BIS-STYRYLBIPHENYL COMPOUNDS

Abstract: Asymmetrical bis-styrylbiphenyl compounds of formula (1) wherein R1 to R6 are as defined in claim 1, are excellently suitable as optical brighteners, for example for polyesters in the spinning melt.

Description: Bis-styrylbiphenyl compounds The present invention relates to novel asymmetrical bis-styrylbiphenyl compounds, to a process for their preparation and to their use as optical brighteners, in particular for polyester spinning melts. Bis-styrylbiphenyl compounds which are suitable as optical brighteners are already known, e.g. from GB-A-1 , 247,934 which also discloses processes for their preparation. However, those processes provide almost exclusively symmetrical compounds, i.e. compounds which carry the same substituents in the same positions at the terminal phenyl radicals. The preparation of asymmetrical bis-styrylbiphenyl compounds is described only in admixture with symmetrical compounds from which they must be separated by elaborate measures, e.g. by recrystallisation. Naturally, the resulting yield of asymmetrical compounds is unsatisfactory. A process has now been found for the preparation of asymmetrical bis-styrylbiphenyl compounds which provides them in high yields and good purity. When used as optical brighteners in polyester spinning melts, the bis-styrylbiphenyl compounds obtained surprisingly have improved whiteness compared to the corresponding symmetrical compounds. Accordingly, this invention relates to asymmetrical bis-styrylbiphenyl compounds of formula wherein R, and R 2 are each independently of the other hydrogen, cyano, halogen, hydroxy, alkyl, cycloalkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyioxy, aryl oraralkyl, wherein R, and R are not both hydrogen at the same time and which substituents are different if they are in the same position of the phenyl ring, and R 3 , R , R5 and R 6 are each independently of one another hydrogen, halogen, alkyl, cycloalkyl or alkoxy. Preferred compounds of this invention correspond to formula wherein Ri and R 2 are each independently of the other hydrogen, cyano, halogen, hydroxy, alkyl, cycloalkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl, at least one of which substituents is not hydrogen, and R3, R , s and R 6 are each independently of one another hydrogen, halogen, alkyl or alkoxy. Preferred meanings of R1 and R 2 are independently of each other cyano, chloro, hydroxy, C C 4 alkyl, C C 4 alkoxy or phenyl. R 3 to R 6 are preferably each independently of one another hydrogen, chloro, C C 4 alkyl or C r C 4 alkoxy. In particularly preferred compounds of formula (1) or (2), all of these substituents are hydrogen. Halogen is fluoro, bromo, iodo or, preferably, chloro. The alkyl groups in the alkyl, alkoxy, alkoxycarbonyl, alkylcarbonyloxy and aralkyl radicals contain, for example, 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms and, most preferably, 1 to 4 carbon atoms. In the optical brighteners of formulae (1) and (2), alkyl is preferably C C alkyl, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl. Cycloalkyl is preferably Cs-C^ycloalkyl, more preferably cyclohexyl. Alkoxy preferably means C C 4 alkoxy, for example methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, isobutoxy and tert-butoxy. Aryl is, for example, naphthyl or, preferably, phenyl, and these radicals can be substituted, for example by alkyl, alkoxy, sulfo, carboxy, halogen or alkoxycarbonyl. Aralkyl preferably means C C 4 alkylenephenyl, more preferably benzyl. Very particularly preferred novel compounds correspond to formula wherein R is hydrogen, cyano, halogen, hydroxy, alkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl. Of these compounds, those are particularly preferred, wherein Rt is C 1 -C 2 alkyl, CrC-salkoxy, cyano or phenyl. The compounds of formula (1 ) are prepared, for example, by reacting 1 mole of a