Substituted malonic acid derivatives and their use as stabilizers

Esters and amides from 4-hydroxy-and 4-amino-polyalkylpiperidines and hydroxybenzylmalonic acids substituted at the central carbon atom with an organic residue, preferably alkyl-, esteralkyl- or phosphonoalkyl-groups, are excellent stabilizers for organic polymers, especially for polyolefins. They protect the polymers as well against light degradation as against thermo-oxidative degradation. The compounds can be prepared by hydroxybenzylation of the corresponding derivatives of substituted malonic acids. Bis-malonic acid derivatives may be obtained from the monomalonics by reaction with formaldehyde.

The invention relates to new esters of hydroxybenzylmalonic acids, to their 
manufacture and to their use as stabilisers for plastics, as well as to 
the material stabilised therewith. 
The compounds concerned are those of the formula I 
##STR1## 
and the acid addition salts thereof, wherein 
n is 1 or 2, 
R.sub.a represents alkyl having 1-6 carbon atoms, 
R.sub.b represents alkyl having 1-6 carbon atoms, 
R.sub.c represents alkyl having 1-9 carbon atoms, phenyl, benzyl or 
phenylethyl, 
R.sub.d represents alkyl having 1-6 carbon atoms, or 
R.sub.c and R.sub.d together represent tetra- or pentamethylene, 
R.sub.e represents hydrogen, alkyl having 1-5 carbon atoms, alkenyl or 
alkynyl having 3-4 carbon atoms or aralkyl having 7-8 carbon atoms, 
R.sub.f represents hydrogen, alkyl having 1-5 carbon atoms, alkenyl or 
alkynyl having 3-4 carbon atoms, or aralkyl having 7-8 carbon atoms, with 
R.sub.e and R.sub.f being mutually exchangeable, and 
X represents oxygen or --NR--, 
R represents hydrogen, alkyl having 1-18 carbon atoms, alkenyl having 3-4 
carbon atoms, alkynyl having 3-4 carbon atoms, cycloalkyl having 5-12 
carbon atoms, aryl having 6-10 carbon atoms, or aralkyl having 7-9 carbon 
atoms, 
R.sub.1 represents hydrogen, --O.sup.., --OH, alkyl having 1-12 carbon 
atoms, alkenyl having 3 or 4 carbon atoms, propargyl, benzyl or a group of 
the formula --CH.sub.2 --CH(OR.sup.5)--R.sup.4 wherein R.sup.4 represents 
hydrogen, methyl or phenyl and R.sup.5 represents hydrogen or a group 
A--CO--, or R.sup.1 represents a group A--CO--, and in both cases A 
represents alkyl having 1-12 carbon atoms, alkenyl having 2 or 3 carbon 
atoms, cyclohexyl, phenyl, benzyl, a phenyl or phenylethyl group 
substituted by 2 alkyl groups each having 1-4 carbon atoms and a hydroxyl 
group, alkylamino having 1-12 carbon atoms, dialkylamino having 2-16 
carbon atoms, anilino, alkoxy having 1-12 carbon atoms, benzyloxy or 
phenoxy, 
R.sup.2 represents a hydroxybenzyl group of the formula II 
##STR2## 
wherein R.sup.6 and R.sup.7 each independently represent an alkyl group 
having 1-9 carbon atoms, aralkyl having 7-9 carbon atoms or cycloalkyl 
having 5-8 carbon atoms, and R.sup.8 represents hydrogen or methyl, and 
R.sub.3 represents, in the case where n is 1, alkyl having 1-20 carbon 
atoms, or alkyl having 1-10 carbon atoms which is substituted by one or 
more of the groups --OR.sup.9, --SR.sup.10, --CO--R.sup.11, --CN, 
--C(O)--YR.sup.12, --O--C(O)R.sup.13 or --P(O)(OR.sup.14).sub.2, wherein 
R.sup.9 denotes phenyl or alkylphenyl having 7-10 carbon atoms, benzyl or 
cyclohexyl, 
R.sup.10 denotes phenyl or alkylphenyl having 7-10 carbon atoms, 
R.sup.11 denotes alkyl having 1-12 carbon atoms, 
Y denotes oxygen or --NR--, whereby R has the above-given meaning, 
R.sup.12 denotes alkyl having 1-18 carbon atoms, cycloalkyl having 5-12 
carbon atoms, or a group of the formula III 
##STR3## 
wherein R.sup.17 has one of the meanings given for R.sup.1, R.sup.13 
denotes alkyl having 1-17 carbon atoms, cycloalkyl having 5-12 carbon 
atoms, or phenyl or phenylalkyl having 7-9 carbon atoms, whereby the 
phenyl radical can be substituted by alkyl having 1-4 carbon atoms and/or 
hydroxyl, and 
R.sup.14 denotes alkyl having 1-8 carbon atoms, allyl or phenyl, and X has 
the above-defined meaning, and 
R.sup.3 further represents an alkyl group having 2-22 carbon atoms which is 
interrupted by --O--, --S--, --SO-- or --SO.sub.2 --, alkenyl having 3-18 
carbon atoms, alkynyl having 3-8 carbon atoms, cycloalkyl having 5-12 
carbon atoms, alkyl-cycloalkyl having 6-18 carbon atoms, cycloalkyl-alkyl 
having 6-14 carbon atoms, aralkyl or alkyl-aralkyl having 7-19 carbon 
atoms, phenyl or a group --OR.sup.15, whereby R.sup.15 can be alkyl having 
1-18 carbon atoms, alkenyl having 3-4 carbon atoms, alkynyl having 3-4 
carbon atoms, cycloalkyl having 5-12 carbon atoms or aralkyl having 7-9 
carbon atoms, or R.sup.3 represents a group --O--C(O)R.sup.16 or 
--NH--C(O)R.sup.16, whereby R.sup.16 can be alkyl having 1-12 carbon 
atoms, alkenyl having 2 or 3 carbon atoms, cyclohexyl, phenyl, benzyl, a 
phenyl or phenylethyl group substituted by 2 alkyl groups each having 1-4 
carbon atoms and a hydroxyl group, or R.sup.3 is a group of the formula 
III or of the formula IV 
##STR4## 
wherein R.sup.18 represents alkyl having 1-20 carbon atoms, allyl, benzyl, 
phenyl, cyclohexyl, alkoxyalkyl having 3-8 carbon atoms, or a group 
--O--C(O)R.sup.16 or --NH--C(O)R.sup.16 as defined above, or has one of 
the meanings given for R.sup.2, and R.sup.19 and R.sup.20 each 
independently represent alkyl having 1-6 carbon atoms, or a radical of the 
formula III, and, in addition, 
R.sub.3 represents, in the case where n is 2, a direct bond, alkylene 
having 1-20 carbon atoms, alkylene having 2-20 carbon atoms which is 
interrupted by one or two of the members --O--, --S--, --SO--, --SO.sub.2 
-- or --CO--O--, arylene-bis-alkylene having 8-14 carbon atoms, alkylene 
having 4-8 carbon atoms or alkynylene having 4-8 carbon atoms. 
