Question

Among the following compounds, the most acidic is

Solution

Correct option is

o-hydroxybenzoic, acid

 

A monosubstituted benzoic acid is stronger than a monosubstituted phenol as former being a carboxylic acid. Among the given substituted benzoic acid, ortho-hydroxy acid is stronger acid although ––OH causes electron donation by resonance effect which tends to decreases acid strength.

It is due to a very high stabilization of conjugate base by intramolecular H-bond which outweight the electron donating resonance effect of ––OH

The overall order of acid-strength of given four acids is ortho-hydroxybenzoic acid (pKa = 2.98) > Toluic acid pKa = 4.37) > p-hydroxybenzoic acid (pKa= 4.58) > p-nitrophenol (pK= 7.15).

                                                                 

SIMILAR QUESTIONS

Q1

Which of the following hydrocarbons has the lowest dipole moment?

Q2

 

Identify the correct order of boiling points of the following compounds

CH3CH2CH2CH2OH,    CH3CH2CH2CHO, CH3CH2CH2COOH

               1                              2                                 3

Q3

Which of the following acids has the smallest dissociation constant?

Q4

 

The bond between carbon atom (1) and carbon atom (2) in compound  

                

                       1      2 

Involves the hybridisation as

Q5

Polarisation of electrons in acrolein may be written as

Q6

The compound which gives the most stable carbonium ion on dehydration is

Q7

The number of sigma and pi-bonds in 1-butene 3-yne are

Q8

Amongst the following, the most basic compound is 

Q9

The hybridisation of carbon atoms in C―C single bond

Q10

 

What is decreasing order of strength of the bases?