ENAMINE DERIVATIVES FOR USE AS ANTIOXYDANTS FOR POLYMERS

Abstract: Compounds belonging to the group of enamines consisting of derivatives of beta -keto-esters, or beta -keto-amides or 1,3-diketones with primary or secondary aliphatic or aromatic amines carrying at least one sterically hindered amine group having general formula (I) in the molecule. The compounds having general formula (I) can be used as antioxidants for organic polymers.

Description: ENAMINE DERIVATIVES FOR USE AS ANTIOXYDANTS FOR POLYMERS The present invention relates to compounds belonging to the group of enamines. More specifically, the present invention relates to compounds belonging to the group of enamines consisting of derivatives of .-keto-esters, or /3-keto- a ides or 1, 3-diketones with primary or secondary aliphatic or aromatic amines carrying at least one sterically hindered amine group in the molecule, a process for their preparation and their use as aπtioxi- dants for organic polymers. The present invention also relates to the polymeric compositions stabilized with the above compounds and the end-articles obtained from these compositions. It is known that organic polymers undergo degradation over a period of time as a result of exposure to atmospheric agents and light and they also easily undergo thermoxidative degradation during processing and transformation processes. The most evident signs of this degradation are, for example, alterations in the mechanical properties of the end-article. To prevent this degradation of the polymeric material, stabilizing compounds are usually introduced into the organic polymers. The Applicant has now found that compounds belonging to the group of enamines consisting of derivatives of 3-keto-esters, or 3-keto-amides or 1, 3-diketones with primary or secondary, aliphatic or aromatic amines carrying at least one sterically hindered amine group in the molecule, are capable of stabilizing organic polymers to which they are added improving their resistance to thermo-oxidation. The present invention therefore relates to compounds belonging to the group of enamines consisting of derivatives of 3-keto-esters, or 3-keto-amides or 1, 3-diketones with primary or secondary, aliphatic or aromatic amines carrying in the molecule at least one sterically hindered amine group having general formula (I): wherein : - m represents an integer from 1 to 3 , extremes included; - n represents an integer from 1 to 4 , extremes included; R 1 represents a triazine having one of the following general formula (II) , (III) or (IV) : wherein R j represents a hydrogen atom; a linear or branched ^-C^ alkyl group; a -NHR 6 amine group or a -SR 6 group wherein R 6 represents a hydrogen atom or a linear or branched C.,-C 18 alkyl group; R, and R 2 , the same or different, represent a hydrogen atom; a linear or branched C^C^ alkyl group; a linear or branched C 2 -C 8 alkoxyalkyl group; a C 5 -C 8 cycloalkyl group optionally containing a heteroatom selected from oxygen, nitrogen and sulfur; a C & -C^ a aryl group; a C 7 -C 20 arylalkyl or alkylaryl group; a group having general formula (V): wherein R 7 represents a hydrogen atom; a linear or branched ^-C^ alkyl group, said alkyl group optionally substituted with a -NHR 8 group or an -OR g group wherein R 8 represents a hydrogen atom, a linear or branched C_,-C 18 alkyl group, or a 6 -C a aryl group; an -01^ group wherein R-, represents a hydrogen atom, or a linear or branched C^-C^ alkyl group ; or, R 1 and R 2 considered jointly with the nitrogen atom, represent a C 5 -C 8 heterocyclic group optionally containing a second heteratom selected from oxygen, nitrogen and sulfur; R 3 and R 4 , the same or different, represent a linear or branched alkyl group; a C 6 -C 18 aryl group; a C 7 -C 20 alkylaryl or arylalkyl group; a linear or branched C^-C 8 alkoxyl group; or, R 4 represents a group having general formula (VI): wherein R 7 has the same meanings defined above; or, R 4 represents an NR 10 R 11 group wherein R 10 and R , the same or different, represent a hydrogen atom; a linear or branched ^-C^ alkyl group; a linear or branched C 2 -C 8 alkoxyalkyl group; a C 5 -C 8 cycloalkyl group optionally containing a heteroatom selected from oxygen, nitrogen and sulfur; a C 6 -C 18 aryl group; a C 7 -C 20 arylalkyl or alkylaryl group; a triazine having one of the following general formulae (II), (III) or (IV): ^ wherein R^ has the same meanings defined above; a group having general formula (V) : wherein R 7 has the same meanings defined above; or, R 10 and R considered jointly with the nitrogen atom, represent a C 5 -C 8 heterocyclic group option- ally containing a second heteroatom selected from oxygen, nitrogen and sulfur; or R 4 represents a group having one of the following general formulae (VII) , (VIII) or (IX) : 0CH 2 —CH—OR 13 (VII) ; CH 2 OR 13 / OCH 2 —C—R 12 (VIII) ; CH 2 OR 13 R 12 —CHOR 13 OCH 2 —C—CH 2 OR 13 (IX) ; CH 2 OR 13 wherein: R 12 represents a hydrogen atom; or a linear or branched C^-C^ alkyl group; - R 13 represents a linear or branched C,-C 18 alkyl group; a -COCH 2 COCH 3 group; or a direct bond ; provided that, when R 1 and R 2 are different from the group having general formula (V) , R 4 represents a group having general formula (VI) . The compounds having general formula (I) can be used as antioxidants for organic polymers. Examples of R 1 , R 2 , R 10 and R groups, as well as a hydrogen atom are: methyl, ethyl, propyl, isopropyl, butyl, octyl, cyclohexyl, benzyl, phenyl, ethylphenyl, methoxyethyl , 4- (2 , 2 , 6 , 6-tetramethyl) piperidinyl , 4- (2 , 2 , 6 , 6-tetramethyl) -1-butoxyethylpiperidinyl , 4- ( 2 , 2 , 6 , 6-tetramethyl ) -1-butoxypiperidinyl , 4- (2 , 2 , 6, 6-tetramethyl) -1-methylpiperidinyl , 3 , 5-dioctylaminotriazine, 3 , 5-dibutylaminotriazine, etc. Examples of C 5 -C 8 heterocyclic groups, when R 1 and R 2 or R 10 and R n are considered jointly with the nitrogen atom, are: morpholine, pyrrolidine, piperidine, piperazine, thiomorpholine, thiazolidine, benzothiazol- idine, etc. Examples of R 3 and R groups are: methyl, ethyl, propyl, isopropyl, phenyl, oxymethyl , oxyethyl , oxybu- tyl, etc. Examples of R 4 groups, when R 4 represents a group θ having general formula (VI), are: 4- (2 , 2 , 6, 6-tetramethyl) piperidinoxy, N-methyl-4- (2,2,6, 6-tetramethyl) pi- peridinoxy, N-methoxyethyl-4- (2 , 2,6, 6-tetramethyl) piperidinoxy, N-methylaminoethyl-4- (2,2,6, 6-tetramethyl) pi- peridinoxy, etc. Examples of R 4 groups, when R represents a group having general formula (VII) , (VIII) or (IX) and n is 2 , are : CH 2 — 0 — CH 2 — 0 — I 1 1 I CH 2 — 0 — ; CH — 0 — ; C 1 H 3 CH 3 — CO — CH 2 - -c=o \ 0 1 CH 2 o / CH 3 —CO—CH 2 —C=0 etc. Examples of R 4 groups, when R 4 represents a group having general formula (VII) , (VIII) or (IX) and n is 3, are: CH 7 0 — / CH 3 — CH 2 — C — CH 2 0 — \ CH 2 0 — °. 