question_answer

Decreasing acidic character of the following compounds is

I. p-Fluorophenol

II. p-Chlorophenol

III. p-Bromophenol

IV. p-Iodophenol

A) \[II>I>III>IV\]     

B) \[I>II>III>IV\]

C) \[IV>III>II>I\]              

D) \[IV>III>I>II\]

Correct Answer: A

Solution :

[a] In case of F, both \[-I\] and \[+R\] effects are considered because of the effective overlap of \[2p(F)-2p(C)\]. But in other halogens, only \[-I\] effect is considered due to ineffective overlap. So net e-withdrawing power of\[Cl>F>Br>I\]. Hence, the acidic order is. \[II>I>III>IV\]