dialdehyde of formula FL R 5 R 6 wherein R 3 , R . Rs and R 6 are each independently of one another hydrogen, halogen, alkyl or alkoxy, with 1 mole of a compound of formula O wherein R T is hydrogen, cyano, halogen, hydroxy, alkyl, cycloalkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl, and R 7 and R 8 are alkyl, cycloalkyl, aryl or aralkyl, to give an intermediate of formula R„ R„ and then reacting this intermediate with 1 mole of a compound of formula O wherein R 2 is hydrogen, cyano, halogen, hydroxy, alkyl, cycloalkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl, and R 7 and R 8 are alkyl, cycloalkyl, aryl or aralkyl, wherein Ri and R 2 are not both hydrogen at the same time and which substituents are different if they are in the same position of the phenyl ring, to give a compound of formula (1). R 7 and R 8 are preferably Cι-C 4 alkyl, phenyl or benzyl. In particularly preferred compounds of formula (5) and (7) these substituents are d-Caalkyl. The compounds (4), (5) and (7) are known or can be prepared in a manner known per se. The reaction of a compound of formula (4) with a compound of formula (5) and the reaction of an intermediate of formula (6) with a compound of formula (7) are carried out in the presence of a strongly basic compound. Such strongly basic compounds are for example: alkali metal hydroxides, alkali metal amides, alkali metal carbonates, alkali metal hydrogen- carbonates or alkali metal alcoholates, in particular the lithium, potassium or sodium compounds. The potassium or sodium alcoholates of aliphatic C 1 -C 4 alcohols are particularly preferred. The solvent used for the reaction of a compound of formula (4) with a compound of formula (6) is a solvent which is inert towards the reactants, preferably an aliphatic alcohol and, more preferably, a CrC 6 alcohol. Suitable are, for example, methanol, ethanol, n-propanol, isopro- panol, butan-1-ol, butan-2-ol, tert-butanol, pentan-1-ol and hexan-1-ol. Of these, methanol is preferred. The reaction temperature is usually in the range from room temperature to the boiling temperature of the solvent. It is preferred to work at about 20 to 80° C, more preferably at 30 to 70° C. The reaction time depends, inter alia, on the kind of reactants used and on the reaction temperature. The temperature is usually in the range from 2 to 48 hours. After the reaction is complete, the reaction mixture is worked up in customary manner and the compounds of formula (6) are isolated, if desired, e.g. by evaporation or by filtration if they are insoluble in the solvent used. The intermediates of formula wherein Ri is hydrogen, cyano, halogen, hydroxy, alkyl, cycloalkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl, and R3, R 4 , R 5 and R 6 are each independently of one another hydrogen, halogen, alkyl or alkoxy, at least one of the substituents R 3 , R 4 , R5 and R 6 not being hydrogen, are novel and are also an object of this invention. To react a compound of formula (6) with a compound of formula (7) an aprotic solvent is used which is inert towards the reactants and in which the compound of formula (6) is at least partially soluble. It is possible to use e.g. dimethylformamide, diethylformamide, di- methylacetamide, dimethylsulfoxide and N-methylpyrrolidone. The reaction temperature is usually in the range from room temperature to the boiling temperature of the solvent. It is preferred to work at about 20 to 80° C, more preferably at 20 to 40° C. The reaction time depends, inter alia, on the kind of reactants used and on the reaction temperature and is generally in the range from 2 to 48 hours. After the reaction is complete, the reaction mixture is worked up in customary manner and the compound of formula (1) is isolated, e.g. by evaporation or by filtration if it is insoluble in the solvent used. The compounds of formula (1) have marked fluorescence in the