Mixtures of esters of polyalkylpiperidine derivatives, of the formulae I and II ##STR1## in which the proportions of I to II are 95 to 70% by weight and 5 to 30% by weight, are obtained by reacting about 2 mols of a piperidine of the formula III ##STR2## with 0.9 to 1.3 mols of a diester of the formula IV ##STR3## in the melt at between 100.degree. and 145.degree. C., in the presence of an alkali metal amide as a catalyst. The mixtures of esters thus obtained are very suitable as light stabilizers for plastics.
Disclosed is a process for the preparation of hindered amine light stabilizers by reacting (a) an alkyl substituted-4-hydroxypiperidine with (b) a dicarboxylic acid ester, in the presence of a catalyst system comprising a basic inorganic compound and a polar aprotic organic compound.
A mixture containing two different compounds of the formula (I) ##STR1## wherein n is an integer from 2 to 22 and R is hydrogen, C.sub.1 -C.sub.8 alkyl, --O.multidot., --OH, --NO, --CH.sub.2 CN, C.sub.1 -C.sub.18 alkoxy, C.sub.5 -C.sub.12 cycloalkoxy, C.sub.3 -C.sub.6 alkenyl, C.sub.3 -C.sub.6 alkynyl, C.sub.1 -C.sub.8 acyl or C.sub.7 -C.sub.9 phenylalkyl unsubstituted or substituted on the phenyl by 1, 2 or 3 C.sub.1 -C.sub.4 alkyl; the weight ratio of the two compounds being 1:20 to 20:1, is useful as stabilizer for organic materials against degradation induced by light, heat or oxidation.
A lubricant based on a mineral or synthetic oil is stabilized against oxidative degradation by the addition of a mixture comprising at least one specified aromatic amine of the formula I or II ##STR1## and at least one sterically hindered amine. The lubricant may contain other antioxidants or other additives. It is preferably used as motor oil.
A lubricant based on a mineral or synthetic oil is stabilized against oxidative degradation by the addition of a mixture comprising at least one specified aromatic amine of the formula I ##STR1## and at least one sterically hindered amine. The lubricant may contain other antioxidants or other additives. It is preferably used as motor oil.
Thermally stable olefin polymers are obtained by addition, before or during polymerization, or after polymerization is substantially complete, but before quenching the catalyst, which terminates the polymerization reaction, of stabilizers of the HALS type ("Hindered Amine Light Stabilizer") of monomeric or oligomeric type, containing in the molecule one or more substituted piperidyl groups having formula: ##STR1## wherein R1 are the same or different from each other and are C.sub.1 -C.sub.4 alkyl radicals, tetramethylpiperidyl radicals, or the alkyl radicals, together with the piperidyl carbon atom to which they are bonded, form a C.sub.5 -C.sub.9 cycloalkyl radical; R.sub.2 are the same or different from each other and are hydrogen, C.sub.1 -C.sub.18 alkyl radicals, C.sub.7 -C.sub.18 aralkyl radicals, or said alkyl radicals together with the piperidyl carbon atom to which they are bonded, are a C.sub.5 -C.sub.10 cycloalkyl radical; R.sub.3 are the same or different from each other and are hydrogen, C.sub.1 -C.sub.18 alkyl radicals or C.sub.7 -C.sub.18 aralkyl radicals; R.sub.4 is hydrogen, a C.sub.1 -C.sub.8 alkyl radical or a benzyl radical; Z is hydrogen or an organic radical. Suitable organic radicals include C.sub.1 -C.sub.18 alkyl; C.sub.1 -C.sub.12 alkylene; C.sub.3 -C.sub.12 alkenyl; C.sub.3 -C.sub.5 alkenyl; C.sub.7 -C.sub.18 aralkyl; C.sub.2 -C.sub.4 acyl; C.sub.2 -C.sub.18 alkanoyl; C.sub.3 -C.sub.18 alkoxyalkyl; C.sub.3 -C.sub.18 alkenoyl; oxyl; cyanomethyl, and xylylenyl radicals; a radical having valence from 1 to 4 and containing from 1 to 4 hydroxyl groups and, optionally, containing ether, ester, or heterocyclic groups, all the valences of this radical being bonded to the nitrogen of the piperidyl rings; a bivalent radical containing one or more ester or amide groups, and a radical ##STR2## wherein R.sub.5 and R.sub.6 are hydrocarbyl radicals. Preferably Z is a C.sub.1 -C.sub.12 alkyl, C.sub.3 -C.sub.8 alkenyl, C.sub.7 -C.sub.11 aralkyl, or a bivalent radical containing one or more ester groups wherein the two valences of said radicals are bonded to piperidyl rings.
