l>electrophilic substitution - the halogenation that benzene

THE HALOGENATION that BENZENE

This page offers you the facts and a simple, uncluttered mechanism for the electrophilic substitution reaction in between benzene and chlorine or bromine in the existence of a catalyst such together aluminium chloride or iron. If you want this mechanism explained to girlfriend in detail, there is a link at the bottom that the page.

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The electrophilic substitution reaction between benzene and also chlorine or bromineThe facts

Benzene reacts v chlorine or bromine in one electrophilic substitution reaction, but only in the visibility of a catalyst. The catalyst is either aluminium chloride (or aluminium bromide if you room reacting benzene through bromine) or iron.

Strictly speaking iron isn"t a catalyst, because it gets permanently readjusted during the reaction. It reacts with few of the chlorine or bromine to kind iron(III) chloride, FeCl3, or iron(III) bromide, FeBr3.

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These stclairdrake.netmpound act as the catalyst and behave specifically like aluminium chloride in this reactions.

The reaction through chlorine

The reaction between benzene and chlorine in the existence of either aluminium chloride or iron offers chlorobenzene.

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or:

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The reaction through bromine

The reaction between benzene and also bromine in the visibility of one of two people aluminium bromide or iron provides bromobenzene. Steel is stclairdrake.netmmonly used because it is cheaper and an ext readily available.

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or:

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The development of the electrophile

We space going to check out the reaction using chlorine and aluminium chloride. If girlfriend want one of the various other stclairdrake.netmbinations, every you have to do is to change each Cl by Br, or each Al by Fe.

As a chlorine molecule philosophies the benzene ring, the delocalised electrons in the ring repel electron in the chlorine-chlorine bond.

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It is the slightly positive finish of the chlorine molecule i m sorry acts as the electrophile. The existence of the aluminium chloride help this polarisation.

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The electrophilic substitution mechanism

Stage one

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Stage two

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The hydrogen is eliminated by the AlCl4- ion which was developed in the an initial stage. The aluminium chloride catalyst is re-generated in this 2nd stage.