Patent Publication Number: US-4256626-A

Title: Multichromophoric ultraviolet stabilizers and their use in organic compositions

Description:
This is a division of application Ser. No. 711,045, filed Aug. 2, 1976, which is a division of Ser. No. 502,330, filed Sept. 3, 1974 now U.S. Pat. No. 4,115,348, issued Sept. 19, 1978. 
    
    
     This invention relates to multichromophoric ultraviolet stabilizers and their use in organic compositions. More particularly, the invention relates to multichromophoric compositions and the stabilization of ultraviolet degradable organic compositions against deterioration resulting from the exposure to such radiations with such multichromophoric compositions. 
     The degradient effects of ultraviolet light on various organic compositions is well known in the art. The photo-deterioration or degradation is of particular concern with organic photo-degradable compositions which are exposed to ultraviolet light, such as sunlight, for long periods of time. One group of such photo-degradable organic compositions are polymeric compositions such as polyolefins, polyesters and the like. On exposure to sunlight for extended periods of time, these polymeric compositions degrade and their physical properties are reduced to render the polymeric composition less useful for most applications. Therefore, considerable effort has been directed to providing a solution to the photo-degradation problem of polymeric compositions. As a result of this effort, there have been discovered many additives and stabilizers which improve the stability of polymeric compositions. 
     Moreover, various additives and stabilizers exhibit the power to absorb ultraviolet radiation within the band of 2900 to 4000 A. and, when incorporated in various plastic materials such as transparent sheets, the resultant sheet acts as a filter for all the radiation passing through and will transmit only such radiations as are not absorbed by the sheet and/or the absorbing agent. It is thus possible to screen out undesirable radiations and utilize the resulting transparent sheet as a filter in many technical and commerical applications, such as wrappings for food products and the like. 
     While there are many additives, stabilizers and mixtures thereof which are known in the art to improve the ultraviolet light stability of organic compositions, there is a need in the art for more efficient and effective stabilizers to prevent the photo-degradation of organic compositions susceptible to photo-degradation. Therefore, to provide a more effective and efficient ultraviolet stabilizer for organic compositions susceptible to such degradation would be an advance in the state of the art. 
     It is, therefore, an object of the present invention to provide more effective and efficient ultraviolet light stabilizer compositions. 
     Another object of the present invention is to provide useful compositions characterized by improved resistance to ultraviolet degradation and deterioration. 
     It is still another object of the present invention to provide compositions containing multichromophoric compositions which are resistant to ultraviolet degradation. 
     It is a still further object of the invention to provide processes for improving the resistance of organic materials to deterioration and degradation by actinic radiation and especially ultraviolet radiation. 
     It is a still further object of this invention to provide compositions and processes for improving the resistance of organic materials to deterioration and degradation by ultraviolet radiations, including short wave-length visible radiations. 
     Further objects and advantages of the invention will be apparent to those skilled in the art from the accompanying disclosure and claims. 
     In accordance with the present invention, multichromophoric compositions are provided which are useful as ultraviolet stabilizers or ultraviolet screening agents. These organic compositions contain at least one heterocyclic group containing compositions connected to a hydroxybenzophenone. The multichromophoric compositions of the present invention have the following structure: 
     
         A-B-C 
    
     wherein A is a group having the structure ##STR1## wherein 
     X is a carbon atom or a nitrogen atom; 
     Y is a carbon atom; 
     Z is an oxygen atom, a sulfur atom, a nitrogen atom, or a nitrogen atom containing a hydrogen atom or an alkyl group having 1 to 12 carbon atoms or an aryl group or substituted aryl group having 6 to 12 carbon atoms; 
     R 1 , R 2 , R 3  and R 4  are hydrogen, hydroxyl, lower alkyl substituted lower alkyl, having 1 to 12 carbon atoms, cycloalkyl, substituted cycloalkyl, aryl substituted aryl, having 6 to 18 carbon atoms, lower alkylaryl, aryl-substituted-aryl, chloro, bromo, alkoxy, substituted amino, cyano, carboxy and the substituents R 1  and R 2 , R 2  and R 3 , and R 3  and R 4 , combined with the carbon atoms to which they are attached, are joined alkylene groups completing a carbocyclic ring, which ring can also be substituted with one or more of the substituents listed above for R 1 , R 2 , R 3  and R 4 . 
