Light stabilizers based on sterically hindered amines

Details Light stabilizers based on sterically hindered amines Light stabilizers based on sterically hindered amines

1998-09-03

2001-01-09

Seaman, D. Margaret (Department: 1612)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C546S156000, C546S157000

Reexamination Certificate

active

06172232

ABSTRACT:

BACKGROUND OF THE INVENTION
It is known that organic materials are damaged by light, radiation, heat or oxygen. There are already numerous documents which describe compounds for stabilizing organic material against these effects. The majority of such compounds are free-radical scavengers, hydroperoxide destroyers, quenchers (extinguishers for excited states) or UV absorbers (cf. R. G{umlaut over (a)}chter, H. M{umlaut over (u)}ller, Plastics Additives Handbook, 3rd Ed., Hanser Verlag, Munich 1990, p. 133 ff.). In the context of UV absorbers, the compounds generally involved are based on 2-hydroxybenzophenone, 2-hydroxyphenyl-benzotriazole, cinnamic esters and oxanilides (cf. R. G{umlaut over (a)}chter, H. M{umlaut over (u)}ller, Plastics Additives Handbook, 3rd Ed., Hanser Verlag, Munich 1990, p. 181 ff.). The class of the o-hydroxy-substituted triphenylpyrimidines can be regarded as a relatively new type of UV stabilizer (DE-A-4416809).
Said classes of compound often have specific disadvantages which occur alongside the desired stabilizing effect. Especially in respect of color behavior, interaction with pigments, compatibility of different, simultaneously employed stabilizers with one another and with the material to be stabilized, resistance to chemicals and water (sensitivity to hydrolysis), storage stability, migration behavior and improvement of stabilization against the damaging effects of heat and light in long-term use, there is a great need for new classes of stabilizer.
Derivatives of 4-hydroxyquinoline-3-carboxylic acid, especially the free acid and the methyl and ethyl esters, have been known for some time in connection with pharmaceutical applications (cf. e.g. B. E. Schroetter et al, Pharmazie (1977), 32(4), 223-5).
The applications known to date relate to the action of 4-hydroxyquinoline-3-carboxylic acid and its esters against bacteria, parasites, tumors, suppurating ulcers, gastrointestinal dysfunctions and as enzyme inhibitors. Derivatives of 4-hydroxyquinoline-3-carboxylic acid are not known for their UV-stabilizing action. Substances which combine a UV stabilizer and a sterically hindered amine simultaneously in the molecule can be particularly effective light stabilizers. In this context, for example, UV absorbers based on 2-hydroxy-benzophenone, on 2-hydroxyphenylbenzotriazole and on cinnamic acids are encountered. This is known, inter alia, from EP-A-389 427; EP-A-10 516; EP-A-16 723; EP-A-200 190; EP-A-593 936; DE-A-4 327 297.
SUMMARY OF THE INVENTION
It has now surprisingly been found that compounds which combine a 4-hydroxyquinoline-3-carboxylic acid derivative and a sterically hindered amine simultaneously in the molecule in the manner shown in formula (I) have an excellent protective effect for organic material against the damaging effects of light, heat and oxygen. In the near UV region, which is of interest, the substances (I) generally possess extinction coefficients of from 10,000 to 15,000 (see Experimental Section).
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present application therefore provides novel compounds of the formula (I)
In this formula
R
1
to R
4
independently of one another are halogen, H, NO
2
, CF
3
, CN; C
1
-C
20
-, preferably C
1
-C
10
-, especially C
1
-C
4
-alkyl, - S-alkyl or —O-alkyl; C
6
-C
14
-, preferably C
6
-C
10
-aryl, —S-aryl or —O-aryl; C
5
-C
13
-, preferably C
5
-C
10
-heteroaryl; C
7
-C
26
-, preferably C
7
-C
13
-alkylaryl, —S-alkylaryl or —O-alkylaryl.
Two of the radicals R
1
to R
4
may together with the parent structure form a 5- to 12-membered, preferably a 5- or 6-membered aliphatic ring which is unsubstituted or substituted by halogen, NO
2
, CN, CF
3
, C
1
-C
20
-, preferably C
1
-C
10
-, especially C
1
-C
4
-alkyl, —O-alkyl or —S-alkyl, C
6
-C
14
-, preferably C
6
-C
10
-aryl, —O-aryl or —S-aryl, C
5
-C
13
-, preferably C
5
-C
10
-heteroaryl, C
7
-C
