The steam volatile compounds among the following are: (A) (see structure) (B) (see structure) (C) (see structure) (D) (see structure)
Choose the correct answer from the options given below:ABCD
(A)(B) and (D) only
(B)(A) and (C) only
(C)(A) and (B) only✓ Correct
(D)(A),(B) and (C) only
Answer: (C)
Solution
A compound is steam volatile when intramolecular hydrogen bonding, rather than intermolecular hydrogen bonding, dominates its structure, since this lowers its effective boiling point and lets it co-distil with steam. The ortho-substituted nitrophenol and nitroaniline can each form a stable five- or six-membered intramolecular hydrogen bond between the –OH/–NH2 group and the adjacent –NO2 group, so both are steam volatile. The isomers where the –OH/–NH2 and –NH2 groups sit apart on the ring instead depend on intermolecular hydrogen bonding, which raises the boiling point and keeps them from distilling with steam. Only the two ortho-substituted compounds are steam volatile.AB
JEE Main · 2025 · 29 Jan 2025 · Shift 1 · Single correct option
