Which hydrogen bond is stronger: intermolecular or intramolecular?

Hydrogen bonding is a weak force of attraction between a hydrogen atom covalently bonded to an electronegative atom (like O, N, or F) and another electronegative atom. The strength of hydrogen bonds can be compared based on whether they occur within the same molecule (intramolecular) or between different molecules (intermolecular).

• Intramolecular Hydrogen Bonding:
  Occurs within a single molecule, usually when hydrogen is positioned between two electronegative atoms inside the same structure. Example: o-nitrophenol. This type provides structural stability and influences boiling/melting points.
• Intermolecular Hydrogen Bonding:
  Occurs between hydrogen atoms of one molecule and electronegative atoms of another molecule. Example: water molecules forming extensive hydrogen bonds.

Which is stronger?

• Intermolecular hydrogen bonding is generally stronger because it occurs between different molecules and results in network formation (e.g., hydrogen bonding in water makes it liquid at room temperature).
• Intramolecular bonds often lead to chelation or ring stabilization but are usually weaker compared to the strong network of intermolecular hydrogen bonds.

Key Takeaways:

• Intermolecular → Intramolecular in terms of overall strength and impact.
• Intermolecular hydrogen bonding increases boiling points, viscosity, and solubility.
• Intramolecular hydrogen bonding stabilizes molecular conformation.