26
-, preferably C
7
-C
13
-alkylaryl, —O-alkylaryl or —S-alkylaryl and can include one or more heteroatoms; this aliphatic ring can in particular be interrupted by —S—, —O—, —N(H)—.
Of the radicals R
1
to R
4
, two adjacent radicals in each case may together with the parent structure form a further 5- or 6-membered, preferably 6-membered aromatic ring which is unsubstituted or substituted by halogen, NO
2
, CF
3
, CN, C
1
-C
20
-, preferably C
1
-C
10
-, especially C
1
-C
4
-alkyl, —O-alkyl or —S-alkyl, C
6
-C
14
-, preferably C
6
-C
10
-aryl, —O-aryl or —S-aryl, C
5
-C
13
-, preferably C
5
-C
10
-heteroaryl, C
7
-C
26
-, preferably C
7
-C
13
-alkylaryl, —O-alkylaryl or —S-alkylaryl and can include one or more heteroatoms, or can be fused with a further aromatic nucleus.
R
5
is H, CN or SR
7
.
R
7
is H; C
1
-C
20
-alkyl which is unsubstituted or substituted by halogen, NO
2
, CN, CF
3
, C
1
-C
20
-, preferably C
1
-C
4
-O-alkyl, C
6
-C
14
-, preferably C
6
-C
10
-aryl, O-C
6
-C
20
-, preferably O-C
6
-C
10
-aryl or O-C
7
-C
26
-, preferably O-C
7
-C
13
-arylalkyl; preferably an unsubstituted C
1
-C
10
-alkyl, especially methyl; or C
6
-C
14
-aryl which is unsubstituted or substituted by halogen, NO
2
, CN, CF
3
, O-C
1
-C
20
-, preferably O-C
1
-C
10
-, especially O-C
1
-C
4
-alkyl, O-C
6
-C
14
-, preferably O-C
6
-C
10
-aryl, or O-C
7
-C
26
-, preferably O-C
7
-C
13
-arylalkyl;
R
6
is
R
8
is hydrogen or a C
1
-C
12
-alkyl group, preferably a C
1
-C
4
-alkyl group, especially a methyl group;
R
9
is hydrogen or a C
1
-C
22
-, preferably a C
1
-C
5
-alkyl group, especially a methyl group, an oxygen radical O*, —OH, —NO, —CH
2
CN, benzyl, allyl, a C
1
-C
30
-, preferably a C
1
-C
10
-alkyloxy group, a C
5
-C
12
-, preferably a C
5
-C
6
-cycloalkyloxy group, a C
6
-C
10
-, preferably a C
6
-C
7
-, especially a C
6
-aryloxy group, where the aryl radical can additionally be substituted; a C
7
-C
20
-, preferably a C
7
-C
10
-arylalkyloxy group, where the aryl radical can additionally be substituted, a C
3
-C
10
-, preferably a C
3
-C
6
-alkenyl group, a C
3
-C
6
-alkynyl group, a C
1
-C
10
-, preferably a C
1
-C
5
-acyl group, halogen, or a phenyl radical which is unsubstituted or substituted by C
1
-C
4
-, preferably by C
1
-C
2
-alkyl,
R
10
is hydrogen or C
1
-C
12
-alkyl group, preferably a C
1
-C
4
-alkyl group, especially a butyl group.
The 4-hydroxyquinoline-3-carboxylic esters, in other words the precursors of the compounds (I) of the invention, can be prepared in accordance with the prior art, especially by the method described, inter alia, in Organic Syntheses Coll. Vol. III, p. 274 and in Houben-Weyl, Heterarene II, Part 1, Volume E7a, p. 343 ff., by the thermal cyclization of appropriately substituted dialkyl(arylamino-methylene)malonates in a high-boiling solvent. These precursors can also be prepared by the methods described in DE-A-2 431 584. The cyclizable dialkyl S-alkyl-substituted (arylamino-methylene)malonates for the synthesis of 4-hydroxyquinoline-3-carboxylic esters having the —S-alkyl substituent, especially the —S-CH
3
-substituent, in position 2 can be prepared in analogy to the method published in Houben-Weyl, Heterarene II, Part 1, Volume E7a, p. 376, especially by reaction of aryl thioisocyanate with the sodium salt of malonic acid and subsequent reaction with alkyl iodide. The precursor for the derivatives having the —CN substituent in position 2 can be prepared by the method described by S. E. J. Glue, I. T. Kay in Synthesis (1977), 607-8.
The cyclizations of these precursors to give the compounds of the invention can be conducted in a high-boiling organic solvent, especially in boiling o-dichlorophenol or in boiling diphenyl ether.
The preparation of the substances of the invention has not been described to date. The novel substances (I) can be prepared by a transesterification starting from a 4-hydroxyquinoline-3-carboxylic ester and an appropriately substituted sterically hindered amine, especially by transesterification with 2,2,6,6-tetramethylpiperidin-4-ol, 2,2,6,6-tetramethylpiperidine-4-amine or N-butyl-2,2,6,6-tetramethylpiperidine-4-amine. A transesterification of this kind can be conducted in an organic sol

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