The skeletons of these types are (the carbon atoms are omitted for brevity): We have previously referred to the condensation of heterocyclic ring systems containing two vicinal carbon atoms with benzene, naphthalene and other nuclei.
The more important nuclei of this type have received special and non-systematic names; when this is not the case, such terms as phen-, benzo-, naphthoare prefixed to the name of the heterocyclic ring.
Carbocyclic rings will next be treated, benzene and its allies in some detail; and finally the heterocyclic nuclei.
The elements which go to form heterocyclic rings, in addition to carbon, are oxygen, sulphur, selenium and nitrogen.
TRIAZOLES (pyrro-a and (3'-diazoles), in organic chemistry, a series of heterocyclic compounds containing the ring complex (annexed formula).
ACRIDINE, C13H9N, in chemistry, a heterocyclic ring compound found in crude coal-tar anthracene.
PYRIMIDINES, METADIAZINES or Miazines, in organic chemistry, a series of heterocyclic compounds containing a ring complex, composed of four carbon atoms and two nitrogen atoms, the nitrogen atoms being in the meta-position.
XANTHONE (dibenzo-y-pyrone, or diphenylene ketone oxide), C H 0 in organic chemistry, a heterocyclic compound containing the ring system shown below.