R.sub.a, R.sub.b and R.sub.d can be straight-chain or branched-chain alkyl 
groups having 1-6 carbon atoms, such as methyl, ethyl, propyl, butyl, 
isobutyl, isopentyl or n-hexyl. 
R.sub.c can be a straight-chain or branched-chain alkyl group having 1-9 
carbon atoms, such as methyl, ethyl, propyl, n-butyl, isobutyl, isopentyl, 
n-hexyl, 2-ethylhexyl, n-nonyl or isononyl. 
R.sub.e and R.sub.f can be alkyl groups having up to 5 carbon atoms, with 
R.sub.e preferably containing 1 carbon atom less than R.sub.b and the 
position of R.sub.e and R.sub.f being exchangeable. R.sub.e and R.sub.f 
can also represent alkenyl or alkynyl, for example allyl, methallyl, 
2-butenyl or propargyl, especially allyl. R.sub.e and R.sub.f can also 
represent aralkyl, for example benzyl, phenylethyl or methylbenzyl, 
preferably benzyl. 
Preferably R.sub.a, R.sub.b, R.sub.c and R.sub.d are methyl, and R.sub.e 
and R.sub.f are hydrogen. 
R.sup.1, R.sup.16 and A as an alkyl group having 1-12 carbon atoms can be a 
primary alkyl group, such as a methyl, ethyl, n-propyl, n-butyl, n-hexyl, 
n-octyl, n-decyl or n-dodecyl group. 
R and R.sup.15 as alkyl having up to 18 carbon atoms can in addition be; 
e.g., tridecyl, hexadecyl or octadecyl. 
R, R.sup.1, R.sup.15, R.sup.16 and A as an alkenyl group can be, e.g., an 
allyl, methallyl or butenyl group. 
R and R.sup.15 as alkynyl having 3-4 carbon atoms can be, e.g., propargyl 
or methylpropargyl. 
R and R.sup.15 as cycloalkyl having 5-12 carbon atoms can be, e.g., 
cyclopentyl, cyclohexyl, cyclooctyl or cyclododecyl. 
R as aryl can be, for example, phenyl, tolyl or naphthyl. 
R and R.sup.15 as aralkyl can be, e.g., benzyl, phenylethyl or 
phenylpropyl. 
If R.sup.1 and/or R.sup.5 represent a group A--CO--, then this can be, 
depending on the meaning of A, a carbonic acid radical such as acetyl, 
propionyl, butyryl, capronyl, caprylol, lauroyl, acryloyl, crotonoyl, 
phenylacetyl, .beta.-(3,5-di-tert. butyl-4-hydroxyphenyl)-propionyl or 
benzoyl; or a carbamoyl radical such as methylcarbamoyl, butylcarbamoyl, 
dodecylcarbamoyl, diethylcarbamoyl, dihexylcarbamoyl, dioctylcarbamoyl or 
phenylcarbamoyl; or a carbonic ester radical such as ethoxycarbonyl, 
isopropoxycarbonyl, 2-ethylhexyloxycarbonyl, dodecyloxycarbonyl, 
benzyloxycarbonyl or phenoxycarbonyl. 
According to its definition by formula II, R.sup.2 can be a para- or 
meta-hydroxybenzyl group. The substituents R.sup.6 and R.sup.7 on the 
benzyl radical can be straight-chain or branched-chain alkyl groups having 
1-9 carbon atoms, e.g. methyl, ethyl, isopropyl, tert.butyl, n-hexyl, 
1,1,3,3-tetramethylbutyl or tert.nonyl. In the case where R.sup.6 or 
R.sup.7 represent cycloalkyl, this can be, for example, cyclopentyl, 
methylcyclopentyl, cyclohexyl or methylcyclohexyl. Where R.sup.6 or 
R.sup.7 represents aralkyl, this can be, e.g., benzyl or 
.alpha.,.alpha.-dimethylbenzyl. R.sup.6 and R.sup.7 are preferably alkyl 
groups having 1-4 carbon atoms, especially methyl or tert.butyl. 
Depending on the value of n, R.sup.3 can be a mono- or bivalent organic 
radical. As alkyl having 1-20 carbon atoms, R.sup.3 can be, e.g., one of 
the alkyl groups given above for R.sup.1 ; it can also represent 
branched-chain alkyl such as isopropyl, isopentyl, 2-ethylbutyl, 
2-ethylhexyl or isononyl, or higher alkyl radicals such as n-hexadecyl, 
n-octadecyl or n-eicosyl. 
