Q9 · CSIR NET Chemistry, December 2016
Paper: CSIR NET December 2016 · Subject: Organic Chemistry · Chapter: General Organic Chemistry · Topic: General Organic Chemistry – General · Marks: 2 · Difficulty: Medium
Methyl groups in the following compound are 

(a)Homotopic
(b)Diasterotopic
(c)Enantiotopic
(d)Constitutionally heterotopic
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
trans-4,5-Diphenyl-2,2-dimethyl-1,3-dioxolane has a C₂ axis through C-2 that swaps the two methyls, so they are homotopic (a).
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