f324 moduale 1 benzene

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  • benzene
    • faraday
      • empirical formula= CH
      • molecular formula= C6H6
    • kekule
      • structure of benzene
        • cyclic
        • 3 double bonds
        • 1 hydrogen on each carbon
      • problems with kekules structure
        • low reactivity of benzene
          • benzene compared to other alkenes is unreactive
          • benzene doesn't undergo electrophilic addition which it should
        • thermodynaic stanbilty
          • the thermodynamic stability of benzene using kekules structure is lower than what it should be
        • bond lenths
          • double bonds are shorter than single bonds
          • kekules structure should be a perfect hexagon but it cant be
        • over come the problems
          • suggested that there is a reversible reaction where the double bonds move place
    • delocalised structure
      • pi- electrons delocalised around the ring, above and below the plane
      • p- orbitals overlap to forma delocalised structure above and below the ring
      • between each carbon is a sigma bond
      • cyclic hydrocarbon with 6 carbons and 56 hydrogens
      • pi- orbitals above and below the ring which form pi bonds
      • bond angle- 120'
      • ring is planer
      • c-c bonds are equal lenth
      • delocalised pi orbital system
    • coulorless liquid
    • sweet oder
    • highly flammable
    • component od petral and cigarette smoke
    • formed naturally in forest fires and volcanoes
    • reactions of benzene
      • bromination
      • nitration
      • clorinattion
      • electron dence ring attracts and electrophiel
    • phenol
      • one of the lone pairs on the oxygen overlap eith the delocalised electrons in the benzene ring and one of the lone pairs from the oxygen
      • affect on both the propities of the benzene ring and the -oh
      • interaction between the delocalised electrons in the benzene ring and 1 of the lone pairs on the oxygen atom
      • -oh has to be directly attached to the benzene structure for it to be a phenol
      • simplest phenol-
      • there is a interaction between the delocalised electrons in the benzene ring and one of the lone pairs from the oxygen
      • phenol reacts more rapidly with bromine than benzene because
        • a lone pair of electrons ion the oxygen atom in the phenol group is drawn to the benzene ring
        • this creates a high electron density in the ring structure and is activated
        • the increase electron density polarises bromine molecules which are then attracted more strongly towards the ring in the benzene structure
      • reactions of phenol with na
        • C6H5OH+Aq -> C6H5O- + H+
          • C6H5Oh is a pink solid at r.t.p
        • phenols form a week acidic solution when dissolved in water
        • C6H5OH + NAOH -> C6H5O-NA+ = H2O
        • C6H5OH + NA -> C6H5O-NA+ + 1/2H2
      • reactions of phenol with BR
        • CH5OH + 3BR -> C6H2BR3OH + 3HBR
      • uses of phenol include: preparation of resins, dyes, explosives, lubricants, pesticides and plastics
  • phenol
    • one of the lone pairs on the oxygen overlap eith the delocalised electrons in the benzene ring and one of the lone pairs from the oxygen
    • affect on both the propities of the benzene ring and the -oh
    • interaction between the delocalised electrons in the benzene ring and 1 of the lone pairs on the oxygen atom
    • -oh has to be directly attached to the benzene structure for it to be a phenol
    • simplest phenol-
    • there is a interaction between the delocalised electrons in the benzene ring and one of the lone pairs from the oxygen
    • phenol reacts more rapidly with bromine than benzene because
      • a lone pair of electrons ion the oxygen atom in the phenol group is drawn to the benzene ring
      • this creates a high electron density in the ring structure and is activated
      • the increase electron density polarises bromine molecules which are then attracted more strongly towards the ring in the benzene structure
    • reactions of phenol with na
      • C6H5OH+Aq -> C6H5O- + H+
        • C6H5Oh is a pink solid at r.t.p
      • phenols form a week acidic solution when dissolved in water
      • C6H5OH + NAOH -> C6H5O-NA+ = H2O
      • C6H5OH + NA -> C6H5O-NA+ + 1/2H2
    • reactions of phenol with BR
      • CH5OH + 3BR -> C6H2BR3OH + 3HBR
    • uses of phenol include: preparation of resins, dyes, explosives, lubricants, pesticides and plastics

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