As a substituted or interrupted alkyl group, R.sup.3 can be, for example, 
one of the following radicals: 2-phenoxyethyl, 2-benzyloxyethyl, 
2-p-tolyloxypropyl, cyclohexyloxymethyl, 2,3-di(phenoxy)propyl, 
2-phenylthioethyl, 2-(4-tert.butylphenylthio)-ethyl, 2-acetylethyl, 
2-isobutyrylethyl, 2-(dodecylcarbonyl)-ethyl, 2-cyanoethyl, cyanomethyl, 
3-cyanopropyl, methoxycarbonylmethyl, dodecyloxycarbonylmethyl, 
2-ethoxycarbonylethyl, 1,2-di(methoxycarbonyl) ethyl, 
2,3-di(ethoxycarbonyl)propyl, 2-(butylaminocarbonyl) ethyl, 
2-(cyclohexyloxycarbonyl)-ethyl, 2-(tert.butyloxycarbonyl)-ethyl, 
2-(octadecyloxycarbonyl)-propyl, 4-(propoxycarbonyl)-butyl, 
2-acetoxyethyl, 1,2-diacetoxy-ethyl, 2-(isooctanoyloxy)-propyl, 
2-(octadecanoyloxy)-ethyl, 2-(cyclopentylcarbonyloxy)-ethyl, 
3-benzoyloxypropyl, 2-(p-tert.butylbenzoyloxy)-ethyl, 
2-salicyloyloxy-ethyl, 2-(3,5-di-tert.butyl-4-hydroxybenzoyloxy)-ethyl, 
2-phenylacetyloxyethyl, 
2-(3,5-di-tert.butyl-4-hydroxyphenylpropionyloxy)-propyl, 
diethylphosphonomethyl, 2-dimethylphosphono-ethyl, 
2-(dioctylphosphono)-ethyl, diphenylphosphonomethyl, 
3-(diallylphosphono)-propyl, methoxymethyl, 2-butoxyethyl, 
2-octadecyloxyethyl, isopropoxymethyl, 3-butylthio-propyl, 
2-dodecylthio-ethyl, 2-(isohexylsulphinyl)-ethyl, 
2-octadecylsulphonyl-ethyl, 2-ethylsulphonyl-propyl, 
2-(2,2,6,6-tetramethylpiperidin-4-yloxycarbonyl)-ethyl, 
2-(1,2,2,6,6-pentamethylpiperidin-4-ylaminocarbonyl)-ethyl, 
2-(2,2,6,6-tetramethylpiperidin-4-yloxycarbonyl)-2-(methoxycarbonyl)-hexyl 
or 2,2-bis-(2,2,6,6-tetramethylpiperidin-4-ylaminocarbonyl)-hexyl. 
As an alkenyl or alkynyl group, R.sup.3 can be, for example, allyl, 
methallyl, 2-buten-1-yl, 3-hexen-1-yl, undecenyl, oleyl, propargyl or 
2-heptyn-1-yl. 
Examples of R.sup.3 as cycloalkyl, alkyl-cycloalkyl or cycloalkyl-alkyl are 
the radicals cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, 
methylcyclopentyl, dimethylcyclohexyl, propylcyclooctyl, 
hexylcyclododecyl, cyclohexylmethyl, 3-cyclooctylpropyl or 
decahydronaphthyl-.alpha.-methyl. 
Examples of R.sup.3 as aralkyl or alkyl-aralkyl are the groups benzyl, 
2-phenylethyl, 2-phenylpropyl, .beta.-naphthylmethyl, 4-methylbenzyl, 
4-t-butylbenzyl or 4-methylnaphthyl-1-methyl. 
R.sup.3 as a group --O--CO--R.sup.16 or --NH--CO--R.sup.16 can be, for 
example, acetoxy, propionoxy, butyroxy, octanoyloxy, dodecanoyloxy, 
acryloxy, crotonoxy, benzoyloxy, phenylacetoxy, 
3,5-di-tert.butyl-4-hydroxybenzoyloxy, acetamino, butyrylamino, 
decanoylamino, acroylamino, benzoylamino or cyclohexylcarbonylamino. 
In the case where n is 2, R.sup.3 represents a direct bond or a bivalent 
organic radical. This can be alkylene, e.g. methylene, ethylene or 
polymethylene having up to 20 carbon atoms; or the alkylene radical is 
interrupted by 1 or 2 hetero members, such as the bivalent radicals, 
--CH.sub.2 O--CH.sub.2 --, --CH.sub.2 CH.sub.2 O--CH.sub.2 CH.sub.2 --, 
--CH.sub.2 CH.sub.2 --O--CH.sub.2 CH.sub.2 --O--CH.sub.2 CH.sub.2 --, 
--(CH.sub.2).sub.3 --S--(CH.sub.2).sub.3 --, --CH.sub.2 CH.sub.2 
--S--(CH.sub.2).sub.4 --S--CH.sub.2 CH.sub.2 --, --CH.sub.2 CH.sub.2 
--SO--CH.sub.2 CH.sub.2 --, --CH.sub.2 CH.sub.2 --SO.sub.2 --CH.sub.2 
--CH.sub.2 CH.sub.2 --, --CH.sub.2 CH.sub.2 --SO.sub.2 --(CH.sub.2).sub.8 
--SO.sub.2 --CH.sub.2 CH.sub.2 --, --CH.sub.2 COOCH.sub.2 CH.sub.2 
OOCCH.sub.2 --, --CH.sub.2 CH.sub.2 COOCH.sub.2 CH.sub.2 OOCCH.sub.2 
CH.sub.2 --, --CH.sub.2 CH.sub.2 --COO(CH.sub.2).sub.4 --OOC--CH.sub.2 
CH.sub.2 --, --CH.sub.2 CH.sub.2 OCO(CH.sub.2).sub.4 COOCH.sub.2 CH.sub.2 
-- and --CH.sub.2 CH.sub.2 OCO(CH.sub.2).sub.8 COOCH.sub.2 CH.sub.2 --. 
