Preparation method of steric hindrance nitroxyl ether

Abstract

Described is a process for the preparation of a sterically hindered alkoxyamine compound comprising the step of reacting a sterically hindered nitroxyl compound with a peroxide selected from the group consisting of a diacyl peroxide of formula (A), a peracid of formula (A) and an oxalato peracid of formula (D), the invention relates to a method for the alkylation of a sterically hindered nitroxyl compound to the corresponding sterically hindered alkoxyamine R-CO-O-O-Z-R (A), r-Z ''-X-CO-CO-O-O-Z''-R (D) wherein each R independently represents a primary or secondary alkyl or cycloalkyl group, preferably comprising from 1 to 15 carbon atoms, and X is oxygen-O-or peroxy-O-O-, Z represents CO or an alkylene group bonded to a quaternary carbon atom, the quaternary carbon atom being an alkylene group of formula (C) R '-C-R' (C), wherein each R'is selected from alkyl groups having 1 to 15 carbon atoms, and Z "represents the alkylene group bonded to a quaternary carbon atom having formula (C). The described process produces the corresponding O-alkylated derivatives of the sterically hindered nitroxyl group, typically referred to as compounds of the N-O-alkyl HALS class, which process has very high selectivity and conversion and does not require the use of catalysts, in particular metal catalysts.

Description

Technical Field

[0001] The present invention relates to a novel process for the alkylation of certain N-oxyl secondary amines and the preparation of the corresponding N-alkoxyamines in high purity. More specifically, the novel chemical process relates to the preparation of such sterically hindered N-alkoxyamines by selective O-alkylation of the nitroxyl group by reaction with certain primary or secondary alkyl groups; the process may further comprise a prior oxidation step to obtain the sterically hindered nitroxyl group from the corresponding secondary (NH) amine.

[0002] Some novel compounds obtainable by the process are further described. The products of the process can be used in various fields of chemistry and polymer technology; an important class of products belongs to sterically hindered amines, which are commonly used in polymer technology, for example as flame retardants, polymerization regulators, or as stabilizers for organic materials (such as organic polymer compositions) against degradation by light, oxygen and / or heat. Background Art

[0003] Many publications describe the use of specific sterically hindered amine compounds as stabilizers for stabilizing organic materials, which are also known as hindered amine light stabilizers (HALS). A valuable class of sterically hindered amines are compounds in which the nitrogen atom is bonded to two tertiary carbon atoms, which are part of two hydrocarbon residues or part of a heterocyclic ring (e.g. a piperidine ring). For use as stabilizers, such compounds may contain unsubstituted nitrogen (NH-HALS) or substituted nitrogen (e.g. N-alkyl HALS); due to the specific properties of these compounds, such as reduced basicity, an important class are HALS compounds whose hindered nitrogen atom carries a further organic substituent attached to the oxygen atom (typically N-O-alkyl HALS, see e.g. US-5204473, US-5096950); such N-O-alkyl HALS compounds are also known as hindered amine ethers. Further applications of sterically hindered amines, especially NO-alkyl HALS, include use 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 Pfaendner, CRChimie [Reports of the French Academy of Sciences: Chemistry] 9 (2006) 1338-1344).

[0004] Most commercial applications of hindered N-alkoxyamines require a well-defined thermal stability of the product. As is well known in the scientific literature, the carbon-oxygen bonds of hindered N-alkoxyamines have low bond energies, and properties such as thermal stability or dissociation are determined by the strength of such bonds. As described in the above references, the thermal degradation of certain N-alkoxyamines (especially N-alkyl HALS) used as flame retardants or in rheology modifier applications is designed to occur at a desired temperature. Typically, at the extrusion temperature, a free radical reaction between the N-alkoxyamine and the molten polymer is triggered. This results in polymer chain breakage or crosslinking, which changes both the rheology of the molten polymer and the mechanical properties of the resulting final plastic product. For such applications, the R groups of the N-alkoxyamines in flame retardants and rheology modifiers are selected to be R substituents with lower thermal stability than light stabilizers. In contrast, typically for light stabilization applications, N-alkoxy derivatives are designed to have the highest possible thermal stability to avoid any changes in the rheology or mechanical properties of the plastic product.

[0005] For the above reasons, in order to manufacture products based on hindered N-alkoxyamines with well-defined thermal stability, it is highly desirable to use a general process which is applicable to a wide range of hindered N-alkoxyamines with a range of different R substituents and which enables high yields and high selectivity in the desired N-alkoxyamine. In fact, many known processes for the manufacture of N-alkoxyamines have low selectivity for the desired product, leading to the formation of undesired by-products, where the thermal stability or activation temperature is outside the desired temperature range. This is even more important for molecules with multiple hindered amine moieties, like precursors of oligomeric HALS stabilizers, flame retardants or rheology modifiers, where such by-products cannot be separated by purification and become part of the final product, with potential negative effects on the thermal stability and color of the product. The preparation of sterically hindered nitroxyl compounds is described, for example, in US Pat. No. 4,665,185; a recent review of oligomeric compounds and methods for converting red nitroxyl species (nitroxyls) into high molecular weight NO-alkyl HALS is given by E. Cote et al. (Org. Process Res. Dev. [Organic Process Research and Development] 2014, 18, 12, 1843-1849 (https: / / doi.org / 10.1021 / op500301r)).

[0006] It is also desirable to use a manufacturing method that has high productivity, low cost and is based on green chemistry principles, especially free of heavy metals.

[0007] Secondary amines or sterically hindered amine precursors are mostly commercially available or can be prepared by applying known methods. These sterically hindered secondary amines characterized by their NH moiety are conveniently converted into the corresponding nitroxyl groups by methods described in the literature. Useful precursors can be found in particular in the above references and the documents cited therein, see for example WO-2008-003605, page 12, line 22 to page 13, line 5.

[0008] Problems arising in the known conversion of suitable precursors, such as HALS with NH- or N-oxyl functional groups, into the corresponding sterically hindered amine alkyl ethers are generally unsatisfactory conversions or percentages of unreacted precursor functional groups in the product, which can be detrimental, for example, to its thermal stability or lead to undesired side reactions. For example, the N-methoxy hindered amines obtained after the thermolysis of a chlorobenzene solution of nitroxyl radicals and di-tert-butyl peroxide (Example 1 of US Pat. No. 5,204,473) require a purification step via chromatography in order to separate the desired product from byproducts and unreacted starting materials.

