Why o-Nitrophenol is more volatile than p-Nitrophenol?

Question

Why o-Nitrophenol is more steam volatile than p-Nitrophenol?

Related, possibly duplicate: Physical properties of phenols, Intermolecular Hydrogen Bonding, and Strength of types of hydrogen bonds? — , Oct 12 '16 at 11:17

score 4 · Accepted Answer · edited Aug 31 '18 at 20:27

4

o-Nitrophenol forms intramolecular H bond whereas molecules of p-Nitrophenol get associated through intermolecular H bond. During boiling, the strong intermolecular H bonding increases the boiling point but intramolecular H bonding cannot do so.

Therefore, o-Nitrophenol is more steam volatile than p-Nitrophenol.

edited Aug 31 '18 at 20:27

A.K.

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answered Oct 12 '16 at 10:50

Vishnu JK

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I understand that there is intramolecular hydrogen bonding in o-Nitrophenol. But, how does that prevent it from interacting with surrounding o-Nitrophenol? Consider 3 charges in space. Say Charge 1 interacts with Charge 2 (let's name it 1-2 interaction). The '1-2 interaction' is not going to affect the '1-3 interaction or 3-2 interaction'. Does it? – Kaushik Feb 17 '21 at 17:09

score 0 · Answer 2 · answered Oct 12 '16 at 11:07

There are two types of hydrogen bond.One is intermolecular hydrogen bond and other is intramolecular hydrogen bond.Intermolecular H-Bond increase the melting point,boiling point of compounds having them while the intramolecular H-Bond have mostly opposite effects to that of intermolecular H-Bond(it decreases melting and boiling point).Since o-nitrophenol forms intramolecular H bond it have low Melting boiling point than p-nitrophenol(which form intermolecular H-Bond).That's why o-Nitrophenol is more steam volatile than p-Nitrophenol.

Why o-Nitrophenol is more volatile than p-Nitrophenol?

2 Answers2