R.sup.3 can also be arylene-bis-alkylene, e.g. p-xylylene, 
benzene-1,3-bis(ethylene), diphenyl-4,4'-bis(methylene) or 
naphthalene-1,4-bis(methylene). It can, finally, be alkenylene or 
alkynylene having 4-8 carbon atoms, such as 2-butenylene-1,4, 
2-butynylene-1,4 or 2,4-hexadiynylene-1,6. 
The compounds of the formula I impart to plastics excellent protection 
against thermal-oxidative ageing, such as light-induced ageing. It is 
known that plastics can be stabilised by the addition of antioxidants or 
of light stabilisers or of a mixture of both, in consequence of which 
their service life is considerably lengthened. There have recently become 
known also stabilisers which simultaneously have an antioxidative and 
light-stabilising action. In DT-OS No. 2,456,864 there have thus been 
described 4-piperidinol esters of mono- and di-(hydroxybenzyl)-malonic 
acids which have a stabilising action that is greater than that of a 
corresponding mixture of a hydroxybenzylmalonate, known as an antioxidant, 
and a 4-piperidinol derivative, known as a light stabiliser. If in the 
compounds of DT-OS No. 2,456,864 a hydroxybenzyl radical or a hydrogen 
atom is replaced by an alkyl group or by another group known as being 
inactive (such as one that has just been defined as R.sup.3), then there 
is surprisingly obtained an increase in the antioxidative and 
light-stabilising effectiveness. Some compounds of the formula I surpass 
in effectiveness in certain plastics all stabilisers at present known, so 
that the invention is therefore of great importance for the technology of 
plastics. 
Preferred compounds of formula I are those wherein R.sub.a to R.sub.d are 
methyl, and R.sub.e and R.sub.f are hydrogen, or wherein R.sub.a and 
R.sub.c are ethyl, R.sub.b, R.sub.d and R.sub.e are methyl, and R.sub.f is 
hydrogen. Also preferred are compounds of formula I wherein X is oxygen or 
NH, R.sup.1 is hydrogen, --O.sup.., --OH, alkyl having 1-4 carbon atoms, 
allyl, propargyl, acetyl, acryloyl or crotonoyl, 
R.sup.2 represents a hydroxybenzyl group of the formula IIa or IIb, 
##STR5## 
R.sup.6 and R.sup.7 each independently represent alkyl having 1 to 4 carbon 
atoms, 
R.sup.8 represents hydrogen or methyl, 
R.sup.3 represents in the case where n is 1 alkyl having 1-18 carbon atoms, 
alkyl having 1-4 carbon atoms which is substituted by one or two of the 
groups --CN, --C(O)--YR.sup.12, --O--C(O)R.sup.13 or 
--P(O)(OR.sup.14).sub.2, wherein Y is --O-- or --NH--, 
R.sup.12 can be alkyl having 1-4 carbon atoms, or a group of the formula 
IIIb 
##STR6## 
R.sup.13 can be alkyl having 1-17 carbon atoms, cyclohexyl, phenyl or 
benzyl, and R.sup.14 can be alkyl having 1-4 carbon atoms or allyl, and 
R.sup.3 further represents alkyl having 2-18 carbon atoms which is 
interrupted by --O-- or --S--, cycloalkyl having 5-12 carbon atoms, 
alkylcycloalkyl having 6-18 carbon atoms, alkenyl having 3-6 carbon atoms, 
alkynyl having 3-6 carbon atoms, phenyl, aralkyl having 7-15 carbon atoms, 
or a group --OR.sup.15, wherein R.sup.15 represents alkyl having 1-12 
carbon atoms, allyl, propargyl or benzyl, or a group --O--COR.sup.16 or 
--NH--COR.sup.16, wherein R.sup.16 represents alkyl having 1-12 carbon 
atoms, phenyl, 3,5-di-tert.butyl-4-hydroxyphenyl or 
2-(3,5-di-tert.butyl-4-hydroxyphenyl)-ethyl, or a group of the formula 
IIIb, or 
in the case where n is 2 
a direct bond, alkylene having 1-12 carbon atoms which can be interrupted 
by one or two of the groups --O--, --S-- or --CO--O--, 
arylene-bis-alkylene having 8-14 carbon atoms or alkylene having 4-8 
carbon atoms. 
Particularly preferred are compounds of the formula I wherein n is 1 or 2, 
R.sub.a, R.sub.b, R.sub.c and R.sub.d are methyl, and 
R.sub.e and R.sub.f are hydrogen, X is oxygen, 
R.sup.1 is hydrogen, --O.sup.., alkyl having 1-4 carbon atoms, allyl or 
acetyl, 
R.sup.2 is a hydroxybenzyl group of the formula IIa or IIb wherein R.sup.6 
represents tert. butyl, R.sup.7 represents methyl or tert.butyl and 
R.sup.8 represents hydrogen or methyl, and 
R.sup.3 represents alkyl having 1-18 carbon atoms, which is substituted by 
1 or 2 groups --C(O)--OR.sup.12, wherein R.sup.12 represents alkyl having 
1-4 carbon atoms or a group of the formula IIIa 
##STR7## 
or is substituted by a group --P(O)(OR.sup.14).sub.2, wherein 
R.sup.14 represents alkyl having 1-4 carbon atoms, or 
R.sup.3 represents allyl, propargyl, benzyl, phenyl, alkylene having 1-8 
carbon atoms or xylylene. 
The present invention embraces also the salts of compounds of the formula 
I, which are formed by the addition of acids in amounts at most equivalent 
to the piperidine groups. Such acids can be inorganic acids such as 
sulphuric, hydrochloric or phosphoric acid, organic carboxylic acids such 
as formic, acetic, oxalic, maleic, benzoic or salicylic acid, organic 
sulphonic acids such as methane- or p-toluenesulphonic acid, or organic 
phosphorus-containing acids such as diphenylphosphoric acid, 
methanephosphonic acid or diphenylphosphinic acid. 
