Preparation of sterically hindered amine ethers

Details Preparation of sterically hindered amine ethers Preparation of sterically hindered amine ethers

2000-06-15

2002-07-16

Shah, Mukund J. (Department: 1624)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S102000, C524S126000, C524S153000, C524S310000, C524S359000, C544S194000, C544S207000, C544S231000, C544S357000, C544S360000, C546S188000, C546S189000, C546S225000, C546S242000

Reexamination Certificate

active

06420462

ABSTRACT:

The invention relates to a new process for the preparation of sterically hindered amine ethers, new compounds of this class, their use as stabilizers for organic material against degradation by light, oxygen and/or heat and corresponding compositions.
A number of publications describe the stabilization of organic material using specific sterically hindered amine (HALS) compounds as stabilizers. A valuable class of sterically hindered amines are compounds wherein the nitrogen atom is part of a heterocyclic ring and the nitrogen atom carries an additional organic substituent linked over an oxygen atom (NOR-HALS; Kurumada et al., J.Polym.Sci, Poly.Chem. Ed. 22, 277-81 (1984); U.S. Pat. No. 5,204,473); the oxygen-linked substituent is introduced in these compounds by etherification of the free oxyl- or hydroxylamine with suitable agents.
Some N-allyl nitroxides rearrange under certain conditions into amine ethers (Meisenheimer rearrangement; Chem. Ber. 52, 1667 (1919); Chem. Ber. 55, 513 (1922)). Cleavage of the nitroxide with formation of alkene and hydroxylamine (Cope elimination) is a competing reaction, the rate of which increases with increasing steric hindrance (J.March, Advanced Organic Chemistry, IV Ed., Wiley, 1992).
Now it has been found that, surprisingly, oxidation of a 1-allyl-substituted sterically hindered amine effectively leads to the corresponding 1-allyloxy-substituted product. The invention therefore pertains to a process for the preparation of a compound of the formula I
wherein
R
1
, R
2
, R
3
and R
4
, independently of each other, are C
1
-C
8
alkyl or C
1
-C
5
hydroxyalkyl, or R
1
and R
2
together with the carbon atom they are attached to are C
5
-C
12
cycloalkyl, or R
3
and R
4
together with the carbon atom they are attached to are C
5
-C
12
cycloalkyl;
R
5
, R
6
, R
7
, R
8
and R
9
, independently of each other, are H, C
1
-C
8
alkyl, C
2
-C
8
alkenyl, C
5
-C
12
aryl, C
1
-C
4
haloalkyl, an electron withdrawing group, or C
6
-C
12
aryl which is substituted by a residue selected from C
1
-C
4
alkyl, C
1
-C
4
alkoxy, halogen; and R
7
and R
8
together may also form a chemical bond; and
R is an organic linking group containing 2-500 carbon atoms and forming, together with the carbon atoms it is directly connected to and the nitrogen atom, a substituted, 5-, 6 or 7-membered cyclic ring structure; R preferably being a C
2
-C
500
hydrocarbon optionally containing 1-200 hetero atoms selected from nitrogen, oxygen, phosphorus, sulfur, silicon and halogen, and,
characterized in that a compound of the formula II
wherein all residues R and R
1
-R
9
are as defined for formula I, is oxidized.
R
7
and R
8
together as a chemical bond form an allenic double bond in formula I, and a triple bond in formula II.
In the compounds of formula I and II and further products, R
1
, R
2
, R
3
and R
4
independently preferably are methyl or ethyl, especially methyl.
R
5
, R
6
, R
7
, R
8
and R
9
as an electron withdrawing group include —CN, nitro, halogen or —COOR
10
where R
10
is C
1
-C
12
alkyl, C
5
-C
12
cycloalkyl, C
7
-C
9
phenylalkyl or phenyl. Preferred as electron withdrawing group are —CN or —COOR
10
where R
10
is C
1
-C
12
alkyl, C
5
-C
12
cycloalkyl or phenyl, especially wherein R
10
is C
1
-C
12
alkyl or cyclohexyl.
Preferably, R
5
, R
6
, R
7
, R
8
and R
9
independently are H or methyl, especially H. Also preferred are compounds wherein R
5
and R
6
independently are H or methyl, especially H, and R
7
, R
8
and R
9
independently are haloalkyl, phenyl, vinyl, nitro, CN, COOR
10
, or R
7
and R
8
together form a chemical bond.
