Definition of quinomethanes

1. Methylidenecyclohexadienones and dimethylidenecyclohexadienes, formally derived from quinones by replacement of one or both of the quinone oxygens by methylidene groups. (The diradical, triplet state of quinodimethanes can also be called o- or p-xylylenes).

   p-quinomethane, p-quinodimethane