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What is the catalyst responsible for the halogenation of benzene?
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Mojolaoluwa Olatunbode
What is the catalyst responsible for the halogenation of benzene?
Actually halogenation is Substitution reactions
In which benzene reacts with chlorine or bromine in the presence of a catalyst, replacing one of the hydrogen atoms on the ring by a chlorine or bromine atom.
The reactions happen at room temperature. The catalyst is either aluminium chloride (or aluminium bromide if you are reacting benzene with bromine) or iron.
Strictly speaking iron isn't a catalyst, because it gets permanently changed during the reaction. It reacts with some of the chlorine or bromine to form iron(III) chloride, FeCl3 or iron(III) bromide, FeBr3
In which benzene reacts with chlorine or bromine in the presence of a catalyst, replacing one of the hydrogen atoms on the ring by a chlorine or bromine atom.
The reactions happen at room temperature. The catalyst is either aluminium chloride (or aluminium bromide if you are reacting benzene with bromine) or iron.
Strictly speaking iron isn't a catalyst, because it gets permanently changed during the reaction. It reacts with some of the chlorine or bromine to form iron(III) chloride, FeCl3 or iron(III) bromide, FeBr3
The catalyst is a Lewis acid, either aluminum(III) or iron(III).
It facilitates the reaction by coordinating a molecule of X2 (Cl2 or Br2). One of the halogens ends up as X-minus, temporarily attached to the catalyst; the other ends up as X-plus, attached to the benzene ring in the cationic intermediate.
The base that deprotonates the intermediate is the halide anion, turned loose from the catalyst.
Alkylation of iron or aluminum cannot take place under these conditions; you need more nucleophilic conditions. Organoaluminum compounds can be made by reacting aluminum(III) halides with Grignard reagents. Such conditions would never allow electrophilic halogenation!
The catalyst is a Lewis acid, either aluminum(III) or iron(III).
It facilitates the reaction by coordinating a molecule of X2 (Cl2 or Br2). One of the halogens ends up as X-minus, temporarily attached to the catalyst; the other ends up as X-plus, attached to the benzene ring in the cationic intermediate.
The base that deprotonates the intermediate is the halide anion, turned loose from the catalyst.
Alkylation of iron or aluminum cannot take place under these conditions; you need more nucleophilic conditions. Organoaluminum compounds can be made by reacting aluminum(III) halides with Grignard reagents. Such conditions would never allow electrophilic halogenation!
Actually halogenation is Substitution reactions
In which benzene reacts with chlorine or bromine in the presence of a catalyst, replacing one of the hydrogen atoms on the ring by a chlorine or bromine atom.
The reactions happen at room temperature. The catalyst is either aluminium chloride (or aluminium bromide if you are reacting benzene with bromine) or iron.
Strictly speaking iron isn't a catalyst, because it gets permanently changed during the reaction. It reacts with some of the chlorine or bromine to form iron(III) chloride, FeCl3 or iron(III) bromide, FeBr3
Actually halogenation is Substitution reactions
In which benzene reacts with chlorine or bromine in the presence of a catalyst, replacing one of the hydrogen atoms on the ring by a chlorine or bromine atom.
The reactions happen at room temperature. The catalyst is either aluminium chloride (or aluminium bromide if you are reacting benzene with bromine) or iron.
Strictly speaking iron isn't a catalyst, because it gets permanently changed during the reaction. It reacts with some of the chlorine or bromine to form iron(III) chloride, FeCl3 or iron(III) bromide, FeBr3
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The catalyst is a Lewis acid, either aluminum(III) or iron(III).
It facilitates the reaction by coordinating a molecule of X2 (Cl2 or Br2). One of the halogens ends up as X-minus, temporarily attached to the catalyst; the other ends up as X-plus, attached to the benzene ring in the cationic intermediate.
The base that deprotonates the intermediate is the halide anion, turned loose from the catalyst.
Alkylation of iron or aluminum cannot take place under these conditions; you need more nucleophilic conditions. Organoaluminum compounds can be made by reacting aluminum(III) halides with Grignard reagents. Such conditions would never allow electrophilic halogenation!
The catalyst is a Lewis acid, either aluminum(III) or iron(III).
It facilitates the reaction by coordinating a molecule of X2 (Cl2 or Br2). One of the halogens ends up as X-minus, temporarily attached to the catalyst; the other ends up as X-plus, attached to the benzene ring in the cationic intermediate.
The base that deprotonates the intermediate is the halide anion, turned loose from the catalyst.
Alkylation of iron or aluminum cannot take place under these conditions; you need more nucleophilic conditions. Organoaluminum compounds can be made by reacting aluminum(III) halides with Grignard reagents. Such conditions would never allow electrophilic halogenation!
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