When Benzene Reacts With 1-Chloropropane We Get Isopropyl Benzene Inst...
Becz. in Friedel craft alkylation Rearrangement of carbocation occur so major product is isopropyl benzene
When Benzene Reacts With 1-Chloropropane We Get Isopropyl Benzene Inst...
Explanation:
Friedel-Crafts alkylation is a type of electrophilic aromatic substitution reaction. When benzene undergoes Friedel-Crafts alkylation with 1-chloropropane, isopropyl benzene is obtained instead of n-propyl benzene. This is due to the nature of the reaction mechanism.
Mechanism of Friedel-Crafts Alkylation:
1. Formation of a Complex:
The reaction begins with the formation of a complex between the Lewis acid catalyst (AlCl3) and the electrophile (1-chloropropane). This complex is highly reactive and is capable of attacking the electron-rich benzene ring.
2. Formation of a Carbocation:
The complex attacks the benzene ring and forms a carbocation intermediate. This intermediate is highly unstable and can undergo rearrangement.
3. Rearrangement:
In the case of n-propyl chloride, the carbocation intermediate undergoes a hydride shift to form a more stable secondary carbocation. This carbocation then reacts with benzene to form n-propyl benzene.
However, in the case of isopropyl chloride, the carbocation intermediate can undergo a methyl shift to form a more stable tertiary carbocation. This carbocation then reacts with benzene to form isopropyl benzene.
4. Deprotonation:
The final step involves the removal of a proton from the newly formed alkylated benzene ring, which results in the formation of the final product.
Conclusion:
In summary, the formation of isopropyl benzene instead of n-propyl benzene in the Friedel-Crafts alkylation reaction between benzene and 1-chloropropane is due to the ability of the carbocation intermediate to undergo a methyl shift to form a more stable tertiary carbocation. This reaction mechanism highlights the importance of understanding the reactivity and stability of carbocation intermediates in electrophilic aromatic substitution reactions.
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