0 CH 2 0— // / CH 3 — CO — CH 2 — C — O — CH 2 — C — CH 2 0 — ; CH 2 0 — etc. Examples of R 4 groups, when R 4 represents a group having general formula (VII) , (VIII) or (IX) and n is 4, are: CH 2 0— / etc. Examples of R 7 groups are: methyl, ethyl, propyl, butyl, ethoxy, butoxy, β-hydroxyethyl, 3-methoxyethyl , 3-butoxyethyl, methylaminoethyl , etc. Examples of R,, R 6 , R 8 , R,, R 12 and R 13 groups, when said groups represent a linear or branched C j -C^ alkyl group, are: methyl, ethyl, propyl, isopropyl, butyl, octyl, etc. Specific examples of compounds having general formula (I) , which should in no way be considered as limiting the scope of the present invention, are: ( IA ) /O (IB) II 3 /2_ -CH-— OCOCH COCH. A further object of the present invention relates to a synthesis process of compounds having general formula (I) . A process for the synthesis of the compounds having general formula (I) of the present invention comprises the reaction of 1-4 moles of a primary or secondary, aliphatic or aromatic amine, having general formula (X) : HNR 1 R 2 (X) wherein R 1 and R 2 have the same meanings defined above, with 1-3 moles of a 3-keto-ester, or a 3-keto-amide, or a 1,3-diketone having general formula (XI): ( R 3 —C—CH 2 —C~) n —R 4 (XI) // li O 0 wherein R 3 , R 4 and n have the same meanings defined above . The above reaction takes place in the presence of an inert organic solvent, preferably a hydrocarbon, in particular toluene, at a temperature ranging from 60 °C to 16Q°C, preferably from 115°C to 150°C, at atmospheric pressure, and for a time ranging from 0.5 to 24 hours, preferably from 3 to 10 hours. Acetic acid can optionally be added as catalyst to this reaction. During the above reaction, reaction water is released which is separated by azeotropic distillation "t using an apparatus for the azeotropic distillation, whereas the organic solvent is recycled. At the end of the reaction, the solvent and possible acetic acid present are removed by distilla- tion thus obtaining a raw product. The desired compound having general formula (I) is purified from the raw product thus obtained by fractionated distillation, operating under vacuum, at a pressure ranging from 0.1 mm/Hg to 50 mm/Hg and a temperature ranging from 40 °C to 200 °C. Or, said compound having general formula (I) is separated by crystallization using techniques known in the art. Examples of primary or secondary, aliphatic or aromatic amines, having general formula (X) which can be used for the purposes of the present invention are: cyclohexylamine, n-butylamine, tert-butylamine, n-octy- lamine, tert-octylamine, n-octadecylamine, n-dodecylam- ine, benzyla ine, 2-methoxyethylamine, 2-furfurylamine, pyrrolidine, piperidine, morpholine, dibenzylamine, aniline, diphenylamine, melamine, 4-amino-2 , 2 , 6 , 6-te- tramethylpiperidine, 4-amino-2, 2,6, 6-tetramethyl-1-me- thylpiperidine, 4-amino-2 ,2,6, 6-tetramethyl-l-butoxyet- hylpiperidine, l-amino-3 , 5-dioctylaminotriazine, etc. Examples of /3-keto-esters or -keto-amides , or 1, 3-diketones having general formula (XI) are: ethyl aceto-acetate, t-butyl aceto-acetate, octadecyl aceto- acetate, ethyl benzoylacetate, acetyl-acetone, benzoyl- acetone, dibenzoyl methane, p-toluylacetone, 4- (2, 2, 6, 6-tetramethyl) piperidinyl aceto-acetate, N-methyl-4- (2, 2, 6, 6-tetramethyl)piperidinyl aceto- acetate, aceto-acetamide, acetoacetanilide, aceto-acet- 4- (2 , 2 , 6, 6,-tetramethylpiperidine) amide, aceto-acet- (3 , 5-dibutyltriazine) -1-amide, etc. The enaminic function of the compounds having general formula (I) synthesized by means of the process described above, is confirmed by NMR spectrometry analysis (obtained using a BRUKER AC 200 spectrometer) executed on samples with a high purity (95% confirmed by gas-chromatography) . Other processes which can be used for the preparation of the compounds having general formula (I) of the present invention, however, are described in literature such as, for example, in Houben-Weyl (1957), Vol. 11/1, pages 172-178. Organic polymers capable of being stabilized with the compounds of the present invention are: (1) polymers of mono-olefins and diolefins such as, for example, polypropylene, polyisobutylene, polybut-1-ene, poly-4-methylpent-l-ene, polyiso- prene . or polybutadiene ; as well as polymers of cyclo-olefins such as, for example, cyclopentene or norbornene; polyethylene (which can be optionally cross-linked) such as, for example, high density polyethylene (HDPE) , low density poly- ethylene (LDPE) , linear low density polyethylene (LLDPE) , branched low density polyethylene (BLDPE) . The polyolefins such as, for example the mono- olefins cited in the previous paragraph, preferably polyethylene and polypropylene, can be prepared with various methods known in literature, preferably using the following methods: (a) radicalic polymerization (generally carried out at a high pressure and high temperature ; (b) catalytic polymerization using a catalyst which normally contains one or more metals of groups IVb, Vb, VIb or VIII of the Periodic Table. These metals generally have one or more ligands such as, for example, oxides, halides, alcoholates, ethers, amines, alkyls, alkenyls and/or aryls which can be it- or σ-co-ordinated. These metal complexes can be in free form or supported in substrates such as, for example activated magnesium chloride, titanium (III) chloride, alumina or silicon oxide. These catalysts can be soluble or insoluble in the 7 reaction medium. The catalysts can be used alone or in the presence of other activators such as, for example, metal alkyls, metal hydrides, halides of metal alkyls, oxides of metal alkyls or metal alkyloxanes, these metals being elements belonging to groups la, Ila and/or Ilia of the Periodic Table. The activators can be conveniently modified with other ester, ether, amine or silyl-ether groups. These catalytic systems are usually called Phillips, Standard Oil Indiana, Ziegler (-Natta) , TNZ (DuPont) , metallocene or "single site catalyst" (SSC) . (2) Mixtures of the polymers described under point (1) such as, for example, mixtures of polypropylene with polyisobutylene; mixtures of polypropylene with polyethylene (for example, PP/HDPE, PP/LDPE) ; mixtures of different types of polyethylene (for example, LDPE/HDPE) . (3) Copolymers of ono-olefins and diolefins with each other or with other vinyl monomers such as, for example, ethylene-propylene copolymers, linear low density polyethylene (LLDPE) and its mixtures with low density polyethylene (LDPE) , propylene/but-1- ene copolymers, propylene/isobutylene copolymers, ethylene/but-1-ene copolymers, ethylene/hexene I 6> copolymers, ethylene/methylpentene copolymers, ethylene/heptene copolymers, ethylene/octene copolymers, propylene/butadiene copolymers, isobutylene/isoprene copolymers, ethylene/alkyl acrylate copolymers, ethylene/alkyl methacrylate copolymers, ethylene/vinyl acetate copolymers and their copolymers with carbon monoxide or ethyl- ene/acrylic acid copolymers and their salts (ionomers) as well as terpolymers of ethylene with polypropylene and a diene such as, for example, hexadiene, dicyclopentadiene or ethylidene-norbor- nene; and mixtures of these copolymers with each other or with the polymers cited in paragraph (1) such as, for example, polypropylene/ethylene- propylene copolymers, LDPE/ethylene-vinylacetate (EVA) copolymers, LDPE/ethylene-acrylic acid (EAA) copolymers, LLDPE/EVA, LLDPE/EAA, and alternating or "random" polyalkylene/carbon monoxide copolymers and their mixtures with other polymers such as, for example, polya ides. (4) Hydrocarbon resins (for example, C 3 -C 9 ) comprising their hydrogenated modifications (for example, adhesive agents) and mixtures with polyalkylene and starch. (5) Polystyrene, poly (p-methylstyrene) , poly (α-methyl- styrene) . (6) Copolymers of styrene or α-methylstyrene with dienes or acrylic derivatives such as, for example, styrene/butadiene, styrene/acrylonitrile, styrene/alkyl methacrylate, styrene/butadiene/ alkyl acrylate, styrene/butadiene/alkyl methacrylate, styrene/maleic anhydride, styrene/acrylo- nitrile/methylacrylate; mixtures, having a high impact strength, between copolymers of styrene and another polymer such as, for example, a polyacry- late, a polymer of a diene or an ethy- lene/propylene/diene terpolymer, block polymers of styrene such as, for example, styrene/butadiene/ styrene, styrene/isoprene/styrene, styrene/ethyle- ne/butylene/styrene or styrene/ thylene/propyl- ene/styrene. (7) Grafted copolymers of styrene or α-methylstyrene such as, for example, styrene in polybutadiene, styrene in polybutadiene or polybutadiene-acrylo- nitrile copolymers; styrene and acrylonitrile (or methacrylonitrile) in polybutadiene; styrene, acrylonitrile and methylmethacrylate in polybutadiene; styrene and maleic anhydride in polybutadiene; styrene, acrylonitrile and