I am really confused about comparing the acidity of p-chloro benzoic acid and p-fluoro benzoic acid.

The question here doesn't have a conclusion and the discussion here is confusing.

My Try:

  • -F and -Cl being +R groups create negative charge on o- and p- positions with respect to them.
  • -F having greater +R effect tends to produce greater negative charge on the positions ortho and para to it
  • -Cl having a greater +I effect tends to create greater amount of $\delta-$ charge than -F
  • The acidity of the molecule depends on the negative charge on the starred carbon atom (greater negative charge$\implies$less acidic):

My Confusions:

  • Is inductive effect strong enough to act para to the specific group?

  • Which among -F and -Cl will produce greater cumulative negative charge on the starred carbon atom, and how?
    The answer given:

    p-chloro benzoic acid is more acidic than p-fluoro benzoic acid, contrary to the order existing between p-chloro benzoic acid, p-bromo benzoic acid and p-iodo benzoic acid

  • $\endgroup$


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