Preparation of n-alkoxyamine HALS from corresponding hydroxylamines

Abstract

A process is described for preparing compounds of the class of sterically hindered alkoxyamines, which process comprises the step of alkylating a sterically hindered hydroxylamine compound to the corresponding sterically hindered alkoxyamine by reacting said sterically hindered nitroxyl compound with a compound capable of generating a carbon centered alkyl radical, typically a primary or secondary alkyl radical, which compound is selected from thermal radical initiators forming radical species within the temperature range 40 to 200°C, and from photoinitiators undergoing photoexcitation upon irradiation with UV light or visible light from the range 180 to 700 nm, especially UV light from the range 180 to 380 nm, the compound capable of generating a carbon centered alkyl radical being typically selected from the class of organic peroxides, azo compounds, benzoyl derivatives, benzophenones derivatives, thioxanthone derivatives, benzoine derivatives, benzoyl phosphine oxide derivatives, for example from diacyl peroxides of the formula (A), peresters of the formula (A) and oxalic acid peresters of the formula (D) R-CO-O-O-Z-R (A), R-Z"-X-CO-CO-O-O-Z"-R (D), wherein each R independently stands for a primary or secondary alkyl or cycloalkyl radical, the primary or secondary alkyl or cycloalkyl radical preferably comprising 1 to 15 carbon atoms, and X is oxygen -O- or a peroxy group -O-O-, Z stands for CO or an alkylene bonded over a quaternary carbon atom, which is an alkylene of the formula (C) R´-C-R´ (C) wherein each R´ is selected from alkyl of 1 to 15 carbon atoms, Z" stands for said alkylene bonded over a quaternary carbon atom of the formula (C). The process described leads to the corresponding O-alkylated derivative of the sterically hindered hydroxylamine, typically a compound of the class known as N-O-alkyl HALS, with extremely high selectivity and conversion rate, and without requirement to use catalysts, especially metal catalysts.

Description

[0001] Preparation of N-alkoxyamine HALS from corresponding Hydroxylamines

[0002] The present invention relates to a novel process for the alkylation of certain N-hydroxy secondary amines and to the preparation of corresponding N-alkoxyamines in high purity. More specifically, the new chemical process pertains to the preparation of such sterically hindered N-alkoxyamines by selective O-alkylation of hydroxylamines by reaction with certain free radical generators.

[0003] Further described are some novel compounds obtainable with the present process. The products of present process may be used in various fields of chemistry and polymer technology; an important class of products belong to the sterically hindered amines, which are commonly used in polymer technology, for example, as flame retardants, polymerization regulators, or as stabilizers for organic material, such as organic polymer compositions, against degradation by light, oxygen and / or heat.

[0004] A number of publications describe the stabilization of organic material using specific sterically hindered amine compounds as stabilizers, such compounds are also known as hindered amine light stabilizers (HALS). For use as stabilizers, such compounds may contain unsubstituted nitrogen (NH-HALS), or substituted nitrogen (e.g. N-alkyl HALS); an important class, due to specific properties such as the reduced basicity of these compounds, are HALS compounds whose hindered nitrogen atom carries an additional organic substituent linked over an oxygen atom (typically N-O-alkyl HALS, see e.g. US-5204473, US-5096950); such N-O-alkyl HALS compounds are also referred to as hindered amine ethers. Further applications of sterically hindered amines, especially N-O-alkyl HALS, include uses as flame retardants, rheology modifiers, free radical initiators for controlled polymerization (see Nitroxyl radicals and nitroxyl ethers beyond stabilization: radical generators for efficient polymer modification, Rudolf Pfa- endner, C. R. Chimie 9 (2006) 1338-1344).

[0005] Most of the commercial applications of hindered N-Alkoxyamines require a well-defined thermal stability of the product. As it is well known in the scientific literature, the Car- bon-Oxygen bond of the hindered N-Alkoxyamines has a low bond energy while properties like thermal stability or dissociation are dictated by such bond strength. As described in above references, the thermal degradation of certain N-Alkoxyamines (especially N-O-alkyl HALS) for use as flame retardants or in rheology modifiers applications, is designed to occur at the desired temperatures. Typically, at the extrusion temperature, to trigger free radical reactions between the N-Alkoxyamines and the molten polymer. This leads to polymer chain scission or crosslinking, which modify both the rheology of the molten polymer and the mechanical properties of the resulting final plastic article. For such applications, the R groups of N-Alkoxyamines in flame retardants and rheology modifiers are selected with an R substituent with a lower thermal stability compared to light stabilizers. Typically for light stabilization applications, in contrast, the N-Alkoxy derivatives are designed with the highest thermal stability possible to avoid any changes in rheology or mechanical properties of the plastic article.

[0006] Due to the above reasons, for the manufacturing of products based on hindered N- Alkoxyamines with well-defined thermal stability, it is very desirable to use a versatile process, applicable to a broad range of hindered N-Alkoxyamines with a range of dif- ferent R substituents, and capable of high yields and high selectivity in the desired N- Alkoxyamine. In fact, many known manufacturing processes of N-Alkoxyamines have low selectivity towards the desired product, leading to the formation of undesired byproducts like sterically hindered amines showing N-oxyl or N-hydroxy functionalities or presence of unreacted educt material such as secondary amine moieties. Such products may show thermal stability or activation temperature outside of the desired temperature range. This is even more important in the case of molecules with multiple hindered amine moieties, like the precursors of oligomeric HALS stabilizers, flame retardant or rheology modifiers, where such by-products cannot be separated by purification and become part of the final products, with potential negative effect on its thermal stability and colour of the product.

[0007] It is desirable to use manufacturing process with high productivity, low cost and based on the principle of Green Chemistry, especially free of heavy metals.

[0008] A number of sterically hindered hydroxylamines, their use as stabilizers especially in coating compositions, and some methods for their preparation, is described e.g. in EP- A-309401. The secondary amine or hindered amine precursors are largely commercially available or can be prepared by the application of known methods. These secondary hindered amines, which are characterized by their N-H moiety, are conveniently converted into the corresponding hydroxylamines by methods described in the literature. Useful precursors can be found, inter alia, in the above references and documents cited therein, see e.g. WO-2008-003605 page 12 line 22 to page 13 line 5.

[0009] A problem arising in known conversions of appropriate precursors such as HALS with NH- or N-hydroxy functionalities into the corresponding sterically hindered amine alkyl ethers is often an unsatisfactory conversion rate, unreacted precursor functionalities or undesired derivatives remaining in the product, which may be detrimental e.g. for its thermal stability or cause undesired side reactions. An example are nitroxides, which may form, due to the high reactivity of nitroxides as oxidation catalysts in presence of oxidants like peroxides and even air, unstable and / or strongly colored byproducts, that would reduce the value of the final product. This may be prevented by following the present process since the sterically hindered hydroxylamine does not show any catalytic effects in presence of an oxidant.

[0010] Conversion of the N-hydroxy precursors into the corresponding sterically hindered amine alkyl ethers still may be improved with regard to efficiency, rate of conversion and environmental aspects.

[0011] The present invention relates to a novel process for the alkylation of sterically hindered hydroxylamines and the preparation of corresponding sterically hindered amine ethers. More specifically, the new chemical process pertains to the preparation of sterically hindered amine ethers by highly selective O-alkylation via generation and coupling of carbon centered radicals starting from an appropriate precursor from the class of free radical initiators or photoinitiators under specific reaction conditions. The sterically hindered amine ether obtainable by the present process thus is characterized by the moiety N-O-alkyl, where alkyl may be straight or branched alkyl or cycloalkyl (i.e. saturated hydrocarbon). Short reaction times, high selectivity and high yields of the desired ni- troxyl ethers are a very important feature of the novel process, especially for the preparation of compounds containing a multitude of hindered amine ether functionalities such as polymeric compounds, due to the high conversion rate of the N-hydroxyl moieties in oligomeric or macromolecular HALS educts. The products of the present process are of high commercial importance as stabilizers, flame retardants, rheology modifiers, or initiators for controlled polymerization.

[0012] It thus has been found that hydroxylamine compounds, such as sterically hindered hydroxylamines, may be alkylated on the oxygen atom to obtain the corresponding sterically hindered alkoxyamine, by reaction with a compound capable of generating a carbon centered radical, specifically an alkyl radical. The general term “alkyl” in this sense is to be understood straight or branched alkyl, in accordance with common products of this class and as explained further below. Such Carbon Centered Radical Initiators (CCRIs, also denoted herein as radical generators) are substances producing carbon centered radical species under relatively mild conditions and promote chemical radical reactions. These substances are widely known and items of commerce; they are activated either by mild temperatures like in the case of thermal initiators or by exposure to radiation in the UV or visible spectra like in the case of photoinitiators. It is generally known that organic radical initiators show equivalent results, note e.g. Pradip Debnath, INTERNATIONAL JOURNAL OF RESEARCH IN PHARMACY AND CHEMISTRY, 2023, 13(2), 189-197; John C. Bevington, Initiation of polymerization: Azo compounds and peroxides, Makromolekulare Chemie, Macromolecular Symposia: Volume 10-11, Issue 1 , 89-107.

