Account for the following: o-nitrophenol has a lower boiling point than p-nitrophenol.
Solution
In o-nitrophenol the –OH hydrogen bonds \textit{within the same molecule} to the adjacent –NO (intramolecular chelation), so molecules stay separate and volatile.
p-Nitrophenol hydrogen bonds \textit{between} molecules, forming associated chains that need extra energy to separate — hence its higher boiling point (and lower steam volatility of the para form).
p-Nitrophenol hydrogen bonds \textit{between} molecules, forming associated chains that need extra energy to separate — hence its higher boiling point (and lower steam volatility of the para form).
CBSE Class 12 Board · 2003 · Delhi Compartment · Subjective