Further preferences for the linking group R are mainly as described below for products of formulae III, IV and V.
Of special importance is a process for the preparation of a compound of the formula I by oxidation of a compound of the formula II,
wherein
R
1
, R
2
, R
3
and R
4
, independently of each other, are C
1
-C
8
alkyl or C
1
-C
5
hydroxyalkyl, or R
1
and R
2
together with the carbon atom they are attached to are C
5
-C
12
cycloalkyl, or R
3
and R
4
together with the carbon atom they are attached to are C
5
-C
12
cycloalkyl;
R
5
, R
6
, R
7
, R
8
and R
9
, independently of each other, are H, C
1
-C
8
alkyl, C
3
-C
8
alkenyl, C
5
-C
12
aryl, an electron withdrawing group, C
6
-C
12
aryl which is substituted by C
1
-C
4
alkyl, C
1
-C
4
alkoxy, halogen; and
R is a C
3
-C
500
hydrocarbon optionally containing 1-200 hetero atoms selected from nitrogen, oxygen, phosphorus, sulfur and halogen, and forming, together with the two carbon and the nitrogen atom, a substituted, 6-membered cyclic ring structure.
Aryl stands for a group obeying the Debye-Hueckel rule; preferred as C
6
-C
12
aryl are phenyl and naphthyl.
Alkyl is a branched or unbranched radical, embracing, within the definitions given, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetra-methylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl or docosyl.
Alkanoyl is alkyl connected over a carbonyl linkage; thus, C
2
-C
20
alkanoyl includes acetyl, propionyl, butyryl, hexanoyl, steaoryl.
Haloalkyl is alkyl substituted by halogen, e.g. 1 or 2 halogen atoms. Halogen atoms are preferably chloro or bromo, especially bromo.
Cycloalkyl is a saturated monovalent monocyclic hydrocarbon residue, e.g. cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl; preferred is cyclohexyl.
Organic residues or hydrocarbons containing heteroatoms, such as alkyl or alkylene interrupted by hetero groups like oxygen or NH, usually contain these heteroatoms as typical functional groups like oxo, oxa, hydroxy, carboxy, ester, amino, amido, nitro, nitrilo, isocyanato, fluoro, chloro, bromo, phosphate, phosphonate, phosphite, silyl, thio, sulfide, sulfinyl, sulfo, heterocyclyl including pyrrolyl, indyl, carbazolyl, furyl, benzofuryl, thiophenyl, benzothiophenyl, pyridyl, chinolyl, isochinolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazolyl, benzotriazolyl, triazinyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, and corresponding saturated and/or substituted groups like, for example, piperidyl, piperazinyl, morpholinyl etc. They may be interrupted by one or more of these groups; usually there are no linkages of the type O—O, O—N (except nitro, cyanato, isocyanato, nitroso), N—N (except in heterocyclic ring structures), N—P or P—P present, regardless of the order.
Preferably, in organic residues or hydrocarbons containing heteroatoms such as R there is not more than one heteroatom attached by a single bond to the same carbon atom. A spacer consisting of one or more heteroatoms usually is embedded in a carbon chain or ring or inserted into a carbon-hydrogen bond.
Compounds of the formula I can be monomeric or polymeric. They contain 1 or more groups of the formula I′
In case that the compounds of the formula I′ are polymeric, they contain a group of the formula I′ in the repeating structural unit.
Starting compounds of the formula II are known in the art or can be obtained in analogy to known compounds. Present process can start from isolated compounds of the formula II or can use the solution of these starting compounds as obtained directly after synthesis.
In the process of present invention, the oxidation reaction can be carried out using known oxidants, e.g. oxygen, peroxides or other oxidizing agents such as nitrates, permanganates, chlorates; preferred are peroxides, such as hydrogen peroxide based systems, especially peracids such as perbenzoic acid or peracetic acid. The oxidant is conveniently used in stoiciometric amount or in excess, e.g. using 1-2 moles active oxyen atoms for each group of the formula I′ in the desired product.
The reaction can be carried out in the presence of a suitabl

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