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16 Cards in this Set
- Front
- Back
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What is a benzene derivative?
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A benzene ring where one of the hydrogen atoms has been replaced by an atom or group of atoms
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What are the properties of benzene?
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Colourless liquid
Sweet odour Highly flammable |
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What was Kekulé's proposed structure of benzene?
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A six-membered carbon ring with alternating single and double bonds.
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Benzene does not, under normal conditions (i.e without the presence of a halogen carrier):
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decolourise bromine water
react with strong acids, such as HCl react with halogens: chlorine, bromine or iodine |
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Why does benzene take part in substitution reactions?
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The organic product retains delocalisation, and hence the stability of the benzene ring
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After the nitryl cation has been formed, what reaction takes place in the nitration of benzene?
What type of reaction is this? |
benzene + NO2+ --> nitrobenzene + H+
This is an electrophilic substitution reaction. |
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After benzene has been nitrated, what happens with the extra proton (H+)?
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Reacts with the hydrosulphate ion formed in the production of the nitryl cation.
HSO4- + H+ --> H2SO4 |
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Name the reagents and conditions in the nitration of benzene
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concentrated nitric and concentrated sulfuric acid (catalyst)
Heated between 50-55 degrees celsius. |
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Comment on the nitration of methylbenzene, comparing it to the nitration of benzene
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Nitration of methylbenzene is 25 times faster than the nitration of benzene.
Produces 2,4,6-trinitromethylbenzene, also known as TNT (trinitrotoluene) |
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Comment on the halogenation of benzene. What is required for halogenation, and what type of reaction is it?
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For halogenation of benzene, it needs to be boiled with the halogen and exposed to UV light. Alternatively, a halogen carrier catalyst is required, such as AlCl3, FeCl3, AlBr3, FeBr3 or Fe.
This is an electrophilic substitution reaction |
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Show the formation of a suitable electrophile in the preparation for the halogenation of benzene
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Cl2 + FeCl3 --> Cl+ + FeCl4-
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After chlorobenzene has been formed, write an equation to show what happens with the proton (H+).
Comment on this result. |
FeCl4- + Cl+ --> FeCl3 + HCl
FeCl3 has been regenerated, therefore it is a catalyst. |
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Why is a halogen carrier needed in the halogenation of bromine?
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Benzene is too stable to react with halogens. There is not enough electron density in the benzene ring to polarise the halogen molecule.
Therefore, a much more powerful electrophile is needed, such as a halide ion. This can be formed in the presence of a halogen carrier. |
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What do you observe if bromine is added to benzene?
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No reaction occurs, bromine mixture remains orange.
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What is an aromatic alcohol?
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A benzene ring with an -OH group attached to a side chain.
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What is a phenol?
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A benzene ring with an -OH group attached DIRECTLY to the benzene ring.
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