| abstract |
1,3,4-Oxadiazolones and 1,3,4-thiadiazolones substituted in position 3 by sterically hindered p-hydroxybenzyl and in position 5 by mono- or divalent hydrocarbon or by alkoxy or alkylthio and the 2-thiono analogs of the above defined compounds can be synthesized by hydroxybenzylation of the corresponding 3-hydrogen compounds, for instance, with formaldehyde and a sterically hindered phenol. Intermediately the 3-hydroxymethyl compounds are formed which may be isolated. The hydroxybenzylation may further be accomplished by means of the corresponding hydroxybenzyl halides, amines or dithiocarbaminates. The products are stabilizers for organic polymers to protect them against thermo-oxydative degradation. They show an outstanding stability against discoloration. |