Examples of compounds of the formula I are: 
butyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis-(2,2,6,6-tetramethyl-4-piperidinyl)ester, 
allyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(1-allyl-2,2,6,6-tetramethyl-4-piperidinyl)ester, 
ethyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(1-hydroxyl-2,2,6,6-tetramethyl-4-piperidinyl)ester, 
propargyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)ester, 
.beta.-methoxyethyl-(3-methyl-5-.alpha.,.alpha.-dimethylbenzyl-4-hydroxyben 
zyl)malonic acid-bis(2,2,6,6-tetramethyl-4-piperidinyl)ester, 
dodecyl-(2,6-dimethyl-4-tert.butyl-3-hydroxybenzyl)-malonic 
acid-bis(1-acryl-2,2,6,6-tetramethyl-4-piperidinyl)ester, 
phenylthiomethyl-(3-tert.butyl-5-tert.amyl-4-hydroxybenzyl)malonic 
acid-bis(1-acetyl-2,2,6,6tetramethyl-4-piperidinyl)ester, ester, 
dodecylthioethyl-(3-methyl-5-cyclohexyl-4-hydroxybenzyl)-malonic 
acid-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)ester, 
dodecylsulphonylethyl-(3-methyl-5-cyclohexyl-4-hydroxybenzyl)-malonic 
acid-bis(1,2,6,6-pentamethyl-4-piperidinyl)ester, 
methyloxycarbonylmethyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl)ester, 
.gamma.-octyloxypropyl-(3-methyl-5-ditert.octyl-4-hydroxybenzyl)-malonic 
acid-bis(1-crotonyl-2,2,6,6-tetramethyl-4-piperidinyl)ester, 
.beta.-butylcarbonylethyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(1-formyl-2,2,6,6-tetramethyl-4-piperidinyl) ester, 
phenylsulphinylmethyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl) ester, 
.beta.-(octyloxycarbonyl)ethyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(1-propyl-2,2,6,6-tetramethyl-5-piperidinyl) ester, 
1,2,2,6,6-pentamethyl-4-piperidineoxycarbonylmethyl-(3,5-di-tert.butyl-4-hy 
droxybenzyl)-malonic acid-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)ester, 
benzyl-(3-methyl-5-ditert.octyl-4-hydroxybenzyl)-malonic 
acid-bis(2,2,6,6-tetramethyl-4-piperidinyl)ester, 
cyclohexyl-(2,3-dimethyl-5-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(2,2,6,6-tetramethyl-4-piperidinyl)ester, 
2,2,6,6-tetramethyl-4-piperidinyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malon 
ic acid-bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) ester, 
.beta.-cyanoethyl-(3-isopropyl-5-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(2,2,6,6-tetramethyl-4-piperidinyl)ester, 
.beta.-diethylphosphonoethyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(2,2,6,6-tetramethyl-4-piperidinyl)ester, 
.beta.-diphenylphosphonoethyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(1-benzyl-2,2,6,6-tetramethyl-4-piperidinyl) ester, 
1,4-di(3,5-di-tert.butyl-4-hydroxyphenyl)-2,2,3,3-tetra-(1,2,2,6,6-pentamet 
hyl-4-piperidinyloxycarbonyl)-butane, 
4,4'-di(3,5-di-tert.butyl-4-hydroxyphenyl)-3,3,3',3'-tetra-(2,2,6,6-tetrame 
thyl-4-piperidinyloxycarbonyl)-dibutylsulphone, 
4,4'-di(3,5-di-tert.butyl-4-hydroxyphenyl)-3,3,3',3'-tetra-(2,2,6,6-tetrame 
thyl-4-piperidinyloxycarbonyl)-dibutyl ether, 
3,3'-di(3,5-di-tert.butyl-4-hydroxyphenyl)-2,2,2',2'-tetra-(1-acetyl-2,2,6, 
6-tetramethyl-4-piperidinyloxycarbonyl)-p-dipropylbenzene, 
1,8-di(3,5-di-tert.butyl-4-hydroxyphenyl)-2,2',7',7'-tetra-(1,2,2,6,6-pent 
amethyl-4-piperidinyloxycarbonyl)-oct-4-ene, 
ethylene-di[.delta.-3,5-di-tert.butyl-4-hydroxyphenyl-.gamma.-.gamma.-bis 
(2,2,6,6-tetramethyl-4-piperidinyloxycarbonyl)-valerianate], 
1,16-bis(3,5-di-tert.butyl-4-hydroxyphenyl)-2,2,15,15-tetra-kis(1-oxyl-2,2, 
6,6-tetramethyl-4-piperidinyloxycarbonyl)-hexadecane, 
1,8-bis(3-methyl-5-tert.butyl-4-hydroxyphenyl)-2,2,7,7-tetra-kis(1-acetyl-2 
,2,6,6-tetramethyl-4-piperidinyloxycarbonyl)-oct-4-ine. 
butyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic acid-bis 
(2,6-diethyl-2,5,6-trimethyl-4-piperidinyl)ester, 
allyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic acid-bis 
(2,6-diethyl-2,5,6-trimethyl-4-piperidinyl)ester, 
propargyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(2,6-diethyl-1,2,5,6-tetramethyl-4-piperidinyl)ester, 
dodecyl-(2,6-dimethyl-4-tert.butyl-3-hydroxybenzyl)malonic 
acid-bis(1-acryl-2,6-diethyl-2,5,6-trimethyl-4-piperidinyl) ester, 
dodecylsulphonylethyl-(3-methyl-5-cyclohexyl-4-hydroxybenzyl)-malonic 
acid-bis(2,6-diethyl-1,2,5,6-tetramethyl-4-piperidinyl) ester, 
methyloxycarbonylmethyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(1-oxyl-2,6-diethyl-2,5,6-trimethyl-4-piperidinyl)ester, 
.beta.-(octyloxycarbonyl)ethyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(1,2,6-tripropyl-2,6-dimethyl-5-ethyl-4-piperidinyl)ester, 
benzyl-(3-methyl-5-di-tert.octyl-4-hydroxybenzyl)-malonic 
acid-bis(2,6-diethyl-2,5,6-trimethyl-4-piperidinyl)ester, 
cyclohexyl-(2,3-dimethyl-5-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(2,6-diethyl-1,2,5,6--tetramethyl-4-piperidinyl)ester, 
2,2,6,6-tetramethyl-4-piperidinyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malon 
ic acid-bis(2,6-diethyl-1,2,5,6-tetramethyl-4-piperidinyl)ester, 
.beta.-cyanoethyl-(3-isopropyl-5-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(2,5,6,6-tetramethyl-2-ethyl-4-piperidinyl) ester, 
.beta.-diethylphosphonoethyl-(3,5-di-tert.butyl-4-hydroxybenzyl)-malonic 
acid-bis(2,6-diethyl-2,5,6-trimethyl-4-piperidinyl) ester, 
1,4-di(3,5-di-tert.butyl-4-hydroxyphenyl)-2,2,3,3-tetra-(2,5,6-trimethyl-2, 
6-diethyl-4-piperidinyloxycarbonyl)-butane. 
