with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to ring carbon atoms

Full Title

Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings > not condensed with other rings > having three or more double bonds between ring members or between ring members and non-ring members > with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to ring carbon atoms