. "These compounds have the general formula: ##STR5## in which X is an oxygen or sulfur atom, R1 and R2 are hydrocarbyl radicals having from 1 to 3 carbon atoms, and R is selected from the group consisting of ##STR6## Particularly useful as ORR agents are: (a) 4-[N-(2,4-xylyl) Carbamoyl] morpholine;" . . . . . .