Friedel craft alkylation reaction

Friedel craft alkylation reaction

In this Friedel craft alkylation reaction Arenes, an alkyl group is introduced on the benzene or arene ring by using the alkyl halide in presence of anhydrous AlCl₃. The reagents can be represented as

1. _{Anhydrous AlCl3}
2. Anhydrous FeCl₃
3. BF₃
4. TiCl₃
5. ZnCl₂
6. SnCl₄

The mechanism of the reaction starts with the formation of an Alkyl carbonium ion. Alkyl halide reacts with anhydrous AlCl3 and acts as a halogen carrier to produce an alkyl carbonium ion (electrophile). The stability of an alkyl carbonium ion is important. 

The alkyl carbonium ion formed reacts with an aromatic ring to produce resonating forms of the arene. This positive charge on the aromatic ring a stabilized by resonating forms.
In resonance hybrid structure the positive charges are distributed over five carbon atoms so relative positive charge density on each carbon atom is very less and thus it is stabilized.

The structure three formed in the resonating forms further stabilizes to give a mono-substituted alkyl derivative.

The H+ ion release in this reaction joins with the conjugate base to form a byproduct here it is termed as spent acid.

The monosubstituted derivative of arenes uses an alkyl halide to give the monosubstituted derivative. While deciding the product of alkylation stability of the carbonium ion formed is to be taken into account. As shown in the examples 

 

 

 

 

Check out reactions

Chlorination Reaction	Bromination Reaction	Nitration Reaction
Sulphonation Reaction	Friedel Craft Alkylation Reaction	Friedel craft Acylation Reaction

 

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Friedel craft alkylation reaction

Friedel craft alkylation reaction

In this Friedel craft alkylation reaction Arenes, an alkyl group is introduced on the benzene or arene ring by using the alkyl halide in presence of anhydrous AlCl₃. The reagents can be represented as

1. _{Anhydrous AlCl3}
2. Anhydrous FeCl₃
3. BF₃
4. TiCl₃
5. ZnCl₂
6. SnCl₄

The mechanism of the reaction starts with the formation of an Alkyl carbonium ion. Alkyl halide reacts with anhydrous AlCl3 and acts as a halogen carrier to produce an alkyl carbonium ion (electrophile). The stability of an alkyl carbonium ion is important. 

The alkyl carbonium ion formed reacts with an aromatic ring to produce resonating forms of the arene. This positive charge on the aromatic ring a stabilized by resonating forms.
In resonance hybrid structure the positive charges are distributed over five carbon atoms so relative positive charge density on each carbon atom is very less and thus it is stabilized.

The structure three formed in the resonating forms further stabilizes to give a mono-substituted alkyl derivative.

The H+ ion release in this reaction joins with the conjugate base to form a byproduct here it is termed as spent acid.

The monosubstituted derivative of arenes uses an alkyl halide to give the monosubstituted derivative. While deciding the product of alkylation stability of the carbonium ion formed is to be taken into account. As shown in the examples 

 

 

 

 

Check out reactions

Chlorination Reaction	Bromination Reaction	Nitration Reaction
Sulphonation Reaction	Friedel Craft Alkylation Reaction	Friedel craft Acylation Reaction

 

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Nucleophilic Substitution reaction	Free Radical substitution reaction	Electrophilic addition reaction	Free radical addition reaction
Nucleophilic addition reaction	Elimination reaction	Bond Fission

 

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Chemistry XII	Mock Test XI	Mock Test XII
Mock Test NEET	Mock Test JEE Mains	Science class 9

 

CBSE Chemistry syllabus

 

https://www.myetutors.com/?p=15745&feed_id=81

Sulphonation reaction Arenes

Sulphonation reaction Arenes:

 

in this Sulphonation reaction Arenes, a sulphonic acid group is introduced on the benzene or arene ring by using the concentrated sulphuric acid or oleum. The reagents can be represented as

1. Concentrated H₂SO₄ 
2. Concentrated H₂SO₄ + SO₃
3. Oleum

There is equilibrium between concentrated sulphuric acid and Sulphur trioxide.

the mechanism of the reaction starts with the formation of Sulphur trioxide gas. Protonation of Sulphur trioxide occurs by forming sulphonium ion, this is due to the fact that there is two dπ-dπ bonds in Sulphur trioxide. These bonds are weak bonds and readily react with a proton to form a sulphonium ion (an electrophile). 

the sulphonium ion formed reacts with an aromatic ring to produce resonating forms of the arene. This positive charge on the aromatic ring a stabilized by resonating forms.
In resonance hybrid structure the positive charges are distributed over five carbon atoms so relative positive charge density on each carbon atom is very less and thus it is stabilized.

The structure three formed in the resonating forms further stabilizes to give mono substituted Sulpho derivative.

The H+ ion release in this reaction joins with the conjugate base to form a byproduct here it is termed as spent acid.

H⁺  + HSO₄ ^-1 → H₂SO₄
The monosubstituted derivative of arenes uses a Fuming sulphuric acid always uses a higher concentration of SO₃ as it is a hygroscopic material and it absorbs water formed in the first step as a result of which more forward reaction takes place and concentration often Sulphonium ion increases the reaction mixture thus the rate of reaction increases and formation of product is higher yield.

 

 

Check out reactions

Chlorination Reaction	Bromination Reaction	Nitration Reaction
Sulphonation Reaction	Friedel Craft Alkylation Reaction	Friedel craft Acylation Reaction

 

You may also like

Nucleophilic Substitution reaction	Free Radical substitution reaction	Electrophilic addition reaction	Free radical addition reaction
Nucleophilic addition reaction	Elimination reaction	Bond Fission

 

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Chemistry XII	Mock Test XI	Mock Test XII
Mock Test NEET	Mock Test JEE Mains	Science class 9

 

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