Question

Intermolecular hydrogen bonding is strongest is:

• A. Methylamine
• B. Phenol
• C. Foramaldehyde
• D. Methanol

Answer 1

Answer: (B)

Phenol

The extent of hydrogen bonding will be more for oxygen than nitrogen due to more electronegative nature of oxygen. Aldehydes have a polar $C-O$ bond whereas hydrogen bonding is an electrostatic interaction. Aldehydes thus from a dipole and have dipole-dipole interactions rather than hydrogen bonding. Phenol has the strongest hydrogen bonding as it has electrophilic benzene ring attracting the lone pair of oxygen, thus increasing its tendency to attract an electron pair of hydrogen.