The compounds of the formula I can be manufactured by various methods which 
consist of several separate steps in varying sequence. The individual 
steps consist of reactions that are known, particularly such reactions 
known from the chemistry of malonic acid derivatives. 
Synthesis can commence with conversion of a malonic acid lower alkyl ester 
such as diethylmalonate, by reaction with a 4-piperidinol or 
4-aminopiperidine of the formula V, into the corresponding bis-piperidinyl 
malonic acid derivative VI. 
##STR8## 
R.sup.1 can already be the substituent desired in the compound of the 
formula I; or the piperidine derivative (V, R.sup.1 .dbd.H) unsubstituted 
on the nitrogen atom is used and the substituent R.sup.1 is introduced 
after the above reaction, or at a later stage in the course of synthesis. 
The introduction of R.sup.1 can be effected by the usual methods for 
N-alkylation or N-acylation; for example by reaction with alkyl halides, 
alkenyl halides, propargyl chloride, benzyl chloride or carboxylic acid 
chlorides, preferably in the presence of molar amounts of a base. 
Hydroxyalkyl radicals are introduced by reaction with epoxides, for 
example ethylene oxide or propylene oxide; and can be converted by 
reaction with carboxylic acid chlorides or carboxylic acid anhydrides into 
the corresponding N-acyloxyalkyl groups. If R.sup.1 is --O.sup.., then 
such N-oxyls can be produced from the NH compounds by oxidation with 
peroxy acids or hydrogen peroxide. By reduction of such N-oxyls, for 
example by means of catalytic hydrogenation, there can be produced the 
compounds wherein R.sup.1 denotes OH. 
As the next step, there can be introduced into the compounds of the formula 
VI either firstly the substituent R.sup.2 and subsequently R.sup.3 or, 
preferably, firstly the substituent R.sup.3 and then R.sup.2. 
The introduction of the hydroxybenzyl group R.sup.2 can be effected by 
reaction with a hydroxybenzyldithiocarbamate of the formula R.sup.2 
--S--CS--N(R.sup.21).sub.2, wherein R.sup.21 represents an alkyl group 
having 1-5 carbon atoms, or both groups R.sup.21 together with the 
nitrogen atom represent a morpholine, pyrrolidine or piperidine ring. Such 
dithiocarbamates are obtainable by reaction of a phenol with formaldehyde, 
carbon disulphide and a secondary amine. 
The reaction of the dithiocarbamates with the compounds of the formula VI 
is performed in the molar ratio of 1:1 in the presence of basic reagents 
such as alkali hydroxides, alkali alcoholates, alkali hydrides or 
alkaline-earth hydrides or alkali amides. These bases are preferably used 
in molar amounts, i.e. there is added per mole of dithiocarbamate one 
equivalent of the base. The reaction can be performed in solution, for 
example in alcohols, ethers or hydrocarbons. Also suitable are polar 
aprotic solvents such as dimethylformamide or dimethylsulphoxide. The 
reaction is carried out preferably in an alcoholic solution with the use 
of alkali hydroxide as the base. 
Another suitable method for introducing the hydroxybenzyl group R.sup.2 
into the comounds VI comprises reacting them with hydroxybenzylamines 
R.sup.2 --N(R.sup.21).sub.2. Such amines are obtainable by reaction of 
phenols with formaldehyde and a secondary amine in a so-called Mannich 
reaction. Their reaction with the compounds VI is likewise accelerated 
with basic catalysts, preferably with alkali amides or alkali alcoholates. 
Also alkali metals are suitable as catalysts. This process differs from 
the dithiocarbamate process, however, in that catalytic amounts, about 0.1 
to 5 Mol-%, of basic catalyst are sufficient. 
Instead of the tertiary amines (Mannich bases), there can also be used the 
quaternisation products thereof. The solvents employed can be those of the 
aforementioned classes: the reaction can however be performed also without 
solvent. 
If X is oxygen, the radical R.sup.2 can be introduced also in the manner of 
a malonic ester synthesis by firstly converting the ester VI by reaction 
with one equivalent of alkali metal, alkali alcoholate, alkali amide or 
alkali hydride, or of a similar basic alkali compound, into the alkali 
compound of VI, and subsequently reacting in the usual manner with 1 mole 
of a hydroxybenzyl halide R.sup.2 Hal (Hal.dbd.Cl, Br or J). Although the 
two aforementioned methods of hydroxybenzylation are preferred, the 
last-mentioned method can be of value in cases in which the halogen 
compound R.sup.2 Hal is readily available. 