[0013] Thermal radical initiator molecules generally possess weak chemical bonds, that can be cleaved homolytically to form radical species by the effect of relatively low temperatures, typically within the range 40 to 200°C, preferably 50 to 160°C, especially 60 to 140°C. Initiators of this class are commercially available; these components generating carbon centered free radicals have a weak chemical bond involving some heteroatoms, that, after the homolytic bond cleavage, typically eliminate a stable gaseous molecule (e.g CO2, N2) and at least one carbon centered radical, typically a primary or secondary alkyl radical. Commercially relevant examples are:

[0014] • organic peroxide initiators, where the weak bond is peroxidic; the class includes di-acyl-peroxides, peresters, percarbonates, perketals which, upon heating, eliminate one molecule of CO2 or ketone and at least one carbon center radical

[0015] • organic azo initiators, where the weak bond is between a c arbon and the nitrogen of the azo moiety (R-N=N-R, where R is as defined below for peroxides) of the molecule, which will be homolytically cleaved upon heating to generate N2 and at least one carbon centered radical.

[0016] Useful photoinitiator molecules generally contain a chromophore, a functional group, that undergoes photoexcitation upon UV or visible light (e.g. 180 to 700 nm) exposure, especially UV light from the range 180 to 380 nm, and a cleavable bond, which cleaves homolytically when the molecule is in the photoexcited state, generating free radical species that leads, directly or indirectly (i.e. after elimination of a gaseous molecule) to at least one carbon centered free radical, typically an alkyl radical such as R' with R as defined below. Certain compounds of the class of organic peroxides and azo compounds are commonly used as photoinitiators. Other classes of commercially relevant photoinitiators are benzoyl derivatives, benzophenones derivatives, thioxanthone derivatives, benzoin derivatives, benzoyl phosphine oxide derivatives.

[0017] Preferred compounds capable of generating a carbon centered alkyl radical for use in the present process are organic peroxides and azo compounds: A preferred radical generator for the purpose is a peroxide:

[0018] The peroxide is typically selected from diacyl peroxides of the formula (A), peresters of the formula (A) and oxalic acid peresters of the formula (D)

[0019] R-CO-O-O-Z-R (A),

[0020] R-Z”-X-CO-CO-O-O-Z”-R (D), wherein each R independently stands for a primary or secondary alkyl or cycloalkyl radical, the primary or secondary alkyl or cycloalkyl radical preferably comprising 1 to 15 carbon atoms, and

[0021] X is oxygen -O- or a peroxy group -O-O-,

[0022] Z stands for CO or an alkylene bonded over a quaternary carbon atom, which is an alkylene of the formula (C)

[0023] R'-C-R' (C) wherein each R' is selected from alkyl of 1 to 15 carbon atoms,

[0024] Z” stands for said alkylene bonded over a quaternary carbon atom of the formula (C).

[0025] The peroxide for use in the present process often is a di-acylperoxide of the formula (B)

[0026] R-CO-O-O-CO-R (B) wherein each R independently stands for a primary or secondary alkyl or cycloalkyl radical, the primary or secondary alkyl or cycloalkyl radical preferably comprising 1 to 15 carbon atoms.

[0027] Summarizing the present invention, it thus has been found that sterically hindered hydroxylamines may be alkylated on the oxygen atom to obtain the corresponding sterically hindered alkoxyamine, described in the literature inter alia as radical scavenging additive also known as N-O-alkyl HALS, by reaction with an alkyl radical releasing compound as described above, e.g. a peroxide of the formula (A)

[0028] R-CO-O-O-Z-R (A), or preferably a di-acylperoxide of the formula (B) R-CO-O-O-CO-R (B) wherein Z stands for CO or an alkylene bonded over a quaternary carbon atom, i.e. an alkylene of the formula (C) wherein each R' is selected from alkyl of 1 to 15 carbon atoms, and each R independently stands for a primary or secondary alkyl or cycloalkyl radical, the primary or secondary alkyl or cycloalkyl radical preferably comprising 1 to 15 carbon atoms.

[0029] The peroxide may also be selected from oxalic acid peresters of the formula (D)

[0030] R-Z”-X-CO-CO-O-O-Z”-R (D), wherein each R independently stands for a primary or secondary alkyl or cycloalkyl radical, the primary or secondary alkyl or cycloalkyl radical preferably comprising 1 to 15 carbon atoms, and

[0031] X is oxygen -O- or, preferably, a peroxy group -O-O-; and Z” stands for alkylene bonded over a quaternary carbon atom of the formula (C)

[0032] R'-C-R' (C) wherein each R' is selected from alkyl of 1 to 15 carbon atoms,

[0033] Such peroxides based on oxalic acid may bring about the advantage of milder reaction conditions, such as reduced reaction temperature as noted further below.

[0034] It has been found that, surprisingly, this reaction leads to the corresponding O-alkylated derivative, preferably N-O-alkyl HALS, with extremely high selectivity and conversion rate, and without requirement to use catalysts, especially metal or iodide catalysts.

[0035] High selectivity and conversion rate are especially important in case of oligomeric or polymeric products for improving the product quality. Such N-alkoxy compounds with high thermal stability are also suitable as stabilizers for polymers with higher extrusion temperature, for example polypropylene fibers and non-wovens, since they will survive the processing without changing properties of the polymer while still providing the undiminished stabilization performance.

[0036] Due to its high conversion rate, the present process is also suitable for improving the product quality of N-O-alkyl HALS products, some of which are commercial, which may be impaired by their content of unreacted educt moieties such as hydroxylamine and / or an undesired coloration of the product. The invention this further pertains to a process as described above for the conversion of a sterically hindered hydroxylamine compound, characterized by comprising one or more groups of the formula (Illa) into the corresponding N-O-alkyl compound, wherein the educt already is partly converted and already comprises one or more groups of the formula (la)

[0037] (la) ; the asterisk in each formula indicating the location of the bond linking these moieties to another part of the molecule, while R denotes the alkyl group defined above.

[0038] Typical sterically hindered alkoxyamine products thus include molecules comprising e.g. 1 to 6 moieties of the formula (la), for example 1 to 5, or 1 to 4 of such moieties, such as the products of educts 1 , 6, 10 to 13 and 16-17 shown further below. Of special technical importance are sterically hindered alkoxyamine products comprising 6 moieties of the formula (la), see for example the alkoxylated products of educts 14 and 15 shown below.

[0039] However, such process for improving the product quality and alkylation rate is, consequently, especially useful in the case of oligomeric or polymeric compounds comprising at least 6, for example 6 to 100, moieties if the formula (la), while also containing some unreacted hydroxylamine moieties, e.g. of the formula (Illa). Typical products of these classes are shown further below (see e.g. formulae (IV) and (V)). Typical products of these classes further include, for example, the alkoxylated products of educts 2-4 and 8-9 shown further below.

[0040] It is another finding of the present invention, that hydroxylamine compounds such as sterically hindered hydroxylamines may be converted in the absence of metal catalysts (also denoted as heavy metals), or even any catalytic agent, to the corresponding alkoxyamines, following the process presently described.

[0041] Within the scope of present invention, the term “primary alkyl” or “secondary alkyl or cycloalkyl” radical denotes any alkyl or cycloalkyl group forming a carbon centered radical, whose radical center bonds to another carbon and 2 hydrogen atoms or to 3 hydrogen atoms, thus forming a primary carbon radical or a methyl radical as a specific form thereof; or the radical center bonds to 2 carbon atoms and 1 hydrogen atom, thus forming a secondary carbon radical. The term “radical” stands for a monovalent group (i.e. primary alkyl group or secondary alkyl or cycloalkyl group) when part of a molecule, like in abovesaid educt and product of the process (i.e. the di-acylperoxide and the alkoxyamine). The primary or secondary carbon of present moiety R is not part of a conjugated system (like benzylic or allylic or cyano); it is preferably not adjacent to an electro-withdrawing group, otherwise the thermal stability would be reduced. The corresponding product of the present process, i.e. the alkoxyamine, thus is characterized by the moiety N-O-C, wherein the carbon atom is part of said “primary alkyl” or “secondary alkyl or cycloalkyl” radical, such as methyl or other moieties defined for R.

[0042] In a preferred process of the invention, R is independently selected from methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl, 1 -pentyl, 2-pentyl, 3-pentyl, 1 -hexyl, 2-hexyl, 3- hexyl, 1 -heptyl, 2-heptyl, 3-heptyl, 4-heptyl, 1 -octyl, 2-octyl, 3-octyl, 4-octyl, nonyl, decyl, undecyl, dodecyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl; especially wherein both residues R stand for the same radical.

[0043] The term “sterically hindered amine” denotes a secondary or tertiary amine whose nitrogen atom bonds to 2 tertiary carbon atoms. These carbon atoms are thus part of branched residues directly besides the nitrogen, which thereby is sterically hindered to act as a nucleophile. The term “tertiary carbon atoms” defines each thereof to bond to 3 further carbon atoms. A valuable class of sterically hindered amines are compounds wherein said nitrogen atom and the neighbouring 2 carbon atoms are part of one heterocyclic ring, such as a piperidine, piperazine (typically 4-piperazine) or piperazinone (typically 4-piperazine-3-one) ring. The sterically hindered hydroxylamine (i.e. N- hydroxy substituted sterically hindered amine) educt thus is of the formula (R2)3-C-N(OH)-C-(R2’)3 (l‘) wherein each of R2and R2’ independently are saturated carbon such as alkyl, alkylene, each of which may be substituted or unsubstituted, and typically are as defined below.

[0044] The term “metal catalysts” typically includes transition metals such as copper, iron, palladium; generally, it stands for any compound comprising a metal element other than alkaline or alkaline earth elements.