     I is a substituent listed above for R 1 , R 2 , R 3  and R 4  and is present on all positions of the benzenoid ring, except the carbon atom attached to the Y substituent and the carbon atom attached to the B group. The B connecting group is attached to the benzenoid ring in the ortho, meta or para position from the carbon atom connected to the Y substituent. The I substituents can all be one of the substituents listed above or different listed substituents. 
     The B group is a group connecting A and C and can be alkylene, arylene, carbonyloxy, oxycarbonylalkyleneoxy, alkyleneoxy, oxycarbonyl, alkylenecarbonyloxy, oxycarbonyloxy, oxyalkylene, alkyleneoxyalkyleneoxy, thio, thioalkyleneoxy, sulfinyldioxy, oxy(alkoxy)phosphinooxy, alkyloxyphosphinylidene, aryloxyphosphinylidene, oxy(alkyl)phosphinyloxy, aminocarbonyl, N-alkylaminocarbonyl, N-arylaminocarbonyl, aminocarbonylalkeneoxy, N-alkylaminocarbonylalkyleneoxy, N-arylaminocarbonylalkyleneoxy, aminocarbonylamino, N-alkylaminocarbonylamino, di(N-alkylamino)carbonyl, N-arylaminocarbonyl, N-alkylaminocarbonyl, di(N-aryl)aminocarbonyl, amino, N-alkylamino, N-arylamino, N-alkylaminoalkyleneoxy, N-arylaminoalkyleneoxy, oxyalkyleneoxy, oxyaryleneoxy, alkyleneaminoalkylene, aryleneaminoarylene, aryleneaminoalkylene and alkyleneaminoarylene. 
     The C group is a hydroxybenzophenone group having the formula ##STR2## 
     I is the same substituent as listed above and is present in all positions of the benzenoid rings except the carbon atom attached to the B group connecting the A and C moieties. The B connecting group is attached to the benzenoid ring in the ortho, meta or para position from the carbonyl group of the benzophenone. The I substituents can all be one of the substituents listed above or different listed substituents. 
     Suitable heterocyclic A groups having the structure ##STR3## are, for example substituted and unsubstituted benzoxazoles, benzothiazoles, indoles and benzimidazoles. 
     Examples of suitable benzoxazoles are those benzoxazoles having the formula ##STR4## such as 4-(5,6-dimethyl-2-benzoxazolyl)phenyl, 4-(2-benzoxazolyl)-2-chlorophenyl, 3-(5-chloro-2-benzoxazolyl)phenyl. 
     Examples of suitable benzothiazoles are those having the formula ##STR5## such as 4-(5,6-dimethyl-2-benzothiazolyl)phenyl, 4-(2-benzothiazolyl)-2-chlorophenyl, 3-(5-chloro-2-benzothiazolyl)phenyl. 
     Examples of suitable benzimidazoles are those having the formula ##STR6## wherein Q is hydrogen or lower alkyl group containing 1 to 12 carbon atoms or aryl group or substituted aryl group having 6 to 18 carbon atoms. Such suitable benzimidazole moieties are, for example, 4-(5,6-dimethyl-2-benzimidazolyl)phenyl, 4-(2-benzimidazolyl)-2-chlorophenyl, 3-(5-chloro-2-benzimidazolyl)phenyl, 4-(1-methyl-2-benzimidazolyl)phenyl, 4-(1-ethyl-5-chloro-2-benzimidazolyl)phenyl. 
