Friedal-craft reaction
Table contents:
History
About reaction
Mechanism
Advantage
Limitations
Example
History-
Friedal craft reaction is discovered by charles friedal ( french scientist ) and james crafts ( American chemist ) in 1877.
About reaction-
Frieda crafts reaction is an electrophilic aromatic substitution reaction including organic coupling reaction. Friedal craft reaction are two type:
-Frieda craft alkylation
-Frieda craft acylation
This reaction involves the replacement of hydrogen atom via an electrophile.
The reactant for this reaction is aluminum trichloride, it is acts as Lewis acid and it is used in generating an electrophile in the process.
👉 Friedal craft alkylation:
This reaction helps in generating alkyl banene via alkyl halide as reactants. The catalyst is aluminum trichloride. Friedal craft alkylation indicate the replacement of an aromatic proton with an alkyl group.
In this reaction carbocation will be generate as intermediate.
Mechanism:
1.The formation of carbocation using Lewis acid aluminium trichloride.
2.Carbocation attack on the aromatic ring.
3.deprotonation of the intermediate will be. And the proton goes to on hydrochloric acid, regenerating aluminium trichloride catalyst.
👉 Frieda craft acylation:
It is the acylation of the aromatic rings, in this reaction involves the addition of the acyl group to aromatic ring. In this reaction reactant is the acid chloride and the catalyst is aluminium trichloride.The reaction is between benzene and acyl chloride under the condition. Lewis acid generate a highly electrophilic acylium kon which is stabilized by resonance.
Mechanism:
Step 1. Forming of acylium ion.
Step 2. Acylium ion attack on the aromatic ring and the aromaticity of the ring.
Step 3. Intermediate complex is deprotonated.
Step 4. Ketone product is formed adding water.
Advantage:
Acylation and alkylation are the advantage of friedal craft reaction.
Limitations:
Friedal craft reaction's limitations are carbocatiom rearrangement and polyalkyaltion . Acylation reaction yields only ketones. Aryl amines can not be formed in this reaction.
Example
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