[0045] The term “alkylate” or “alkylation” denotes the reaction proceeding in the process of the invention, comprising the formation of a chemical bond between alkyl group such as R and the oxygen of the hydroxylamine radical (i.e. substitution of the hydrogen of the hydroxylamine with the R of the peroxide). In a typical process of the invention, the sterically hindered alkoxyamine obtained is a compound of the formula (I)

[0046] (R2)3-C-N(OR)-C-(R2’)3 (I) wherein R is as defined above; each R2and R2’ is a hydrocarbon, and preferably an R2and R2’ are interlinked to form one divalent hydrocarbon residue, all R2and R2’ together containing 2 to 500 carbon atoms, and optionally further containing one or more moieties selected from the group consisting of tertiary nitrogen moieties, secondary nitrogen moieties; ester moieties COO; chloro.

[0047] R is preferably alkyl selected from Ci-Ci2alkyl or Cs-Cscycloalkyl; and each R2is a hydrocarbon, and preferably interlinked to form one divalent hydrocarbon residue, both R2together containing 2 to 500 carbon atoms and optionally one or more tertiary nitrogen moieties, one or more ester moieties COO, and / or one or more divalent moieties >N- OR.

[0048] The sterically hindered hydroxylamine educt typically belongs to the class of 1 -hydroxy -2,2,6,6-tetramethyl-piperidines containing one or more moieties of the formula (Illa), and the corresponding sterically hindered alkoxyamine compound belongs to the class of 1-alkoxy-2,2,6,6-tetramethyl-piperidines containing one or more moieties of the formula (la), wherein the asterisk indicates the location of the bond linking these moieties to another part of the molecule and R is as defined above.

[0049] The sterically hindered alkoxyamine compound obtainable in present process often conforms to the formula (lb)

[0050] (HA)PY (lb) wherein

[0051] HA is a hindered amine ether moiety (HE) of the formula (la) as defined above; p is a number from the range 1 to 6, and wherein

[0052] Y is hydrogen, oxo, or Y is an anchor group of valency 2 to 6 of the formula (IX) T3-(N[T4]-A2)q-N[TiT2] (IX) wherein q ranges from 0 to 3, or Y is an anchor group as further defined below; when p is 1 ,

[0053] Y is an anchor group of the formula -DC-Ai; when p is 2, Y is an anchor group of the formula DC-A2-DC; or Y is said divalent anchor group of the formula (IX), wherein q is zero, T3 stands for an open bond, T1 is as defined for R1 and T2is a divalent ami- notriazinyl of the formula (X)

[0054] (X), or q is 1 , each of T1 and T3 is as defined for R1 and each of T2and T4is said divalent aminotriazinyl of the formula (X); when p is 3, Y is a trivalent anchor group of the formula (IX), wherein q is zero, T3 stands for an open bond, T1 is as defined for R1 and T2is a trivalent diaminotriazinyl of the formula (XI)

[0055] (XI), or q is 1 , T1 is as defined for R1, T2is a divalent aminotriazinyl of the formula (X), and T3 and T4independently stand for an open bond or a divalent aminotriazinyl of the formula (X); when p is 4, Y is a tetravalent anchor group of the formula (IX), wherein q is 3 and T2and two of the residues T4stand for a divalent diaminotriazinyl of the formula (XI), while each T1 and T3 and the remaining residue T4are as defined for R1; when p is 5, Y is a pentavalent anchor group of the formula (IX), wherein q is 1 , T1 is a trivalent diaminotriazinyl of the formula (XI), T3 is a divalent aminotriazinyl of the formula (X), and T2and T4independently stand for an open bond or a divalent aminotriazinyl of the formula (X); when p is 6, Y is a hexavalent anchor group of the formula (IX), wherein q is 1 , each of Ti and T3 is a trivalent diaminotriazinyl of the formula (XI), and T2 and T4 independently stand for an open bond or a divalent aminotriazinyl of the formula (X); or q is 2 and T2 and each T4 stand for a trivalent diaminotriazinyl of the formula (XI), while each T1 and T3 is as defined for R1; or q is 3 and T2 and two of the residues T4 stand for a trivalent diaminotriazinyl of the formula (XI), while each T1 and T3 and the remaining residue T4 are as defined for R1; or q is 3 and T2 and T3 and one of the residues T4 stand for a trivalent diaminotriazinyl of the formula (XI), while each T1 and the remaining residue T4 are as defined for R1;

[0056] A1 is Ci-Ci2alkyl or C2-Ci2alkyl interrupted by O or COO; or is di(dialkylamino)triazinyl whose alkyl groups are selected from Ci-Ci2alkyl and preferably are identical;

[0057] A2 is C2-Ci2alkylene;

[0058] DC is a divalent connecting moiety, typically a direct bond, an ester moiety -COO-, ether moiety -O-, or amino moiety of the formula -NR1-; and

[0059] R1 is H or lower alkyl, especially H or Ci-Cealkyl; and

[0060] X is Cl or N(Ri)2.

[0061] The number of open bonds in the anchor group Y equals p.

[0062] Each of the moieties of formulae (X) and (XI) contain two different classes of open bonds, one at the triazine core and one (formula (X)) or two (formula (XI)) at NR1. When present in the anchor group of the formula (IX), the one open bond from the triazine core always bonds to the nitrogen atom in formula (IX). Consequently, the open bonds at NR1 bond to the moiety of formula (la) or (Illa).

[0063] Examples for preferred products obtainable in the present process are compounds of the formula (lb) wherein Y is an anchor group of the formula (IX), wherein q is from the range 0 to 3; each of TI, T2, Ts and, if present, T4, is as defined for R1 or is an open bond or is diaminotriazinyl of the formula (XII) and in case that p is 4 or 6, also Y comprises a tetravalent or hexavalent moiety of the formula (XIII)

[0064] (XIII); wherein each of R'and R'i is as defined for Ri or is an open bond, provided that the number of open bonds in the anchor group Y equals p.

[0065] An example is a compound comprising an anchor group of the formula (XIII) wherein A2 is tetra-, penta- or hexamethylene, each R'1 is an open bond, each of R' is C2-C6 alkyl, especially butyl; the anchor group thus providing 6 open bonds, one on each aliphatic nitrogen atom. The term “aliphatic” is herein understood as not belonging to a ring structure comprising double bonds. All 6 open bonds thus are linked to a hindered amine moiety of the formula (la).

[0066] Consequently, the sterically hindered hydroxylamine educt typically conforms to the formula (Ic)

[0067] (HOx)pY (Ic) wherein

[0068] HOx is a hindered amine hydroxylamine moiety of the formula (Illa) as defined above; and p and Y are as defined for formula (lb) above.

[0069] The reaction is typically carried out for a period of 5 minutes to 100 hours. The reaction is typically carried out in the absence of a heavy metal catalyst.

[0070] The invention further pertains to a process for converting a sterically hindered secondary amine (i.e. an N-H amine as educt) into the corresponding alkoxylated amine (i.e.

[0071] N-O-alkyl amine, preferably N-O-alkyl HALS) by i) contacting the secondary hindered amine with a suitable oxidant to obtain the corresponding nitroxide (NO ) or hydroxylamine (NOH); ii) optionally contacting the nitroxide product of step (i) with a reducing agent to obtain a compound comprising hydroxylamine moieties; and subsequently iii) reacting the hydroxylamine product obtained in step (i) or step (ii) with a compound capable of generating alkyl radicals, e.g. with a peroxide of the formula (A) or preferably (B), in accordance with the method described above.

[0072] Preferably, the secondary amine educt is an oligomeric or polymeric compound comprising at least 6, especially 6 to 100, moieties 2,2,6,6-tetramethyl-piperidin-4-yl, Examples for such secondary hindered amine educts are listed further below (e.g. Educts 1 to 17). Consequently, the invention further pertains to a process for converting a sterically hindered nitroxyl compound (i.e. an N-oxyl amine as educt) into the corresponding alkox- ylated amine (i.e. N-O-alkyl amine, preferably N-O-alkyl HALS) by subjecting a nitroxyl educt subsequently to steps (ii) and (iii) as described herein; examples for suitable nitroxyl educts are derived from the corresponding secondary amine educt by replacing N-H by N-oxyl.

[0073] Each of the above steps, i.e. step (i) oxidizing the secondary amine to the oxyl or directly to the hydroxyl amine, optional step (ii) reducing said oxyl to hydroxyl, and step (iii) of present invention converting said hydroxylamine into the corresponding alkoxyamine, is typically carried out in the liquid phase and at a temperature from the range 0 to 140°C, e.g. 0 to 120° C, especially in the presence of an inert solvent.

[0074] Methods for carrying out present step (i), and oxidants used for this step, are generally known in the art (see e.g. documents cited above). Oxidants are typically peroxides like hydrogen peroxide, hydrogen peroxide releasing compounds, peracids (e.g. peracetic acid), or potassium peroxysulfate of the formula K(OH)SO4 (available as its triple salt with KHSO4 and K2SO4 under the trade name Oxone®), typically in presence of SiO2, for direct conversion of the secondary sterically hindered amine to the hydroxylamine.

