Cycloheptatriene
Structural formula | ||||||||||||||||
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General | ||||||||||||||||
Surname | Cycloheptatriene | |||||||||||||||
other names |
Tropilids |
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Molecular formula | C 7 H 8 | |||||||||||||||
Brief description |
Yellow liquid with an unpleasant odor |
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External identifiers / databases | ||||||||||||||||
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properties | ||||||||||||||||
Molar mass | 92.14 g mol −1 | |||||||||||||||
Physical state |
liquid |
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density |
0.95 g cm −3 (25 ° C) |
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Melting point |
−80 ° C |
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boiling point |
117 ° C |
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Refractive index |
1.5211 |
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safety instructions | ||||||||||||||||
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Toxicological data | ||||||||||||||||
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C |
Cycloheptatriene (outdated: tropilides ; derived from tropane , which itself is derived from atropine ) is a cyclic unsaturated hydrocarbon with the empirical formula C 7 H 8 and three conjugated double bonds .
Cycloheptatriene is a structural isomer of toluene . B. can be converted photochemically .
Tropylium cation
The reaction of cycloheptatriene with bromine or hydride ion acceptors such as triphenylcarbenium tetrafluoroborate forms the aromatic tropylium cation ( cycloheptatrienylium , [C 7 H 7 ] + ) with elimination of a hydride ion (H - ):
Cycloheptatriene has an angled structure with different bond lengths between the carbon atoms , while the tropylium cation is completely planar with identical CC distances and equivalent hydrogen atoms . This cation was predicted by Hückel as early as 1931 , but was not detected until 1954 by William von Eggers Doering and Lawrence H. Knox .
Under electron impact conditions (in the mass spectrometer), almost all benzyl compounds rearrange with ring expansion before fragmentation, so that a tropylium cation is formed.
Individual evidence
- ↑ a b c d e f g Datasheet Cycloheptatriene from AlfaAesar, accessed on January 26, 2013 ( PDF )(JavaScript required) .
- ↑ Cycloheptatriene data sheet from Sigma-Aldrich , accessed on March 23, 2011 ( PDF ).
- ^ JE Huheey, EA Keiter, RL Keiter: Inorganic Chemistry: Principles of Structure and Reactivity , 2003, Walter de Gruyter , ISBN 3-11-017903-2 .
- ^ W. von E. Doering, LH Knox: The Cycloheptatrienylium (Tropylium) Ion. In: Journal of the American Chemical Society. 76, 1954, pp. 3203-3206, doi: 10.1021 / ja01641a027 .
- ^ Collective of authors: Analytikum , VEB Deutscher Verlag für Grundstoffindustrie Leipzig, 1971, p. 338.