     Examples of suitable indole moieties are those having the formula ##STR7## wherein Q is hydrogen or lower alkyl group containing 1 to 12 carbon atoms or aryl group or substituted aryl group having 6 to 18 carbon atoms. Such suitable indole moieties are, for example, 3-(1-ethyl-5-cyano-2-indolyl)phenyl, 3-(5-chloro-2-indolyl)phenyl, 3-(1-methyl-2-indolyl)phenyl, 3-(5-methyl-2-indolyl)phenyl, 3-(1-methyl-2-indolyl)phenyl, 3-(5-methyl-2-indolyl)phenyl, 3-(5-chloro-2-indolyl)-phenyl, 3-(5-acetamido-2-indolyl)phenyl, 3-(2-indolyl)phenyl, 4-(1-ethyl-2-indolyl)phenyl, 4-(5-cyano-2-indolyl)phenyl, 4-(5-methyoxy-2-indolyl)phenyl, 4-(1-methyl-2-indolyl)phenyl, 4-(5-methyl-5-phenyl-2-indolyl)phenyl, 4-(4,5-dichloro-2-indolyl)phenyl, 4-(2-indolyl)phenyl. 
     Suitable B groups are for example alkylene, arylene, carbonyloxy, oxycarbonylalkyleneoxy such as oxycarbonylmethyleneoxy, oxycarbonylethleneoxy, oxycarbonyl-1,4-butanediyloxy, oxycarbonyl, alkyleneoxycarbonyloxy such as methyleneoxycarbonyloxy, ethyleneoxycarbonyloxy, 1,4-butanediyloxycarbonyloxy, 1,5-pentanediyloxycarbonyloxy, oxycarbonyloxy, alkyleneoxy such as methyleneoxy, ethyleneoxy, 1,3-propanediyloxy and the like, alkyleneoxyalkyleneoxy such as methyleneoxymethyleneoxy, ethyleneoxyethyleneoxy, methyleneoxyethyleneoxy, ethyleneoxymethyleneoxy and the like, oxyalkyleneoxy such as oxymethyleneoxy, oxyethyleneoxy, oxy-1,4-butanediyloxy and the like, thio, thioalkyleneoxy such as thiomethyleneoxy, thioethyleneoxy and the like, sulfinyldioxy, oxy(alkoxy)phosphinooxy such as oxy(methoxy)phosphinooxy, oxy(ethoxy)phosphinooxy, oxy(butoxy)phosphinooxy and the like, alkyloxyphosphinylidene such as methoxyphosphinylidene, butoxyphosphinylidene,, and the like, aryloxyphosphinylidene such as phenoxyphosphinylidene, naphthoxyphosphinylidene, 3-methylphenoxyphosphinylidene, and the like, oxy(alkyl)phosphinyloxy such as oxy(methyl)phosphinyloxy, oxy(propyl)phosphinylidene, oxy(hexyl)phosphinylidene and the like, aminocarbonyl, N-alkylaminocarbonyl such as N-methylaminocarbonyl, N-ethylaminocarbonyl, N-butylaminocarbonyl and the like, N-arylaminocarbonyl such as N-phenylaminocarbonyl, N-(3-methylphenyl)aminocarbonyl and the like, aminocarbonylalkyleneoxy such as aminocarbonylmethyleneoxy, aminocarbonyl-1,4-butanediyloxy, N-methylaminocarbonylmethyleneoxy, N-phenylaminocarbonylethylenoxy and the like, aminocarbonylamine, alkylaminocarbonylamino such as N-methylaminocarbonylamino, N-ethylaminocarbonylamino and the like, di(N-alkylamino)carbonyl such as N-methylaminocarbonyl-N&#39;-methylamino, N-ethylaminocarbonyl-N&#39;-methylamino, N-ethylaminocarbonyl-N&#39;-butylamino and the like, N-arylaminocarbonylamino such as N-phenylaminocarbonylamino, N-(3-methylphenyl)-aminocarbonylamino, N-arylaminocarbonyl-N&#39;-arylamino, such as N-phenylaminocarbonyl-N&#39;-phenylamino, N-alkylaminocarbonyl-N&#39;-arylamino such as N-methylaminocarbonyl-N&#39;-phenylamino and the like, N-arylaminocarbonyl-N&#39;-alkylamino such as N-phenylaminocarbonyl-N&#39;-methylamino or N-methylaminocarbonyl-N&#39;-phenylamino and the like, amino, alkyleneamino such as methyleneamino, 1,4-butanediylamino, 1,5-pentanediylamino, and the like, aryleneamino such as phenyleneamino and the like, N-alkylaminoalkenoxy such as N-methylaminomethyleneoxy, N-ethylaminomethyleneoxy and the like, N-arylaminoalkyleneoxy such as N-phenylaminomethyleneoxy, N-phenylaminoethyleneoxy and the like, oxyalkyleneaminoalkyleneoxy such as oxymethyleneaminomethyleneoxy, oxymethyleneaminoethyleneoxy and the like, alkyleneaminocarbonylamino such as methyleneaminocarbonylamino, ethyleneaminocarbonylamino and the like, oxyalkylene(N-alkyl)aminoalkyleneoxy such as oxymethylene(N-methyl)aminomethyleneoxy and the like, alkyleneaminoalkylene such as methyleneaminomethylene, ethyleneaminoethylene and the like, aryleneaminoarylene such as phenyleneaminophenylene and the like, aryleneaminoalkylene such as phenyleneaminomethylene and the like, alkyleneaminoarylene such as methyleneaminophenylene and the like. 
