Tinuvin P-hindred amine light stabilizer and derivatives...

Details Tinuvin P-hindred amine light stabilizer and derivatives... Tinuvin P-hindred amine light stabilizer and derivatives...

2002-07-25

2003-08-26

McKane, Joseph K. (Department: 1626)

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C548S260000

Reexamination Certificate

active

06610856

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to invention relates to a novel photo-stabilizer of the general formula (I):
wherein R
1
is hydrogen, halogen, C
1
to C
12
alkyl, alkoxy (linear and branched), R
2
is hydrogen, C
1
-C
8
alkyl, cyclopentyl, cyclohexyl or cumyl, R
3
is hydrogen, C
1
-C
4
alkyl, R
4
is methyl or ethyl, R
5
is C
1
-C
8
alkyl, alkyl phenyl, alkoxy, acyl, cycloalkyl and allyl, X is O, NH, C
1
-C
8
alkyloxy and alkylamino (linear or branched). More particularly, the present invention relates to the said compound of formula I prepared using bromo derivative of Tinuvin P of the general formula (II).
wherein R
1
is hydrogen, halogen, C
1
to C
12
alkyl, alkoxy (linear and branched), R
2
is hydrogen, C
1
-C
8
alkyl, cyclopentyl, cyclohexyl or cumyl, as disclosed in our co-pending patent application Ser. No. 09/749,277 by reacting with a compound of the formula (IV).
wherein R
3
is hydrogen, C
1
-C
4
alkyl, R
4
is methyl, ethyl, R
5
is C
1
-C
8
alkyl, alkyl phenyl, alkoxy, acyl, cycloalkyl and allyl, X is OH, NH
2
, C
1
-C
8
alkyloxy and alkylamino (linear or branched).
BACKGROUND OF THE INVENTION
Polymers have replaced metals glass, ceramics and papers in packaging, automobiles, building construction, electronics, electrical equipment, furniture, pipes and heavy industrial equipment. In a nutshell, from agriculture to transport and aerospace to food packaging, the use of plastics has become an integral part of our daily life. Polymers, all natural and synthetic, in common use, are susceptible to thermal/photo-oxidative degradation upon exposure to natural and artificial weathering. The deterioration of these polymeric materials is mainly due to the UV portion of sunlight reaching the earth surface. The net result of degradation is the loss in the molecular weight and macroscopic physical properties. In order to avoid this loss, different types of photo-stabilizers have been devised that protect the polymeric substrate from detrimental effect of light. Compatible and mobile light stabilizers usually prove to be best choice to attain the desired photostability. Most of these stabilizers are commercially available and are successfully employed, single and/or in combination with other stabilizers for the polymer stabilization. Researchers have even attempted to study the combined effect screeners, quencher, ultraviolet absorbers and thermal stabilizers. An ample literature on the synthesis and application of these photostabilizers is available to date. Depending upon the type of combination, the effect of the stabilizers can be synergistic and antagonistic. The efficacy of the stabilizer depends on many factors viz. type of combination, proportion of additive, compatibility with the polymer and molecular weight of the stabilizer. Hindered amine light stabilizer (HALS) and benzotriazole based UV absorbers are known to work in synergism and there is no literature on the synthesis of the coupled derivatives of HALS and UV absorbers.
Keeping in view the above-mentioned requirements we have designed and synthesized a novel HALS coupled to an UV absorber. Following patents and literature provide information about synthesis of the photo-stabilizers and the photo-stabilization efficiencies of HALS and UV absorbers solely in presence of each other. JP 200119260: April 2000; U.S. Pat. No. 5,977,219: November 1999; JP 4263874 A2 September 1999; EP 924248 A1: June 1999; U.S. Pat. No. 5,739,348: April 1998; WO 9739052 A1: October 1997; U.S. Pat. No. 5,362,881 November 1994; U.S. Pat. No. 5,086,097 February 1994; Polym. Photochem, 5, 351 (1984), Polym, Degrad, Stab, 8, 133, (1984) and Polym Degrad. Stav. 32, 71 (1991). The process for the synthesis of compound having formula (II) has been disclosed in our co-pending patent application Ser. No. 09/749,277. An online search using SCIFINDER and CHEMICAL ABSTRACT search engines did not provide any positive result for any molecule similar to that synthesised in this invention.
