the present invention relates to a photo - stabilizer of the general formula : wherein r 1 is hydrogen , halogen , c 1 to c 12 alkyl , alkoxy , r 2 is hydrogen , c 1 - c 8 alkyl , cyclopentyl , cyclohexyl or cumyl , r 3 is hydrogen , c 1 - c 4 alkyl , r 4 is methyl or ethyl , r 5 is c 1 - c 8 alkyl , alkyl phenyl , alkoxy , acyl , cycloalkyl and allyl , x is o , nh , c 1 - c 8 alkyloxy and alkylamino , to derivatives and intermediates thereof .