Question

Which of the following alkyl halides will undergo $S_{N}1$ reaction most readily?

• A. $(C{H}_3{)}_{3}C-F$
• B. $(C{H}_3{)}_{3}C-Cl$
• C. $(C{H}_3{)}_{3}C-Br$
• D. $(C{H}_3{)}_{3}C-I$

Answer 1

Answer: (D)

$(C{H}_3{)}_{3}C-I$

All options given are alkyl halide (tertiary) so all will form tertiary carbocation.

But order of leaving group ability Is $I^{-}$ > $B{r}^{-}$ > $C{l}^{-}$ > $F^{-}$

$S_{N}1$ mechanism goes through formation of carbocation.

More easily leaving group leaves more easily the carbocation will form.

Option D is correct.