Question: why is oxepin not aromatic?
Answer: 1 Answer. Oxepin is certainly not aromatic. If it were flat and the oxygen atom was sp2 hybridized, then it would be an 8π-electron anti-aromatic system, but to avoid being anti-aromatic, it exists in a boat-like conformation, with incomplete conjugation of the π-system. ... Benzene Oxide-Oxepin Valence Tautomerism.