[0075] Reduction of nitroxyl to the hydroxylamine (optional step ii) is carried out using typical reducing agents known in the art, like hydrazine, or hydrogen with or without suitable catalysts like Pd, Pt or other transition metals, ascorbic acid, sulfur-containing compounds such as sodium thiosulfate, sodium (bi-)sulfite. Alternatively, boron-or alumini- um-containing reagents such as borhydrides or borohydrides, aluminum hydrides, silanes, phosphorous-containing reagents such as hypophosphourus acid and derivatives, Hantzsch esters, formic acid or its salts, 1 ,4-cyclohexadiene, fomaldehyde, di- thiothreitol may be used. Also, the reduction may be carried out electrochemically. The reaction is typically carried out in the presence of solvents and at temperatures as described herein for steps (i) or (iii).

[0076] Preferred temperatures, especially for present step (iii), are from the range 15 to 100° C, especially 30 to 100°C, most preferably in case that the peroxide used in present process is a diacyl peroxide (formula A) or oxalic acid perester (formula D).

[0077] Present process, including steps (i) and (ii), and optional step (iii), is preferably carried out in the presence of a solvent, which is selected from non-polar solvents like C5-C12 hydrocarbons, for example alkanes, cycloalkanes, aromatic hydrocarbons or arylalkanes, optionally dried; and polar solvents like alcohols, ethers, esters, especially comprising methyl and / or tert.-alkyl moieties, for example tert.butanol, methyl-tert. butyl ether, methyl acetate, tert. butyl acetate. Of special technical importance are mixtures of such non-polar and polar solvents. Of specific technical interest is a process, wherein the reaction is carried out under a protective gas excluding oxygen, for example under nitrogen.

[0078] Of special industrial importance is a process for alkylating a sterically hindered hydroxylamine compound to the corresponding sterically hindered alkoxyamine, which process comprises reacting said sterically hindered hydroxylamine compound with a per- oxide of the formula (A) or especially formula (B) as described above; for example by converting a sterically hindered nitroxyl compound conforming to the formula into the corresponding hydroxylamine (step ii), and subsequently into the sterically hindered alkoxyamine (step iii) conforming to the formula (V) wherein n in each formula ranges from 1 to 10 and R is as defined in claim 1 or 2, and preferably is C1-C5alkyl, especially 1-propyl.

[0079] In a process of special technical importance according to present invention, the compound capable of generating a carbon centered alkyl radical is a peroxide of formula (A) or (D) and the sterically hindered alkoxyamine product conforms to the formula (V), or conform to the formula (V’) shown further below, wherein more than 87%, typically 90 to 99.9%, especially 96% to 99.9%, of N-0 moieties are present in alkylated form as N-OR, wherein R is Ci-Csalkyl, especially 1 -propyl, and containing remaining moieties R as hydrogen

[0080] Likewise important is a process wherein, in a first step (i), the sterically hindered secondary amine educt of the formula where n is as defined above for formula (V), is converted into said sterically hindered nitroxyl compound or into the corresponding hydroxylamine, said process comprising the following steps: i) contacting said secondary hindered amine educt with a suitable oxidant to obtain said nitroxide (NO ) compound or said hydroxylamine compound; ii) optionally reacting the nitroxide product obtained in step (i) with with a reducing agent to convert it into the corresponding hydroxylamine, and iii) reacting the hydroxylamine obtained with a compound capable of generating alkyl radicals, for example with a peroxide of the formula (A) or preferably (B), to obtain abovesaid compound of the formula (V).

[0081] Due to the high conversion rate achieved in the present process, the conversion of large molecules comprising a multitude of hydroxylamine groups, e.g. 6 or more, leads to a N-O-alkyl product which is substantially different from the products obtained with conventional alkylations. The invention thus further pertains to an oligomeric or polymeric product comprising compounds containing at least 6, for example 6 to 100, especially 8 to 100, or even 10 to 100 moieties of the formula (la), wherein the asterisk indicates the location of the bond linking these moieties to another part of the molecule,

[0082] (la); as obtainable in the present process, or as obtained in a process starting from an educt comprising the number of moieties as given above in form of an educt moiety selected from the group consisting of 2,2,6, 6-tetramethyl-piperidine-4-yl, 2,2,6,6-tetramethyl-1- oxyl-piperidine-4-yl, 2,2,6,6-tetramethyl-1-hydroxy-piperidine-4-yl. By preparing said product from its high molecular weight educt by modification of its N-H, N-oxyl and / or N-OH moiety to the desired N-OR moiety, by products comprising unreacted or partially reacted educt moieties become part of the end product. Preparation of such products using the present process with its high conversion rate thus leads to a novel product of this oligomeric or polymeric class. The novel product is preferably an oligomeric or polymeric sterically hindered alkoxyamine compound corresponding to one of the formulae (IV) or (V)

[0083] (IV), wherein A2, and R1 are as defined in previous claims and R is as defined below for formula (V), wherein n ranges from 1 to 10 and R is as defined in claim 1 or 3, and preferably is C1-C5alkyl, especially 1 -propyl; characterized in that said oligomeric or polymeric product is obtainable by the process according to present disclosure. As it is typical for polymers, such oligomers or polymers often contain species which may vary in their chain length or molecular weight; an example is the product of the above formula (V) which may include species with 1 to 10 repeating units, as indicated by n. Present process is especially useful for converting the heavier hydroxylamine educt species (see eg. Formula V” below), with n e.g. ranging from 3 to 10, into the desired alkoxyamine variant. As noted above, such alkoxyamine includes alkyloxy as well as cycloalkyloxy in accordance with the definitions; and further, present invention also includes a novel product comprising an oligomeric or polymeric sterically hindered alkoxyamine compound corresponding to one of the formulae (IV) or (V) as shown above, typically in form of a mixture of compounds falling under the same formula, which is obtained from an educt of formula (IV”) or (V”) wherein E is selected from hydrogen, oxyl or hydroxy.

[0084] As noted above, prior art conversions of oligomeric or polymeric HALS into N-O-alkyl typically lead to products containing certain amounts of unreacted educt moieties like NH, N-OH, nitroxyl and potentially further moieties remaining unreacted resulting from side reactions. In consequence of the high conversion rate of hydroxylamines according to the present process to alkoxyamine in the product, present invention provides a novel product comprising one or more compounds represented by abovesaid formula (V), which is characterized in that it contains more than 87%, preferably 90 to 99.9%, more preferably more than 95%, typically 96% to 99.9%, of educt hydroxylamines con- verted into alkoxyamine moieties N-OR as shown in formula (V), especially wherein R is 1 -propyl. As common in the case of oligomeric or polymeric alkoxylated HALS, the product comprises a mixture of compounds, wherein, besides compounds conforming exactly to the formula (V), compounds alike those of formula (V) are contained but with one or more moieties N-OR replaced by nitroxyl and / or hydroxylamine, typically also other derivatives of tetramethylpiperidine moiety such as N-H, lower alkylamine, which corresponds to unreacted material or moieties, or products of side reactions. Present invention thus allows for an enormous reduction of such unreacted educt moieties like hydroxylamine or the colored nitroxyls remaining in the end product, e.g. to 0.1 to 4 % of hydroxylamines initially present in the educt of present step (iii).

[0085] Some of the hydroxylamines useful as educts in the present process, e.g. as educt for step iii) noted above, are novel compounds. The present invention thus further pertains to a compound of the formula (V’) wherein n ranges from 1 to 10, especially 3 to 10, and R is hydrogen.

[0086] Since present process further may provide novel compounds showing hydroxylamine besides alkoxyamine functionalities, compounds of the formula (V’), wherein n ranges from 1 to 10 and R is hydrogen or Ci-Csalkyl, provided that said compound comprises at least one moiety R which is hydrogen.

[0087] Preferred secondary amine educts for present step (i) include the following compounds:

[0088] Educt 1 of the formula:

[0089]

[0090] 5 wherein n ranges from 1 to 10 (available as Chimassorb 2020 [RTM] from BASF);

[0091] Educt 3 of the formula: wherein n ranges from 1 to 10, especially 4 to 5 (available as Chimassorb 944 [RTM] from BASF);

[0092] Educt 4 of the formula: which is available as Cyasorb UV-3346 (RTM; CAS-No. 90751-07-8) from Solvay;

[0093] Educt 5 of the formula: which has been described as educt for example 11 in US-5130429 (related to Chimassorb 119 [RTM], BASF); the analogous structure (with 3 instead of 4 R groups in the tetramine), in form of the N-cyclohexyloxy derivative is available as Flamestab NOR 116 [RTM] from BASF; Educt 6 of the formula:

[0094] which is available as Cyasorb 3853 (RTM; CAS-No. 24860-22-8);

[0095] Educt 7 of the formula: which is available as Uvinul 4050 (RTM; CAS-No. 123172-53-8);

[0096] Educt 8 of the formula: which is available as Uvinul 5050 (RTM; CAS-No. 199237-39-3); Educt 9 of the formula: wherein R represents a moiety of the formula wherein the wiggled line denotes the bond to the molecule shown above

[0097] (Uvasorb HA 88 [RTM]; CAS-No. 136504-96-6), available from 3V Sigma; which is available as Nylostab S-EED (RTM; CAS-No. 42774-15-2) from Clariant; Educt 11 of the formula:

[0098]

[0099] Educt 12 of the formula:

[0100] 5 Educt 13 of the formula:

[0101]

[0102]

[0103] (which is the secondary amine analogue of examples 1-3 of WO2012-052377); Educt 16 of the formula:

[0104] Educt 17 of the formula:

[0105] (bis(2, 2,6,6- tetramethylpiperidin-4-yl)sebacate; available as Tinuvin 770 [RTM] from BASF). Educts 12, 13 and especially 16 are useful as an intermediate for oligomeric HALS and corresponding oligomeric N-O-alkyl HALS.