dissolved or finely divided state. They can thus be used for optically brightening a range of materials, in particular organic materials. This invention thus also relates to the use of the compounds of formula (1 ) for optically brightening organic materials, and to organic materials comprising at least one compound of formula (1), as well as to a process for optically brightening organic materials, which process comprises incorporating into, or applying to, these materials at least one compound of formula (1). The organic materials which can be brightened according to this invention by means of compounds of formula (1) include synthetic, semi-synthetic or natural, especially polymeric, materials. Suitable materials are, for example, a) polymerisation products based on organic compounds containing at least one polyme- risable carbon-carbon double bond, for example polymers based on unsaturated carboxylic acids or derivatives thereof (such as acryl esters, acrylic acids, acrylonitrile and their derivatives), on olefin hydrocarbons (such as ethylene, propylene, styrene) or on vinyl compounds or vinylidene compounds (such as vinyl chloride, vinyl alcohol, vinylidene chloride); b) polymerisation products which are obtainable by ring-opening, for example polyamides of the caprolactam type, and also polymers which are obtainable both via polyaddition and via polycondensation, such as polyethers or polyacetals; c) polycondensates, such as polyesters, polyamides, melamine resins or polycarbonates; d) polyaddition products, such as polyurethanes, or e) semi-synthetic materials, such as cellulose ester, cellulose ether, regenerated cellulose. The novel compounds are particularly preferably used for optically brightening polyesters, in particular polyethylene glycol terephthalate, in the spinning melt, since they do not decompose at the required temperatures. Surprisingly, the novel asymmetrical compounds of formula (1) have a higher degree of whiteness on the cited materials than the corresponding symmetrical compounds. They are furthermore distinguished by particularly good fastness to sublimation. The following Examples illustrate the invention in more detail. Parts and percentages are by weight and temperatures are given in degrees Celsius. Example 1 : 4-r2-(4 ' -FormylH .1 ' -biphenyl -vOethenyllbenzonitrile 3.15 g (15 mmol) of 4,4 ' -biphenyldialdehyde are suspended in 100ml of methanol at room temperature. A solution of 1.62 g (30 mmol) of sodium methylate in 4.7 ml of methanol is added dropwise to this suspension over 10 minutes, and this mixture is then heated to 40° C. A solution of 3.38 g (15mmol) of 4-(dimethoxyphosphonomethyl)benzonitrile in 16 ml of methanol is then added dropwise over 30 minutes. After the addition is complete, the reaction mixture is allowed to cool to room temperature and is then stirred for another 20 hours at room temperature. The precipitated solid is subjected to filtration, washed with 2 x 50 ml of methanol and once with 50 ml of hexane and is then dried at 80° C under vacuum. This yields 3.89 g (12.6 mmol) of the compound of formula 2.5 g of this compound are recrystallised in 50 ml of 1 ,2-dichlorobenzene. The mixture is heated until the solid is completely dissolved and is then cooled and charged with 1.5 g of tonsil. This mixture is refluxed and subjected to hot filtration. The filtrate is again refluxed and is then cooled in an oil bath. This yields 1.18 g of the analytically pure compound of the above formula. 