A2 OCR Salters B Chemistry 12.4 Reactions of arenes

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  • Created by: Emily
  • Created on: 08-01-13 09:25
How are electrons arranged in benzene?
The 6 electrons of the delocalised system are free to move around the ring. They spread out in a cloud extending above and below the ring forming regions of high electron density
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The areas of high electron density in a benzene ring tend to attract...
Positive ions or atoms with a partial positive charge (so benzene reacts with electrophiles)
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Why does benzene undergo substitution rather than addition reactions?
In substitution reactions the stable benzene ring system is kept intact
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Why are substitution reactions of benzene relatively slow?
The first step involves disrupting the delocalised electron system which requires a large amount of energy
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Benzene can react with bromine in the presence of...
A catalyst e.g. iron filings or iron (III) bromide (FeBr3)
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What is produced from the bromination of benzene?
Bromobenzene and hydrogen bromide
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What are the conditions for the nitration of benzene?
Nitrating mixture (concentrated nitric and sulfuric acid) and temperature below 55 degrees Celsius
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What is produced from the nitration of benzene?
Nitrobenzene and water
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What are the conditions for the chlorination of benzene?
Aluminium chloride (AlCl3) catalyst often used. Reaction must be carried out in anhydrous conditions as AlCl3 reacts violently with water
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What two reactions are part of the Friedel-Crafts reactions?
Alkylation and acylation
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What are ionic liquids?
Liquids at room temperature that only contain ions. They are usually made up of organic cations and organic/inorganic anions
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Why have ionic liquids been promoted as new 'green' alternatives to conventional laboratory solvents?
Low volatility reduces emissions, low flammability and toxicity increases safety, temperature at which Friedel-Crafts reactions can be carried out at are lower, they are easily recycled which saves resources and money
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Card 2

Front

The areas of high electron density in a benzene ring tend to attract...

Back

Positive ions or atoms with a partial positive charge (so benzene reacts with electrophiles)

Card 3

Front

Why does benzene undergo substitution rather than addition reactions?

Back

Preview of the front of card 3

Card 4

Front

Why are substitution reactions of benzene relatively slow?

Back

Preview of the front of card 4

Card 5

Front

Benzene can react with bromine in the presence of...

Back

Preview of the front of card 5
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