Question

The electrophilic aromatic substitution of isopropylbenzene with FeBr3, Br2 gives 1-bromo-4-isopropylbenzene. Complete the curved-arrow mechanism below, beginning with formation of the active brominating reagent. Remember to include lone pairs and formal charges where appropriate.

Answer 1

Answer:

See explanation below

Explanation:

When the bromine (Br₂) reacts in presence of FeBr₃ with the isopropylbenzene, the isopropylbenzene is a ring activator, therefore, it will promote the substitution in the ortho and para positions. However, as the Isopropyl is voluminic, the ortho position would have steric hindrance and hence, this product is not formed in greater proportions. Instead, the para position becomes more available to reaction, and this product is formed in majority.

The mechanism of reaction can be seen in the following picture, along with the products of the reaction

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