     wherein C is a hydroxybenzophenone group having the formula ##STR8## are for example, hydroxybenzophenones, 2-hydroxybenzophenone, 2,4-dihydroxy-4&#39;-methylbenzophenone, 2&#39;,4-dihydroxy-3,5-diisopropylbenzophenone, 5-chloro-2,4-dihydroxybenzophenone, 2,3&#39;-dihydroxybenzophenone, 2,5-dihydroxybenzophenone, 4-amino-2-hydroxybenzophenone, 2,2&#39;-dihydroxybenzophenone, 2-hydroxy-4&#39;methoxybenzophenone, 2-hydroxy-4&#39;-octyloxybenzophenone, 2,2&#39;,4-trihydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone. 
     The heterocyclic compositions can be added to organic compositions which are susceptible to ultraviolet degradation. Such compositions include, for example, polymeric compositions such as polyester fiber and molding compositions, such as polyethylene terephthalate, polymethylene terephthalate and the like; polyolefins such as, for example, high, medium and low density polyethylene, polypropylene, polybutene and the like; polyamides such as N-methoxymethyl polyhexamethylene adipamide and the like; polycarbonates; polyvinyl chlorides and copolymers; cellulose esters; acrylic/butadiene/styrene plastic; polyacrylics such as methyl methacrylate; polystyrene; gelatin; vinylidene chloride copolymers such as vinylidene chloride/vinyl acetate copolymers; ethylene vinyl acetate copolymers; cellulose ethers such as methyl cellulose; polyvinyl esters such as polyvinyl acetate; polyethylene oxide; polyvinyl acetals; polyformaldehydes; and polyurethanes. Such compositions also include natural and synthetic rubbers, such as polybutadiene, and unsaturated organic compositions such as oils and the like, as well as compositions containing such organic compositions. 
     The multichromophoric compositions, as effective ultraviolet stabilizers or screening agents, are generally used in an amount of from 0.01 to 10%, by weight, based on the weight of the organic material to which they are added. While a detectable amount of ultraviolet screening and stabilization may be obtained with amounts less than 0.01%, this amount of stabilization or screening would be of little practical utility in a commercial application. Moreover, while amounts greater than 10%, by weight, provide effective ultraviolet stability and screening, such concentrations are undesirable because of cost and the deleterious effect which such concentrations may have on the mechanical properties of the organic composition in which the stabilizer is incorporated. Preferably, the stabilizer is used in an amount of from about 0.1 to about 3%, by weight. For example, an amount of 2%, by weight, of the stabilizer effectively stabilizes cellulose acetate butyrate plastic compositions. 
     The ultraviolet stabilized organic compositions of the present invention may also contain other additives, pigments, colorants, stabilizers and the like. For example, polymeric compositions, such as polyolefins, may also contain and generally do contain other additives such as white or colored pigments or colorants, antioxidants, plasticizers, flow aids, processing aids, polymeric modifiers and the like. 
