| 摘要 |
<IMAGE> (I) in which R is hydrogen, unsubstituted C1-18alkyl, unsubstituted C1-21alkyl carbonyl, unsubstituted C2-19alkenyl carbonyl, phenyl carbonyl, phenyl C1-4alkyl carbonyl, C1-4alkyl phenyl carbonyl or oxygen; both R1's and CH3 or together form -CH2)5; both R2's are CH3 or together form -CH2)5; R3 has a significance of R, independently of R, except for oxygen; X is -O-, -NH- or <IMAGE> m is an integer from 1 to 4 inclusive; R4 is a saturated or unsaturated aliphatic group unsubstituted or substituted by one or two groups selected from -OH and C1-4alkoxy and which can be interrupted by an oxygen or sulphur atom; or an aromatic group unsubstituted or substituted by one or two groups selected from -OH, C1-4alkyl and C1-4alkoxy are useful as U.V. light stabilizers in polymeric organic compounds.
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