maleic anhydride or maleimide in polybutadiene; styrene and male- imide in polybutadiene; styrene and alkylacrylates or methacrylates in polybutadiene; styrene and acrylonitrile in ethylene/propylene/diene terpoly- mers, styrene and acrylonitrile in polyalkyl acrylates or polyalkyl methacrylates, styrene and acrylonitrile in acrylate/butadiene copolymers, as well as mixtures of the copolymers listed above with the copolymers cited under point (6) such as, for example, mixtures of known copolymers such as ABS, MBS, ASA or AES ; (8) Polymers containing halogens such as, for example, polychloroprene, chlorinated rubbers, chlorinated or sulfochlorinated polyethylene, ethylene and chlorinated ethylene copolymers, homopoly ers and copolymers of epichlorohydrin, in particular polymers of vinyl compounds containing halogens such as, for example, polyvinyl chloride, poly- vinylidenechloride, polyvinyl fluoride or polyvin- ylidenefluoride; and also their copolymers such as, for example, vinyl chloride/vinylidenechlo- ride, vinyl chloride/vinyl acetate or vinylidene- chloride/vinyl acetate. (9) Polymers deriving from α,3-unsaturated acids and their derivatives such as, for example, polyacry- lates and polymethacrylates, polymethyl methacry- lates, polyacrylamides and polyacrylonitriles, modified with butyl acrylate. (10) Copolymers of monomers according to point (9) with each other or with other unsaturated monomers such as, for example, acrylonitrile/butadiene copolymers, acrylonitrile/alkylacrylate copolymers, acrylonitrile/alkoxyalkyl acrylate copolymers or acrylonitrile/vinyl halide copolymers or acryloni- trile/alkyl methacrylate/butadiene terpoly ers. (11) Polymers deriving from unsaturated alcohols and amines, or their acyl or acetal derivatives such as, for example, polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate, polyvinyl butyrral, polyallyl phthalate or polyallyl melamine; and also their copolymers with the olefins listed under point (1). (12) Homopolymers and copolymers of cyclic ethers such as, for example, polyalkylene glycols, polyethyl- ene oxide, polypropylene oxide, or copolymers of the compounds described above with bis-glycidyl ethers. (13) Polyacetals such as, for example, polyoxymethylene and polyoxymethylenes which contain ethylene oxide as comonomer; polyacetals modified with thermo- X Z. plastic polyurethanes, acrylates or MBS. (14) Polyphenylene oxides and sulfides and mixtures of polyphenylene oxides with styrene or polyamide polymers. (15) Polyurethanes deriving from hydroxy1-terminated polyethers, polyesters or polybutadienes on the one hand and aliphatic or aromatic polyisocyanates on the other, as well as the precursors of the above compounds . (16) Polyamides and copolyamides deriving from dia ines and dicarboxylic acids and/or aminocarboxylic acids or from the corresponding lactams such as, for example, polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12, 4/6, 12/12, polyamide 11, polyamide 12 , aromatic polyamides obtained starting from m-xylene diamine and adipic acid; polyamides prepared from hexamethylenediamine and isophthalic and/or terephthalic acid and with or without an elastomer as modifier, for example, poly-2, 4, 4-trimethylhexamethylene terephthala ide or poly-m-phenylene isophthala ide; and also block copolymers of the above polyamides with poly- olefins, olefinic copolymers, ionomers or elastomers chemically bound or grafted; or with polye- thers such as, for example, polyethylene glycol, 2.3 polypropylene glycol or polytetramethylene glycol; as well as polyamides or copolyamides modified with EPDM or ABS ; and polyamides condensed during processing ("RIM polyamide system") . (17) Polyureas, polyimides, polyamide-imides and polybenzoimidazoles . (18) Polyesters deriving from dicarboxylic acids and diols and/or from hydroxycarboxylic acids or from the corresponding lactones such as, for example, polyethylene terephthalate, polybutylene tereph- thalate, poly-1, 4-dimethylolcyclohexane terephthalate and polyhydroxybenzoates, as well as block copolyether esters deriving from polyethers with hydroxyl-terminated groups; and also polyesters modified with polycarbonates or MBS. (19) Polycarbonates and polyester carbonates. (20) Polysulfones, polyethersulfones and polyetherketo- nes. (21) Cross-linked polymers deriving from aldehydes on the one hand and from phenols, urea and melamines on the other, such as, for example, phenol/formaldehyde resins, urea/formaldehyde resins and mela- mine/formaldehyde resins . (22) Drying or non-drying alkyd resins. (23) Resins based on unsaturated polyesters deriving from copolyesters of dicarboxyl acids saturated and unsaturated with polyhydric alcohols and vinyl compounds as cross-linking agents, and also the above resins containing halogens and having a good flame-resistance. (24) Cross-linkable acrylic resins deriving from substituted acrylates such as, for example, epoxy acrylates, urethane acrylates or polyester acrylates. (25) Alkyd resins, resins based on polyesters or acrylated resins cross-linked with melamine resins, urea resins, resins based on polyisocyana- tes or epoxy resins. (26) Cross-linked epoxy resins deriving from polyepoxi- des such as, for example, bis-glycidyl ethers or cycloaliphatic diepoxides. (27) Natural polymers such as, for example, cellulose, rubber, gelatine, and their derivatives chemically modified to give homologous polymers such as, for example, cellulose acetates, propionates and butyrates, or cellulose ethers such as, for example, methyl-cellulose; as well as hydrocarbon resins ("rosins") or their derivatives. (28) Mixtures of the above polymers ("polyblends") such as, for example, PP/EPDM, polyamides/EPDM or ABS , zs PVC/EVA, PVC/ABS, PVC/MBS , PC/ABS , PBTP/ABS , PC/ASA, PC/PBT, PVC/CPE, PVC/acrylates, POM/ther- moplastics PUR, PC/thermoplastics PUR, POM/acryla- tes, POM/MBS, PPO/HIPS, PPO/PA 6.6 and copolymers, PA/HDPE, PA/PP, PA/PPO. In particular, the compounds having general formula (I) can be used in the stabilization of poly- ols. The incorporation of the compounds having general formula (I) of the present invention into organic polymers, is carried out according to methods known in the art. For example, the compounds having general formula (I) can be added to the organic polymers, optionally in the presence of other additives, in the step following their preparation, or immediately before the transformation process. The compounds having general formula (I) of the present invention are incorporated into the polymer to be stabilized in a quantity ranging from 0.02% to 3% by weight, preferably between 0.05% and 1%. A further object of the present invention relates to polymeric compositions containing an organic polymer and an effective quantity of one or more compounds having general formula (I) . As already mentioned above, the compounds having general formula (I) of the present invention can be combined with other conventional additives or their mixtures. These additives are added in a quantity ranging from about 0.1% to about 5% by weight of the weight of the polymeric compositions to be stabilized, preferably from about 0.5% to about 3% by weight. Some of the additives used are listed below as an example. 1. Antioxidants 1.1 Alkylated monophenols such as, for example: 2 , 6-di-t-butyl-4-methylphenol ; 2-t-butyl-4 , 6-dimethylphenol ; 2 , 6-di-t-butyl-4-ethylphenol ; 2 , 6-di-t-butyl-4-n-butylphenol ; 2 , 6-di-t-butyl-4-isobutylphenol ; 2 , 6-di-cyclopentyl-4-methylphenol ; 2- (α-methylcyclohexyl ) -4 , 6-dimethylphenol ; 2 , 6-dioctadecyl-4-methylphenol ; 2,4, 6-tricyclohexylphenol ; 2 , 6-di-t-butyl-4-methoxymethylphenol ; 2 , 6-di-nonyl-4-methylphenol ; 2 , 4-dimethyl-6- ( 1 ' -methylundec-1 ' -yl ) phenol ; 2 , 4-dimethyl-6- ( 1 'methylhectadec-l ' -yl) phenol ; 2, 4-dimethyl-6- (l'-methyltridec-l'-yl) phenol ; and their mixtures. 