Question

hich of the following is the strongest acid: A. o- Fluorophenol B. o- Chlorophenol C. o-Bromophenol​

Answer 1

Answer:

hich of the following is the strongest acid:

is

Explanation:

B. o- Chlorophenol

Answer 2

Answer:

The strongest acid is (B)o- Chlorophenol

Explanation:

The order is

O-chlorophenol > o-bromophenol > o-iodophenol > o-fluorophenol

Several factors are playing a role here:

1. Inductive effects which suggests the fluoro is strongest, as it is highly electron withdrawing.

2. Charge delocalization Oxygen and halogen both have lone pairs that can delocalize into the ring and generate partial charges.It is more difficult to estimate because both electronegativity and size play a role. However, the delocalization of a halogen lone pair produces a negative ortho charge, which reduces acidity. Due to size, the delocalization order is F>Cl>Br>I.

3. Hydrogen Bonding: Because of the halogen, the original phenol has a chelating 5 membered H bonded ring (-O-H-X-). This will be fairly strong for F, weak for Cl, and almost non-existent for Br and I. H-bonding will decrease acidity because it stabilises the phenol but not the phenoxide.

#SPJ2