Abstract: The present invention relates to new stabilizers of polymers and co-polymers of vinyl chloride corresponding to the general formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6, which are the same or different, represent:R.sub.1 = a hydrogen atom or a branched- or straight-chain alkyloxy group containing from 1 to 12 carbon atoms,R.sub.2 = a hydrogen atom, a branched-or straight-chain alkyl group containing from 1 to 3 carbon atoms or a branched- or straight-chain alkyloxy group containing from 1 to 12 carbon atoms,R.sub.3 and R.sub.5 = a hydrogen atom, a hydroxy group, a branched- or straight-chain alkyl group containing from 1 to 3 carbon atoms or a branched- or straight-chain alkyloxy group containing from 1 to 12 carbon atoms,R.sub.4 = a hydrogen atom, a hydroxy group, a branched- or straight-chain alkyl group containing from 1 to 3 carbon atoms or a branched- or straight-chain alkyloxy group containing from 2 to 12 carbon atoms,R.sub.