Question

Predict the major product for the following reaction:

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

Solution:-

• Above reaction undergoes Electrophilic Substitution Reaction.
• An electrophilic substitution reaction is a chemical reaction in which the functional group attached to a compound is replaced by an electrophile.
• The displaced functional group is typically a hydrogen atom.
• Electrophilic substitution reactions generally proceed via a three-step mechanism that involves the following steps.

Step 1:- Generation of an electrophile

• The HBr molecule is an electrophile because it accepts a pair of electrons.
• It splits into H^∂+ and Br^∂- to protonate the compound.

$\mathrm{HBr}\rightleftharpoons \left[{\mathrm{H}}^{\mathrm{\delta }+}\right]+\left[{\mathrm{Br}}^{\mathrm{\delta }-}\right]$

Step 2:- Formation of Carbocation

• In step 2, the attacking electrophile is the already polarised i.e Hydrogen bromide molecule , which splits to protonate the alkene forming the carbocation and a bromide ion.
• The HBr molecule is an electrophile because it accepts a pair of electrons from the alkene π bond to form the new C-H bond.

Step 3: Removal of Proton from the intermediate.

• In step 3,the bromide ion formed in step (1) rapidly combines with the carbocation to form the 2-bromo 4-methyl 3-pentene
• . The bromide ion donates a pair of electrons to form the new C-Br bond

Hence, Correct Option - D