1 H-NMR spectrum: (360 MHz, [D 6 ]DMSO): δ = 7.4 (d); 7.6 (m); 7.8 (m); 8.0 (AA ' XX ' ); 10.1 (s) Example 2: 2-r2-(4 ' -Formviπ .1 ' -biphenyll-4-yl)ethenyllbenzonitrile 3.15 g (15mmol) of 4,4 ' -biphenyldialdehyde are suspended in 100 ml of methanol at room temperature. A solution of 1.62 g of sodium methylate in 4.7 ml of methanol is added drop- wise to this suspension over 10 minutes, and this mixture is then heated to 40° C. A solution of 3.38 g (15 mmol) of 2-(dimethoxyphosphonomethyl)benzonitrile in 16 ml of methanol is added dropwise over 30 minutes at this temperature. After the addition is complete, the reaction mixture is allowed to cool to room temperature and is stirred for another 20 hours at room temperature. The precipitated solid is subjected to filtration, washed with 2 x 50 ml of methanol and once with 50 ml of hexane and is then dried at 80°C under vacuum. This yields 3.2 g (10.3 mmol) of the compound of formula 2.2 g of this compound are recrystallised in 40 ml of chlorobenzene. The mixture is heated until the solid is completely dissolved and is then cooled and charged with 0.5 g of tonsil. The mixture is refluxed and subjected to hot filtration. The filtrate is again refluxed and is then cooled in an oil bath. This yields 1.25 g of the analytically pure compound of the above formula. 1 H-NMR spectrum: (360 MHz, [D β ]DMSO): δ = 7.4 - 8.1 (m); 10.1 (s) Example 3: 2.4 ΪH .1 ' -Biphenyll-4.4 ' -diyldi-2.1 -ethenedivDbisbenzonitrile 46.41 g (0.15 mol) of 4-[2-(4 ' -formyl[1 ,1 ' -biphenyl]-4-yl)ethenyl]benzonitrile, obtained according to Example 1 , and 37.16 g (0.165 mol) of 2-(di-methoxyphosphonomethyl)ben- zonitrile are suspended in 400 ml of N.N-dimethylformamide. A solution of 10.80 g of sodium methylate in 32 ml of methanol is added dropwise to this suspension over 60 minutes. A beige to brown suspension is obtained which is stirred for another 3 hours at room temperature. After adding 150 ml of methanol, the mixture is stirred for 10 minutes and the pre- cipated solid is subjected to filtration. The filtrate is washed with 2 x 25 ml of water and then with 2 x 50 ml of methanol and dried at 80° C under vacuum. This yields 53.83 g of the compound of formula 48.83 g of this compound are recrystallised in 500 ml of 1 ,2-dichlorobenzene. The mixture is heated until the solid is completely dissolved and is then cooled and charged with 3.0 g of tonsil. This mixture is refluxed and subjected to hot filtration. The filtrate is again refluxed and is then cooled in an oil bath. This yields 41.5 g of the analytically pure compound of the above formula. 1 H-NMR spectrum, (360 MHz, [D 6 ]DMSO): δ = 7.44 (m); 7.53 (d); 7.64 (d); 7.75 - 8.05 (m); 8.15 (d) Example 4: 3,4'-(H , 1 '-Biphenvn-4.4'-diyldi-2, 1 -ethenedivObisbenzonitrile late Under a weak stream of nitrogen, 4.64g (0.015mol) of 4-[2-(4'-formyl[1 ,1 ' -biphenyl]-4-yl)- ethenyljbenzonitrile, obtained according to Example 1 , and 4.39g (0.0165mol) of 3-(dimeth- oxyphosphonomethyl)benzonitrile are suspended in 40ml of N,N-dimethylformanπide. A solution of 3.6 g (0.02mol) of sodium methylate 30% is then added dropwise to this suspension over 25 minutes. This mixture is stirred for four hours at room temperature and then for another hour at 50°C. After allowing the mixture to cool, 25ml of methanol are added. After filtration, the product is washed with methanol and water and then dried at 70°C under vacuum. This yields 4.9g of the product in the form of pale yellow crystals. Example 5: 2.3'-(f 1.1 '-Biphenyl1-4.4'-diyldi-2.1 -ethenedivhbisbenzonitrile ate Under a weak stream of nitrogen, 4.64g (0.015mol) of 2-[2-(4 ' -formyl[1 ,1 ' -biphenyl]-4-yl)- ethenyljbenzonitrile, obtained according to Example 2, and 4.39g (0.0165mol) of 3-(dimeth- oxyphosphonomethyl)benzonitrile are suspended in 40ml of N,N-dimethylformamide. A solution of 3.6 g (0.02mol) of sodium methylate 30% is added dropwise to this suspension over 25 minutes. This mixture is stirred for five hours at room temperature and then for another hour at 50°C. After allowing the mixture to cool, 35ml of methanol are added and the product is subjected to filtration, washed with methanol and water and then dried at 70°C under vacuum. This yields 4.45g of the product in the form of pale yellow crystals.