[0106] Nitroxyl compounds suitable as educt for step (ii) in the process of the invention include the compound of the formula wherein n is from the range 1 to 10; as well as any of the above secondary amine educts for present step (i) in oxidized form, as available as product of the present step (i).

[0107] Preferred products of the present process include the following compounds: a) Bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate (i.e. Tinuvin 123 [RTM],

[0108] CAS-No. 129757-67); b) the product of CAS No. 191680-81-6 of the formula wherein N4-amine is a trivalent amine of the formula (Xa)

[0109] XHN-CH2CH2CH2-NX-CH2CH2CH2-NX-CH2CH2CH2-NHX (Xa), wherein 1 symbol X stands for hydrogen and 3 symbols X stand for a bond (Flamestab NOR 116 [RTM]);

[0110] wherein n is a number from the range 1 to 10.

[0111] Also preferred as products of the present process are monomeric hindered amine ethers such as those of formula wherein R is as defined above and Z is hydrogen, OH or OR or OCOR or N(Ri)R or oxo (i.e. 0=); some preferred oligomeric compounds obtainable in accordance with the process of the invention conform with the formula (XV)

[0112] wherein R, Ri are as defined above, and wherein R is preferably n-propyl or n-octyl or n-undecyl, and / or Ri is preferably n-butyl; as well as N-O-alkyl HALS compounds (a) and (b) above.

[0113] Sterically hindered alkoxyamine compounds, e.g. of the formula (I), which are obtainable in the present process, especially compounds containing moieties of the formula (la), such as the above compound of the formula (XV) or compounds a) to d), are effective stabilizers for organic materials such as organic polymers against the detrimental effects of light, oxygen and / or heat. Organic polymers, which may be stabilized in this way, are for example those listed in GB-A-2334717 from page 30, 10thline from bottom, until page 35 line 9 from bottom; typical compositions of the present invention are analogous to those described subsequently in this document from page 35 line 8 from bottom until page 36 replacing the HALS compound featured in GB-A-2334717 with the present sterically hindered alkoxyamine or one of the products of the below examples. Corresponding compositions may be thermoplastic polymer compositions, or may be coating compositions analogous to those described in GB-A-2334717 on pages 48 to page 54 line 19, which comprise one or more organic polymers. The compositions typically further contain coadditives such as disclosed in GB-A-2334717, pages 37 to 47.

[0114] As noted above, compound mixtures as presently obtainable and containing functionalities of formula (la) are advantageously usable as stabilizers for organic material, such as organic polymer compositions, against degradation by light, oxygen and / or heat. Products of the present process may also show an improved thermal stability compared to corresponding compositions or compounds prepared according to prior art processes as well as an improved antioxidant performance, especially during polymer processing conditions, preventing the degradation or oxidation of polymers during high temperature processing (e.g. extrusion, molding, etc).

[0115] The examples below further illustrate the invention. All parts or percentages, in the examples as in the remainder of the description and in the claims, are by weight, unless stated otherwise. Room temperature denotes a temperature from the range 20-30°C. Overnight denotes a time period of at least 12 hours and up to 16 hours. Wherever mentioned, lower alkyl stands for Ci-Csalkyl, especially Ci-Cealkyl, such as methyl, ethyl, propyl, butyl, pentyl, hexyl. All peroxides (educt of formula A according to present process, such as di-butanoyl peroxide) are obtained in analogy to R. F. Drury and Z, L. Kaplan, Journal of the American Chemical Society, 94:11, May 31, 1972. The alkylation rate (NO-alkyl content) is determined from proton NMR as shown in Table 1, if not indicated otherwise. Within the formulae given, Bu as well as C4H9 each stands for 1- butyl. The index n used in formulas denotes a number of repetition, typically at least 3, for example 3 to 1000, if not defined otherwise.

[0116] Abbreviations:

[0117] HPLC high pressure liquid chromatography

[0118] T temperature (given in °C if not otherwise indicated)

[0119] RTM registered trade mark

[0120] 1 H NMR proton nuclear magnetic resonance

[0121] MTBE methyl tert.-butyl ether

[0122] TMP tetramethyl piperidine

[0123] BSTFA N,O-Bis(trimethylsilyl)trifluoroacetamide (Sigma-Aldrich)

[0124] TMCS trimethylchlorosilane (Sigma-Aldrich)

[0125] Example 1 (prior art): Oxidation of the secondary hindered amine Educt 2 (available as Chimassorb® 2020; prepared in analogy to methods known in the art, e.g. from Tianjin Huagong, 2006, 20, 20-21, 30; Journal of Molecular Catalysis A: Chemical, 2006, 248: 109-112) in accordance with Org. Process Res. Dev. 2014, 18, 1843-1849.

[0126] The obtained product (i.e. the oxydated Educt 2) is a red powder of melting range 95° to 120°C.;

[0127] UV: A solution of 0.100 g in 5.00 ml of toluene gives a UV absorption of 0.792 at 470 nm.

[0128] IR (representative bands): 2930.7 (m), 1529.1 (s), 1471 (s), 1421.5 (s), 1360.6 (m), 1310.3 (m), 1283.2 (s), 1176.4 (s), 1087.6 (s), 809.0 (m).

[0129] Example 2 (reduction Variant 1):

[0130] 0.440 g of the product of example 1 is dissolved in 5.0 ml of toluene. While heating to 60°C, 0.50 ml of a 64% solution of hydrazine in water is added under N2 atmosphere. The reaction mixture is stirred for 105 min, then 2 ml of water are added and stirring is continued for another 2 min. Stirring is stopped, and after 30 min the phases are separated. The organic layer is dried in vacuo to give an off-white foam, 0.44g.

[0131] 1-H NMR (300MHz; CDCI3=7.26 ppm): 5.22 (m), 3.37 (m), 3.31 (m), 1.62 (m), 1.26 (m), 0.95 (m).

[0132] IR: 2928.7 (s), 1527.1 (I), 1470.1 (I), 1421.4 (I), 1359.9 (m), 1309.5 (m), 1174.5 (s), 1085.7 8s), 952.0 (s), 808.8 (m). UV: An oxygen-free solution of 0.100 g in 5.00 ml of toluene gives a UV absorption of 0.167 at 470 nm. reduction Variant 2 30 g of the orange solid obtained in the previous example 1 is introduced in a 500 ml stainless steel pressure reactor equipped with stirring and heating mantle, containing 100 ml of chlorobenzene. Then 5 g of Pd 5% over carbon are added, the pressure reactor closed, evacuated and filled with nitrogen twice, then 60 bar of hydrogen gas are introduced in the reactor and left to react under vigorous stirring at 90°C for 12 hours. The pressure reactor is then evacuated, and opened under nitrogen atmosphere, the slurry filtered to remove the catalysts, the solution concentrated under vacuum to yield 30 grams of a white powder.

[0133] 3b, reduction Variant 3:

[0134] In analogy to WO2001090113 example A10, 0.1 mol of 2,2,6, 6-tetramethylpiperidine N- oxide are hydrogenated to saturation at 4 bar in 20 ml of toluene using 0.05 g of platinum (10% on carbon).

[0135] 3c, reduction Variant 4:

[0136] The product of example 1 (1 ,00 g) is dissolved in toluene (5.0 ml) and 1 ,4- cyclohexadien (5.0 ml) are added. The reaction mixture is stirred in a closed vessel at 65°C until discoloration. Subsequent removal of all volatiles provides a white foam (0.98 g).

[0137] 1-H NMR (300MHz; CDCI3=7.28 ppm): 5.24 (m), 3.39 (m), 3.33 (m), 1.64 (m), 1.28 (m), 0.97 (m). Oxidation of the secondary hindered amine (Chimassorb® 2020) directly to the N-hydroxy educt of the below formula (V’) using potassium peroxysulfate of the formula K(OH)SO4 (available as its triple salt with KHSO4 and K2SO4 under the trade name Oxone®) in presence of SiO2; prepared with methodology analogous to methods known in the art, e.g Fields, John D.; et al Journal of Organic Chemistry (2000), 65(19), 5937-5941).

[0138] Educt of formula (V’): wherein n ranges from 1 to 10 and R is hydrogen.

[0139] Example 5 (invention): Conversion of the intermediate obtained in example 2 (of formula V’) into an alkoxyamine ether

[0140] The product of example 2 (0.10 g) is dissolved in 4 ml of toluene under nitrogen atmosphere. The mixture is heated to 100 °C. A solution of 0.17 g of di-butyryl peroxide (prepared according to R. F. Drury and Z, L. Kaplan, Journal of the American Chemical Society, 94: 11 , May 31 , 1972) of the formula

[0141] (MW 174), in an inert solvent is added over the period of 5 min. After 60 min, heating is stopped and 2 ml of water are added.

[0142] Then, the organic phase is concentrated in vacuo at 80 °C. Twice, 3 ml of toluene are added and the reaction mass is concentrated to complete dryness.

[0143] Yield: 0.11 g; pale yellow foam of melting range 90 to 110 °C.

[0144] NMR: 1-H NMR (300 MHz; CDCI3=7.26 ppm): 5.17 (m), 3.74 (m), 3.46 (m), 3.31 (m), 1.59 (m), 1.25 (m), 0.95 (m); 95% alkoxylation degree.