[0009] The conversion of N-oxyl precursors to the corresponding sterically hindered amine alkyl ethers can still be improved in terms of efficiency and environmental aspects. Summary of the invention

[0010] The present invention relates to a novel process for the alkylation of sterically hindered nitroxyl groups and the preparation of the corresponding sterically hindered nitroxyl ethers. More specifically, the new chemical process involves the preparation of sterically hindered nitroxyl ethers by highly selective O-alkylation, starting from appropriate precursors of the free radical initiator or photoinitiator type, by generating and coupling carbon-centered free radicals under specific reaction conditions. Short reaction times, high selectivity and high yields of the desired nitroxyl ethers are very important features of the novel process, especially for the preparation of compounds containing multiple hindered amine ether functional groups, such as polymeric compounds, due to the high conversion of the N-oxyl moiety in oligomeric or macromolecular HALS. The products of the present process are of high commercial importance as stabilizers, flame retardants, rheology modifiers, or initiators for controlled polymerization.

[0011] Thus, it has been found that sterically hindered nitroxyl compounds, as described in the literature inter alia as precursors for the preparation of free radical scavenging additives like NO-alkyl HALS, can be alkylated on the oxygen atom by reaction with peroxides to give the corresponding sterically hindered alkoxyamines.

[0012] The peroxide is selected from diacyl peroxides having formula (A), peresters having formula (A) and oxalic acid peresters having formula (D)

[0013] R-CO-OOZR (A),

[0014] RZ”-X-CO-CO-OOZ”-R (D),

[0015] wherein each R independently represents a primary or secondary alkyl or cycloalkyl group, the primary or secondary alkyl or cycloalkyl group preferably containing 1 to 15 carbon atoms, and

[0016] X is oxygen -O- or peroxy -OO-,

[0017] Z represents CO or an alkylene group bonded to a quaternary carbon atom, the quaternary carbon atom being an alkylene group having the formula (C)

[0018] R′-CR′(C)

[0019] wherein each R′ is selected from an alkyl group having 1 to 15 carbon atoms,

[0020] Z" represents the alkylene group bonded to the quaternary carbon atom of the formula (C).

[0021] In the case where Z is CO, the sterically hindered nitroxyl compound is not 4-hydroxy-1-oxy-2,2,6,6-tetramethyl-piperidine.

[0022] The peroxide used in the present process is typically a diacyl peroxide having the formula (B) R-CO-OO-CO-R(B)

[0023] wherein each R independently represents a primary or secondary alkyl group or a cycloalkyl group, the primary or secondary alkyl group or the cycloalkyl group preferably containing 1 to 15 carbon atoms.

[0024] To summarize the present invention, it has thus been found that sterically hindered nitroxyl compounds, such as those described in the literature as precursors for the preparation of free radical scavenging additives such as NO-alkyl HALS, can be alkylated on the oxygen atom to give the corresponding sterically hindered alkoxyamines by reaction with a peroxide of formula (A)

[0025] R-CO-OOZR(A),

[0026] or preferably a diacyl peroxide having formula (B)

[0027] R-CO-OO-CO-R(B)

[0028] wherein Z represents CO or an alkylene group bonded to a quaternary carbon atom (ie, an alkylene group having the formula (C))

[0029]

[0030] wherein each R′ is selected from an alkyl group having 1 to 15 carbon atoms,

[0031] And each R independently represents a primary or secondary alkyl or cycloalkyl group, the primary or secondary alkyl or cycloalkyl group preferably containing 1 to 15 carbon atoms.

[0032] The peroxide may also be selected from oxalic acid peresters having formula (D)

[0033] RZ”-X-CO-CO-OOZ”-R(D),

[0034] wherein each R independently represents a primary or secondary alkyl or cycloalkyl group, the primary or secondary alkyl or cycloalkyl group preferably containing 1 to 15 carbon atoms, and

[0035] X is oxygen -O- or preferably peroxy -OO-;

[0036] and Z" represents an alkylene group R'-CR'(C) bonded to a quaternary carbon atom having the formula (C)

[0037] wherein each R′ is selected from an alkyl group having 1 to 15 carbon atoms,

[0038] Such peroxides based on oxalic acid may offer the advantage of milder reaction conditions, such as reduced reaction temperatures, as further noted below.

[0039] It has been found that, surprisingly, this reaction produces the corresponding O-alkylated derivatives, preferably NO-alkyl HALS, with very high selectivity and conversion and without the need for the use of catalysts, especially metal or iodide catalysts.

[0040] In the case of oligomeric or polymeric products, high selectivity and conversion are particularly important for improving product quality. Such N-alkoxy compounds with high thermal stability are also suitable as stabilizers for polymers with higher extrusion temperatures (e.g., polypropylene fibers and nonwovens) because they will withstand processing without changing the properties of the polymer while still providing undiminished stabilizing properties.

[0041] Due to its high conversion rate, the process is also suitable for improving the product quality of NO-alkyl HALS products, some of which are commercial, which may be impaired by their content of unreacted nitroxyl groups and / or undesirable coloration of the product.

[0042] The present invention further relates to a method as described above for converting a sterically hindered nitroxyl compound characterized in that it contains one or more groups of formula (IIIa)

[0043]

[0044] Conversion into the corresponding NO-alkyl compound, wherein the educt is already partially converted and already contains one or more groups of the formula (Ia)

[0045]

[0046] The asterisks in each formula indicate the position of the bond connecting these moieties to another part of the molecule, and R represents an alkyl group as defined above.

[0047] Thus, such methods for improving product quality and alkylation yield are particularly useful in the case of oligomeric or polymeric compounds comprising at least 6, e.g., 6 to 100, moieties of formula (Ia) while also containing some unreacted nitroxyl moieties, e.g., moieties of formula (IIIa). Typical products of these classes are further shown below.

[0048] Another discovery of the present invention is that, according to the presently described process, nitroxyl compounds (such as sterically hindered nitroxyl) can be converted to the corresponding alkoxyamines in the absence of metal catalysts (also denoted heavy metals), or even any catalysts.

[0049] In the context of the present invention, the term "primary alkyl" or "secondary alkyl or cycloalkyl" means any alkyl or cycloalkyl group forming a carbon-centered group, the radical center of which is bonded to another carbon and 2 hydrogen atoms or 3 hydrogen atoms, thus forming a primary carbon group or a methyl group as a special form thereof; or the radical center is bonded to 2 carbon atoms and 1 hydrogen atom, thus forming a secondary carbon group. The term "radical" represents a monovalent group (i.e., a primary alkyl or secondary alkyl or cycloalkyl group) that is part of a molecule, like in the above-mentioned educts and products of the process (i.e., diacyl peroxides and alkoxyamines). The primary or secondary carbon of this part R is not part of a conjugated system (like a benzyl or allyl or cyano group); it is preferably not adjacent to an electron withdrawing group, otherwise the thermal stability will be reduced.

[0050] 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; in particular wherein two residues R represent the same group.

[0051] The term "sterically hindered amine" denotes a secondary or tertiary amine whose nitrogen atom is bonded to two carbon atoms, each of which is a quaternary carbon.

