Double bonds can also act like Lewis bases, sharing their electrons with Lewis acids. Use curved arrows to show how each double bond below will react with HCl and draw the resulting carbocation.

The species which accepts the lone pair of an electron is called Lewis acid.

The species that donates the lone pair of an electron is called Lewis base.

$\mathrm{\pi }$bonds also act as lewis bases because they share their electrons with lewis acids.

In this reaction$\mathrm{\pi }$ bond of ethene attacks on data-custom-editor="chemistry" $\mathrm{HCI}$the molecule to form chloroethane. The reaction proceeds as follow;

The species which accepts the lone pair of an electron is called Lewis acid.

The species that donates the lone pair of an electron is called Lewis base.

$\mathrm{\pi }$bonds also act as lewis bases because they share their electrons with lewis acids.

In these reaction$\mathrm{\pi }$ bond of but-2-ene react with $\mathrm{HCI}$which result in the formation of 2-chlorobutane. The reaction mechanism is as follow;

The species which accepts the lone pair of an electron is called Lewis acid.

The species that donates the lone pair of an electron is called Lewis base.

$\mathrm{\pi }$bonds also act as lewis bases because they share their electrons with lewis acids.

In this reaction $\mathrm{HCI}$add across the double bond which results in the formation of the following compound;