Each of the three described methods produces a hydroxybenzyl malonic acid 
derivative of the formula VII, into which the substituent R.sup.3 has to 
be subsequently introduced: 
##STR9## 
The introduction of the substituent R.sup.3 can be effected by the 
conventional method of C-alkylation of malonic esters, whereby firstly VII 
is converted into its alkali compound, and this is then reacted with a 
halogen compound R.sup.3 Hal or R.sup.3 Hal.sub.2. Hal in this case again 
denotes Cl, Br or J. Depending on whether n is to be 1 or 2 in the 
compound of the formula I resulting from the synthesis, there is used per 
mole of alkali compound of VII one mole of a monohalide R.sup.3 Hal or a 
half mole of a dihalogen compound R.sup.3 Hal.sub.2. Examples of these are 
halides of alkyl, cycloalkyl, aralkyl, alkenyl or alkynyl, and dihalides 
of alkylene, alkenylene, alkynylene or xylylene. Further examples are 
halogenocarboxylic acid esters such as chloroacetic acid esters of mono- 
or bivalent hydroxyl compounds, or carboxylic acid esters of 
halogenohydrines such as esters of 2-chloroethanol or 3-bromopropanol. 
Also halogenophosphonic acid esters, such as 
dimethyl-chloromethylphosphonate or diethyl-2-bromoethylphosphonate, are 
suitable for this purpose. 
If iodine is used instead of an organic halogen compound, there are 
obtained compounds of the formula I wherein n is 2 and R.sup.3 is a direct 
bond. 
In addition to this conventional method of C-substitution with halogen 
compounds, it is possible to use for the introduction of the radical 
R.sup.3 the method of the so-called Michael addition, by which method 
compounds having activated double bonds can be added, under the influence 
of basic catalysts, to the central carbon atom of the compound VII. The 
best known sort of such reactions is the cyanoalkylation with 
acrylonitrile. Also suitable however are acrylic acid esters and 
methacrylic acid esters, maleic acid esters, itaconic acid esters, vinyl 
ketones, vinyl sulphones, vinyl esters of carboxylic acids or esters of 
vinylphosphonic acid. The catalysts employed for the purpose are used in 
amounts of about 0.5 to 5 Mol-%. Examples of applicable catalysts are 
again alkali alcoholates, alkali amides, alkali hydrides or alkali 
hydroxides, or quaternary ammonium bases such as benzyltrimethylammonium 
hydroxide. The reactions are preferably performed in solution both in the 
case of the conventional malonic acid substitution and in the case of the 
process of Michael addition. There can be used aprotic solvents such as 
hydrocarbons or ethers, for instance benzene, toluene, dioxane or 
tetrahydrofuran, or polar solvents such as dimethylformamide. 
Compounds of the formula I wherein R.sup.3 is a radical of the formula IV 
can be produced by condensation of two different malonic acid derivatives 
with formaldehyde in the approximate molar ratio 1:1:1, and subsequent 
introduction of one or two hydroxybenzyl groups. 
Compounds of the formula I wherein R.sup.3 is a group of the formula III 
can be obtained by condensation of a malonic acid derivative of the 
formula VI with a 4-oxopiperidine and subsequent hydrogenation of the 
formed piperidylidene compound. 
A special method for the introduction of phosphonomethyl groups as 
substituent R.sup.3 consists of reacting a malonic acid derivative VII 
with formaldehyde and a phosphite of the formula P(OR.sup.14).sub.3. 
Furthermore, a specific substituent R.sup.3 can be firstly introduced by 
one of the processes mentioned, and then converted in an additional 
reaction step into another group R.sup.3. For example, it is possible by 
the addition of ethyl acrylate to introduce the group R.sup.3 
.dbd.CH.sub.2 CH.sub.2 COOC.sub.2 H.sub.5, which is then converted in a 
second step by transesterification with ethylene glycol into the bivalent 
group R.sup.3 .dbd.--CH.sub.2 CH.sub.2 COOCH.sub.2 CH.sub.2 OOCCH.sub.2 
CH.sub.2. In a similar manner, an intermediate halogenoalkyl group can be 
converted into a phenoxyalkyl or a phosphonoalkyl group. Alkylthioalkyl 
groups can be converted by oxidation into the corresponding sulphoxides or 
sulphones. This kind of oxidation of the substituent R.sup.3 can be 
performed simultaneously with the introduction of oxygen as R.sup.1, for 
example by oxidation with percarboxylic acids. The introduction of R.sup.1 
can also be performed together with the introduction of R.sup.3 if R.sup.1 
and R.sup.3 are identical, e.g. as alkyl, alkenyl, propargyl or benzyl. 
By virtue of these various possibilites for the carrying out of the 
individual reaction steps, namely 
introduction of the piperidinyl radical, 
introduction of the group R.sup.2, 
introduction of the group R.sup.3, 
and optionally introduction of R.sup.1, 
the sequence of the individual steps selected will be that which appears 
most advantageous for the case in question. 
In the Examples subsequently given, the introduction of R.sup.2 is 
described principally as the final step. Any other step however can 
essentially be selected as the final step. 
If in the compounds of the formula VI, the substituent R.sup.3 is firstly 
introduced according to the above-described methods, there are obtained 
the intermediates of the formula VIII 
##STR10## 
which likewise are novel compounds. 
The compounds of the formula I can be used according to the present 
invention as stabilisers for plastics to protect them from damage caused 
by the action of oxygen, heat and light. Examples of such plastics are the 
following polymers. 
1. Polymers of monoolefines and diolefines, for example polyethylene (which 
optionally can be crosslinked), polypropylene, polyisobutylene, 
polymethylbutene-1, polymethylpentene-1, polyisoprene or polybutadiene. 
2. Mixtures of the polymers mentioned under (1), for example mixtures of 
polypropylene with polyethylene or with polyisobutylene. 
3. Copolymers of monoolefines and diolefines, such as, for example, 
ethylene/propylene copolymers, propylene/butene-1 copolymers, 
propylene/isobutylene copolymers, ethylene/butene-1 copolymers and also 
terpolymers of ethylene with propylene and a diene, such as hexadiene, 
dicyclopentadiene or ethylidenenorbornene. 
