While separating a mixture of ortho and para nitrophenols by steam distillation, name the isomer which will be steam volatile. Give reason.
Among the mixture of ortho and para nitrophenols, o-Nitrophenol is the isomer which is steam volatile. This characteristic allows for the effective separation of the ortho and para isomers using steam distillation.
The reason for this difference in volatility is the type of hydrogen bonding present. o-Nitrophenol exhibits intramolecular hydrogen bonding, which keeps the molecules separate and allows them to vaporize easily. In contrast, p-nitrophenol shows intermolecular hydrogen bonding, which causes the association of molecules. This association makes p-nitrophenol less volatile compared to the ortho isomer.
Explanation
The answer is derived directly from the textbook context which states that o-Nitrophenol is steam volatile due to intramolecular hydrogen bonding, whereas p-nitrophenol is less volatile due to intermolecular hydrogen bonding causing molecular association.
Solution Steps
Step 1: Identify the steam volatile isomer from the context (o-Nitrophenol).
Step 2: Identify the reason for volatility (intramolecular hydrogen bonding).
Step 3: Contrast with the other isomer (p-nitrophenol has intermolecular hydrogen bonding causing association).