The most famous is the first, which is doubly misnamed, since it is not a temple and its contour is too unsymmetrical to be described properly as elliptical.
In 1866 Sir James Dewar proposed an unsymmetrical form (II); while in 1867, A.
Therefore formula (2), being unsymmetrical, is impossible.
This is obviously unsymmetrical, consisting of an aliphatic and an aromatic nucleus; Claus explained the formation of the same phthalic acid from the oxidation of either nucleus by supposing that if the aromatic group be oxidized, the aliphatic residue assumes the character of a benzene nucleus.
Pyridine gives origin to: pyridazine or ortho-diazine, pyrimidine or metadiazine, pyrazine or para-diazine, osotriazine, unsymmetrical triazine, symmetrical triazine, osotetrazone and tetrazine.