A composition comprising an organic material and, as stabiliser, a compound having the formula ##SPC1##And salts thereof, wherein R.sub.1 and R.sub.2 are the same or different and each is an alkyl residue having from 1 to 12 carbon atoms or R.sub.1 and R.sub.2, together with the carbon atom to which they are bound, form a cycloalkyl residue having from 5 to 12 carbon atoms in the ring, Y is O, hydrogen, a straight or branched alkyl residue having from 1 to 20 carbon atoms, an alkenyl or alkynyl residue having from 3 to 12 carbon atoms, an aralkyl residue having from 7 to 12 carbon atoms or a group having the formula ##EQU1## wherein R is hydrogen, or a methyl or phenyl residue and R.sub.3 is hydrogen or a straight- or branched chain alkyl residue having from 1 to 12 carbon atoms.