Claims: What is claimed is 1. A bis-styrylbiphenyl compound of formula R, wherein R, and R 2 are each independently of the other hydrogen, cyano, halogen, hydroxy, alkyl, cycloalkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl, wherein R, and R 2 are not both hydrogen at the same time and which substituents are different if they are in the same position of the phenyl ring, and R 3 . R 4 . Rs and R 6 are each independently of one another hydrogen, halogen, alkyl, cycloalkyl or alkoxy. 2. A compound according to claim 1 of formula R_ R. wherein R, and R 2 are each independently of the other hydrogen, cyano, halogen, hydroxy, alkyl, cycloalkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl, at least one of which substituents is not hydrogen, and R 3 . R . Rs and R 6 are each independently of one another hydrogen, halogen, alkyl or alkoxy. 3. A compound according to either claim 1 or claim 2, wherein Ri and R 2 are each independently of the other cyano, chloro, hydroxy, C C 4 alkyl, CrC 4 - alkoxy or phenyl. 4. A compound according to any one of claims 1 to 3, wherein R 3 to R 6 are each independently of one another hydrogen, chloro, C 1 -C 4 alkyl or C C 4 alkoxy. 5. A compound according to any one of claims 1 to 4, wherein R 3 to R 6 are each hydrogen. 6. A compound according to claim 1 of formula wherein R T is hydrogen, cyano, halogen, hydroxy, alkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl. 7. A compound according to claim 6, wherein Ri is CrC 2 alkyl, Cι-C 2 alkoxy, cyano or phenyl. 8. A process for the preparation of the compound of formula (1) according to claim 1 , which comprises reacting 1 mole of a dialdehyde of formula wherein R3. R , Rs and R 6 are each independently of one another hydrogen, halogen, alkyl or alkoxy, with 1 mole of a compound of formula wherein R ! is hydrogen, cyano, halogen, hydroxy, alkyl, cycloalkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl, and R 7 and R 8 are each alkyl, cycloalkyl, aryl or aralkyl, to give an intermediate of formula and then reacting this intermediate with 1 mole of a compound of formula O wherein R 2 is hydrogen, cyano, halogen, hydroxy, alkyl, cycloalkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl, and R 7 and R 8 are each alkyl, cycloalkyl, aryl or aralkyl, wherein Ri and R 2 are not both hydrogen at the same time and which substituents are different if they are in the same position of the phenyl ring, to give a compound of formula (1 ). 9. A process according to claim 8, which comprises using compounds of formulae (5) and (7), wherein R 7 and R 8 are each C 1 -C 4 alkyl, phenyl or benzyl. 10. A process according to claim 8, which comprises using compounds of formulae (5) and (7), wherein R 7 and R 8 are identical and are each C,-C 2 alkyl. 1 1. A process according to any one of claims 8 to 10, which comprises using a compound of formula (4), wherein R 3 , R 4 , R 5 and R 6 are each hydrogen. 12. An intermediate of formula wherein Ri is hydrogen, cyano, halogen, hydroxy, alkyl, cycloalkyl, alkoxy, carboxy, alkoxycarbonyl, alkylcarbonyloxy, aryl or aralkyl, and R 3 . R , Rs and R 6 are each independently of one another hydrogen, halogen, alkyl or alkoxy, at least one of the substituents R 3 , R 4 , R 5 and R 6 not being hydrogen. 13. Use of the compound of formula (1) according to claim 1 for optically brightening organic materials. 14. An organic material comprising at least one compound of formula (1) according to claim 1. 15. A process for optically brightening organic materials, which comprises incorporating into, or applying to, these materials at least one compound of formula (1 ) according to claim 1.

Inventors: OHREN STEFAN, REINEHR DIETER, OHREN, STEFAN, REINEHR, DIETER
Applicants: CIBA SC HOLDING AG, OHREN STEFAN, REINEHR DIETER, CIBA SPECIALTY CHEMICALS HOLDING INC., OHREN, STEFAN, REINEHR, DIETER
Application year: 2000
Main classification: C07C255
IPC codes: C07C253, C07C255, C08K5, C09B23, C09B57