Cycloheptatriene

Tropilidene

Yellow liquid with unpleasant odor

Liquid

0.95 g · cm -3 ( 25 ° C)

-80 ° C

117 ° C.

1.5211

Risk

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Cycloheptatriene (obsolete: tropilidene; derived from tropane, which is itself derived from atropine ) is a cyclic unsaturated hydrocarbon with the formula C7H8 and three conjugated double bonds.

Cycloheptatriene is a structural isomer of toluene, in which it can be converted photochemically, for example.

Tropylium

By reaction of cycloheptatriene with bromine or hydride acceptors such Triphenylcarbeniumtetrafluoroborat formed by elimination of a hydride ion (H- ), the aromatic tropylium cation ( cycloheptatrienylium, [ C7H7 ] ):

Cycloheptatriene has a bent structure with different bond lengths between the carbon atoms, while the tropylium cation is constructed completely planar with identical C-C distances and equivalent hydrogen atoms. This cation was predicted by Hückel in 1931, but proved only in 1954 by William von Eggers Doering and LH Knox.

Under electron impact conditions ( in the mass spectrometer ), almost all benzyl store to before the fragmentation of ring expansion, so that a tropylium cation.