Question

Which of the following is less acidic among the given halogen compounds?

• A. $CH{F}_3$
• B. $CH{I}_3$
• C. $CHC{l}_3$
• D. $CHB{r}_3$

Answer 1

Answer: (A)

Due to stronger-$I$-effect of $F$ than that of $Cl,CH{F}_3$ should be more acidic than $CHC{l}_3.$ But actually reverse is true. This is due to : $CC{l}^{3-}$ left after the removal of a proton from $CHC{l}_3$ is stabilised due to presence of d-orbitals in $Cl$ than: $C{F}_3^{-}$ left after the removal of a proton from $CH{F}_3$ which is not stabilised due to the absence of d-orbitals on $F$.