Abstract: &bgr;-Ketoesters and their enamines derived from alcohols or polyols are suitable for stabilizing polymers, and are represented by formulae: A[(O—CHR4—Z—CHR5)m—O—CO—CHR1—CO—R3]n and A[(O—CHR4—Z—CHR5)m—O—CO—CR1═C(—NHR2)—R3]n, wherein: A is the residue of an alcohol or polyol selected from hydroxyalkanoic acid esters, sugars and their glycosides, sugar alcohols, sugar acids and their esters, and oligosaccharides; m is an integer number from 0 up to 6; n is a number from 1 up to the total number of hydroxyl groups in the polyol; R1 is hydrogen, C1-C8 alkyl, C3-C8 alkenyl or cycloalkyl (alkyl) or C6-C8 aryl or aralkyl; R2 is hydrogen, C1-C6 alkyl, C2-C6 hydroxyalkyl or C3-C6 alkenyl; R3 is C1-C18 alkyl, alkoxy or alkylamino, C3-C18 alkenyl, alkanoylmethyl, alkoxycarbonylmethyl or cycloalkyl(alkyl), C6-C18 aryl, aryloxy, arylamino, aralkyl, aralkoxy or aralkylamino, or C8-C18 aroylmethyl, arylox

Abstract: Natural cyclic polyalcohols such as polyfructoses and, dehydration products of sugar alcohols can be used for stabilising thermoplastic polymers, at a ratio of 0.001-5 phr of polyol with respect to the polymer. The cyclic polyol is in particular inulin or sorbitan. The polymer to be stabilised is in particular PVC, PE, PP or a halogenated rubber.