Question

$C{{H}_{3}}-CHF-C{{H}_{2}}^{+}$, $C{{H}_{3}}-CHCl-C{{H}_{2}}^{+}$
Which is more stable by inductive effect.

Answer 1

Hint: Inductive Effect refers to the phenomenon by which a permanent dipole arises in a given molecule due to the unequal sharing of the bonding electrons in the molecule. This effect can arise in sigma bonds whereas the electromeric effect can only arise in pi bonds.

Complete step by step solution: When any electron releasing group or electron withdrawing group is attached with a chain of carbon atoms then partially positive or negative charge arises on the carbon chain atoms which causes permanent dipole in the molecule this type of effect is known as inductive effect. There are two types of inductive effect known as +I effect and –I effect.
-I effect occurs when an electronegative atom like halogen is attached to a chain of atoms resulting in unequal sharing of electrons which generates a positive charge. It causes a permanent dipole in the molecule wherein the electronegative atom holds a negative charge. On the other hand when an alkyl group is attached to a carbon chain then this is called +I effect. Molecules given in the question are carbocation in nature i.e. an ion which is positively charged carbon atom. Stability of carbocation is generally related with the –I effect.
$Stability$ $of$ $Carbocation$ $\propto \dfrac{1}{-I \, effect}$
Fluorine has maximum –I effect as it is highly electronegative in nature so it is least stable in nature.

So, we can say that $C{{H}_{3}}-CHCl-C{{H}_{2}}^{+}$ is more stable as compare to $C{{H}_{3}}-CHF-C{{H}_{2}}^{+}$.

Note: Electronegativity is generally denoted by the symbol $\chi $ which measures the tendency of an atom to attract a shared pair of electrons. An atom's electronegativity is affected by both its atomic number and the distance of valence electrons from the charged nucleus. Higher the value of the electronegativity, more an atom or group attracts electrons.