[0052] The term "metal catalyst" typically includes transition metals such as copper, iron, palladium; in general, a metal catalyst represents any compound containing a metal element other than an alkali metal or an alkaline earth metal element.

[0053] The term "alkylate" or "alkylation" refers to the reaction carried out in the process of the present invention involving the formation of a chemical bond between an alkyl group (eg, R) and the oxygen of a nitroxyl group.

[0054] In a typical method of the present invention, the sterically hindered alkoxyamine obtained is a compound having formula (I)

[0055] (R2)2N-OR(I)

[0056] wherein R is as defined in claim 1 or 2 or 3;

[0057] Each R2 is a hydrocarbon and is preferably linked to each other to form a divalent hydrocarbon residue, the two R2 together contain 2 to 500 carbon atoms, and optionally further contain one or more moieties selected from the group consisting of: tertiary nitrogen moiety; secondary nitrogen moiety; ester moiety COO; chlorine.

[0058] R is preferably selected from C1-C 12 and each R2 is a hydrocarbon, and is preferably linked to each other to form a divalent hydrocarbon residue, the two 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.

[0059] The sterically hindered nitroxyl educts belong to the class of 1-oxy-2,2,6,6-tetramethyl-piperidines containing one or more moieties of formula (IIIa), and the corresponding sterically hindered alkoxyamine compounds belong to the class of 1-alkoxy-2,2,6,6-tetramethyl-piperidines containing one or more moieties of formula (Ia), wherein the asterisk indicates the position of the bond connecting these moieties to another part of the molecule

[0060]

[0061] and R is as defined above.

[0062] The sterically hindered alkoxyamine compounds obtainable in the present process generally conform to the formula (Ib):

[0063] (HA) p Y(Ib)

[0064] in

[0065] HA is a hindered amine ether moiety (HE) having formula (Ia) as defined above;

[0066] p is a number in the range of 1 to 6,

[0067] And among them

[0068] Y is hydrogen, oxo, or Y is a 2- to 6-valent anchor group T3-(N[T4]-A2) having the formula (IX) q -N[T1T2](IX)

[0069] where q is in the range of 0 to 3,

[0070] or Y is an anchoring group as further defined below;

[0071] When p is 1,

[0072] Y is an anchoring group having the formula -DC-A1;

[0073] When p is 2, Y is an anchoring group having the formula DC-A2-DC;

[0074] or Y is a divalent anchoring group having formula (IX), wherein

[0075] q is 0, T3 represents an open bond, T1 is as defined for R1 and T2 is a divalent aminotriazine radical having formula (X)

[0076]

[0077] or q is 1, each of T1 and T3 is as defined for R1 and each of T2 and T4 is said divalent aminotriazine group having formula (X);

[0078] When p is 3, Y is a trivalent anchoring group of formula (IX) wherein q is 0, T3 represents an open bond, T1 is as defined for R1 and T2 is a trivalent diaminotriazine group of formula (XI)

[0079]

[0080] or q is 1, T1 is as defined for R1, T2 is a divalent aminotriazine group having formula (X), and T3 and T4 independently represent an open bond or a divalent aminotriazine group having formula (X);

[0081] when p is 4, Y is a tetravalent anchoring group of formula (IX) wherein q is 3 and two of T2 and the residue T4 represent a divalent diaminotriazine group of formula (XI), whereas each of T1 and T3 and the remaining residue T4 are as defined for R1;

[0082] When p is 5, Y is a pentavalent anchoring group having formula (IX), wherein q is 1, T1 is a trivalent diaminotriazine group having formula (XI), T3 is a divalent aminotriazine group having formula (X), and T2 and T4 independently represent an open bond or a divalent aminotriazine group having formula (X);

[0083] When p is 6, Y is a hexavalent anchoring group having formula (IX) wherein

[0084] q is 1, each of T1 and T3 is a trivalent diaminotriazine group having the formula (XI), and T2 and T4 independently represent an open bond or a divalent aminotriazine group having the formula (X);

[0085] or q is 2 and T2 and each T4 represents a trivalent diaminotriazine group having formula (XI), and each T1 and T3 is as defined for R1;

[0086] or q is 3 and T2 and two of the residues T4 represent a trivalent diaminotriazine group of formula (XI), whereas each of T1 and T3 and the remaining residues T4 are as defined for R1;

[0087] or q is 3 and T2 and T3 and one of the residues T4 represent a trivalent diaminotriazine group of formula (XI), whereas each T1 and the remaining residue T4 are as defined for R1;

[0088] A1 is C1-C 12 Alkyl or C2-C with O or COO inserted 12 Alkyl; or a di(dialkylamino)triazine group, wherein the alkyl group is selected from C1-C 12 alkyl and are preferably identical;

[0089] A2 is C2-C 12 Alkylene;

[0090] DC is a divalent linking moiety, typically a direct bond, an ester moiety -COO-, an ether moiety -O-, or an amino moiety having the formula -NR1-; and

[0091] R1 is H or lower alkyl, especially H or C1-C6 alkyl; and

[0092] X is Cl or N(R1)2.

[0093] The number of open bonds in the anchor group Y is equal to p.

[0094] Each of the moieties of formula (X) and (XI) contains two different types of open bonds, one at the triazine core and one (formula (X)) or two (formula (XI)) at NR1. When present in an anchoring group of formula (IX), one open bond from the triazine core is always bonded to a nitrogen atom in formula (IX). Thus, the open bond at NR1 is bonded to a moiety of formula (Ia) or (IIIa).

[0095] Examples of preferred products obtainable in the process of the invention are compounds of formula (Ib) wherein Y is an anchoring group of formula (IX),

[0096] Where q is in the range of 0 to 3;

[0097] Each of T1, T2, T3 and (if present) T4 is as defined for R1, or is an open bond or is a diaminotriazine radical having formula (XII)

[0098]

[0099] And in the case where p is 4 or 6, Y also includes a tetravalent or hexavalent moiety having formula (XIII)

[0100]

[0101] wherein each of R′ and R′1 is as defined for R1 or is an open bond,

[0102] The prerequisite is that the number of open bonds in the anchoring group Y is equal to p.

[0103] Examples are compounds comprising an anchor group of formula (XIII), wherein A2 is tetra-, penta- or hexamethylene, each R'1 is an open bond, each of the R's is a C2-C6 alkyl, especially a butyl group; the anchor group thus provides 6 open bonds, one on each aliphatic nitrogen atom. The term "aliphatic" is understood herein to mean a ring structure that does not contain double bonds. All 6 open bonds are thus connected to the hindered amine moiety of formula (Ia).

