Question

The most suitable method of separation of 1: 1 mixture of ortho- and para-nitrophenols is ______.

Options

• sublimation

• chromatography

• crystallisation

• steam distillation

Answer 1

The most suitable method of separation of 1: 1 mixture of ortho- and para-nitrophenols is steam distillation.

Explanation:

In ortho-nitrophenol, there is intramolecular hydrogen bonding, while in para-nitrophenol, there is intermolecular hydrogen bonding, due to which paraisomers have stronger attraction between molecules which results in it being non-molecular. But orthoisomers lack this interaction among their molecules which results in it being water or steam. Thus, due to these properties these two isomers can be separated by steam distillation. Being volatile, ortho-nitrophenol vaporises with steam leaving behind non-volatile component that is para-nitrophenol. Being immiscible with water, ortho-nitrophenol then separates from water (steam) at later stage.