Unit 4 Aromatic chemistry

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What are the properties of benzene?
it is a colourless volitile liquid which is immiscible in water
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Why is Kekule's theory wrong?
only 3 isomers of dibromobenzene-predicted=4,benzene isn't as reactive as predicted-doesn't decolourise B2water(test for C=C),enthalpy of hydrogenisation is more than x3 lower than predicted,bonds are all the same length (C-C/C=C=different lengths)
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How is benzene bonded?
Cs are bonded with intimediate bonds with a cloud os delocalised Pi electrons above and below the ring
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Why does benzene undergo electrophillic substitution but not electrophillic addition?
high elctron density attracts electrophilic attack, but addition would disrupt the ring and is not energetically favoured.
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What are the conditions for the nitration of benzene?
conc nitric acid, conc sulphuric acid and 50degreesC
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What are the equations for the nitration of benzene?
HNO3 + H2SO4 -> H2NO3+ +HSO4- H2NO3+ -> NO2+ + H2O
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In the nitration of benzene, which species are the electrophiles and nulceophiles?
electrophile=NO2+ nucleophile=HSO4-
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How can Nitrobenzene be converted to aminobenzene?
by reducing the NO2 group to a NH2 group using a reducing agent of Fe/Sn with moderately conc HCl
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How are azo dyes produced?
Phenylamine is converted into benzenediazonium chloride and then reacting these together in a coupling reaction
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What are the azo groups and the aromatic groups together called?
chromophore
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How is the nitration of benzene used in industry?
for the production of explosives (TNT from ethylbenzene) this is because the induction effect of the methyl group favours substitution of the ortho and para positions
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Waht does the Friedel-Craft alkylation of benzene require?
a haloalkane, AlCl3/FeCl3 catalyst and 40degree heat
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What are the uses of Friedel-Craft alkylation?`
The manufacture of TNT, the production of polystyrene, oxidisesd to form phenol and propanone
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How can ethylbenzene be prepared?
from the acylation of benzene with enthanoyl chloride which first produces phenylethane. This is then reduced with H2/Ni.
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Card 2

Front

Why is Kekule's theory wrong?

Back

only 3 isomers of dibromobenzene-predicted=4,benzene isn't as reactive as predicted-doesn't decolourise B2water(test for C=C),enthalpy of hydrogenisation is more than x3 lower than predicted,bonds are all the same length (C-C/C=C=different lengths)

Card 3

Front

How is benzene bonded?

Back

Preview of the front of card 3

Card 4

Front

Why does benzene undergo electrophillic substitution but not electrophillic addition?

Back

Preview of the front of card 4

Card 5

Front

What are the conditions for the nitration of benzene?

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