[0104] Thus, the sterically hindered nitroxyl educt typically conforms to formula (Ic)

[0105] (HOx) p Y(Ic)

[0106] in

[0107] HOx is a hindered amineoxy moiety having formula (IIIa) as defined above;

[0108] and p and Y are as defined above for formula (Ib).

[0109] 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.

[0110] The present invention further relates to a process for converting sterically hindered secondary amines (ie NH amines as educts) into the corresponding alkoxylated amines (ie NO-alkylamines, preferably NO-alkyl HALS), which process is carried out by:

[0111] i) contacting the hindered secondary amine educt with a suitable oxidant to obtain nitroxide (NO·); and subsequently

[0112] ii) reacting the product obtained in step (i) with a peroxide of formula (A) or preferably (B) according to the process described above.

[0113] Each of the above steps, i.e., step (i) oxidation of the secondary amine to the oxy group and step (ii) conversion of the nitroxyl group to the corresponding alkoxy amine, is typically carried out in the liquid phase and at a temperature in the range of 0°C to 140°C (e.g. 0°C to 120°C), especially in the presence of an inert solvent.

[0114] Methods for carrying out this step (i) and oxidizing agents for use in this step are generally known in the art (see for example the documents cited above). The oxidizing agent is typically a peroxide like hydrogen peroxide, a compound releasing hydrogen peroxide, a peracid (eg peracetic acid).

[0115] Preferred temperatures, especially for this step (ii), are in the range of 15°C to 100°C, especially 30°C to 100°C, most preferably when the peroxide used in the process is a diacyl peroxide (formula A) or an oxalic acid perester (formula D).

[0116] The present process comprising step (i) and step (ii) is preferably carried out in the presence of a solvent 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 containing methyl and / or tert-alkyl moieties, for example tert-butanol, methyl-tert-butyl ether, methyl acetate, tert-butyl acetate. Of particular technical importance are mixtures of such non-polar and polar solvents. Of particular technical interest is a process in which the reaction is carried out under a protective gas excluding oxygen, for example under nitrogen.

[0117] Of particular industrial importance is a process for the alkylation of a sterically hindered nitroxyl compound to the corresponding sterically hindered alkoxyamine, which process comprises reacting the sterically hindered nitroxyl compound with a peroxide of formula (A) or in particular formula (B) as described above, and wherein the sterically hindered nitroxyl compound corresponds to the formula

[0118]

[0119] And the sterically hindered alkoxyamine conforms to formula (V)

[0120]

[0121] (V)

[0122] Where n is in the range of 1 to 10 in each formula

[0123] And R is as defined in claim 1 or 2, and is preferably C1-C5 alkyl, especially 1-propyl.

[0124] Also of interest is a process in which, in a first step (i), a sterically hindered secondary amine having the formula

[0125]

[0126] wherein n is as defined above for formula (V),

[0127] Converted into the sterically hindered nitroxyl compound, the method comprising

[0128] i) contacting the hindered secondary amine educt with a suitable oxidant to obtain the nitroxide (NO·) compound; and subsequently

[0129] ii) reacting the product obtained in step (i) with a peroxide of formula (A) or preferably (B) to obtain the above-mentioned compound of formula (V).

[0130] Due to the high conversions achieved in the present process, the conversion of macromolecules comprising multiple nitroxyl groups (e.g. 6 or more) produces NO-alkyl products that are substantially different from those obtained with conventional alkylation. The present invention therefore further relates to oligomeric or polymeric products comprising compounds comprising at least 6, e.g. 6 to 100, in particular 8 to 100, moieties of formula (Ia), wherein the asterisk indicates the position of the bond connecting these moieties to another part of the molecule,

[0131]

[0132] As obtainable in the present process. The novel product is preferably an oligomeric or polymeric sterically hindered alkoxyamine compound corresponding to one of the formulae (IV) or (V)

[0133]

[0134] wherein A2 and R1 are as defined in the preceding claims and R is as defined below for formula (V),

[0135]

[0136] Where n is in the range of 1 to 10

[0137] and R is as defined in claim 1 or 3, and is preferably C1-C5 alkyl, especially 1-propyl;

[0138] Characterized in that the oligomeric or polymeric product is obtainable by the process according to the present disclosure.

[0139] As mentioned above, prior art conversion of oligomeric or polymeric HALS to NO-alkyl typically results in a product containing a certain amount of unreacted nitroxyl groups, as well as other moieties that potentially remain unreacted due to side reactions. Due to the high conversion of nitroxyl groups to alkoxyamines in the product according to the present process, the present invention provides a novel product comprising one or more compounds represented by formula (V) above, characterized in that it contains greater than 87%, preferably 90 to 99.9%, more preferably greater than 95%, typically 96% to 99.9% of the educt nitroxyl groups converted to alkoxyamine moieties N-OR as shown in formula (V), especially wherein R is 1-propyl. Thus, the product comprises a mixture of compounds containing compounds similar to those of formula (V), but having one or more moieties N-OR replaced by nitroxyl groups, typically also other derivatives of the tetramethylpiperidine moiety, such as NH, hydroxylamine or lower alkylamine, which correspond to unreacted materials or moieties, or products of side reactions. The invention thus allows a substantial reduction in the nitroxyl groups remaining in the final product, for example to 0.1 to 4% of the nitroxyl groups initially present in the educt.

[0140] Preferred secondary amine educts for use in this step (i) include the following compounds:

[0141] The educt 1 has the following formula:

[0142]

[0143] The educt 2 has the following formula:

[0144]

[0145] wherein n is in the range of 1 to 10 (available from BASF as Chimassorb 2020 [RTM]);

[0146] The educt 3 has the following formula:

[0147] wherein n is in the range of 1 to 10, in particular 4 to 5 (available from BASF as Chimassorb 944 [RTM]);

[0148] The educt 4 has the following formula:

[0149]

[0150] It is available from Solvay as Cyasorb UV-3346 (RTM; CAS No. 90751-07-8);

[0151] The educt 5 has the following formula:

[0152]

[0153] It has been described in US Pat. No. 5,130,429 (related to Chimassorb 119 [RTM], BASF) as the educt of Example 11; a similar structure in the form of an N-cyclohexyloxy derivative (with 3 instead of 4 R groups in the tetraamine) is available from BASF as Flamestab NOR 116 [RTM];

[0154] The educt 6 has the following formula:

[0155]

[0156] It is available as Cyasorb 3853 (RTM; CAS No. 24860-22-8);

[0157] The educt 7 has the following formula:

[0158] It is available as Uvinul 4050 (RTM; CAS No. 123172-53-8);

[0159] The educt 8 has the following formula:

[0160] It is available as Uvinul 5050 (RTM; CAS No. 199237-39-3);

[0161] The educt 9 has the following formula:

[0162]

[0163] Where R represents a wherein the wavy line represents the bond to the molecule shown above

[0164] (Uvasorb HA 88 [RTM]; CAS No. 136504-96-6), available from 3V Sigma;

[0165] The educt 10 has the following formula:

[0166] It is available from Clariant as Nylostab S-EED (RTM; CAS No. 42774-15-2);

[0167] The educt 11 has the following formula:

[0168]

[0169] The educt 12 has the following formula:

[0170]

[0171] The educt 13 has the following formula:

[0172]

[0173] The educt 14 has the following formula:

[0174]

[0175] The educt 15 has the following formula:

[0176]

[0177] (which is the secondary amine analog of Examples 1-3 of WO 2012-052377); educt 16 having the following formula:

[0178]

[0179] The educt 17 has the following formula:

[0180] (bis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate; available from BASF as Tinuvin 770 [RTM]).