OBJECTS OF THE INVENTION
The main object of the invention is to provide a process for the preparation of novel Tinuvin P-Hindred Amine Light Stabilizer (TP-HALS) derivatives, which can fulfil the above mentioned prerequisites. Moreover, this class of combination of HALS and benzoriazole are known to be compatible with polyolefins, polycarbonate, polystyrene and diene—elastomers and can even be added in an additive proportion to obtain desired photo-stability of various other polymers.
SUMMARY OF THE INVENTION
Accordingly the present invention provides a novel Tinuvin P-Hindred Amine Light Stabilizer derivative of the general formula (I):
wherein R
1
is hydrogen, halogen, C
1
to C
12
alkyl, alkoxy (linear and branched), R
2
is hydrogen, C
1
-C
8
alkyl, cyclopentyl, cyclohexyl or cumyl, R
3
is hydrogen, C
1
-C
4
alkyl, R
4
is methyl or ethyl, R
5
is C
1
-C
8
alkoxy, acyl, cycloalkyl and allyl, X is O, NH, C
1
-C
8
alkyloxy and alkylamino (linear or branched).
The present invention also provides a process for preparation a novel Tinuvin P-Hindred Amine Light Stabilizer derivative of the general formula (I) comprising dissolving a compound having formula (II)
wherein R
1
is hydrogen, halogen, C
1
to C
12
alkyl, alkoxy (linear and branched), R
2
is hydrogen, C
1
-C
8
alkyl, cyclopentyl, cyclohexyl or cumyl, with an organic base in a dry organic solvent under inert condition, agitating it initially for a period of 20-30 minutes followed by addition of an hydroxy protecting group and stirring the reaction mixture for 10-14 min under inert atmosphere, followed by evaporating the organic solvent and drying the residue, subsequently dissolving the residue in a low boiling organic solvent followed by filtering the insoluble mass and evaporating the solvent to obtain a compound having general formula (III)
wherein R
1
is hydrogen, halogen, C
1
to C
12
alkyl, alkoxy (linear and branched), R
2
is hydrogen, C
1
-C
8
alkyl, cyclopentyl, cyclohexyl or cumyl, and Y is tertbutyldimethylsilyl, tertbutyldiphenylsilyl, dimethyithexylsilyl, benzoyl, benzyl, and acetyl,
dissolving compound of formula (III) in a dry organic solvent under inert condition and simultaneously dissolving compound of formula (IV)
wherein R
3
is hydrogen, C
1
-C
4
alkyl, R
4
is methyl, ethyl, R
5
is C
1
-C
8
alkyl, alkyl phenyl, alkoxy, acyl, cycloalkyl and allyl, X is OH, NH
2
, C
1
-C
8
alkyloxy and alkylamino (linear or branched) separately but in the same solvent and adding to it a dry metal hydride, agitating the solution for 30-60 minutes, cooling it to 4-8° C. and then adding the solution of compound of formula III gradually over a period of 30-60 minutes, agitating the reaction mixture for 2-4 hrs, followed by refluxing the same for 2-4 hrs, cooling the reaction mixture to room temperature and agitating for 4-6 hrs followed by evaporating the organic solvent under reduced pressure, dissolving the solid mass in water and extracting the product in an organic solvent through repeated extractions and evaporating the organic solvent to obtain a compound of formula (V)
wherein R
1
is hydrogen, halogen, C
1
to C
12
alkyl, alkoxy (linear and branched), R
2
is hydrogen, C
1
-C
8
alkyl, cyclopentyl, cyclohexyl or cumyl, R
3
is hydrogen, C
1
-C
4
alkyl, R
4
is methyl or ethyl, R
5
is C
1
-C
8
alkyl, alkyl phenyl, alkoxy, acyl, cycloalkyl and allyl, X is O, NH, C
1
-C
8
alkyloxy and alkylamino (linear or branched), Y is tertbutyldimethylsilyl, tertbutyldiphenylsilyl, dimethylthexylsilyl, benzoyl, benzyl, and acetyl, taking the compound (V) with a hydroxy deprotecting reagent and stirring the reaction mixture at room temperature for 1-3 hrs followed by addition of water and extracting the product in an organic solvent, drying the solvent with an anhydrous inorganic salt after neutralization with an inorganic base an evaporating the solvent to obtain the compound of formula I.
In one embodiment of the invention, the organic solvent used for dissolving the compound of formula (II) is selected from the group consisting of pyridine, dichlorom

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