7 1.2 Alkylthiomethylphenols such as, for example: 2 , 4-dioctylthiomethyl-6-t-butylphenol ; 2 , 4-dioctylthiomethyl-6-methylphenol ; 2 , 4-dioctylthiomethyl-6-ethylphenol ; 2 , 6-didodecylthiomethyl-4-nonylphenol . 1.3 Hydroquinones and alkylated hydroquinones such as, for example: 2 , 6-di-t-butyl-4-methoxyphenol ; 2 , 5-di-t-butylhydroquinone ; 2 , 5-di-t-amylhydroquinone; 2 , 6-diphenyl-4-octadecyloxyphenol ; 2 , 6-di-t-butylhydroquinone ; 2 , 5-di-t-butyl-4-hydroxyanisol ; 3 , 5-di-t-butyl-4-hydroxyanisol ; 3 , 5-di-t-butyl-4-hydroxyphenyl stearate; bis (3 ,5-di-t-butyl-4-hydroxyphenyl) adipate. 1.4 Tocopherols such as, for example: α-tocopherol, .-tocophercl, γ-tocopherol, <S-tocopherol and their mixtures (Vitamin E) . 1.5 Hydroxylated thiodiphenyl ethers such as, for example: 2, 2'-thiobis-(6-t-butyl-4-methylphenol) ; 2, 2 '-thiobis-(4-octylphenol) ; 4,4' -thiobis- (6-t-butyl-3-methylphenol) ; 4 ,4 '-thiobis- (6-t-butyl-2-methylphenol) ; 2.6> 4,4' -thiobis- ( 3 , 6-di-sec-amylphenol ) ; 4 , 4 '-bis- (2 , 6-dimethyl-4-hydroxyphenyl) disulfide. 1.6 Alkylidene-bisphenols such as, for example: 2 , 2 '-methylenebis- (6-t-butyl-4-methylphenol) ; 2, 2' -methylenebis- (6-t-butyl-4-ethylphenol) ; 2 , 2 '-methylenebis [4-methyl-6- (α-methylcyclohexyl) phenol] ; 2,2 '-methylenebis (4-methyl-6-cyclohexylphenol) ; 2 ,2 ' -methylenebis (6-nonyl-4-methylphenol) ; 2,2' -methylenebis ( 4 , 6-di-t-butylphenol ) ; 2,2' -ethylidenebis ( 4 , 6-di-t-butylphenol ) ; 2, 2 '-ethylidenebis (6-t-butyl-4-isobutylphenol) ; 2,2' -methylenebis [ 6- (α-methylbenzyl) -4-nonylphe- nol] ; 2,2' -methylenebis [ 6- ( , α-dimethylbenzyl) -4-nonyl- phenol] ; 4, 4 '-methylenebis (2 , 6-di-t-butylphenol) ; 4,4' -methylenebis ( 6-t-butyl-2-methylphenol) ; 1, 1-bis- (5-t-butyl-4-hydroxy-2-methylphenyl) - butane ; 2 , 6-bis- (3-t-butyl-5-methyl-2-hydroxybenzyl) -4- methylphenol ; 1,1, 3-tris- (5-t-butyl-4-hydroxy-2-methylphenyl) - butane ; 1, 1-bis— (5-t-butyl-4-hydroxy-2-methyl-phenyl) -3- * . n-dodecylmercaptobutane ; ethyleneglycol bis [3 , 3-bis (3 '-t-butyl-4 ' -hydroxy- phenyl) butyrate] ; bis (3-t-butyl-4-hydroxy-5-methylphenyl) dicyclopen- tadiene ; bis [ 2- (3 ' -t-butyl-2 ' -hydroxy-5 ' -methylbenzyl) -6-t- butyl-4-methylphenyl]terephthalate; 1, 1-bis (3 , 5-dimethyl-2-hydroxyphenyl) butane; 2 , 2-bis (3 , 5-di-t-butyl-4-hydroxyphenyl) propane; 2 , 2-bis (5-t-butyl-4-hydroxy-2-methylphenyl) -4-n- dodecylmercaptobutane ; 1, 1, 5, 5-tetra(5-t-butyl-4-hydroxy-2-methylphenyl) - pentane. 1.7 Benzyl compounds containing 0, N or S such as, for example: 3 , 5 , 3 ' , 5 ' -tetra-t-butyl-4 , 4 ' -dihydroxydibenzyl ether; octadecyl-4 -hydroxy-3 , 5-dimethylbenzylmercapto- acetate ; tris ( 3 , 5-di-t-butyl-4 -hydroxybenzyl ) amine ; bis ( 4 -t-butyl-3-hydroxy-2 , 6-dimethylbenzyl ) dithio- terephthalate ; bis ( 3 , 5-di-t-butyl-4 -hydroxybenzyl ) sul f ide ; iso-octyl-3 , 5-di-t-butyl-4 -hydroxybenzylmercapto- acetate ; 3θ 1.8 Hydroxybenzylated malonates such as, for example: dioctadecyl-2 , 2-bis (3 , 5-di-t-butyl-2-hydroxyben- zyl) malonate; dioctadecyl-2- (3-t-butyl-4-hydroxy-5-methylben- zyl) malonate; didodecylmercaptoethyl-2 , 2-bis (3 , 5-di-t-butyl-4- hydroxybenzyl ) malonate ; bis[4-(l,l,3, 3-tetramethylbutyl) phenyl ] -2 , 2- bis (3 , 5-di-t-butyl-4-hydroxybenzyl) malonate. 1.9 Aromatic hydroxybenzyl compounds such as, for example: 1,3, 5-tris ( 3 , 5-di-t-butyl-4-hydroxybenzyl ) -2 , 4 , 6- trimethylbenzene ; l,4-bis-(3, 5-di-t-butyl-4-hydroxybenzyl) -2,3,5,6- tetramethylbenzene; 2,4, 6-tris(3 , 5-di-t-butyl-4-hydroxybenzyl) phenol . 1.10 Triazine compounds such as, for example: 2,4-bis(octylmercapto) -6- (3 , 5-di-t-butyl-4-hydro- xyaniline) -1,3, 5-triazine; 2-octylmercapto-4 , 6-bis (3 , 5-di-t-butyl-4-hydro- xyaniline) -1,3, 5-triazine; 2-octylmercapto-4 , 6-bis (3 , 5-di-t-butyl-4-hydro- xyphenoxy) -1,3, 5-triazine; 2,4,6-tris-(3, 5-di-t-butyl-4-hydroxyphenoxy) - 1,2, 3-triazine; 3/ 1, 3,5-tris(3 , 5-di-t-butyl-4-hydroxybenzyl) isocya- nurate ; 1,3, 5-tris (4-t-butyl-3-hydroxy-2 , 6-dimethylben- zyl) isocyanurate; 2,4,6-tris-(3 , 5-di-t-butyl-4-hydroxyphenylethyl) - 1,3, 5-triazine; 1,3, 5-tris ( 3 , 5-di-t-butyl-4-hydroxyphenylpropio- nyl)hexahydro-l, 3 , 5-triazine; 1, 3 , 5-tris- (3 , 5-dicyclohexyl-4 -hydroxyben- zyl) isocyanurate. 1.11 Benzylphosphonates such as, for example: dimethyl-2 , 5-di-t-butyl-4-hydroxybenzylphosphona- te; diethyl-3 , 5-di-t-butyl-4-hydroxybenzylphosphcnate; dioctadecyl-3 , 5-di-t-butyl-4-hydroxybenzylphospho- nate ; dioctadecyl-5-t-butyl-4-hydroxy-3-methylbenzylpho- sphonate ; calcium salts of monoethyl ester of 3,5-di-t- butyl-4-hydroxybenzylphosphonic acid. 1.12 Acylaminophenols such as, for example: 4-hydroxylauranilide; 4-hydroxystearanilide; octyl-N- ( 3 , 5-di-t-butyi-4-hydroxyphenyl) carbamate . 1.13 Esters of β- (3 , 5-di-t-butyl-4-hydroxyphenyl) pro- pionic acid with monohydric or polyhydric alcohols such as, for example: methanol, ethanol, octanol, octadecanol, 1,6- hexandiol, 1, 9-nonandiol, ethylene glycol, 1,2- propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol , tris (hydroxyethyl) isocyanurate, N,N'-bis (hydroxyethyl) oxamide, 3-thioundecanol, 3- thiopentadecanol, trimethylhexandiol , trimethyl- olpropane, 4-hydroxymethyl-l-phospho-2 , 6, 7-trioxa- bicyclo[2.2. 2] octane. 1.14 Esters of β- (5-t-butyl-4-hydroxy-3-methylphe- nyl)propionic acid with monohydric or polyhydric alcohols such as, for example: methanol, ethanol, octanol, octadecanol, 1,6- hexandiol, 1, 9-nonandiol, ethylene glycol, 1,2- propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate, N,N' -bis (hydroxyethyl) oxamide, 3-thioundecanol, 3-thiopentadecanol, trimethylhexandiol, trimethy- lolpropane, 4-hydroxymethyl-l-phospho-2 , 6,7-trio- xabicyclo [2.2.2] octane . 1.15 Esters of β- (3 , 5-dicyclohexyl-4-hydroxyphenyl) pro- pionic acid with monohydric or polyhydric alcohols such as, for example: methanol, ethanol, octanol, octadecanol, 1,6-he- xandiol, 1, 9-nonandiol, ethylene glycol, 1,2-pro- panediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate, N,N'-bis (hydroxyethyl) oxamide, 3-thioundecanol, 3-thio- pentadecanol , trimethylhexandiol, trimethylol- propane, 4-hydroxymethyl-l-phospho-2 , 6, 7-trioxabi- cyclo[2.2.2]octane. 1.16 Esters of (3 , 5-di-t-butyl-4-hydroxyphenyl) acetic acid with monohydric or polyhydric alcohols such as, for example: methanol, ethanol, octanol, octadecanol, 1,6- hexandiol, 1, 9-nonandiol, ethylene glycol, 1,2- propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate, N, N' -bis (hydroxyethyl) oxamide , 3-thioundecanol , 3-thiopentadecanol, trimethylhexandiol, trimethy- lolpropane, 4-hydroxymethyl-l-phospho-2 , 6,7-trio- xabicyclo [2.2.2] octane . 1.17 Amides of β- (3 , 5-di-t-butyl-4-hydroxyphenyl) - propionic acid such as, for example: N,N'-bis(3, 5-di-t-butyl-4-hydroxyphenylpropio- nyl) hexamethylenediamine ; N,N'-bis (3 , 5-di-t-butyl-4-hydroxyphenylpropio- nyl) trimethylenedia ine; N,N'-bis (3 , 5-di-t-butyl-4-hydroxyphenylpropio- nyl)hydrazine. 2. Ultra-violet ray and light stabilizers. 