Abstract: A class of compounds are disclosed of the formula: ##STR1## wherein R represents an alkylene or alkylidene radical having from 2 to 10 carbon atoms, which compounds are effective inhibitors for oxidation prone hydrocarbon materials in general and represent singularly effective stabilizersfor rubber, both natural and synthetic, as well as certain plastic compositions containing a rubbery phase. An improved process for preparing the aforesaid compounds and certain homologs thereof likewise representing useful oxidation inhibitors is additionally disclosed.