Question

Arrange the (C -H) bonds x, y, and z in decreasing order of their bond dissociation energies in homolysis.

• A. $y>x>z$
• B. $z>x>y$
• C. $z>y>x$
• D. $y>z>x$

Answer 1

Answer: (C)

$z>y>x$

Bond dissociation energy in hamolytic cleavage is directly prpoprtional to the bond strength as $z\to s{p}^2$ hybridised $\to$ more strong than $y$ and $x$

$y\to$ having partial $s{p}^2$ character because of hyperconjugation.

$x\to$ No hyperconjugation, purely $s{p}^3\to$ weakest bond.

Bond dissociation energy order is

$z>y>x$