Below are the enantiomers of 1,2-dimethylazetidine. One group around nitrogen is a lone pair, but these two enantiomers can be separated. Explain why.

• A. The enantiomers can be separated because 1,2-dimethylazetidine exhibits resonance, making the nitrogen sp² hybridized, and preventing the interconversion of the enantiomers.
• B. The enantiomers can be separated because the nitrogen in the ring cannot meet the 120° bond angle requirement for amine inversion, preventing the interconversion of the enantiomers.
• C. The enantiomers can be separated because the nitrogen needs to be protonated first as a requirement for amine inversion, preventing the interconversion of the enantiomers.
• D. The enantiomers can be separated because nitrogen is an asymmetric center. The lone pair does not affect the interconversion of the enantiomers.

Answer: (B)