Q3 · CSIR-NET Chemistry, June 2018
Paper: CSIR-NET June 2018 · Subject: Organic Chemistry · Chapter: General Organic Chemistry · Topic: Aromaticity · Marks: 2 · Difficulty: Medium
The correct statement about the following species is 
A B
A B(a)Both A and B are aromatic
(b)A is aromatic and B is anti-aromatic
(c)A is non aromatic and B is antiaromatic
(d)A is aromatic and B is homoaromatic
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
The cyclooctatetraene dication has 6π electrons in a planar ring and is aromatic. Oxepin is an 8π (4n) system, formally antiaromatic, and avoids it by puckering and by valence tautomerism (b).
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