[0145] IR: 2931.5 (s), 1530.7 (I), 1471.5 (m), 1422.1 (m), 1359.4 (m), 1310.9 (m), 985.1(s), 809.3 (s).

[0146] Example 6 (invention): Conversion of the oxidated educt of example 1 into an alkoxyamine ether and determination of residual hydroxylamine content via derivatization to NO-silyl ether

[0147] The product of example 1 (0.60 g) is dissolved in 4.0 ml of toluene. The solution is heated to 90 °C and 1 .0 ml of 68% aq. hydrazine solution is added. The mixture is stirred until a colorless solution is obtained. The reaction mixture is cooled, then the aqueous phase is removed. The organic phase is concentrated in vacuo. 5 ml of toluene is added and the solvent is removed in vacuo (azeotropic drying). The product is dried at 80 °C, 10 mbar for 30 mins. A white foam is obtained. The foam is dissolved in 4 ml of toluene under N2 atmosphere. While heating and stirring at 95°C, 0.41 g of dibutyryl peroxide dissolved in an inert solvent is added in one batch. After 15 mins., 1.0 ml of BSTFA (with 1% TMCS) (B-023, Supelco) is added and stirring is continued at 95°C for 10 mins. Subsequently, all volatiles are removed in vacuo at 95°C and 5 mbar.

[0148] Yield: 0.47 g of a colorless, glassy foam.

[0149] An NMR sample is immediately prepared and measured; proton spectrum (C6D6, 7.16 ppm): 5.55 (m, 1 H), 3.85 (m, 1.86H; OCH2-Et), 3.61 m, (3.19H), 2.00 - 0.8 (several m, 33.47H), 0.06 (s, 0.61 H; N-O-SiMe3)

[0150] The content of N-alkoxyamine ether is thus determined as 93%.

[0151] The content of hydroxylamine trimethylsilylether is thus determined as 6.8%.

[0152] Example 7 (comparison with product obtained in accordance with prior art): The product of example 5 is compared with the product obtained according to W02008 / 003605, example D, page 16 a) Comparison of NOR contents by NMR:

[0153] Proton spectra are measured in CDCI3. The NOR content is calculated via relation of the NO-CH2-Et integral to the integral of the proton of the 4-position of the piperidine ring.

[0154] NOR content of product of present example 5 (invention): 95%

[0155] NOR content of product of W02008 / 003605, example D (prior art): 85% b) Comparison of product qualities after heat treatment by UV-absorption

[0156] 5% solutions of products of present example 5 and of W02008 / 003605 example D in 1 ,2,4-trichlorobenzene are prepared. Then, the samples solutions are heated while being stirred at 210°C under inert atmosphere for 10 min to mimic the thermal stress in a polymer extrusion process. The absorption at 470 nm is measured (A2, see table below). As further comparison, the absorption of the pure solvent 1,2,4- trichlorobenzene at 470 nm is detected.

[0157] To allow a more precise assessment of the absorption for both samples, 0.500 g of the sample solutions after heat treatment are diluted with 2.50 g of 1,2,4-trichlorobenzene. Then the absorption is measured again (A3); the results are compiled in the following table.

[0158] Table: Comparison of color stability (470 nm) after heat treatment

[0159] The product of present invention shows a distinctly better color stability upon heating. Example 8: Improvement of the color and alkoxyamine content of commercial Tinuvin® NOR® 371 (available from BASF)

[0160] 1.00 g of Tinuvin® NOR® 371 is dissolved in a mixture of 6 ml of toluene and 1 ml of t- butanol. 1.0 ml of 68 % aqueous hydrazine is added and the mixture is stirred under inert atmosphere at 70°C. After 3 h, another 1.0 ml of hydrazine solution is added and stirring is continued for another 4 hours. The phases are separated and the organic solvents are completely removed in vacuo. The obtained white foam (0.88g) is dissolved in 4 ml of toluene. Dibutanoyl peroxide (0.50 g, dissolved in an inert solvent) is added to the reaction mixture in small portions at 95°C. After 1 hour, 2 ml of water and 5 drops of 10% aq. NaOH are added. The phases are separated and the organic solvents are completely removed in vacuo. 0.83 g of a white foam is obtained. The alkoxyamine content is determined by 1 H NMR to be 96.5%.

[0161] UV absorption measurement at 470 nm

[0162] Reference: toluene = 0.165

[0163] Product concentration: 0.200g in 10.00 g toluene

[0164] Example 9: Improvement of the color and alkoxyamine content of commercial Tinuvin® NOR® 356 (available from BASF)

[0165] 1.00 g of Tinuvin® NOR® 356 is dissolved in a mixture of 6 ml of toluene and 1 ml of t- butanol. 1.0 ml of 68% aqueous hydrazine is added and the mixture is stirred under inert atmosphere at 70°C. After 3 h, another 1.0 ml of hydrazine solution is added and stirring is continued for another 4 hours. The phases are separated and the organic solvents are completely removed in vacuo. The obtained white foam (0.84g) is dissolved in 4 ml of toluene. Dibutanoyl peroxide (0.50 g, dissolved in an inert solvent) is added to the reaction mixture in small portions at 95°C. After 1 hour, 2 ml of water and 5 drops of 10% aq. NaOH are added. The phases are separated and the organic solvents are completely removed in vacuo. 0.79 g of an off-white foam is obtained. The alkoxyamine content as determined by 1 H NMR is higher as the content of the starting material.

[0166] UV absorption measurement at 470 nm

[0167] Ref: toluene = 0.165

[0168] Product concentration: 0.200g in 10.00 g toluene

[0169] Example 10: Conversion of a monomeric hydroxylamine 0.625 g of 4-acetamido, 2,2,6, 6-tetramethylpiperidin-1-oxyl (4-Acetamido-TEMPO, Sigma-Aldrich 390380) is dissolved in 5 ml of toluene. 1.5 ml of 68 % aq. Hydrazine is added and the mixture heated to 70°C. After 30-60 mins a clear suspension is obtained. The reaction mixture is filtered to yield 553 mg of colorless crystals (hydroxylamine). To the hydroxylamine are added 5 ml of toluene and the suspension is heated to 70°C. 0.70 ml of 50% dibutyryl peroxide in an inert solvent are added dropwise while heating to 95°C. After 60 mins., the reaction mixture is washed with 5% Na2CO3 at 90 °C. After 10 mins, the organic phase is removed and concentrated in vacuo (80°C, 10 mbar). A yellow oil is obtained (478 mg) that slowly crystallizes.

[0170] The NMR shows the presence of expected N-alkoxyamine.

[0171] NMR (CDCI3 = 7.26 ppm): 4.04 (m, 1 H), 3.61 (dd, 2H), 1 .89 (s, 3H), 1 .66 (m, 2H), 1 .47 (m, 2H), 1.30 (m, 2H), 1.12 (s, 6H), 1.09 (s, 6H), 0.87 (s, 3H)

[0172] Example 11 : Conversion of a dimeric hindered amine light stabilizer Uvinul® 4050 (available from BASF)

[0173] 1.0 g of Uvinul® 4050 is dissolved in a mixture of toluene (5 ml) and t-butanol (2 ml). 10.1 mg Na2WO4 dissolved in 0.5 ml H2O are added and heating to 50 °C is started. 1.0 ml of 40% aq. H2O2 is added in one portion. The reaction mixture is stirred at 65°C. After 3 h another 1.0 ml of 40% aq. H2O2 is added. Stirring is continued for 18 h. A reddish suspension is obtained. The aqueous phase is removed. Water (3 ml) is added, the reaction mass is stirred for 10 mins. Then, the aqueous phase is removed and the reaction mass is concentrated in vacuo (8 mbar, 75°C, 2 h) to yield 0.91 g of a red foam. 0.25 g of the obtained product is dissolved / suspended in 3 ml of toluene in an inert atmosphere (N2). At 62 °C, 1.0 ml 68% aq. hydrazine is added. After 10 min. of stirring, a colorless solution is obtained. The reaction mixture is concentrated in vacuo (7 mbar, 80°C) to obtain a colorless foam (0.22 g; hydroxylamine). The hydroxylamine is dissolved / suspended in 3 ml of toluene. 0.5 ml of 50% dibutyryl peroxide in an inert solvent is added over 20 mins at 60-92°C. A yellow solution is formed within 30 mins. Stirring is continued at 92°C for another hour. The organic phase is washed with 10% NaOH, then water, and brine. The organic phase is dried in vacuo to yield a beige product (0.17 g). The presence of the N-alkoxyamine groups is demonstrated by NMR. NMR (CDCI3 = 7.26 ppm): 8.15 (1 H), 8.05 (1 H), 3.69 (6H), 3.60 (2H), 3.18 (4H), 1.80- 1.20 (36H), 1.20 (12H), 1.18 (12H), 0.94 (6H).

