in solid form for 24 hours, in 80% yield.;For concentrating air sensitive compounds, a modified rotatory evaporator was designed and made. For the very air-sensitive reactions, an all-in-one apparatus was designed and made, in which a reaction container, a filter and a NMR tube are connected safely into a very tiny space.;A quite detailed up-date review of aromaticity and annulene is provided.;AM1 calculation for 13-methylphenalene showed the following. The bond dissociation energy of carbon-carbon bond of the methyl in 13-methylphenalene is as low as 8.71 kcal/mol; Y-hyperconjugation (a new type conjugation) might occur; and methyl-group shift would take place at temperature above {dollar}-{dollar}111{dollar}\sp\circ{dollar}C.;The (4n+2) {dollar}\pi{dollar} electron monocyclic aromaticity rule is explained by group theory. A new aromatic system possessing D{dollar}\sb{lcub}\rm 3h{rcub}{dollar} symmetry and 6n {dollar}\pi{dollar} electron rule is proposed. MO studies, resonance energy per atom (REPA) and {dollar}\sp1{dollar}H NMR data of the parent members of this system support that 6n {dollar}\pi{dollar} electron aromatic compounds show higher aromaticity than (4n+2) {dollar}\pi{dollar} electron monocyclic compounds. This notion may be significant to understand the nature of general aromaticity and to predict some stable compounds especially poly-ionic compounds.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
