Compounds Having The Group -c(=x)-x-nx-, Wherein The X's May Be The Same Or Diverse Chalcogens, Nx Is A Divalent Chalcogen Or A Chain Of Divalent Chalcogens Single Bonded To Each Other, And The Terminal X Is Bonded Directly To Carbon, Which Carbon May Be Single Bonded To Any Atom But May Be Multiple Bonded Only To Carbon (e.g., Percarboxylate Esters, Etc.) Patents (Class 560/302)