Q6 · CSIR NET Chemistry, December 2013
Paper: CSIR NET December 2013 · Subject: Organic Chemistry · Chapter: General Organic Chemistry · Topic: General Organic Chemistry – General · Marks: 2 · Difficulty: Medium
Amongst the following, the compound which has the lowest energy barrier for the cis-trans isomerisation is:
(a)
(b)
(c)
(d)
Answer
Answer: C ✓ checked by 4AB · confidence high
Explanation
The central C=C acquires single-bond character when polarisation gives two aromatic rings: only (c), a sesquifulvalene (cyclopentadienide + tropylium), does so, hence the lowest rotational barrier.
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