2.1 Derivatives of 2- (2 '-hydroxyphenyl) benzotriazoles such as, for example: 2- (2 '-hydroxy-5'methylphenyl) benzotriazole; 2- (3 ' , 5 '-di-t-butyl-2 ' -hydroxyphenyl) benzotriazole; 2- (5 '-t-butyl-2 '-hydroxyphenyl) benzotriazole; 2- [ 2 ' -hydroxy-5 '-(1,1,3,3-tetramethylbutyl) phenyl]benzotriazole; 2- (3 ' , 5 ' -di-t-butyl-2 '-hydroxyphenyl) -5-chloroben- zotriazole; 2- (3 ' -t-butyl-2 ' -hydroxy-5 ' -methylphenyl) -5-chlo- robenzotriazole; 2- (3 ' -sec-butyl-5 '-t-butyl-2 '-hydroxyphenyl) benzo- triazole; 2- ( 2 ' -hydroxy-4 ' -octyloxyphenyl ) benzotriazole ; 2- ( 3 ' , 5 ' -di-t-amyl-2 ' -hydroxyphenyl) benzotriazole ; 2 - [ 3 ' , 5 ' -bis ( α , -dimethylbenzyl ) -2 ' -hydroxyphenyl ] benzotriazole ; mixtures of 2 - [ 3 ' -t-butyl-2 ' -hydroxy-5 ' - ( 2-octylo- xycarbonylethyl) phenyl) -5-chorobenzotriazole, 2- [ 3 ' -t-butyl-5 ' - (2- (2-ethylhexyloxy) carbonylethyl) - 2 ' -hydroxyphenyl ] -5-chlorobenzotriazole, 2- [ 3 ' -t- butyl-2 ' -hydroxy-5 ' - (2-methoxycarbonylethyl) phe- nyl]-5-chlorobenzotriazole, 2- [3 '-t-butyl-2 '- hydroxy-5 ' - ( 2-methoxycarbonylethyl) phenyl ] benzotriazole, 2- [3 '-t-butyl-2 '-hydroxy-5'-(2-octylo- xycarbonylethyl) phenyl] benzotriazole, 2- [3 '-t- butyl-5'- (2- (2-ethylhexyloxy) carbonylethyl) -2 '- hydroxyphenyl) benzotriazole, 2- (3 'dodecyl-2 ' - hydroxy-5'-methylphenyl) benzotriazole and 2- [3 '-t- butyl-2 ' -hydroxy-5 ' - ( 2-iso-octyloxycarbonylethyl) phenyl] benzotriazole, 2, 2 '-methylene-bis[4- (1, 1,- 3 , 3-tetramethylbutyl) -6-benzotriazol-2-yl-phenol] ; esterification product of 2- [3 '-t-butyl-5' - (2- methoxycarbonylethyl ) -2 ' -hydroxyphenyl ] -2H-benzo- triazole with polyethylene glycol 300; [R-CH 2 CH 2 -COO(CH 2 ) 3 ] 2 wherein R = 3 '-t-butyl-4- hydroxy-5 ' -2H-benzotriazol-2-yl-phenyl . 2.2 Derivatives of 2-hydroxybenzophenones such as, for example: 4-hydroxy-; 4-methoxy-; 4-octyloxy-; 4- decyloxy-; 4-dodecyloxy- ; 4-benzyloxy- ; 4, 2 ',4'- trihydroxy- ; 2 ' -hydroxy-4 , 4 ' -dimethoxy . 2.3 Esters of benzoic acids, optionally substituted, such as, for example: phenyl salicylate, 4-t- butylphenyl salicylate, octylphenyl salicylate, benzoyl-resorcinol , bis (4-t-butylbenzoyl) -resor- cinol, dibenzoyl-resorcinol, 2 , 4-di-t-butylphenyl- 3 , 5-di-t-butyl-4-hydroxybenzoate, hexadecyl-3 , 5- di-t-butyl-4-hydroxybenzoate, octadecyl-3 , 5-di-t- butyl-4-hydroxybenzoate, 2-methyl-4, 6-di-t-butyl- phenyl-3 , 5-di-t-butyl-4-hydroxybenzoate. 2.4 Acrylates such as, for example, ethyl or isoctyl α-cyano-3 ,/3-diphenylacrylate ; methyl α-carbometho- xycinnamate, methyl or butyl α-cyano-3-methyl-p- methoxycinnamate, methyl α-carbomethoxy-p-methoxy- cinnamate, N- (/3-carbomethoxy-_-cyanovinyl) -2- methylindoline. 2.5 Nickel compounds such as, for example, complexes of 2,2'-thio-bis-[4-(l,l,3,3-tetramethylbutyl)phe- nol], for example 1:1 or 1:2 complexes, with or without additional ligands such as n-butylamine, triethanolamine or N-cyclohexyldiethanolamine, nickel dibutyldithiocarbamate, nickel salts of monoalkyl esters of 4-hydroxy-3 , 5-di-t-butyl- benzyl-phosphonic acid, such as methyl or ethyl esters, nickel complexes with ketoximes such as 2- hydroxy-4-methylphenyl undecyl ketoxime, nickel complexes of l-phenyl-4-lauroyl-5-hydroxypyrazol with or without additional ligands. 7 2.6 Oxamides such as, for example: 4,4' -dioctyloxyoxanilide ; 2,2' -diethoxyoxanilide ; 2,2' -dioctyloxy-5 , 5 ' -di-t-butoxanilide ; 2,2 '-didodecyloxy-5, 5 '-di-t-butoxanilide; 2-ethoxy-2 '-ethyloxanilide; N, N' -bis ( 3-dimethylaminopropy1) oxamide ; 2-ethoxy-5-t-butyl-2 '-ethoxanilide and its mixtures with 2-ethoxy-2 ' -ethyl-5 , 4 ' -di-t-butoxanili- de; and mixtures of disubstituted ortho- and para- methoxy anilides and mixtures of disubstituted ortho and para-ethoxy anilides. 2.7 2- (2-hydroxyphenyl) -1, 3 , 5-triazines such as, for example: 2,4,6-tris(2-hydroxy-4-octyloxyphenyl) -1,3, 5-tri- azine; 2- (2-hydroxy-4-octyloxyphenyl) -4, 6-bis (2 , 4-dime- thylphenyl) -1, 3 ,5-triazine; 2- (2 , 4-dihydroxyphenyl) -4, 6-bis(2,4-dimethylphe- nyl) -1,3,5-triazine; 2 , 4 -bis- (2-hydroxy-4-propyloxyphenyl) -6- (2 , 4- di ethylphenyl) -1, 3 ,5-triazine; 2-(2-hydroxy) -4, 6-bis ( 4 -me thy 1 phenyl ) -1,3,5- triazine; 2- (2-hydroxy-4-dodecyloxyphenyl) -4,6-bis(2,4- 3<S> dimethylphenyl) -1,3, 5-triazine; 2- [ 2-hydroxy-4- ( 2-hydroxy-3-butyloxypropoxy) phenyl] -4, 6-bis (2, 4-dimethyl) -1,3, 5-triazine; 2- [ 2-hydroxy-4- ( 2-hydroxy-3-octyloxy-propyloxy) - phenyl] -4 , 6-bis (2, 4-dimethyl) -1, 3 , 5-triazine. 3. "Metal-deactivators" such as, for example: N,N- diphenyloxamide, N-salicylal-N' -salicyloyl-hydra- zine, N,N'-bis(salicyloyl)hydrazine; N,N'-bis (3 , 5- di-t-butyl-4-hydroxyphenylpropionyl) hydrazine, 3- salicyloylamino-1, 2 , 4-triazole, bis (benzylidene) o- xalyl dihydrazide, oxanilide, isophthaloyl dihydrazide, sebacoyl bisphenylhydrazide, N,N'-diace- tyladipoyl dihydrazide, N,N'-bis (salicyloyl) oxal- lyl dihydrazide, N,N'-bis (salicyloyl) thiopropionyl dihydrazide. 4. Phosphites and phosphonites such as, for example: triphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris (nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phos- phite, distearyl pentaerythritol diphosphite, tris (2 , 4-di-t-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, bis (2 , 4-di-t-butyl- phenyl) pentaerythritol diphosphite, bis (2 , 5-di-t- butyl-4-methylphenyl) pentaerythritol diphosphite, diisodecyloxypentaerythritol diphosphite, bis (2, 4- 0) di-t-butyl-6-methylphenyl) pentaerythritol diphosphite, bis[2,4,5-tris(t-butylphenyl) ]pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis- (2 , 4-di-t-butyl-phenyl) -4 , 4 '-diphenylile- nediphosphonite , 5-iso-octyloxy-2 ,4,8, 10-tetra-t- butyl-12H-di-benzo[d,g] -1,3, 2-dioxaphosphocine, 6- fluoro-2 ,4,8, 10-tetra-t-butyl-12-methyl-diben- zo[d,g]-l,3, 2-dioxaphosphocine, bis (2 , 4-di-t-bu- tyl-6-methylphenyl)methylphosphite, bis (2 , 4-di-t- butyl-6-methylphenyl) ethylphosphite. 5. Agents which are capable of destroying peroxides such as, for example, esters of -thiodipropionic acid such as lauryl, stearyl, myristyl or tridecyl esters, mercaptobenzimidazole or zinc salt of 2- mercaptobenzimidazole, zinc dibutyldithiocarbama- te, dioctadecyldisulfide pentaerythritol tetrakis (/3-dodecylmercapto)propionate. 6. Stabilizers of polyamides such as, for example, copper salts combined with compounds of iodine and/or phosphorous, divalent manganese salts. 7. Basic co-stabilizers such as, for example: mela- mine, polyvinylpyrrolidone, dicyanodiamide, triallyl cyanurate, derivatives of urea, derivatives of hydrazine, amines, polyamides, polyure- thanes, salts of alkaline metals and salts of earth-alkaline metals of fatty acids such as, for example, Ca-stearate, Zn-stearate, Mg-stearate, Mg-behenate, Na-ricinoleate, K-palmitate, antimo- nium-pyrocatecholate , tin-pyrocatecholate . 8. Nucleating agents such as, for example: 4-t-butyl- benzoic acid, adipic acid, diphenylacetic acid. 9. Fillers and reinforcing agents such as, for example: calcium carbonate, silicates, glass fibres, asbestos, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, carbon black, graphite. 10. Other additives such as, for example: plastici- zers, lubricants, emulsifying agents, pigments, optical brighteners, flame-retardants (for exam- pie, bromides, chlorurates, phosphorates and phosphorous/halogen mixtures) , antistatic agents, blowing agents, thiosynergizing agents such as, for example, dilauryl thiodipropionate or diste- aryl thiodipropionate. 11. Benzofuranones and indolinones such as, for ex.: 3- [ 4- ( 2-acetoxyethoxy) phenyl ] -5 , 7-di-t-butylben- zofuran-2-one ; 5 , 7-di-t-butyl-3- [ 4- ( 2-stearoyloxyethoxy ) phenyl ] benzofuran-2-one ; 3,3' -bis [ 5 , 7-di-t-butyl-3- [4- ( 2-hydroxyethoxy) phe- nyl]benzofuran-2-one] ; 5,7-di-t-butyl-3-(4-ethoxyphenyl)benzofuran-2-one; 3- (4-acetoxy-3 , 5-dimethylphenyl) -5, 7-di-t-butyl- benzofuran-2-one ; 3-(3 , 5-dimethyl-4-pivaloyloxyphenyl) -5, 7-di-t- butyl-benzofuran-2-one; or those described in U.S. patents 4.325.863, 4.338.244, 5.175.312, 5.216.052, 5.252.643, 4.316.611, 4.316.622, 4.316.876 or in European patent applications 589.839 and 591.102. In order to verify the stabilizing activity of the compounds having general formula (I) of the present invention, differential thermal analysis was used, revealing the time necessary for starting up the oxidation reaction of the system. For this purpose a non-stabilized polyol was used, of the type Glendion FG 3501 sold by EniChem S.p.A., and the stabilizer was added at levels of 0.15%. The oxygen absorption induction time measurement was carried out on the polyol at a temperature of 130 °C and 140 °C under a stream of oxygen. The greater the