Fundamentals of Organic ChemistryChemistryGeneral Organic Chemistry
Which of the following statements regarding the effect of hydrogen bonding on the acidic character of a species is correct?
Options
- AHydrogen bonding always increases the acidic character of a species.
- BHydrogen bonding always decreases the acidic character of a species.
- CHydrogen bonding may increase or decrease the acidic character of a species.
- DHydrogen bonding plays no role in determining the acidity of a species.
Correct answer
C. Hydrogen bonding may increase or decrease the acidic character of a species.
Step-by-step solution
Hydrogen bonding can either increase or decrease the acidic character of a species depending on whether it stabilizes the conjugate base or the undissociated acid. If hydrogen bonding stabilizes the conjugate base formed after the removal of a proton, the acidic character increases. For example, the first ionization constant ( K_ a1 ) of maleic acid is higher than that of fumaric acid because the maleate monoanion is stabilized by intramolecular hydrogen bonding. If hydrogen bonding stabilizes the undissociated aci