Cyclohexene, Benzene and Phenol - Reactivity and structure

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  • Created by: Danny
  • Created on: 07-10-12 18:10

Three Flaws in Kekules structure of Benzene:

  • Low Reactivity (3 Double bonds should of made Benzene reactive/unstable however it is a stable molecule)
  • Lower Enthalpy (Expected Enthalpy = -360kjmol-1 -- Actual Enthalpy              
    - 208kjmol-3)
  • Carbon-Carbon bond lengths are not symmetrical as stated (x-ray diffraction proved this)

Reactions Under normal Conditions:

Benzene will not:

  • De-colourise Bromine water
  • React with strong acids
  • React with halogens 

Cyclohexene will:

  • Decolourise Bromine water
  • React with strong acids
  • React with halogens

Features of Benzene:

Benzene is a cyclic hydrocarbon with a structural formula of C6H6, the shape around each carbon is trigonal planar which has a bond angle of 120 degrees.
The electrons in the P-orbitals overlap, this results in a ring of electron density above and below the plane of Carbon atoms. This produces a 'pi-cloud' where one carbon atom contributes one electron forming a delocalised system of six electrons. 

To preserve stability, Benzene takes part in Electrophilic substitution reactions (Electrophile substitutes an atom)

Electrophile: is an atom that is attracted to an electron rich centre which accepts a pair of electrons forming a dative covelant bond.

Delocalised: Electrons are shared between more than two atoms.

Nitrification of Benzene:

Reagents required:

  • Concentrated HNO3
  • Concentrated H2SO4

Conditions Required:

  • 50 degrees Celsius
  • Reflux 

Bromination of Benzene:

  • Benzene is too stable to…


geology wizard

is this from the ocr course?

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