[0181] The educts 12 , 13 and in particular 16 can be used as intermediates for oligomeric HALS and the corresponding oligomeric NO-alkyl HALS.

[0182] Nitroxyl compounds suitable for use as intermediates in the process of the present invention include compounds having the formula

[0183]

[0184] Where n is in the range of 1 to 10;

[0185] and any of the above secondary amine educts used in present step (i) in oxidized form, as obtainable as the product of present step (i).

[0186] Preferred products of this method include the following compounds:

[0187] a) bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate (i.e., Tinuvin 123 [RTM], CAS No. 129757-67);

[0188] b) Products with the formula CAS No. 191680-81-6

[0189]

[0190] Wherein the N4-amine is a trivalent amine having the formula

[0191] XHN-CH2CH2CH2-NX-CH2CH2CH2-NX-CH2CH2CH2-NHX(Xa), wherein 1 symbol X represents hydrogen and 3 symbols X represent a bond (Flamestab NOR 116[RTM]);

[0192] c)

[0193] Where n is a number in the range of 1 to 10.

[0194] Additionally, preferred products of the present process are monomeric hindered amine ethers, such as those having the formula

[0195]

[0196] wherein R is as defined above and Z is hydrogen, OH or OR or OCOR or N(R1)R or oxo (ie, O=);

[0197] Some preferred oligomeric compounds obtainable according to the process of the present invention conform to formula (XV)

[0198]

[0199] wherein R, R1 are as defined above, and wherein R is preferably n-propyl or n-octyl or n-undecyl, and / or R1 is preferably n-butyl;

[0200] and the above NO-alkyl HALS compounds (a) and (b).

[0201] The sterically hindered alkoxyamine compounds, for example of formula (I), obtainable in the process, in particular compounds containing a moiety of formula (Ia), such as the compounds of formula (XV) or compounds a) to d) described above, are effective stabilizers of organic materials, such as organic polymers, against the harmful effects of light, oxygen and / or heat. Organic polymers which can be stabilized in this way are, for example, those listed in GB-A-2334717 from page 30, line 10 to page 35, line 9; typical compositions of the invention are similar to those described subsequently in that document from page 35, line 8 to page 36, replacing the HALS compound appearing in GB-A-2334717 with the sterically hindered alkoxyamine of the invention or one of the products of the following examples. The corresponding compositions may be thermoplastic polymer compositions or may be coating compositions similar to those described in GB-A-2334717 from page 48 to page 54, line 19, comprising one or more organic polymers. The composition typically further contains a co-additive as disclosed in GB-A-2334717, pages 37 to 47.

[0202] As mentioned above, compound mixtures as currently available and containing functional groups with formula (Ia) are advantageously useful as stabilizers for organic materials (e.g., organic polymer compositions) to resist degradation by light, oxygen, and / or heat. The products of the present method may also show improved thermal stability and improved antioxidant properties, particularly during polymer processing conditions, to prevent degradation or oxidation of polymers during high temperature processing (e.g., extrusion, molding, etc.), compared to corresponding compositions or compounds prepared according to prior art methods. DETAILED DESCRIPTION

[0203] The following examples further illustrate the present invention. Unless otherwise stated, in the examples and in the remainder of the specification and in the claims, all parts or percentages are by weight. Room temperature means a temperature in the range of 20°C to 30°C. Overnight means a period of at least 12 hours and at most 16 hours. Wherever mentioned, lower alkyl represents C1-C8 alkyl, especially C 1-C6 alkyl, such as methyl, ethyl, propyl, butyl, pentyl, hexyl. All peroxides (educts with formula A according to the process of the invention, such as dibutyryl peroxide) are obtained analogously to RFDrury and Z, L.Kaplan, Journal of the American Chemical Society [American Chemical Society], 94:11, May 31, 1972. If not otherwise specified, the alkylation rate (NO-alkyl content) is determined by proton NMR as shown in Table 1. In the given formula, Bu and C4H9 each represent 1-butyl. If not otherwise defined, the index n used in the formula represents the number of repetitions, typically at least 3, for example 3 to 1000.

[0204] abbreviation:

[0205] HPLC High Pressure Liquid Chromatography

[0206] T Temperature (given in °C if not otherwise specified)

[0207] RTM Registered Trademark

[0208] 1H NMR Proton Nuclear Magnetic Resonance

[0209] MTBE Methyl tert-butyl ether

[0210] TMP Tetramethylpiperidine

[0211] Example 1 (Prior Art ): Educt 2( 2020; from Org.Process Res.Dev. [Organic Process Research and Development] 2014, 18, 1843-1849)

[0212] At ambient temperature, a solution of Na2CO3·10H2O (1.08 g, 3.77 mmol) and Na2WO4·2H2O (0.93 g, 2.82 mmol) in deionized water (13 g) was added to a solution of educt 2 (commercial product of BASF) (324 g, about 108 mmol) in toluene (486 g). Then, 50% H2O2 (308 g, 4.52 mol) was charged to the reaction mixture via a pump over 8 h, while the temperature was maintained at 60° C. Next, a 25% aqueous Na2CO3 solution (97 g) was added over 0.5 h, and stirring was continued at 60° C. for 1 hour. After phase separation at 70° C. and removal of the aqueous phase, the organic phase was washed with 23% NaCl (75 g). The aqueous phase was separated and a slightly reddish organic phase (709 g) was obtained. The pure product was obtained as a red powder by removal of the organic solvent in vacuo (see also Table 2).

[0213] Example 2 : The intermediate obtained in Example 1 (educt 1) is converted into an alkoxyamine ether

[0214] a) 4.32 g of the intermediate of Example 1 were dissolved in 30 ml of chlorobenzene. 2.66 g of dibutyryl peroxide were added in small portions while the reaction mass was heated to 90° C. The temperature was kept between 90° C. and 100° C. for 75 min. After cooling, 2 ml of water were added, stirring was continued for 30 min, and then all volatile components were removed in vacuo at up to 90° C. The alkoxyamine content was determined by 1HNMR.

