Question

Which of the following has two stereoisomers?

• A. None of these
• B. Only I
• C. Only III
• D. I and III

Hint:

Nitrogen compounds can be chiral if: • Nitrogen is attached to four different groups • Inversion is restricted

Answer 1

The Correct Option is D

Step 1: A molecule shows stereoisomerism if it has a chiral center or restricted rotation leading to non-superimposable mirror images.
Step 2: Structure (I) has a tetrahedral nitrogen attached to four different groups, hence it shows optical isomerism.
Step 3: Structure (II) has two identical substituents on nitrogen, so it is achiral.
Step 4: Structure (III) again has four different substituents around nitrogen, making it chiral.