Q30 / 125 · BITSAT 2013 · Chemistry
Which of the following is less acidic among the given halogen compounds?
- Correct answerA$\mathrm{CHF}_{3}$
- B$\mathrm{CH}_{3}$
- C$\mathrm{CHCl}_{3}$
- D$\mathrm{CHBr}_{3}$
Solution
Due to stronger-I-effect of $\mathrm{F}$ than that of Cl, $\mathrm{CHF}_{3}$ should be more acidic than $\mathrm{CHCl}_{3} .$ But actually reverse is true.
This is due to : $\mathrm{CCl}_{3}^{-}$ left after the removal of a proton from $\mathrm{CHCl}_{3}$ is stabilised due to presence of $d$ -orbitals in
Cl than: $\mathrm{CF}_{3}^{-}$ left after the removal of a
proton from $\mathrm{CHF}_{3}$ which is not stabilised due to the absence of $d$ -orbitals on $\mathrm{F}$.
Hence, the correct answer is option: 'A'.