Question

The order of stability of the carbon carbocations $1^{\circ },2^{\circ },3^{\circ }$ and ${}^{⨁}C{H}_3$ :

• A. $\stackrel{⨁}{C}{H}_3>1^{\circ }>2^{\circ }>3^{\circ }$
• B. $1^{\circ }>2^{\circ }>3^{\circ }>\stackrel{⨁}{C}{H}_3$
• C. $1^{\circ }>2^{\circ }>\stackrel{⨁}{C}{H}_3>3^{\circ }$
• D. $3^{\circ }>2^{\circ }>1^{\circ }>\stackrel{⨁}{C}{H}_3$

Answer 1

The correct option is D $3^{\circ }>2^{\circ }>1^{\circ }>\stackrel{⨁}{C}{H}_3$

Carbocations are stabilized by neighboring carbon atoms. Carbons (alkyl groups in particular) as being “electron-releasing” groups through inductive effects. That is, a carbon (electronegativity 2.5) connected to hydrogen (electronegativity 2.2) will be electron rich, and can donate some of those electrons to the neighboring carbocation. Therfore the order of stability of carbocation is $3^o>2^o>1^o>C{H}_3^{+}$