| abstract |
A compound having the formula:- ##SPC1## n And salts thereof, wherein R 1 , R 2 , R 3 and R 4 are the same or different and each is hydrogen, an alkyl residue having from 1 to 9 carbon atoms, a cycloalkyl residue having from 5 to 14 carbon atoms or a cycloalkyl-alkyl residue having from 7 to 14 carbon atoms, Y is hydrogen, 0°, an alkyl residue having from 1 to 4 carbon atoms, or an aralkyl residue having from 7 to 12 carbon atoms and Z is hydrogen, an unsubstituted or substituted alkyl residue having from 1 to 20 carbon atoms, an alkenyl or alkynyl residue having from 2 to 20 carbon atoms, a cycloalkyl residue having from 5 to 12 carbon atoms, an aralkyl residue having from 7 to 12 carbon atoms, an aryl residue having from 6 to 12 carbon atoms, or the group having the formula: wherein Z 1 has the same significance as Z as hereinbefore defined, or Z 1 is a group --NR 5 R 6 wherein R 5 is hydrogen or an alkyl residue having from 1 to 4 carbon atoms and R 6 is hydrogen, an alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group having from 5 to 12 carbon atoms, an aralkyl residue having from 7 to 12 carbon atoms or an aryl residue having from 6 to 12 carbon atoms having light stabilising activity. |