Write the structure of the major product in each of the following reactions:

In reaction (i) propene when treated with water in acidic medium undergoes addition reaction to give alcohol. This is demonstrated in the following reaction:

The mechanism is as follows:

Step 1: formation of carbocation

The acidic hydrogen is attacked by the double bond to form ethyl carbocation. The H⁺ ion is due to acidic medium.

Step 2: attack of water molecule

Ethylium ion is attacked by the lone pair of water molecule to form an intermediate which is instable and will lose a proton.

Step 3: regeneration of acidic hydrogen

The acidic hydrogen is removed to get the final product of ethanol, as in the entire process only a water molecule is added the reaction is called as hydration reaction.

Thus the final product is propa-1-ol.

Reaction (ii) gives:

The final products include mixture of but-1-ene and but-2-ene, but the reaction takes place following β-elimination reaction which states that the hydrogen atom is removed from that carbon atom that have least number of hydrogen atoms. Thus but-2-ene is the major product.

Reaction (iii) involves Friedel Crafts acylation of benzene to give a nucleophilic substituted product where Br is replaced by carbonyl chloride i.e. it forms benzoyl chloride as the product.

As the C-Br bond is subjected to form double bonds during resonance, it is not easy to break. But due to presence of a Lewis acid, the polarity is more pronounced in the C-Br bond so its fission is facilitated. So the product is benzoyl chloride.