     These novel multichromophoric ultraviolet stabilizers may be incorporated into organic compositions by melt-blending or may be added onto the surface of an organic plastic material prior to being molded into a suitable object. These materials can also be added to coatings and the like which can be applied to the surface of a molded object. 
    
    
     This invention will be further illustrated by the following examples although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention. 
     EXAMPLE 1 
     Preparation of 4-(2-[4-(2-benzoxazolyl)phenoxy]ethoxy)-2-hydroxybenzophenone (I). Equal molar quantities of p-hydroxybenzaldehyde and o-aminophenol in excess nitrobenzene was refluxed for five hours. The nitrobenzene was removed and the residue was washed with hot xylene. 2-(4-Hydroxyphenyl)benzoxazole was obtained by crystallization from ethanol in 64% yield (m.p. 253°). A mixture of the sodium salt of 2-(4-hydroxyphenyl)benzoxazole (0.01 mole) and 4-(2-bromoethoxy)-2-hydroxybenzophenone (0.01 mole) in 250 ml of ethanol was refluxed for 20 hours. The reaction mixture was cooled, 200 ml. of water was added and the product, I, was filtered out. Other multichromophoric compounds can be prepared by substitution of other benzoxazoles for 2-(p-hydroxyphenyl)benzoxazole. 
     Other novel multichromophoric compounds can be prepared by substitution of other benzoxazoles for 2-(p-hydroxyphenyl)benzoxazole such as 2-(o-hydroxyphenyl)benzoxazole, 2-(m-hydroxyphenyl)benzoxazole, 2-(3-chloro-4-hydroxyphenyl)benzoxazole, 2-(3-methyl-4-hydroxyphenyl)benzoxazole, 2-(3,5-dimethyl-4-hydroxyphenyl)benzoxazole, 2-(3,5-dichloro-4-hydroxyphenyl)benzoxazole, 2-(3,5-dimethoxy-4-hydroxyphenyl)benzoxazole, 2-(2-chloro-4-hydroxy)benzoxazole, 2-(2,6-dichloro-4-hydroxyphenyl)benzoxazole and 2-(2,6-dimethyl-4-hydroxyphenyl)benzoxazole. 
     This example hereinabove shows the B linking group as an oxyalkyleneoxy group. Other B linking groups can be provided as known in the art as for example: 
     1. an oxycarbonylalkyleneoxy by esterification of an acid or acid chloride with an alcohol or phenol in alkaline medium; 
     2. an oxycarbonyloxy by the reaction of phosgene with alcohol or phenol in alkaline medium; 
     3. an alkyleneoxy by the reaction of halide with alkali salt of alcohol or phenol; 
     4. an alkyleneoxyalkyleneoxy by the reaction of halide with alkali salt of alcohol or phenol; 
     5. a sulfinyldioxy by the reaction of thionyl chloride with alcohol or phenol in alkaline solution; 
     6. a thio by the reaction of a sodium sulfide with a halide; 
     7. an oxy(alkoxy)phosphinoxy by the reaction of a dichlorophosphite with phenol in the presence of a base; 
     8. alkyl(or aryl)oxyphoshinylidene by the reaction of a halophosphate with phenol or alcohol; 
     9. oxy(alkyl)phosphinyloxy by the reaction of a phosphonyl chloride with phenol or alcohol: 
     10. an N-alkyl or N-arylaminocarbonyl by the reaction of an acid chloride with an amine; 
     11. an N-alkyl or N-arylaminocarbonylalkoxy by the reaction of an acid chloride with an amine; 
     12. an N-alkyl or N-arylaminocarbonylamino by the reaction of phosgene with an amine; 
     13. an N-alkyl or N-arylaminoalkylene by the reaction of an alkyl halide with an amine; 
     14. an N-alkyl or N-arylaminoalkyleneoxy by the reaction of an oxyalkyl halide with an amine. 