oxygen absorption induction time, the better is the stabilizing system used. Proof of the good stabilizing capacity of the compounds having general formula (I) of the present 4≥- invention was provided by observing the oxygen absorption induction time of the polyol to which the compounds having general formula (I) had been added, compared with the stabilizing capacity of the commer- cial product BHT, corresponding to 2 , 6-di-t-butyl-4- methylphenol, and with the polyol without stabilizers (see Example 7 below) . In addition, the importance of the molecular structure of the compounds having general formula (I) was demonstrated by comparing with an enamine having the formula (Compound Nr. 5, see Example 5 below): which lacks the structure of the enamine double bond conjugated with the carbonyl double bond which is present, however, in the above compounds having general formula (I) ; and with an enamine having the formula (Compound Nr. 6, see Example 6 below): CH 3 —C=CH—COOCH 2 CH 3 C 18 H 37 -NH which lacks the sterically hindered amine group. Some illustrative but non-limiting examples are provided for a better understanding of the present invention and for its embodiment. EXAMPLE 1 Preparation of /3-methoxyethylamine crotonate of 4- (2 / 2,6,6-tetraπ_ethyl)piperidinyl (Compound Nr. 1) having the following formula: 24.13 g (0.1 moles) of 2 , 2 , 6 , 6-tetramethyl-4-pi- peridinyl-aceto-acetate, 24 g of toluene, 7.51 g (0.1 moles) of 2-methoxyethylamine and 0.23 g of glacial acetic acid, are charged into a 250 ml four-necked reactor, equipped with a stirrer, thermometer and reflux condenser with a water separator. The reaction mass is maintained under stirring and reflux heated for 4 hours, to a temperature ranging from 115°C to 118 "C. During this period there is the formation of reaction water which is separated by azeotropic distillation: 1.5 g of reaction water are separated. The solvent and acetic acid are removed by distillation and the raw residue thus obtained is subjected to fractionated distillation. This distillation is carried out in a distiller consisting of a 100 ml boiler equipped with a thermome- ter, stirrer, column, condenser and device for the collection of fractions. A central fraction containing 26.6 g of distilled product corresponding to Compound Nr. 1, is collected from the above distillation, operating under the following conditions: temperature at the head: 146°C-151°C; temperature of the boiler: 148 "C-152 °C; vacuum: 0.1 mm/Hg. Compound Nr. 1 thus obtained, analyzed by gas- chromatography (GC) , proves to be 97.5% pure, with a yield of about 89.2%. Compound Nr. 1 is characterized by NMR analysis which confirms its enamine structure. - 1 H-NMR (200 MHz, CDCl 3 ~TMS) δ (ppm) : NH (broad) 8.50 ppm; C=CH (s) 4.34 ppm; the other signals are in accordance with the structure. The other compounds (Compounds Nr. 2-11) are prepared analogously to Example 1, of which only the reaction conditions and characteristics are specified. EXAMPLE 2 Preparation of β- (2,2 , 6 , 6,-tetramethγlpiperidine-4- amino) ethyl crotonate (Compound Nr. 2) having the following formula: Amine: 4-amino-2, 2 , 6, 6-tetramethylpiperidine; 31.25 g (0.2 moles) . Carbonyl compound: ethyl aceto-acetate; 26.03 g (0.2 moles) . - Solvent: toluene; 50 g. - Catalyst: acetic acid; 0.3 g - Reaction water separated: 3.3 g Duration and reaction temperature: 5 hours at 126°C-128°C. - Distillation range: 118°C-133°C (head); 130°C- 144°C (boiler); 0.10 mm/Hg - 0.15 mm/Hg (vacuum). Product obtained: 47.5 g. GC Purity: 98.9%. Yield: 88.4% - '1 H-NMR (200 MHz, CDC1 3 -TMS) δ (ppm): NH (d) 8.39 ppm; C=CH (s) 4.35 ppm; the other signals are in accordance with the structure. EXAMPLE 3 Preparation of β- (2 ,2 , 6 , 6,-tetramethylpiperidine-4- amino) crotonate of 4- (2 , 2 , 6, 6-tetramethyl) piperidinyl 4. 0 (Compound Nr. 3) having the following formula: Amine: 4-amino-2 , 2 , 6, 6-tetramethylpiperidine; 31.25 g (0.2 moles) . - Carbonyl compound: 2 , 2 , 6 , 6-tetramethyl-4-piperidi- nylaceto-acetate; 48.5 g (0.2 moles). Solvent: toluene; 50 g. Catalyst: acetic acid; 0.3 g Reaction water separated: 3.44 g - Reaction time and temperature: 3.5 hours at 114 'C- 128°C. In this case the raw residue obtained is not subjected to fractionated distillation as the end- product crystallizes in the reaction medium at room temperature. When the crystallization is complete, the product obtained is filtered, washed with toluene and dried. Product obtained: 41.4 g. GC Purity: 98.9%. - Yield: 54.4% 1 H-NMR ( 200 MHz , CDCl 3 ~TMS ) δ ( ppm) : NH ( d) 8 . 32 ppm; C=CH (s) 4.30 ppm; the other signals are in accordance with the structure. Melting point: 151 "C. EXAMPLE 4 Preparation of 2- (2,2,6,6-tetramethylpiperidine-4- amino) -2-pentene-4-one (Compound Nr. 4) having the following formula: Amine: 4-amino-2 , 2 , 6, 6-tetramethylpiperidine; 62.5 g (0.4 moles) . Carbonyl compound: acetylacetone; 40.05 g (0.4 moles) . Solvent: toluene; 50 g. Catalyst: acetic acid; 0.6 g - Reaction water separated: 7.2 g Reaction time and temperature: 4 hours at 120 °C- 138°C. In this case the raw residue obtained is not subjected to fractionated distillation as the end- product crystallizes in the reaction medium at room 4δ> temperature. When the crystallization is complete, the product obtained is filtered, washed with toluene and dried. Product obtained: 71 g. - GC Purity: > 99%. Yield: 83.6% 1 H-NMR (200 MHz, CDCl 3 ~TMS) δ (ppm): NH (d) 10.48 ppm; C=CH (s) 4.60 ppm; the other signals are in accordance with the structure. - Melting point: 103 °C. EXAMPLE 5 Preparation of 4-piperidino-2,2 / 6,6-tetra_αethyl-l,2 - 5,6-tetrahydropyridine (Compound Nr. 5) having the following formula: Compound Nr. 5 is synthesized operating according to the procedure described by M. Dagonneau et al. in "Synthesis" (1984), page 902. The product obtained has a purity > 99%. EXAMPLE 6 Preparation of /3-octadecylamino ethyl crotonate (Compound Nr. 6) having the following formula: ^ CH 3 — C=CH — COOCH 2 -CH 3 C 18 H 37 -NH Amine: octadecylamine; 53.9 g (0.2 moles). Carbonyl compound: ethyl acetoacetate; 26.03 g (0.2 moles) . - Solvent: toluene; 50 g. Catalyst: acetic acid; 0.3 g Reaction water separated: 3.5 g Reaction time and temperature: 1 h 45' at 118 °C- 130°C. The product is isolated as boiler residue after distillation under vacuum of the solvent and acetic acid. Product obtained: 75 g. - GC Purity: 98.2%. Yield: 98.3% H-NMR (200 MHz, CDCl 3 ~TMS) <S (ppm) : NH (broad) 8.53 ppm; C=CH (s) 4.40 ppm; the other signals are in accordance with the structure. - Melting point: 40.5°C. EXAMPLE 7 Preparation of β- (2 ,2 , 6, 6-tetramethylpiperidine-4- amino) t-butyl crotonate (Compound Nr. 7) having the following formula: CH, Amine: 4-amino-2 , 2 , 6, 6-tetramethylpiperidine; 31.25 g (0.2 moles) . - Carbonyl compound: t-butyl aceto-acetate; 31.64 g (0.2 moles) . Solvent: toluene; 50 g. Catalyst: acetic acid; 0.3 g Reaction water separated: 3.2 g - Reaction time and temperature: 5 hours at 122 °C- 123°C. Distillation range: 142°C-162 0 C (head); 146°C- 183°C (boiler); 0.10 mm/Hg - 0.15 mm/Hg (vacuum). Product obtained: 37.1 g. - GC Purity: 91.6%. Yield: 62.6% Melting point: 86.7°C (solid at room temperature). EXAMPLE 8 Preparation of β- (2 ,2 , 6, 6-tetramethylpiperidine-4- amino) octadecyl crotonate (Compound Nr. 8) having the 5 / following formula: H 3 C — — H — COOC } g H j η NH Amine : 4-amino-2 , 2 , 6 , 6-tetramethylpiperidine ; 13 . 22 g ( 0. 