Sankyo Company, Limited

Hisayu Ohsawa

Tomoyuki Kurumada

Takaaki Yamazaki

Keisuke Murayama

Katsuaki Matsui

Noriyuki Ohta

Susumu Higashida

Satoru Naito

Kohtaro Kanetaki

Compounds of formula (I): ##STR1## wherein: R.sup.1 represents an alkyl group having from 1 to 6 carbon atoms;

Phenylalkanoic acid esters and their use as antioxidants

4-Piperidone derivatives having the formulae ##SPC1## Wherein R represents a phenyl or naphthyl group which may be substituted with nitro, lower alkyl, halogen, hydroxyl, lower alkyl hydroxy, hydroxy lower alkyl or formyl or a 5- or 6-membered heterocyclic group having as a hetero atom at least one of oxygen atom, sulfur atom and nitrogen atom and R.sub.1 represents hydrogen atom or an alkyl group of 1 to 4 carbon atoms. They are useful as stabilizers for various synthetic polymers against their photo- and thermal-deteriorations and the 4-piperidone derivatives (II) are prepared from the corresponding 2,2,6,6-tetramethyl-4-oxopiperidine derivatives by reaction with an aldehyde and the 4-piperidone derivatives (I) are prepared from the 4-piperidone derivatives (II) through dehydration.

4-Piperidone derivatives, their preparation and their use as stabilizers

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Tokyo, Japan

Hisayu Ohsawa