[0215] b) A mixture of 2.9 g of the intermediate of Example 1 in toluene (80 ml) was slowly heated to 80° C. with stirring. Starting from 40° C., 2.4 g of dibutyryl peroxide were added in 5 portions over a period of 60 min. Stirring was continued for 120 min. to provide a yellow / orange solution. After cooling, 5 ml of water were added, stirring was continued for 30 min, and all volatile components were then removed in vacuo. The alkoxyamine content was determined to be 95% by 1H NMR.

[0216] c) A mixture of 0.65 g of the intermediate of Example 1 in toluene (5 ml) was slowly heated to 90° C. with stirring. Starting at 40° C., 1.3 g of dibutyryl peroxide were added in portions over a period of 60 min. Stirring was continued for 120 min. to give a yellow solution. After cooling, all volatile components were removed in vacuo. The alkoxyamine content was determined to be 95% by 1H NMR.

[0217] Example 3 : Improve business 371 (available from BASF).

[0218] 5.0g 371 was dissolved in 20 ml of toluene. The mixture was heated to 85° C. under vigorous stirring. Dibutyryl peroxide (2.1 g) was added to the reaction mixture in small portions over a period of 6 hours. Stirring was then continued for an additional 8 hours. After cooling, all volatiles were removed in vacuo to provide a pale yellow foam. The removal of the initial color was evident from the UV / VIS measurements shown in Table 2.

[0219] Example 4 : Improve business 371 Alkoxyamine content

[0220] 0.5g 371 was dissolved in 5 ml of toluene. Dibutyryl peroxide (0.25 g) was added to the reaction mixture at ambient temperature. The mixture was heated to 50 ° C until the red color disappeared. Then, 2 ml of water was added dropwise and stirring was continued for 0.5 hours. After cooling, all volatiles were removed in vacuo to provide an optimized product. The alkoxyamine content was determined to be 99% by 1H NMR.

[0221] Example 5 : Improve business Color and alkoxyamine content of 356 (available from BASF)

[0222] 0.5 g of commercially available 356 (educt) was dissolved in 5 ml of toluene. Dibutyryl peroxide (0.25 g) was added to the reaction mixture at ambient temperature. The mixture was heated to 50 ° C until the red color disappeared. Then, 2 ml of water was added dropwise and stirring was continued for 0.5 hours. After cooling, all volatiles were removed in a vacuum to provide a light yellow foam. According to the total amount of reactive nitrogen moieties that can be converted into alkoxyamines, 96% was converted, as determined by 1H-NMR. Visual comparison shows that the reddish color of the educt has disappeared to a large extent in the product, as also shown in Table 2.

[0223] Example 6 : General procedure for the preparation of tert-butyl peroxyesters (not part of the present invention)

[0224] Under nitrogen atmosphere, 25ml of MTBE, 4.1ml (22mmol) of 5.5M tert-butyl hydroperoxide solution in decane and 2.5ml (30.0mmol) of pyridine were loaded into a 100ml 3-necked flask equipped with a magnetic stirrer, a condenser, a thermometer and an addition funnel and cooled with an ice-water bath. The stirred mixture was cooled to 0°C. Over a period of 10-15 minutes, a solution of the desired acyl chloride (e.g., acetyl chloride, oxalyl chloride; monofunctional acyl chloride is 22mmol; oxalyl dichloride is 11.0 mmoles; dissolved in 5ml MTBE, respectively) was slowly added. Soon after the addition began, pyridinium chloride was formed into a solid. After addition, the reaction mass was stirred at 2°C for 60 minutes. Then 10mL of water was added and the reaction mass was stirred for another 10 minutes at 3°C ​​to 4°C. The aqueous layer was then separated, and the organic layer was washed three times with 35mL of 5% HCl aqueous solution, and then washed twice with 75mL water. The product solution was dried over 5% by weight anhydrous MgSO4 and, after separating the drying agent by filtration, stored in a refrigerator at 4°C.

[0225] Example 7 (present invention) : The product of Example 1 is converted into the product of Example 6

[0226] a) 3.0 ml of tert-butyl peracetate (50 wt.% solution in aliphatic hydrocarbon) was diluted with 3.0 ml of xylene. 2.8 g of a solution of the product of Example 1 in xylene was added at 132° C.-138° C. over a period of 45 min. After stirring for a further 2 hours, a pale yellow solution was obtained. All volatiles were removed in vacuo at 90° C. to give an off-white foam, 2.47 g. The alkoxyamine content was determined to be 84% by 1H NMR.

[0227] b) A solution of di-tert-butyl peroxalate in toluene was heated to 60-70° C. A solution of the product of Example 1 in toluene was added over a period of 30 min. After stirring for an additional 2 hours, a pale yellow solution was obtained. All volatiles were removed in vacuo to produce an off-white foam. The presence of the alkoxyamine was confirmed by proton NMR (signal at 3.74 ppm).

[0228] Example 8 (not part of the present invention)

[0229] a) Prepare the educt compound 1 having the formula

[0230]

[0231] In a 1 1 stainless steel autoclave equipped with mechanical stirring were added: 110 g of N,N,N',N'-tetrabutyl-6-chloro-1,3,5-triazine-2,4-diamine (prepared as described in Katritzky, Alan R.; Oniciu, Daniela C.; Ghiviriga, Ion; Barcock, Richard A. Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999), 1995, #4 p. 785) dissolved in 300 ml of xylene, 64 g of 2,2,6,6-tetramethyl-4-n-butylamine-piperidine (nBut-TAD, commercially available from Evonik or other suppliers), and then 43 ml of 30% NaOH aqueous solution. The autoclave was then closed, placed under vigorous stirring and heated to 180° C. and then allowed to react for 12 hours.

[0232] The reaction mixture was cooled to 50°C, the aqueous phase was discarded, and the organic phase was washed several times with deionized water under vigorous stirring until the pH of the aqueous phase was neutral.

[0233] The organic phase was then transferred to a rotary evaporator and all solvents were removed under vacuum to obtain an off-white solid which was dried in a vacuum oven overnight.

[0234] The final product (educt 1, MW 567, white powder) was weighed to calculate the yield and characterized by NMR.

[0235] Example 9: Preparation and selective alkylation of compound 2 having the following formula

[0236]

[0237] In a 350 ml round-bottom flask equipped with a mechanical stirrer, a reflux condenser, a thermometer, and an addition funnel were introduced at room temperature: 100 ml of toluene, 100 ml of tert-butyl alcohol, 25 g of compound 1 and 9 g of NaHCO3 dissolved in 120 ml of deionized water. The reaction mixture was heated to 50°C.