[0174] Example 12: Conversion of a polymeric, hindered amine light stabilizer Uvinul® 5050 (available from BASF)

[0175] 1.0 g of Uvinul® 5050 is dissolved in a mixture of toluene (5 ml) and t-butanol (2 ml). 10.1 mg Na2WO4 dissolved in 0.5 ml H2O are added and heating to 50 °C is started. 1.0 ml of 40% aq. H2O2 is added in one portion. The reaction mixture is stirred at 65°C. After 3 h another 1.0 ml of 40% aq. H2O2 is added. Stirring is continued for 18h. A pale, reddish solution is obtained. The aqueous phase is removed. Water (3 ml) is added, the reaction mass is stirred for 10 mins. Then, the aqueous phase is removed and the reaction mass is concentrated in vacuo (8 mbar, 75°C, 2 h) to yield 0.91 g of a red foam. The obtained product is dissolved in 8 ml of toluene in an inert atmosphere (N2). At 62 °C, 1.0 ml 68% aq. Hydrazine is added. After 10 min. of stirring, a colorless solution is obtained. The reaction mixture is concentrated in vacuo (7 mbar, 80°C) to obtain a colorless foam (0.90 g; hydroxylamine). The hydroxylamine is dissolved in 5 ml of toluene. 1 .5 ml of 50% dibutyryl peroxide in an inert solvent is added over 20 mins at 60-92°C. A yellow solution is formed within 30 mins. Stirring is continued at 92°C for another hour. The organic phase is washed with 10% NaOH, then water, and brine. The organic phase is dried in vacuo to yield a beige-brown foam (0.71 g). The presence of the N-alkoxyamine groups is demonstrated by NMR.

[0176] NMR: 4.38 (1 H), 3.72 (2H), 3.25 - 0.75 (58H)

[0177] NOR content: 94%

[0178] Example 13: Conversion of the oligomeric hindered amine light stabilizer Chimassorb® 944 (available from BASF) into an alkoxyamine

[0179] In analogy to the examples 1), 2) and 5) Chimassorb® 944 is converted into the N-O- propyl derivative. The N-alkoxyamine content ias determined to be 99% by NMR. NMR (CDCI3 = 7.26 ppm): 5.17 (m, 1 H), 3.74 (m, 1.98 H), 3.46 (m, 1.49 H), 3.31 (m, 1.77H), 2.5 - 0.8 (m, 34.53H)

[0180] Example 14: Reaction of a monomeric hydroxylamine with dilauroylperoxide (DLP)

[0181] 4-Acetamido-1 -hydroxy-2, 2, 6, 6-tetramethylpiperidine (163 mg) as prepared in example 10) is suspended in 3 ml of toluene. 0.33 g of dilauroylperoxide is added and the mixture is heated to 95°C. After a while, the suspension turns into a colorless solution. After 60 mins, the organic phase is concentrated in vacuo (90°C, 10 mbar) to afford a pale yellow oil that slowly crystallizes (135 mg).

[0182] The NMR shows the presence of expected product 1-undecyloxy-4-acetamido-2, 2,6,6- tetramethylpiperidine.

[0183] NMR (CDCI3): 4.16 (m, 1 H), 3.73 (t, 2H), 2.35 (t, 2H), 1.97 (s, 3H), 1.78 (m, 2H), 1.65 (m, 2H), 1.53 (m, 2H), 1.28 (m, 36H), 1.21 (s, 6H), 1.19 (s, 6H), 0.90 (s, 3H)

[0184] Example 15: Reaction of an oligomeric hydroxylamine with a perester 0.50 g of product of example 2) is dissolved in a mixture of 4 ml tert-butyl benzene and 1.0 ml of 1 ,2-dichlorobenzene. 1.5 ml tert-butyl peroxy acetate (50 wt. % in odorless mineral spirits; Sigma-Aldrich 388076) was added and the mixture was heated to 155°C for 60 min. Then, the organic phase is concentrated in vacuo (90°C, 10 mbar) to obtain a brownish oil. The oil is diluted with 1.5 ml of toluene and the product precipitated from alcohol. After filtration, a beige powder is obtained.

[0185] Yield: 95 mg

[0186] NOR content ~ 99%

[0187] NMR (CDCI3 = 7.26 ppm): 5.20 (m, 1 H), 3.73 (m, 1.99H), 3.50-3.20 (m, 2.88H), 2.00- 0.80 (m).

[0188] Example 16: Preparation of 1 ,3,5-Triazine-2,4,6-triamine, A / 2,A / 2,A / 4,A / 4,N6-pentabutyl-A / 6- (1-propoxy-2,2,6,6-tetramethyl-4-piperidinyl)- 1 ,3,5-T riazine-2,4,6-triamine, A / 2,A / 2,A / 4,A / 4, N6-pentabutyl-A / 6-(2,2 ,6,6-tetramethyl-4- piperidinyl-1 -oxyl) (360 mg) is dissolved in toluene (5 ml). 1 ml of aqueous hydrazine (64%) is added and the reaction mixture is stirred at 70°C for 60 min. After that all vola- tiles are removed in vacuo (12 mbar, 80°C, 30 min). A colorless oil (hydroxylamine) is obtained (360 mg). The hydroxylamine is dissolved in toluene (5 ml) and heated under N2 to 65 °C. Subsequently, 0.2 ml of 50% dibutyryl peroxide in an inert solvent is added, then the reaction mixture is heated to 95°C and another 0.2 ml of peroxide solution is added. A light yellow reaction mass is obtained. After 45 min stirring at 95 °C, all volatiles are removed in vacuo to afford a pale yellow oil (365 mg).

[0189] NMR (CDCI3 = 7.28 ppm): 5.18 (m, 1 H), 3.74 (t, 2H), 3.47 (m, 8H), 3.31 (m, 2H), 1.80- 0.85 (m). The signal at 3.74 ppm proves the presence of the alkoxyamine.

Claims

Claims:

1. Process for alkylating a sterically hindered hydroxylamine compound, which sterical- ly hindered hydroxylamine compound is characterized in that its nitrogen atom bonds to 2 tertiary carbon atoms, to the corresponding sterically hindered alkoxyamine, which process comprises reacting said sterically hindered hydroxylamine compound with a compound capable of generating a carbon centered alkyl radical, which compound is selected from thermal radical initiators forming radical species within the temperature range 40 to 200°C, and photoinitiators undergoing photoexcitation upon irradiation with UV light or visible light from the range 180 to 700 nm, especially UV light from the range 180 to 380 nm, the compound capable of generating a carbon centered alkyl radical being selected from the class of compounds generating a primary or secondary alkyl radical, and / or from the class of organic peroxides, azo compounds, benzoyl derivatives, benzophenones derivatives, thioxanthone derivatives, benzoine derivatives, benzoyl phosphine oxide derivatives.

2. Process of claim 1 wherein the compound capable of generating a carbon centered alkyl radical is a peroxide selected from diacyl peroxides of the formula (A), peresters of the formula (A) and oxalic acid peresters of the formula (D)R-CO-O-O-Z-R (A),R-Z”-X-CO-CO-O-O-Z”-R (D), wherein each R independently stands for a primary or secondary alkyl or cycloalkyl radical, the primary or secondary alkyl or cycloalkyl radical preferably comprising 1 to 15 carbon atoms, andX is oxygen -O- or a peroxy group -O-O-,Z stands for CO or an alkylene bonded over a quaternary carbon atom, which is an alkylene of the formula (C)R'-C-R' (C) wherein each R' is selected from alkyl of 1 to 15 carbon atoms,Z” stands for said alkylene bonded over a quaternary carbon atom of the formula (C).

3. Process of claim 1 or 2, wherein the sterically hindered hydroxylamine compound comprises one or more moieties 1-hydroxy-2,2,6,6-tetramethyl-piperidine of the formula (Illa), wherein the asterisk indicates the location of the bond linking the moiety to another part of the moleculeand the corresponding sterically hindered alkoxyamine compound belongs to the class of 1-alkoxy-2,2,6,6-tetramethyl-piperidines containing one or more moieties of the formula (la), wherein the asterisk indicates the location of the bond linking these moieties to another part of the moleculewherein R is as defined in claim 2.

4. Process according to claim 3, wherein the sterically hindered alkoxyamine compound conforms to the formula (lb)(HA)PY (lb) whereinHA is a hindered amine ether moiety (HE) of the formula (la); p is a number from the range 1 to 6, and whereinY is an anchor group of valency 2 to 6 of the formula (IX)T3-(N[T4]-A2)q-N[TiT2] (IX) wherein q ranges from 0 to 3, or Y is an anchor group as further defined below; when p is 1 ,Y is an anchor group of the formula -NR1-A1; when p is 2, Y is an anchor group of the formula DC-A2-DC; or Y is said divalent anchor group of the formula (IX), whereinq is zero, T3 stands for an open bond, T1 is as defined for R1 and T2 is a divalent aminotriazinyl of the formula (X)(X), or q is 1 , each of Ti and T3 is as defined for R1 and each of T2 and T4 is said divalent aminotriazinyl of the formula (X); when p is 3, Y is a trivalent anchor group of the formula (IX), wherein q is zero, T3 stands for an open bond, T1 is as defined for R1 and T2 is a trivalent diaminotriazinyl of the formula (XI)(XI), or q is 1 , T1 is as defined for R1, T2 is a divalent aminotriazinyl of the formula (X), and T3 and T4 independently stand for an open bond or a divalent aminotriazinyl of the formula (X); when p is 4, Y is a tetravalent anchor group of the formula (IX), wherein q is 3 and T2 and two of the residues T4 stand for a divalent diaminotriazinyl of the formula (XI), while each T1 and T3 and the remaining residue T4 are as defined for R1; when p is 5, Y is a pentavalent anchor group of the formula (IX), wherein q is 1 , T1 is a trivalent diaminotriazinyl of the formula (XI), T3 is a divalent aminotriazinyl of the formula (X), and T2 and T4 independently stand for an open bond or a divalent aminotriazinyl of the formula (X); when p is 6, Y is a hexavalent anchor group of the formula (IX), wherein q is 1 , each of T1 and T3 is a trivalent diaminotriazinyl of the formula (XI), and T2 and T4 independently stand for an open bond or a divalent aminotriazinyl of the formula (X); or q is 2 and T2 and each T4 stand for a trivalent diaminotriazinyl of the formula (XI), while each T1 and T3 is as defined for R1; or q is 3 and T2 and two of the residues T4 stand for a trivalent diaminotriazinyl of the formula (XI), while each T1 and T3 and the remaining residue T4 are as defined for R1; or q is 3 and T2 and T3 and one of the residues T4 stand for a trivalent diaminotriazinyl of the formula (XI), while each T1 and the remaining residue T4 are as defined for R1;A1 is Ci-Ci2alkyl or C2-Ci2alkyl interrupted by O or COO;A2 is C2-Ci2alkylene;DC is a divalent connecting moiety, typically a direct bond, an ester moiety -COO-, ether moiety -O-, or amino moiety of the formula -NRi-; andRi is H or Ci-Csalkyl, especially Ci-Cealkyl; andX is Cl or N(Ri)2; or the sterically hindered hydroxylamine compound is an oligomeric or polymeric compound comprising 6 or more, especially 7 or more, more especially 7 to 100 moieties of the formula (la) and / or (Illa), where at least one moiety of the formula (la) is present.