     EXAMPLE 2 
     Preparation of 4-(2-[4-(2-benzothiazolyl)phenoxy]ethoxy)-2-hydroxybenzophenone (II). 
     A hot solution of 16 g. of zinc, o-aminophenylmercaptide and 12.5 g. of p-hydroxybenzaldehyde in 1 l. of acetic acid was treated with hydrogen sulfide for two hours, filtered hot, diluted with an equal volume of water and cooled. 2-(p-Hydroxyphenyl)benzothiazole (47% yield, m.p. 227°-229° F.) was obtained. The 2-(p-hydroxyphenyl)benzothiazole was reacted with 4-(2-bromoethoxy)-2-hydroxybenzophenone as in Example 1 to produce 4-(2-[4-(2-benzothiazolyl)phenoxy]ethoxy)-2-hydroxybenzophenone. 
     Other more multichromophoric compounds can be prepared by substitution of other benzothiazoles for 2-(p-hydroxyphenyl)benzothiazole such as 2-(o-hydroxyphenyl)benzothiazole, 2-(m-hydroxyphenyl)benzothiazole, 2-(3-chloro-4-hydroxyphenyl)benzothiazole, 2-(3-methyl-4-hydroxyphenyl)benzothiazole, 2-(3,5-dimethyl-4-hydroxyphenyl)benzothiazole, 2-(3,5-dichloro-4-hydroxyphenyl)benzothiazole, 2-(3,5-dimethoxy-4-hydroxyphenyl)benzothiazole, 2-(2-chloro-4-hydroxy)benzothiazole, 2-(2,6-dichloro-4-hydroxyphenyl)benzothiazole and 2-(2,6-dimethyl-4-hydroxyphenyl)benzothiazole. 
     EXAMPLE 3 
     Preparation of 4-{2-[4-(I-ethyl-2-benzimidazolyl)phenoxy]ethoxy}-2-hydroxybenzophenone (III). 
     N,N&#39;-Bis(p-propoxybenzoyl)-o-phenylenediamine (m.p. 196° C.) [prepared in 86% yield from p-propoxybenzoyl chloride and o-phenylenediamine] was heated (200° C.) for four hours with concentrated hydrochloric acid. Mixture was cooled, neutralized with sodium bicarbonate and filtered. Recrystallization from ethanol gave 2-(p-hydroxyphenyl)benzimidazole (Yield 76%, m.p. 286°-288° C.). A well stirred mixture of 2-(p-hydroxyphenyl)benzimidazole (0.1 mole), iodoethane (0.1 mole) and sodium bicarbonate (0.12 mole) in 200 ml of acetone was refluxed overnight, filtered and the acetone removed on the steam bath. The isolated 2-(p-hydroxyphenyl)-1-methylbenzimidazole was reacted with 4-(2-bromoethoxy)-2-hydroxybenzophenone as in Example 1 to produce 4-{2-[4-(1-ethyl-2-benzimidazolyl)phenoxy]ethoxy}-2-hydroxybenzophenone. 
     Other novel multichromophoric compounds can be prepared by substitution of other benzimidazoles for 2-(p-hydroxyphenyl)-1-ethyl benzimidazole such as 2-(o-hydroxyphenyl)-1-methylbenzimidazole, 2-(m-hydroxyphenyl)-1-methylbenzimidazole, 2-(p-hydroxyphenyl)-1-phenylbenzimidazole, 2-(o-hydroxyphenyl)-1-phenylbenzimidazole, 2-(m-hydroxyphenyl)-1-phenylbenzimidazole, 2-(3,5-dichloro-4-hydroxyphenyl)-1-ethylbenzimidazole, 2-(3,5-dichloro-4-hydroxyphenyl)-phenylbenzimidazole, 2-(3-chloro-4-hydroxyphenyl)-1-ethylbenzimidazole, 2-(3,5-dimethoxy-4-hydroxyphenyl)-1-methylbenzimidazole, 2-(3,5-dimethoxy-4-hydroxyphenyl)-1-phenylbenzimidazole and 2-(2-chloro-4-hydroxyphenyl)-1-ethylbenzimidazole. 
