JEE Advanced Chemistry: Nitrogen-Containing Organic Compounds questions with solutions

Q1. Consider three species: (I) Ph-CH2-N=O (phenyl nitroso), (II) Ph-CH=N-OH (one geometric isomer of oxime), (III) Ph-CH=N-OH (other geometric isomer of oxime). Which of the following is/are correct? (A) I is more stable than II and III (B) II and III are more stable than I (C) II and III are diastereomers (D) III is a tautomer of I

1. (A) I is more stable than II and III
2. (B) II and III are more stable than I
3. (C) II and III are diastereomers
4. (D) III is a tautomer of I

Answer: (B) II and III are more stable than I

Primary nitroso compounds (I) are generally less stable than their oxime tautomers (II and III), so B is correct. II and III are geometric (E/Z) diastereomers due to restricted rotation about the C=N double bond (C correct). III is a tautomer of I (D correct). A is wrong.