| 摘要 |
<p>The invention relates to 1,3,4-oxadiazolones and 1,3,4thiadiaxolones of the general formula I (I) wherein R1 denotes alkyl, cycloalkyl or aralkyl, R2 denotes hydrogen, alkyl, cycloalkyl or aralkyl, R3 denotes hydrogen or alkyl with 1 to 4 C-atoms, R4, if ??1, denotes hydrogen, alkyl, oxaalkyl, thiaalkyl, cycloalkyl, an alkylthio or alkoxy froup, a substituted or unsubstituted aralkyl or arly group or a group or if ??2, denotes alkylene, oxaalkylene or thiaalkylene, vinylene or arylene, Y and Z independently of one another denote oxygen or sulphur and m denotes the number 1 or 2. Hindered p-hydroxybenzyl residue and in position 5 by a monoor divalent hydrocarbon residue or by an alkoxy or alkylthio residue. Further representatives are the 2-thiono. These compounds can be synthesized by hydroxybenzylation of the corresponding 3-hydrogen compounds for instance with formaldehyde and a sterically hindered phenol. The products are stabilizers for organic polymers to protect them against thermo-oxydative degadation. They show an outstanding stability against discoloration.</p> |