     EXAMPLE 4 
     Preparation of 4-{2-[4-(1-ethyl-2-indolyl)phenoxy]ethoxy}-2-hydroxybenzophenone (IV). 
     4-Hydroxyacetophenone phenylhydrazone (47 g.) was fused with 250 g. zinc chloride (10 min. at 180° C.), poured into 3 l. 0.3 HCl, heated and stirred for 1 hour on the steam bath, cooled to 0° and filtered. The precipitate was extracted with pet. ether and allowed to stand. 2-(p-hydroxyphenyl)indole (17 g., m. 224°-229°) was isolated. A well stirred mixture of 2-(p-hydroxyphenyl)indole (0.1 mole), iodoethane (0.1 mole) and sodium bicarbonate (0.12 mole) in 200 ml. of acetone was refluxed overnight, filtered and the acetone removed on the steambath. The isolated 2-(p-hydroxyphenyl)-1-ethylindole was reacted with 4-(2-bromoethoxy)-2-hydroxybenzophenone as in Example 1 to produce 4-{2-[4-(1-ethyl-2-indolyl)phenoxy]ethoxy}-2-hydroxybenzophenone. 
     Other novel multichromophoric compounds can be prepared by substitution of other indoles for 2-(p-hydroxyphenyl)-1-ethylindole such as 2-(o-hydroxyphenyl)-1-ethylindole, 2-(m-hydroxyphenyl)-1-ethylindole, 2-(p-hydroxyphenyl)-1-phenylindole, 2-(o-hydroxyphenyl)-1-phenylindole, 2-(3,5-dimethyl-4-hydroxyphenyl)-1-ethylindole, 2-(3,5-dimethyl-4-hydroxyphenyl)-1-phenylindole, 2-(3,5-dichloro-4-hydroxyphenyl)-1-ethylindole, 2-(3,5-dichloro-4-hydroxyphenyl)-1-phenylindole, 2-(3,5-dimethoxy-4-hydroxyphenyl)-1-ethylindole, 2-(3,5-dimethoxy-4-hydroxyphenyl)-1-phenylindole, 2-(2-chloro-4-hydroxyphenyl)-1-ethylindole, 2-(2-methyl-3-hydroxyphenyl)-1-ethylindole, 2-(2-hydroxy-4-methylphenyl)-1-ethylindole and 2-(2-hydroxy-4-chlorophenyl)-1-ethylindole. 
     EXAMPLE 5 
     The ultraviolet stabilization provided by the heterocyclic compound of the present invention is shown for poly(tetramethylene terephthalate) in Table 1. 
     A dry mixture of the stabilizer and granulated poly(tetramethylene terephthalate) were extruded into 1/16-inch diameter rods, pelletized and injection molded into 21/2×1/2×1/16-inch flat bars; these flat bars were exposed to a 280-700 mm. mercury lamp source until a flatwise impact strength of less than 6 was obtained (initial values were all &gt;17). 
     The text results are summarized in Table 1. 
     
                       TABLE 1                                                     
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Effectiveness of Ultraviolet Stabilizers in                               
Poly(tetramethylene terephthalate)                                        
Compound  FWIS (Flatwise Impact Strength                                  
(0.5%)    Initial     300 hr.     300 hr.                                 
______________________________________                                    
none      20           3           1                                      
I         17          15          19                                      
II        19          19          12                                      
III       17          19          19                                      
IV        17          16          11                                      
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     These multichromophoric compositions find particular utility as ultraviolet stabilizers in organic compositions requiring ultraviolet stability. Such compositions include polymeric compositions such as, for example, polyester fiber and molding compositions, poly-α-olefins, polyamides, acrylics, cellulose esters and the like, as well as molded or shaped articles, film and coatings formed from such materials and the like. Such compositions also include natural and synthetic rubbers, such as natural rubber, as well as organic materials such as oils, fats, and unsaturated organic materials and materials having such materials contained therein such as paints, varnishes, cosmetics and the like. 
     The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.