Question

Which of the following is an example of Heterolytic fission?

• A. $C{H}_3-OH$
• B. $C{H}_3-Cl$
• C. F - F
• D. None of these

Answer 1

Answer: (A), (B)

The correct options are
A $C{H}_3-OH$
B $C{H}_3-Cl$

Heterolytic fission occurs in polar solvents, catalysed by acids or bases, greatly influenced by polarity of solvents. Here, the ions are formed. In an organic compound such as R - G, two types of ions are formed.

$R-G\to R^{+}+G^{-}$ ($R^{+}$ is known as carbonium ion)

$R-G\to R^{-}+G^{+}$ ($R^{-}$ is known as carbanion ion)

The factor which favours heterolysis is a greater difference of electronegativity between A and B.

Thus,

(i) Heterolytic bond fission gives carbocation or carbanion as reaction intermediate.

(ii) Mechanism of the reaction in which heterolytic bond fission takes place is known as heterolytic mechanism or ionic mechanism.

(iii) The energy required for heterolytic bond fission is always greater than that for homolytic bond fission due to electrostatic force of attraction between ions.

Therefore, there should be difference in electronegativity.

$C{H}_3-OH\Rightarrow$ Difference in electronegativity of $C$ and $O$
$C{H}_3-Cl\Rightarrow$ Difference in electronegativity of $C$ and $Cl$
$F-F\Rightarrow$ No Difference
Therefore, (a) and (b) are correct.