5. Process of claim 1 or 2 or 3 or 4, wherein the alkyl moiety of the sterically hindered alkoxyamine and / or R in formula (A) or (D) is independently selected from methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl, 1 -pentyl, 2-pentyl, 3-pentyl, 1 -hexyl, 2-hexyl, 3-hexyl, 1 -heptyl, 2-heptyl, 3-heptyl, 4-heptyl, 1 -octyl, 2-octyl, 3-octyl, 4-octyl, nonyl, decyl, undecyl, dodecyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl; especially wherein both residues R stand for the same radical.

6. Process of claim 1 or 2 or 3 or 4 or 5, wherein the reaction is carried out at a temperature from the range 0 to 140° C, for example 0 to 120° C, and especially in the presence of an inert solvent.

7. Process according to any of the preceding claims, wherein the compound capable of generating a carbon centered alkyl radical is a diacyl peroxide of the formula (A) or a oxalic acid perester of the formula (D) and the reaction is carried out at a temperature from the range 15 to 100° C, especially 30 to 100°C; or the peroxide is a perester of the formula (A) and the reaction is carried out at a temperature from the range 30 to 140° C, especially 50 to 140°C.

8. Process according to any of the preceding claims, wherein the reaction is carried out for a period of 5 minutes to 100 hours and / or the reaction is carried out in the absence of a heavy metal catalyst and / or wherein the reaction is carried out under a protective gas excluding oxygen, for example under nitrogen.

9. Process according to any of the preceding claims, wherein the reaction is carried out in the presence of a solvent, which is selected from non-polar solvents like C5-C12 hydrocarbons, for example alkanes, cycloalkanes, aromatic hydrocarbons or arylalkanes, optionally dried; and polar solvents like alcohols, ethers, esters, especially comprising methyl and / or tert.-alkyl moieties, for example tert.butanol, methyl-tert. butyl ether, methyl acetate, tert. butyl acetate; and mixtures of non-polar and polar solvents.

10. Process according to any of claims 3 to 9, wherein the sterically hindered alkoxyamine obtained in said process is a compound of the formula (I)(R2)3-C-N(OR)-C-(R2’)3 (I) wherein R is as defined in any of claims 2 or 5; each R2 and R2’ is a hydrocarbon, and preferably an R2 and R2’ are interlinked to form one divalent hydrocarbon residue, all R2 and R2’ together containing 2 to 500 carbonatoms, and optionally further containing one or more moieties selected from the group consisting of tertiary nitrogen moieties, secondary nitrogen moieties; ester moieties COO; chloro; and preferably wherein R is alkyl selected from Ci-Ci2alkyl or Cs-Cscycloalkyl; and each R2 is a hydrocarbon, and preferably interlinked to form one divalent hydrocarbon residue, both R2 together containing 2 to 500 carbon atoms and optionally one or more tertiary nitrogen moieties, one or more ester moieties COO, and / or one or more divalent moieties >N-OR; and most preferably wherein the sterically hindered hydroxylamine compound belongs to the class of 1 -hydroxy-2, 2, 6, 6-tetramethyl-piperidines containing one or more moie- ties of the formula (Illa), and the corresponding sterically hindered alkoxyamine compound belongs to the class of 1 -alkoxy-2, 2, 6, 6-tetramethyl-piperidines containing one or more moieties of the formula (la), wherein the asterisk indicates the location of the bond linking these moieties to another part of the molecule(la) (Hla) and R is alkyl selected from Ci-Ci2alkyl or Cs-Cscycloalkyl.11 . Process according to any of the preceding claims for the preparation of a sterically hindered alkoxyamine compound, which conforms to the formula (XIV) or (XV)wherein R, Ri are as defined in the foregoing claims, and Z is hydrogen or OR or OCOR or N(Ri)R or oxo; or is bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate; or is an oligomeric or polymeric compound comprising at least 6, for example 6 to 100, moieties if the formula (la) wherein the asterisk indicates the location of the bond link- ing these moieties to another part of the molecule(la); for example the product of CAS No. 191680-81-6 of the formulaN4-aminewherein N4-amine is a trivalent amine of the formula XHN-CH2CH2CH2-NX-CH2CH2CH2-NX-CH2CH2CH2-NHX, wherein 1 symbol X stands for hydrogen and 3 symbols X stand for a bond; preferably an oligomeric or polymeric sterically hindered alkoxyamine compound corresponding to one of the formulae (IV) or (V)wherein A2 is C2-Ci2alkylene;R1 is H or Ci-Csalkyl, especially Ci-Cealkyl; and and R is as defined below for formula (V),wherein n ranges from 1 to 10 and R is as defined in claim 1 or 3, and preferably is Ci-Csalkyl, especially 1-propyl.

12. Process according to any of claims 1 to 11 , wherein the sterically hindered hydroxylamine compound is represented by one of the formulae (IV) or (V)(IV), wherein A2 is C2-Ci2alkylene;R1 is H Ci-Csalkyl, especially Ci-Cealkyl; andR is as defined in claim 1 or 3, and preferably is C1-C5alkyl, especially 1-propyl;wherein n is from the range 1 to 10 and R is as defined above; or is the product of CAS No. 191680-81-6 represented by the formulaN4-aminewherein N4-amine is a trivalent amine of the formula XHN-CH2CH2CH2-NX-CH2CH2CH2-NX-CH2CH2CH2-NHX, wherein 1 symbol X stands for hydrogen and 3 symbols X stand for a bond; and wherein one or more of the residues O-R or O-cycloalkyl is replaced by hydroxyl.

13. Process according to any of the preceding claims, wherein, in a first step (i) and optional second step (ii), a sterically hindered secondary amine educt, typically comprising one or more moieties 2,2,6,6-tetramethyl-piperidin-4-yl, is converted into said sterically hindered hydroxylamine compound, which is subsequently converted into the sterically hindered alkoxyamine, said process comprising(i) contacting said secondary hindered amine educt with a suitable oxidant to obtain a sterically hindered oxylamine or sterically hindered hydroxylamine;(ii) optionally contacting the sterically hindered oxylamine obtained as oxidated product of step (i) with a reducing agent to obtain a sterically hindered hydroxylamine; and subsequently(iii) reacting the sterically hindered hydroxylamine obtained in step (i) or optional step (ii) with with a compound capable of generating a carbon centered alkyl radical in accordance with any of claims 1 to 12;and wherein, preferably, the secondary amine educt is an oligomeric or polymeric compound comprising at least 6, especially 6 to 100, moieties 2,2,6,6-tetramethyl- piperidin-4-yl, such as a compound selected from the following Educt 2 of the formula:Educt 3 of the formula: wherein n ranges from 1 to 10, especially 4 to 5;Educt 4 of the formula:Educt 8 of the formula: of CAS-No. 199237-39-3;Educt 9 of the formula:with R being a moiety of the formula of CAS-No. 136504-96-6;14. Oligomeric or polymeric product comprising compounds containing at least 10, for example 10 to 100, moieties of the formula (la), wherein the asterisk indicates the location of the bond linking these moieties to another part of the molecule,preferably an oligomeric or polymeric sterically hindered alkoxyamine compound corresponding to formula (V)wherein n ranges from 3 to 10and R is as defined in claim 2, and preferably is Ci-Csalkyl, especially 1 -propyl; characterized in that said oligomeric or polymeric product is obtainable by the process according to any of claims 1 to 13, or in case that the product is represented by formula (V), alternatively by the process of claim 14.

15. Compound represented by the formula (V’),wherein n ranges from 1 to 10 and R is hydrogen or Ci-Csalkyl, provided that at least one moiety R is hydrogen; and preferably of formula (V) according to claim 15, characterized in that it contains more than 87%, typically 90 to 99.9%, especially 96% to 99.9%, of N-0 moieties in alkylated form as N-OR, wherein R is Ci-Csalkyl, especially 1 -propyl, and containing remaining moieties R as hydrogen.

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