Consider the methyl substituted benzoic acids.

$1 .$ PhCOOH

$2 .$ $o - C H_{3} C_{6} H_{4} C O O H$

$3 .$ $p - C H_{3} C_{6} H_{4} C O O H$

$4 .$ $m - C H_{3} C_{6} H_{4} C O O H$

The correct sequence of acidity is

Question

Consider the methyl substituted benzoic acids. 1 . PhCOOH 2 . o - C H 3 C 6 H 4 C O O H 3 . p - C H 3 C 6 H 4 C O O H 4 . m - C H 3 C 6 H 4 C O O H The correct sequence of acidity is

TestHub · Accepted Answer

Both p- and m-methyl groups are electron-donating and acid weakening. Hyperconjugation of $p - C H_{3}$ produces a little extra $δ^{-}$ on the ring carbon, bearing the $C O O^{-}$ . This results in more effective electron-donation and acid-weakening. This makes $p - C H_{3} C_{6} H_{4} C O O H$ less acidic than $m - C H_{3} C_{6} H_{4} C O O H$ .

$o - C H_{3} C_{6} H_{4} C O O H$ is a stronger acid than benzoic acid, due to ortho-effect.

$p - C H_{3} C_{6} H_{4} C O O H$ < $m - C H_{3} C_{6} H_{4} C O O H$ < PhCOOH < $o - C H_{3} C_{6} H_{4} C O O H$

Chemistry - GOC Question with Solution | TestHub

Options:

Doubts & Discussion