aromatics Flashcards
(12 cards)
molecular formula of benzene
C₆H₆
why is Kekule’s structure for benzene wrong?
- benzene doesn’t decolourise bromine water
- all C-C bonds in benzene are the same length
describe the bonding in benzene
-each C has three covalent bonds
-spare electrons overlap
-delocalised ring of pi electrons
describe the shape in benzene
-(each C has) trigonal planar
-6 carbons/ 120 degree bond angle
- C-C bonds in benzene shorter than C-C single bonds but longer than C=C double bonds
order of the lengths of different C bonds
C=C < C-C in benzene < C-C single bond
explain why benzene is more stable than Kekule’s structure
-due to delocalised ring of electrons
-expected ΔH is -360
-actual ΔH is 152 less exothermic
equation for generation of ⁺NO₂
H₂SO₄ + HNO₃ → HSO₄⁻ + ⁺NO₂ + H₂O
equation for regeneration of acid catalyst
HSO₄⁻ + H⁺ → H₂SO₄
equation for conversion of nitrobenzene to phenylamine
C₆H₅NO₂ + 6[H] → C₆H₅NH₂ + 2H₂ O
explain why methylbenzene is more reactive than benzene
-methyl group has positive inductive effect; it pushes electrons towards delocalised ring of electrons
-stronger attraction to electrophile
general equation for generation of R-C₊=O
R-COCl + AlCl₃ → R-C₊=O + AlCl₄⁻
equation for generation of AlCl₃ catalyst
AlCl₄⁻ + H⁺ → AlCl₃ + HCl
