What effect on boiling and melting points does intramolecular hydrogen bonding have?
The effect of intramolecular forces versus intermolecular forces on boiling and melting points is sometimes seen when we compare the boiling points of ortho- and para-nitrophenol (or similar compounds).
Para-nitrophenol shows intermolecular hydrogen bonding, which causes an increase in boiling point as different molecules bond better with each other, as compared to ortho-nitrophenol, where there is intramolecular hydrogen bonding, which does not help in increasing the boiling point, hence p-nitrophenol has a higher boiling point than o-nitrophenol.
However, while comparing intramolecular bonding with no hydrogen bonding, no difference can be expected unless the intramolecular bonding affects the intermolecular bonding in some way, for instance by changing size and thus packing.