Friedel Crafts reactions are the chemical reaction invented by the great French chemist Charles Friedel and American chemist James Crafts in the year 1877. Friedel Crafts reaction is an organic chemical reaction that takes place between acylation and alkylation.
As we know that the resonance is involved in in the benzene ring, the delocalized electrons span completely over carbon atoms. Even the arenium ion is partially stabilized due to this process. The benzene is subjected to an electrophilic substitution reaction due to the partial stability of arenium ion. The hydrogen atom of benzene is now replaced by the electrophile in an electrophilic substitution reaction involving benzene.
The reaction shown below explains both types of the Friedel Crafts reaction of benzene.
An acyl or alkyl group is replaced by a hydrogen atom belonging to the benzene ring in this reaction. These reactions are highly spontaneous nature since the aromaticity of the benzene ring isn’t disturbed evenly. Friedel Crafts acylation and alkylation reactions can be considered examples of electrophilic substitution reactions of benzene.
Friedel Crafts alkylation reaction
Friedel–Crafts alkylation comprises the process of alkylation of an aromatic ring with an alkyl halide using a strong Lewis acid, like ferric chloride, aluminium chloride, or MXn reagent as a catalyst. The general mechanism of Friedel Crafts alkylation reaction using tertiary alkyl halides is as shown below.
Friedel Crafts acylation reaction
The method of processing the aromatic ring with an acyl halide with a Lewis acid (Example: anhydrous Aluminium chloride) results in the formation of acyl benzene. The reaction described above is commonly known as Friedel Crafts acylation reaction. Note that the viability of the Friedel–Crafts acylation is dependent on the firmness of the acyl chloride reagent.
Friedel Crafts Alkylation and Acylation Reactions of Benzene
The process of Alkylation and Acylation Reactions of Benzene is as given below:
Step 1: Generation of electrophile
Step 2: Formation of arenium ion:
Step 3: Removal of positive charge from the carbocation intermediate:
Ozonolysis is a process in which unsaturated bonds of alkynes, alkenes, or azo compounds are cleaved with ozone and is an organic reaction. Alkynes and alkenes form organic compounds in which the carbon-carbon multiple bonds are substituted by a carbonyl group and azo compounds form nitrosamines. The outcome of the reaction depends on the type of multiple bonds being oxidized and the work-up conditions.
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