Question

Rank the following carbocations in order of decreasing stability.

Rank the following carbocations in order of decreasing stability.

Answer 1

Stability of the carbocations depends on inductive effect of methyl group. This effect changes the charge on the carbocation. Methyl group is an electron releasing group Inductive effect: Inductive effect is an electronic effect due to the polarization of sigma bonds within a molecule. It results in a permanent dipole in the bond. It is due to the electronegativitv dıfference between the atoms in a molecule Carbon has slightly more electronegative than hydrogen atom. Thus carbon atom of methyl group has partial negative charge; carbon atom can donate its electron density to the neighboring carbocation. Carbocation with more methyl groups will have less charge density; due to this less charge, carbon possesses lower energy. Carbocation with lower energy gets high stability Therefore, tertiary carbocation has more stability than the secondary, primary carbocation CH CH3 CH3 CH3 СНЗ Tertiary carbocation Secondary carbocation Primary carbocation

Therefore, decreasing order of stability of the carbocations is as follows: CH3 CH3 Tertiary carbocation HC_CH CH3 Secondary carbocation CH2 CH3 Primary carbocation CH3

Answer 2

Answer 3