[0238] 19.5 g of 35% peracetic acid were introduced dropwise from a dropping funnel, keeping the temperature below 60° C. The reaction mixture was then cooled to 20° C., transferred to a separating funnel, and the aqueous phase was discarded. The organic phase was then washed several times with water until neutral pH.

[0239] At this point, about 0.5 ml of dibutyryl peroxide (prepared according to RF Drury and Z, L. Kaplan, Journal of the American Chemical Society, 94: 11, May 31, 1972) (MW 174) having the formula was added to the reaction mixture, heated to 80°C and allowed to react overnight.

[0240]

[0241] At the end of the reaction, the mixture was washed with an aqueous solution of sodium sulfite and then concentrated in a rotary evaporator to remove the solvent and all volatile products. The product having the formula

[0242]

[0243] It was characterized by HPLC and 1H-NMR.

[0244] 1 H-NMR(CDCl3), δ(ppm)0.83-1.08(m,30H),1.26-1.40(m,10H),1.44-1.64(m,14H),1.73(qt,2H),3.20-3.35(m,10H),3.43(m,1H),3.71(t,2H).

[0245] HPLC (Waters Alliance 2690 / 2695 HPLC system with Waters 2996 PDA detector, column Hypersil GOLD TM C4×5 cm; method: isocratic 95 / 5 CH 3 CN / H 2 O, temperature 70° C., 1.0 ml / min, UV detector at 240 nm) showed 2% of the residual peak of the starting material and 95% of the peak of the desired product.

[0246] Example 10: Reaction of dilauroyl peroxide with compound 2

[0247] The procedure described in Example 2 was repeated except that dibutyryl peroxide was replaced by di-1-dodecanoyl peroxide. The product, 2-(1-undecyloxy-2,2,6,6-tetramethylpiperidin-4-yl)-butylamino-4,6-bis(dibutylamino)-1,3,5-triazine, was characterized by HPLC and 1H-NMR.

[0248] The excellent quality of the products of the present process is also apparent from the following tables. Table 1 summarizes the data on the alkylation rate of the nitroxyl intermediates obtained by 1H-NMR; Table 2 shows data indicating the color of certain products by UV / Vis measurement of the absorption at 470 nm (maximum absorption of nitroxide radicals in solution).

[0249] Table 1: Alkylation rate of nitroxyl intermediates detected by 1H-NMR

[0250]

[0251]

[0252] *) Reference signal: proton (1H) at position 4 of the TMP ring

[0253] **) Based on the amount of nitroxide radicals educted

[0254] Table 2: Absorption at 470 nm, compared by UV / Vis measurement

[0255]

[0256] *) Maximum absorption of nitroxide radicals in solution

[0257] Treatment according to the present method produces a less colored product with a significantly improved alkylation rate.

Claims

1. A method for alkylating a sterically hindered nitroxyl compound to a corresponding sterically hindered alkoxyamine according to claim 1, comprising reacting the sterically hindered nitroxyl compound with a peroxide selected from the group consisting of a diacyl peroxide having formula (A), a perester having formula (A) and an oxalic acid perester having formula (D) R-CO-OOZR(A), RZ”-X-CO-CO-OOZ”-R(D), wherein each R independently represents a primary or secondary alkyl or cycloalkyl group, the primary or secondary alkyl or cycloalkyl group preferably containing 1 to 15 carbon atoms, and X is oxygen -O- or peroxy -OO-, Z represents CO or an alkylene group bonded to a quaternary carbon atom, the quaternary carbon atom being an alkylene group having the formula (C) R′-CR′(C) wherein each R′ is selected from an alkyl group having 1 to 15 carbon atoms, Z" represents the alkylene group bonded to the quaternary carbon atom of formula (C), Provided that, when Z is CO, the sterically hindered nitroxyl compound is not 4-hydroxy-1-oxy-2,2,6,6-tetramethyl-piperidine.

2. A method for alkylating a sterically hindered nitroxyl compound to a corresponding sterically hindered alkoxyamine according to claim 1, comprising reacting the sterically hindered nitroxyl compound with a peroxide having the formula (A): R-CO-OOZR(A), wherein each R independently represents a primary or secondary alkyl or cycloalkyl group, the primary or secondary alkyl or cycloalkyl group preferably containing 1 to 15 carbon atoms, and Z represents CO or an alkylene group bonded to a quaternary carbon atom, the quaternary carbon atom being an alkylene group having the formula (C) R′-CR′(C) wherein each R′ is selected from an alkyl group having 1 to 15 carbon atoms, Provided that, when Z is CO, the sterically hindered nitroxyl compound is not 4-hydroxy-1-oxy-2,2,6,6-tetramethyl-piperidine.

3. The method according to claim 1 or 2, wherein: The peroxide has the formula (A) and is a diacyl peroxide, and Z represents CO, or is a perester and Z represents an alkylene group bonded to a quaternary carbon atom having the formula (C), or a process according to claim 1, wherein the peroxide is an oxalic acid perester having the formula (D) And in this method, The sterically hindered nitroxyl compound comprises one or more moieties having the formula (IIIa) 1-oxy-2,2,6,6-tetramethyl-piperidine, wherein the asterisk indicates the position of the bond connecting these moieties to another part of the molecule and the corresponding sterically hindered alkoxyamine compounds belong to the class of 1-alkoxy-2,2,6,6-tetramethyl-piperidines containing one or more moieties of formula (Ia), wherein the asterisk indicates the position of the bond connecting these moieties to another part of the molecule wherein R is as defined in claim 1 or 2.

