Question

Electrophilic addition reaction proceeds in two steps. The first step involves the addition of an electrophile. The type of intermediate formed in the first step of the following addition reaction is:
${\text{H}}_3\text{C - HC = C}{\text{H}}_2\text{ + }\stackrel{+}{\text{H}}\to$
A. $\text{2}{}^{\circ }$ carbanion
B. $1{}^{\circ }$ carbocation
C. $\text{2}{}^{\circ }$ carbocation
D. $1{}^{\circ }$ carbanion

Answer 1

Hint: The stability of the carbocation is important because more is the stability of a carbocation more are the chances of the feasibility of the reaction. Carbocation consists of a positive on the carbon atom which is formed by the loss of an electron.

Complete step by step answer:
-In the given question, propene is given to us which is reacting with the hydrogen ion and we have to tell the intermediate product which will be formed.
-As we know that hydrogen ion is an electrophile because it tends to accept a pair of electrons and also consist of a positive charge.
-So, firstly the pi- bond present between central carbon and adjacent carbon breaks and two conditions are formed:
I)

-So, here the hydrogen atom attaches to the carbon which has an extra pair of electrons and the central gains a positive charge which is now known as carbocation or secondary carbocation.
-It is a secondary carbocation because it is connected to two carbon atoms.

II)

-Here, the carbocation formed is primary because it is connected to only one carbon atom.
-But as we know that primary carbocation is less stable than the secondary carbocation because more is the alkyl group attaches more will the electron density on the carbocation.
-This is so because the alkyl group is the electron-donating group and gives electron density to the neighbouring carbon.
-Hence, the intermediate formed will be the secondary carbocation.
So, the correct answer is “Option C”.

Note: As the name tells electrophilic addition reactions are those in which the electrophile attacks on the unsaturated bond. That’s why a compound must have a double or triple bond to undergo electrophilic addition reaction.