085 moles) . Carbonyl compound: octadecyl aceto-acetate; 30 g (0.085 moles) . Solvent: toluene; 25 g. Catalyst: acetic acid; 0.15 g Reaction water separated: 1.21 g Reaction time and temperature: 3 h 45' at 132 °C- 138 0 C. In this case the raw reaction mass is not subjected to fractionated distillation as the end-product crystallizes in the reaction medium at room temperature. When the crystallization is complete, the product obtained is filtered, washed with toluene and dried. Product obtained: 21.7 g. GC Purity: 99%. Yield: 51.8% Melting point: 53.7°C. EXAMPLE 9 5.2- Preparation of 1-phenyl-l- (2 ,2 , 6, 6-tetramethylpiperi- dine-4-amino) -2-benzoyl-ethylene (Compound Nr. 9) having the following formula: Amine: 4-amino-2 , 2 , 6 , 6-tetramethylpiperidine ; 38.57 g (0.247 moles). Carbonyl compound: dibenzoyl methane; 44.85 g (0.2 moles) . Solvent: toluene; 50 g. Catalyst: acetic acid; 0.9 g - Reaction water separated: 4.8 g .Reaction time and temperature: 22 h at 159 °C- 163°C. In this case the raw reaction mass is not subjected to fractionated distillation as the end-product crystallizes in the reaction medium at room temperature. When the crystallization is complete, the product obtained is filtered, washed with toluene and dried. Product obtained: 32.25 g. GC Purity: 92%. - Yield: 44.5% Melting point: 99°C. EXAMPLE 10 Preparation of β- (2,2,6,6-tetramethyl-piperidine-4- amino) anilide crotonate (Compound Nr. 10) having the following formula: Amine: 4-amino-2 , 2 , 6 , 6-tetramethylpiperidine ; 31.25 g (0.2 moles) . Carbonyl compound: aceto-acetanilide; 35.44 g (0.2 moles) . - Solvent: methanol; 100 g. Catalyst: acetic acid; 0.4 g Reaction water separated: in this case the reaction water is not separated. Reaction time and temperature: 13 h at 20°C-26 <, C. In this case the raw reaction mass is not subjected to fractionated distillation as the end-product crystallizes in the reaction medium at room temperature. When the crystallization is complete, the product obtained is filtered, washed with n-pentane and dried. - Product obtained: 54.34 g. GC Purity: > 97%. Yield: 86.1% Melting point: 188°C. EXAMPLE 11 Preparation of l-methyl-1- (2,2,6, 6,-tetramethyl-piperi- dine-4-amino)-2-benzoyl-ethylene (Compound Nr. 11) having the following formula: Amine: 4-amino-2 , 2 , 6 , 6-tetramethylpiperidine; 31.25 g (0.2 moles). Carbonyl compound: benzoyiacetone; 32.44 g (0.2 moles) . Solvent: toluene; 100 g. Catalyst: acetic acid; 0.4 g - Reaction water separated: 3.2 g Reaction time and temperature: 6 h at 118°C-120°C. In this case the raw reaction mass is not subjected to fractionated distillation as the end-product crystallizes in the reaction medium at room tempera- ture. When the crystallization is complete, the product obtained is filtered, washed with n-pentane and dried. Product obtained: 50.2 g. GC Purity: > 98.5%. Yield: 83.5% - Melting point: 112 °C. EXAMPLE 12 Stabilizing activity test of the Compounds having general formula (I) on polyol. The oxidation kinetics of the polyol stabilized with Compounds 1-11 prepared as described in Examples 1-11 above, are observed by differential thermal analysis at 130 ° C and at 140 °C. Inside the measurement capsule, the systems analyzed are brought in 5 minutes to the test tempera- ture under nitrogen. Oxygen is then passed (7 ml/h) and the oxidation kinetics are observed in relation to the heat developed during the process. The induction time is calculated in the intersection point with the time axis of the tangent at the oxidation curve at 1 W as illustrated in Figure 1: the abscissa indicates the time in minutes, the ordinate the trend of the heat developed in mW. The addition of the polyol is obtained by mixing the polyol with the products to be analyzed, Compounds 1-11 and 2 , 6-di-t-butyl-4-methylphenol (BHT), in a quantity equal to 0.15%, the mixture being stirred until complete dissolution of the products used is obtained. A non-stabilized polyol of the type Glendion FG 3501 produced and sold by EniChem S.p.A., is used as polyol . Table 1 indicates the induction times in minutes of the oxygen absorption during the thermo-oxidation of the polyol at 130 °C and at 140 °C. 7 TABLE 1 The results shown in Table 1 clearly demonstrate that, when the compounds having general formula (I) , Compounds 1-4 and 7-11, are used, the oxygen absorption induction times in the thermo-oxidation of the polyol are considerably higher than those obtained by using BHT. In addition, these results show that the compounds, such as Compound Nr. 5, in which tetramethylpi- peridine is present but not the enamine double bond conjugated with the carbonyl double bond, they are not capable of stabilizing the polyol. The same result is obtained using Compound Nr. 6 in which there is the enamine double bond conjugated with the carbonyl double bond but not tetramethylpiperidine.

Claims: °> CLAIMS 1. Compounds belonging to the group of enamines consisting of derivatives of 0-keto-esters, or β- keto-amides or 1, 3-diketones with primary or secondary, aliphatic or aromatic amines carrying in the molecule at least one sterically hindered amine group having general formula (I) : R 3 I [ R r — (—N—C=CH~C—) m — ] n ~R 4 (I) I I R 2 O wherein: m represents an integer from 1 to 3 , extremes included; n represents an integer from 1 to 4 , extremes included; R 1 represents a triazine having one of the following general formulae (II) , (III) or (IV): So wherein R^ represents a hydrogen atom; a linear or branched C^C^ alkyl group; a -NHR 6 amine group or a -SR 6 group wherein R 6 represents a hydrogen atom or a linear or branched C^C^ alkyl group; R 1 and R 2 , the same or different, represent a hydrogen atom; a linear or branched C.,-C 18 alkyl group; a linear or branched C 2 -C 8 alko- xyalkyl group; a C 5 -C 8 cycloalkyl group optionally containing a heteroatom selected from oxygen, nitrogen and sulfur; a C 6 -C 18 aryl group; a C * 7 -C 20 - • arylalkyl or alkylaryl group; a group having general formula (V) : wherein R 7 represents a hydrogen atom; a linear or branched ^-C^ alkyl group, said alkyl group optionally substituted with a - NHR 8 group or an -0R 8 group wherein R 8 repre- sents a hydrogen atom, a linear or branched 0,-C^ alkyl group, or a C 6 -C 18 aryl group; an -0R 9 group wherein R 9 represents a hydrogen atom, or a linear or branched C,-C 18 alkyl group ; - or, R 1 and R 2 considered jointly with the nitrogen atom, represent a 5 -C z heterocyclic group optionally containing a second hetera- tom selected from oxygen, nitrogen and sulfur; - R 3 and R 4 , the same or different, represent a linear or branched C^C^ alkyl group; a C 6 -C 18 aryl group; a C 7 -C 20 alkylaryl or arylalkyl group; a linear or branched C^C g alkoxy1 group ; - or, R 4 represents a group having general formula (VI) : wherein R 7 has the same meanings defined above ; or, R 4 represents an NR^R^ group wherein R 10 and R^, the same or different, represent a hydrogen atom; a linear or branched ^ -C^ alkyl group; a linear or branched C 2 ~C 8 alko- xyalkyl group; a C 5 -C 8 cycloalkyl group optionally containing a heteroatom selected from oxygen, nitrogen and sulfur; a C 6 -C 18 aryl group; a C 7 -C 20 arylalkyl or alkylaryl group; a triazine having one of the following general formulae (II), (III) or (IV): wherein R 5 has the same meanings defined above; a group having general formula (V): wherein R 7 has the same meanings defined above ; or, R 10 and R Ή considered jointly with the nitrogen atom, represent a C S ~C Q heterocyclic group optionally containing a second hetero- atom selected from oxygen, nitrogen and sulfur; or R 4 represents a group having one of the following general formulae (VII) , (VIII) or (IX): R 12 OCH 2 —CH—0R 13 (VII) ; CH 2 0R 13 I • OCH 2 —C—R 12 (VIII) ; CH 2 0R 13 R 12 —CH0R 13 OCH 2 —C—CH 2 0R 13 (IX) ; CH 2 OR 13 wherein: R 12 represents a hydrogen atom; or a linear or branched ^-C^ alkyl group; R 13 represents a linear or branched C,-C 18 alkyl group; a -COCH 2 COCH 3 group; or a direct bond; provided that, when R 1 and R 2 are different from the group having general formula (V) , R 4 repre- sents a group having general formula (VI) . 