4. The method according to claim 3, wherein: The sterically hindered alkoxyamine compound conforms to formula (Ib) (HA) p Y(Ib) in HA is a hindered amine ether moiety (HE) having formula (Ia); p is a number in the range of 1 to 6, And among them Y is a 2- to 6-valent anchoring group having formula (IX) <h2 style=";text-align:left;direction:ltr">T3-(N[T4]-A2)<h2 style=";text-align:left;direction:ltr"> q <h2 style=";text-align:left;direction:ltr"> -N[T1T2](IX) where q is in the range of 0 to 3, or Y is an anchoring group as further defined below; When p is 1, Y is an anchoring group having the formula -NR1-A1; When p is 2, Y is an anchoring group having the formula DC-A2-DC; or Y is a divalent anchoring group having formula (IX), wherein q is 0, T3 represents an open bond, T1 is as defined for R1 and T2 is a divalent aminotriazine group having formula (X) or q is 1, each of T1 and T3 is as defined for R1 and each of T2 and T4 is said divalent aminotriazine group having formula (X); When p is 3, Y is a trivalent anchoring group of formula (IX) wherein q is 0, T3 represents an open bond, T1 is as defined for R1 and T2 is a trivalent diaminotriazine group of formula (XI) or q is 1, T1 is as defined for R1, T2 is a divalent aminotriazine group having formula (X), and T3 and T4 independently represent an open bond or a divalent aminotriazine group having formula (X); when p is 4, Y is a tetravalent anchoring group of formula (IX) wherein q is 3 and two of T2 and the residue T4 represent a divalent diaminotriazine group of formula (XI), whereas each of T1 and T3 and the remaining residue T4 are as defined for R1; When p is 5, Y is a pentavalent anchoring group having formula (IX), wherein q is 1, T1 is a trivalent diaminotriazine group having formula (XI), T3 is a divalent aminotriazine group having formula (X), and T2 and T4 independently represent an open bond or a divalent aminotriazine group having formula (X); When p is 6, Y is a hexavalent anchoring group having formula (IX) wherein q is 1, each of T1 and T3 is a trivalent diaminotriazine group having the formula (XI), and T2 and T4 independently represent an open bond or a divalent aminotriazine group having the formula (X); or q is 2 and T2 and each T4 represents a trivalent diaminotriazine group having formula (XI), and each T1 and T3 is as defined for R1; or q is 3 and T2 and two of the residues T4 represent a trivalent diaminotriazine group of formula (XI), whereas each of T1 and T3 and the remaining residues T4 are as defined for R1; or q is 3 and T2 and T3 and one of the residues T4 represent a trivalent diaminotriazine group of formula (XI), whereas each T1 and the remaining residue T4 are as defined for R1; A1 is C1-C 12 Alkyl or C2-C with O or COO inserted 12 alkyl; A2 is C2-C 12 Alkylene; DC is a divalent linking moiety, typically a direct bond, an ester moiety -COO-, an ether moiety -O-, or an amino moiety having the formula -NR1-; and R1 is H or lower alkyl, especially C1-C6 alkyl; and X is Cl or N(R1)2; Or the sterically hindered nitroxyl compound is an oligomeric or polymeric compound comprising 6 or more, in particular 7 or more, more in particular 7 to 100 moieties of formula (Ia) and / or (IIIa), wherein at least one moiety of formula (IIIa) is present.

5. The method according to claim 1 or 2 or 3 or 4, wherein: 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; in particular wherein two residues R represent the same group.

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

7. A method according to any one of the preceding claims, wherein: The peroxide is a diacyl peroxide of formula (A) or an oxalic acid perester of formula (D) and the reaction is carried out at a temperature in the range of 15°C to 100°C, especially 30°C to 100°C; or the peroxide is a perester of formula (A) and the reaction is carried out at a temperature in the range of 30°C to 140°C, especially 50°C to 140°C.

8. A method according to any one 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 that does not include oxygen, for example under nitrogen.

9. A method according to any one of the preceding claims, wherein: The reaction is carried out in the presence of a solvent 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 containing 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. The method according to any one of claims 3 to 9, wherein: The sterically hindered alkoxyamine obtained in the process is a compound having formula (I) (R2)2N-OR(I) wherein R is as defined in claim 1 or 2; Each R2 is a hydrocarbon, and preferably linked to each other to form a divalent hydrocarbon residue, the two R2 together contain 2 to 500 carbon atoms, and optionally further contain one or more moieties selected from the group consisting of: a tertiary nitrogen moiety; a secondary nitrogen moiety; an ester moiety COO; chlorine; and preferably wherein R is selected from C1-C 12 alkyl or C5-C8 cycloalkyl; and each R2 is a hydrocarbon, and preferably connected to each other to form a divalent hydrocarbon residue, the two R2 together contain 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 nitroxyl compound belongs to the class of 1-oxy-2,2,6,6-tetramethyl-piperidines containing one or more moieties having formula (IIIa), 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 having formula (Ia), wherein the asterisk indicates the position of the bond connecting these moieties to another part of the molecule and R is selected from C1-C 12 Alkyl or C5-C8 cycloalkyl alkyl.

11. A process according to any one of the preceding claims for preparing a sterically hindered alkoxyamine compound which corresponds to formula (XIV) or (XV) wherein R, R1 are as defined in the preceding claims, and Z is hydrogen or OR or OCOR or N(R1)R or oxo; or bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate; or an oligomeric or polymeric compound comprising at least 6, for example 6 to 100, moieties of formula (Ia), wherein the asterisk indicates the position of the bond connecting these moieties to another part of the molecule For example, the product having the formula CAS No. 191680-81-6 Wherein the N4-amine is a trivalent amine having the formula XHN-CH2CH2CH2-NX-CH2CH2CH2-NX-CH2CH2CH2-NHX, wherein 1 symbol X represents hydrogen and 3 symbols X represent bonds; Preferably, the oligomeric or polymeric sterically hindered alkoxyamine compound corresponds to one of the following formulae (IV) or (V): Where A2 is C2-C 12 Alkylene; R1 is H or lower alkyl, especially C1-C6 alkyl; and and R is as defined below for formula (V), Where n is in the range of 1 to 10 And R is as defined in claim 1 or 3, and is preferably C1-C5 alkyl, especially 1-propyl.

12. The method according to any one of claims 1 to 11, wherein: The sterically hindered nitroxyl compound is represented by one of the formulas (IV) or (V) Where A2 is C2-C 12 Alkylene; R1 is H or lower alkyl, especially C1-C6 alkyl; and R is as defined in claim 1 or 3, and is preferably C1-C5 alkyl, especially 1-propyl; wherein n is in the range of 1 to 10 and R is as defined above; Or the product represented by the following formula CAS No. 191680-81-6 Wherein the N4-amine is a trivalent amine having the formula XHN-CH2CH2CH2-NX-CH2CH2CH2-NX-CH2CH2CH2-NHX, wherein 1 symbol X represents hydrogen and 3 symbols X represent bonds; And wherein one or more of these residues OR or O-cycloalkyl is replaced by a nitroxyl group.

13. A method according to any one of the preceding claims, wherein: In a first step (i), a sterically hindered secondary amine educt, typically comprising one or more 2,2,6,6-tetramethyl-piperidin-4-yl moieties, is converted into the sterically hindered nitroxyl compound, the method comprising (i) contacting the hindered secondary amine product with a suitable oxidant to obtain a nitroxide free radical (NO . ); and subsequently (ii) reacting the product obtained in step (i) with a peroxide according to any one of claims 1 to 13; And wherein, preferably, the secondary amine educt is an oligomeric or polymeric compound containing at least 6, especially 6 to 100 moieties of 2,2,6,6-tetramethyl-piperidin-4-yl, such as a compound selected from the following The educt 2 has the following formula: Where n is in the range of 1 to 10; The educt 3 has the following formula: wherein n is in the range of 1 to 10, in particular 4 to 5; The educt 4 has the following formula: CAS No. 90751-07-8; The educt 5 has the following formula:

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