Question

Question: Draw the structure of a $1°,2°,3°$, , carbocation, each having molecular formula . Rank the three carbocations in order of increasing stability.

Short answer

Answer

The structure of $1°,2°,3°$and carbocations, each having the molecular formula is provided below.

The carbocations can be ranked in the order of increasing stability as follows:

Step-by-step solution

Carbocations

Carbocations are “electron-deficient” species comprising a trigonal planar shape. Several factors provide stability to a carbocation, and one of them is the inductive effect.

Structures of 1°,2°,3° carbocations possessing the molecular formula C4H9+

The structures of $1°,2°,3°$carbocations, comprising the molecular formula , can be given as:

Structure of various carbocations comprising the molecular formula

The alkyl groups exhibit a positive inductive effect by donating electron density, thereby stabilizing the electron-deficient carbon. Tertiary carbocations are highly stable because the electron-deficient carbon is linked to three alkyl groups.

Arrangement of carbocations in the increasing order of stability

The stability of a carbocation is based on various effects, such as the inductive effect and hyperconjugation. The carbocations can be arranged in the order of increasing stability as:

Arrangement of carbocations in the increasing order of stability

The alkyl groups exhibit a positive inductive effect by donating electron density, thereby stabilizing the electron-deficient carbon. Tertiary carbocations are highly stable because the electron-deficient carbon is linked to three alkyl groups.