Draw conjugate acid of 4-hydroxypyridine and choose the best reason why it’s more basic than pyridine.

• A. -OH group acts as EWG through resonance, which decreases its acidity.
• B. -OH is an EWG, which decreases electron density of N making it more electrophilic, therefore making it more basic.
• C. -OH is an EDG through inductive effect, which induces electrons towards the N.
• D. -OH is an EDG, which increases electron density of N making it more nucleophilic, therefore making it more basic.

Answer: (D)

Verified step by step guidance

1. Identify the structure of 4-hydroxypyridine. It is a pyridine ring with a hydroxyl group (-OH) attached to the fourth carbon in the ring.
2. To draw the conjugate acid of 4-hydroxypyridine, add a proton (H⁺) to the nitrogen atom in the pyridine ring. This is because the nitrogen atom is the basic site in pyridine.
3. The addition of a proton to the nitrogen atom results in a positively charged nitrogen, forming the conjugate acid.
4. Consider the effect of the -OH group on the basicity of the nitrogen. The -OH group can act as an electron-donating group (EDG) through resonance, which increases the electron density on the nitrogen.
5. The increased electron density on the nitrogen makes it more nucleophilic, enhancing its ability to accept a proton, thus making 4-hydroxypyridine more basic than pyridine. The correct reasoning is that the -OH is an EDG, which increases electron density of N making it more nucleophilic, therefore making it more basic.