2. The compounds belonging to the group of enamines according to claim 1, wherein groups R 1 , R 2 , R 10 and R 117 as well as the hydrogen atom, are: methyl, ethyl, propyl, isopropyl, butyl, octyl, cyclohexyl, benzyl, phenyl, ethylphenyl, methoxyethyl , 4- (2, 2, 6, 6-tetramethyl) piperidinyl, 4- (2, 2 , 6, 6-tetramethyl) -1-butoxyethylpiperidinyl, 4- (2 , 2 , 6, 6- tetramethyl) -1-butoxypiperidinyl , 4- (2 , 2 , 6, 6- tetramethyl) -1-methylpiperidinyl, 3 , 5-dioctyl- aminotriazine, 3 , 5-dibutylaminotriazine. 3. The compounds belonging to the group of enamines according to claim 1, wherein the C 5 -C & heterocyclic groups, when R 1 and R 2 or R 10 and R n are considered jointly with the nitrogen atom, are: morpholine, pyrrolidine, piperidine, piperazine, thiomorpholine, thiazolidine, benzothiazolidine. 4. The compounds belonging to the group of enamines according to claim 1, wherein the R 3 and R groups are: methyl, ethyl, propyl, isopropyl, phenyl, oxymethyl , oxyethyl , oxybutyl . 5. The compounds belonging to the group of enamines according to claim 1, wherein the R 4 groups, when R 4 represents a group having general formula (VI) , are: 4- (2 , 2 , 6 , 6-tetramethyl) piperidinoxy, N-me- thyl-4- (2 , 2,6, 6-tetramethyl) piperidinoxy , N-me- thoxyethyl-4-(2,2, 6, 6-tetramethyl) piperidinoxy, N- methylaminoethyl-4-(2, 2,6, 6-tetramethyl) piperidinoxy. 6. The compounds belonging to the group of enamines according to claim 1, wherein the R 4 groups, when R 4 represents a group having general formula (VII), (VIII) or (IX) and n is 2, are: CH 2 — 0 — CH 2 — 0 — I CH 3 CH 3 — CO — CH 2 — C=0 t 1 0 1 CH-, 1 1 — 0 — CH 2 — C — CH 2 - — 0— ; 1 1 CH 2 1 1 0 / CH 3 — CO — CH 2 — C=0 7. The compounds belonging to the group of enamines according to claim 1, wherein the R 4 groups, when R 4 represents a group having general formula (VII), (VIII) or (IX) and n is 3 , are: CH 2 0— / CH,—CH,—C—CH,0— CH 2 0— 0 CH 2 0— // / CH 3 —CO—CH 2 —C—O—CH 2 —C C-—CH.,0— \ CH 2 0— 8. The compounds belonging to the group of enamines according to claim 1, wherein the R 4 groups, when R 4 represents a group having general formula (VII), (VIII) or (IX) and n is 4, are: CH 2 0— / —0CH 2 —C—CH 2 0— ; \ CH 2 0— 9. The compounds belonging to the group of enamines according to claim 1, wherein the R 7 groups are: methyl, ethyl, propyl, butyl, ethoxy, butoxy, β- hydroxyethyl , /3-methoxyethyl , 3-butoxyethyl, methylaminoethyl . 10. The compounds belonging to the group of enamines according to claim 1, wherein the R 5 , R 6 , R 8 , R^ R 12 and R 13 groups, when said groups represent a linear or branched C,-^ alkyl group, are: methyl, ethyl, propyl, isopropyl, butyl, octyl. 11. A compound belonging to the group of enamines according to claim 1, consisting of 3-methoxyethy- lamine crotonate of 4- (2 , 2 , 6, 6-tetramethyl) piperi- dinyl . 12. A compound belonging to the group of enamines according to claim 1, consisting of β- (2 , 2 , 6 , 6 , - tetramethylpiperidine-4-amino) ethyl crotonate. 13. A compound belonging to the group of enamines according to claim 1, consisting of β- (2 , 2 , 6, 6, - tetramethylpiperidine-4-amino) crotonate of 4- (2 , 2 , 6 , 6-tetramethyl) piperidinyl . 14. A compound belonging to the group of enamines according to claim 1, consisting of 2- (2, 2,6, 6- tetramethylpiperidine-4-amino) -2-pentene-4-one. 15. A compound belonging to the group of enamines according to claim 1, consisting of 0- (2, 2,6,6- tetramethylpiperidine-4-amino) t-butyl crotonate . 16. A compound belonging to the group of enamines according to claim 1, consisting of 3- (2, 2, 6,6- tetramethylpiperidine-4-amino) octadecyl crotonate. 17. A compound belonging to the group of enamines according to claim 1, consisting of 1-phenyl-l- (2,2,6, 6-tetramethylpiperidine-4-amino) -2-benzoyl- ethylene. 18. A compound belonging to the group of enamines according to claim 1, consisting of β- (2, 2,6,6- tetramethyl-piperidine-4-amino) anilide crotonate. 19. A compound belonging to the group of enamines according to claim 1, consisting of 1-methyl-l- (2,2,6,6, -tetramethyl-piperidine-4-amino) -2- benzoyl-ethylene . 20. A process for the synthesis of the compounds having general formula (I) according to any of the previous claims, which comprises the reaction of 1-4 moles of a primary or secondary, aliphatic or aromatic amine, having general formula (X) : HNR 1 R 2 (X) wherein R 1 and R 2 have the same meanings defined above, with 1-3 moles of a /3-keto-ester, or a β- keto-amide, or a 1,3-diketone having general formula (XI) : ( R 3 —C—CH 2 —C—) ~R 4 (XI) // If 0 O wherein R 3 , R 4 and n have the same meanings defined above, wherein the above reaction takes place in the presence of an inert organic solvent, at a temperature ranging from 60 °C to 160 °C, at atmospheric pressure, and for a time ranging from 0.5 to 24 hours. 21. The process for the synthesis of the compounds having general formula (I) according to claim 20, wherein the organic solvent is a hydrocarbon. 22. The process for the synthesis of the compounds having general formula (I) according to claim 21, wherein the hydrocarbon is toluene. ώ 23. The process for the synthesis of the compounds having general formula (I) according to claim 20, wherein the reaction temperature is between 115 °C and 150°C. 24. The process for the synthesis of the compounds having general formula (I) according to claim 20, wherein the reaction time is between 3 and 10 hours. 25. The process for the synthesis of the compounds having general formula (I) according to claim 20, wherein acetic acid is added as catalyst. 26. The process for the synthesis of the compounds having general formula (I) according to claim 20, wherein the primary or secondary, aliphatic or aromatic amines, having general formula (X) are: cyclohexylamine, n-butylamine, tert-butylamine, n- octylamine, tert-octylamine, n-octadecylamine, n- dodecylamine, benzylamine, 2-methoxyethylamine, 2- furfurylamine, pyrrolidine, piperidine, morpho- line, dibenzylamine, aniline, diphenylamine, melamine, 4-amino-2 ,2,6, 6-tetramethylpiperidine, 4-amino-2 ,2,6, 6-tetramethyl-l-methylpiperidine, 4- amino-2 ,2,6, 6-tetramethyl-l--butoxyeτ_.hylpiperidine, l-amino-3 , 5-dioctylaminotriazine. 27. The process for the synthesis of the compounds 7θ having general formula (I) according to claim 20, wherein the 3-keto-esters or 3-keto-amides, or 1, 3-diketones having general formula (XI) are: ethyl aceto-acetate, t-butyl aceto-acetate, octadecyl aceto-acetate, ethyl benzoylacetate, acetyl-acetone, benzoylacetone, dibenzoyl methane, p-toluylacetone, 4- (2 , 2 , 6, 6-tetramethyl) piperidi- nyl aceto-acetate, N-methyl-4- (2 , 2 , 6, 6-tetramethyl) piperidinyl aceto-acetate, aceto-acetamide, acetoacetanilide, aceto-acet-4- (2 , 2 , 6 , 6 , -tetrame- thylpiperidine) amide, aceto-acet- (3 , 5-dibutyltria- zine) -1-amide. 28. Polymeric compositions containing an organic polymer and an effective quantity of one or more of the compounds having general formula (I) according to any of the previous claims. 29. The polymeric compositions according to claim 28, wherein the compounds having general formula (I) are combined with other stabilizers. 30. The polymeric compositions according to claim 28 or 29, wherein the organic polymer is selected from polyols. 31. End-articles obtained from the processing of the polymeric compositions according to any of the claims from 28 to 30. 7' 32. Use of the compounds having general formula (I) according to any of the claims from 1 to 27, as antioxidants for organic polymers.

Inventors: ADOVASIO MAURO, BROUSSARD FABIO, CRISCI LUCIANA, SALINA ARMANDO, ADOVASIO, MAURO, BROUSSARD, FABIO, CRISCI, LUCIANA, SALINA, ARMANDO
Applicants: ADOVASIO MAURO, BROUSSARD FABIO, CRISCI LUCIANA, GREAT LAKES CHEMICAL ITALIA, SALINA ARMANDO, ADOVASIO, MAURO, BROUSSARD, FABIO, CRISCI, LUCIANA, GREAT LAKES CHEMICAL ITALIA S.R.L., SALINA, ARMANDO
Application year: 1998
Main classification: C07D401
IPC codes: C07D211, C07D401, C08K5, C08L101, C09K15