4. Polystyrene. 
5. Copolymers or styrene or .alpha.-methylstyrene, such as, for example, 
styrene/butadiene, styrene/acrylonitrile, styrene/acrylonitrile/methyl 
acrylate; mixtures, of high impact strength, of styrene copolymers and 
another polymer, such as, for example, a polyacrylate, a diene polymer or 
an ethylene/propylene/diene terpolymer; and block copolymers of styrene, 
such as, for example, styrene/butadiene/styrene, styrene/isoprene/styrene 
or styrene/ethylene/butylene/styrene. 
6. Graft copolymers of styrene, such as, for example, styrene on 
polybutadiene, styrene and acrylonitrile on polybutadiene and mixtures 
thereof with the copolymers mentioned under (5), such as are known as 
so-called ABS polymers. 
7. Halogen-containing polymers, such as, for example, polyvinyl chloride, 
polyvinylidene chloride, polyvinyl fluoride, polychloroprene, chlorinated 
rubbers and copolymers, such as vinyl chloride/vinylidene chloride, vinyl 
chloride/vinyl acetate or vinylidene chloride/vinyl acetate. 
8. Polymers which are derived from .alpha.,.beta.-unsaturated acids and 
derivatives thereof, such as polyacrylates and polymethacrylates, 
polyacrylamides and polyacrylonitrile. 
9. Polymers which are derived from unsaturated alcohols and amines or acyl 
derivatives or acetals thereof, such as polyvinyl alcohol, polyvinyl 
acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate, 
polyvinylbutyral, polyallyl phthalate, polyallyl-melamine and copolymers 
thereof with other vinyl compounds, such as ethylene/vinyl acetate 
copolymers. 
10. Homopolymers and copolymers of epoxides, such as polyethylene oxide, 
polypropylene oxide or polyisobutylene oxide. 
11. Polyacetals, such as polyoxymethylene and those polyoxymethylenes which 
contain ethylene oxide as a comonomer. 
12. Polyphenylene oxides. 
13. Polyurethanes and polyureas. 
14. Polycarbonates. 
15. Polysulphones. 
16. Polyamides and copolyamides which are derived from diamines and 
dicarboxylic acids and/or from aminocarboxylic acids or the corresponding 
lactams, such as polyamide 6, polyamide 6/6, polyamide 6/10, polyamide 11, 
polyamide 12 or poly-m-phenylene-isophthalamide. 
17. Polyesters which are derived from dicarboxylic acids and dialcohols 
and/or from hydroxycarboxylic acids or the corresponding lactones, such as 
polyethylene terephthalate, polybutylene terephthlate and 
poly-1,4-dimethylol-cyclohexane terephthalate, as well as 
copolyether-esters, wherein all or a part of the used diol is an 
ether-diol or polyetherdiol. 
18. Crosslinked polymers which are derived from aldehydes on the one hand 
and phenols, ureas and melamines on the other hand, such as 
phenol/formaldehyde resins, urea/formaldehyde resins and 
melamine/formaldehyde resins. 
19. Alkyd resins, such as glycerol/phthalic acid resins and mixtures 
thereof with melamine/formaldehyde resins. 
20. Unsaturated polyester resins which are derived from copolyesters of 
saturated and unsaturated dicarboxylic acids with polyhydric alcohols and 
vinyl compounds as crosslinking agents. 
21. Crosslinked epoxide resins which are derived from polyepoxides, for 
example from bis-glycidyl ethers or from cycloaliphatic diepoxides. 
22. Natural polymers, such as cellulose, rubber, proteins and derivatives 
thereof which are chemically modified in a polymer-homologous manner, such 
as cellulose acetates, cellulose propionates and cellulose butyrates, or 
cellulose ethers, such as methylcellulose. 
Of particular importance is the stabilisation of polyolefins, styrene 
polymers and polyurethanes, for which the malonates of the formula I are 
excellently suitable. Examples of such plastics are: polyethylene of high 
and of low density, polypropylene, ethylene/propylene copolymers, 
polystyrene, styrene/butadiene/acrylonitrile copolymers, mixtures of 
polyolefins or of styrene polymers, polyurethanes based on polyether or 
polyester--in the form of lacquers, elastomers or foam plastics. 
The stabilisers are added to the plastics at a concentration of 0.01 to 5 
percent by weight, calculated on the material to be stabilised. There is 
preferably incorporated into the material 0.03 to 1.5 percent by weight, 
particularly preferably 0.2 to 0.6 percent by weight, of the compounds, 
relative to the material to be stabilised. 
Incorporation can be effected after polymerisation, for example by the 
mixing of the compounds and, optionally, further additives into the melt, 
by methods normally used in industry, either before or during moulding; or 
by application of the dissolved or dispersed compounds to the polymers, 
optionally with subsequent removal of the solvent by evaporation. 
The new compounds can be added also in the form of a master batch, which 
contains these compounds for example at a concentration of 2.5 to 25 
percent by weight, to the plastics to be stabilised. 
In the case of cross-linked polyethylene, the compounds are added before 
cross-linking. 
In addition to the compounds of the formula I, there can be added to the 
plastics also known stabilisers or co-stabilisers. These can be, e.g., 
antioxidants, light stabilisers or metal-deactivators; or co-stabilisers 
such as those of the phosphorous acid ester type. There can also be added 
other additives common in plastics technology, such as flameproofing 
agents, antistatic agents, plasticisers, lubricants, blowing agents, 
pigments, reinforcing substances or fillers. 
The invention therefore relates also to the plastics stabilised by the 
addition of 0.01 to 5 percent by weight of a compound of the formula I, 
which plastics can if required also contain known conventional additives. 
The plastics stabilised in this manner can be employed in the most varied 
forms, e.g. as sheet, fibres, tapes or profiles, or as binders for 
lacequers, adhesives or cements. 
The invention relates further to the compounds of the formula VIII and to 
their use as light stabilisers for plastics. The substrates, quantity 
ratios and processes of incorporation suitable for this purpose are the 
same as those for the use of the compounds of the formula I.