GB1577127A - Benzotriazole derivatives and their use as optical brightening agents - Google Patents

Description

(54) NOVEL BENZOTRIAZOLE DERIVATIVES AND THEIR USE AS OPTICAL BRIGHTENING AGENTS (71) We, SANDOZ PRODUCTS LIMITED, of Calverley Lane, Horsforth near Leeds, England, a British company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to benzimidizole derivatives of formula 1

where either R1, R2, R3 and R4, independently, are hydrogen, C14alkyl, Cl~4alkoxy, halogen, cyano, carboxy, alkoxy (C14)carbonyl, -CONR6R7, -SO2NR6Rv, -SO2R8, alkyl (C,~4) carbonyloxy, or Alkoxy monosubstituted by phenyl, alkoxy-(C14)carbonyl, cyano, carboxy or -CONR6R7, with the proviso that a maximum of one of R1 and R2 and a maximum of one of R3 and R4 can signify a group selected from cyano, carboxy, alkyl (C14)carbonyloxy, -CONR6R7, -SO2NR6R7 and -SO2R5, or one or both pairs R1 and R2, and R3 and R4, are on adjacent carbon atoms and form a fused benzene ring, any pair not forming a ring being as defined above, R5 is C14alkyl, unsubstituted or mono-substituted by hydroxy, cyano, phenyl, C2~4alkenyl, carboxy, C1-4alkoxycarbonyl or -CONR6R7; or unsubstituted phenyl, R6 and R7, independently, are hydrogen or C1-4alkyl, R8 is C14alkyl, preferably methyl, and X is O or S, which compounds are in free base, acid addition salt or quaternary ammonium salt form.

By"halogen", as used above, is meant chlorine or bromine, chlorine being the preferred halogen.

In the compounds of formula I, R1 and R2 preferably are, independently, hydrogen; C14alkyl; chlorine; or C14alkoxy, unsubstituted or mono-substituted by phenyl, alkoxy(C14)carbonyl, carboxy, cyano or -CONR6R7;or, together, form a fused benzene ring. More preferably one of R1 and R2 is hydrogen or C14alkyl, the other C14alkyl; chlorine; or C14alkoxy, unsubstituted or mono-substituted by phenyl or alkoxy(C14)car- bonyl, any alkyl as R1 or R, preferably being methyl and any unsubstituted alkoxy preferably being C1-2alkoxy, more preferably methoxy. Still more preferably one of R1 and R2 is hydrogen, and most preferably the other is C,~4alkoxy, unsubstituted or monosubstituted by phenyl or alkoxy (C,~4)carbonyl.

Of R3 and R4, preferably one is hydrogen or C1-4alkyl, the other hydrogen, C1-4alkyl, chlorine or -SO2R8, more preferably one being hydrogen, the other being hydrogen or C14alkyl. Again, any alkyl as R3 or R4 is preferably methyl.

Where the R1/R2 or R/R4 bearing is mono substituted, the substituent is preferably in the 5- or 6-position, more preferably in the 6-position, especially for the Rl/R2 bearing ring, and, when di-substituted, one of the substituents is preferably in the 6-position. Preferably the R,/R2 bearing ring is mono or disubstituted, more preferably mono-substituted.

The preferred forms of the compounds of formula I are the acid addition salt and quaternary ammonium salt forms, particularly the latter. Such forms arise from the basic nature of'the heterocyclic nitrogens present both in the benzimidazole and the benzoxazole or benthiazole rings. Whilst it is possible to protonate or quaternise both rings in the compounds of formula I using relatively forcing conditions, it is possible, because of the higher basicity of the benzimidazole ring, to protonate or quaternise this ring alone and, indeed, those acid addition salt and quaternary ammonium salts of the compounds of formula I, wherein only the benzimidazole ring is protonated or quaternised, are preferred.

As examples of quaternising groups may be given C14-alkyl, e.g. methyl, ethyl, isopropyl, n-propyl, n-butyl, C1-4alkyl mono-substituted by phenyl, e.g. benzyl, C1-4alkyl mono-substituted by C1 2alkoxycarbonyl, e.g. -CH2CO2CH3 and -CH2CO2C2H5, C14al- kyl mono-substituted by -CONR6R7, e.g. -CH2CONH2 and -CH2CON(CH3)2, -CH2 CH=CH2, -CH2-C(CH3)=CH2, -CH2COOH and -CH2CN. The anion may be any non-chromophoric anion.

Since the intended use of the compounds is as optical brightening agents, positions of and combinations of substituents which yield compounds having an unduly strong coloured hue should, of course, be avoided.

A particular class of compounds of Formula I are those in which Rl, R2, R3 and R4 are other than C14 alkoxy mono-substituted by phenyl, alkoxy (C14)-carbonyl, cyano, carboxy or -CONR6R1.

The preferred compounds of the invention may be represented by the formula I',

wherein R2' is C14alkyl; chlorine; or C14alkoxy, unsubstituted or mono-substituted by phenyl or alkoxy(C1 4)carbonyl, r and R1, is H or C14alkyl, one of R3' and R4' is hydrogen or C14alkyl, (preferably methyl) and the other is hydrogen, C14alkyl (preferably methyl), chlorine or -SO2CH3, preferably one being hydrogen or methyl, the other being hydrogen, R9 is C1-4alkyl, unsubstituted or mono-substituted by alkoxy(C12)carbonyl, phenyl or -CONR6R7, R5 is as hereinbefore defined and A (3 is a non-chromophoric anion.

Particular groups of preferred compounds of formula 'I' are those in which R1' is hydrogen; one of R3, and R4' is hydrogen and the other is hydrogen, C1-4alkyl, chlorine or -SO2CH3; R9 is C14 alkyl, unsubstituted or mono-substituted by C12 alkoxy-carbonyl and R2' is either (a) C14 alkyl, C14 alkoxy or chlorine or (b) C14 alkoxy mono-substituted by phenyl, alkoxy(C14)-carbonyl; carboxy, cyano or -CONR6R,.

In compounds I', R9 is preferably unsubstituted C14alkyl, more preferably methyl or ethyl. R5, both in compounds I and I', is preferably C14alkyl, unsubstituted or mono-substituted by hydroxy, cyano, phenyl or alkoxy-(C14)carbonyl, more preferably C 4alkyl, unsubstituted or mono-substituted by phenyl or alkoxy-(C 4)carbonyl. In any hydroxy substituted alkyl as R5, the hydroxy group is preferably other than on the a-carbon atom, it preferably being on the carbon atom.

R2, is preferably C1 -4alkoxy, unsubstituted or mono-substituted by phenyl or alkoxy (C1-4)carbonyl, R1' is preferably hydrogen.

X, both in compounds I and I', is preferably 0.

As a further preferred class of compounds of formula I may be given those of formula I",

where R2" is C1 4alkoxy, unsubstituted or mono-substituted by phenyl or alkoxy(C1 4)car- bonyl, more preferably methoxy or alkoxy(C1 2)carbonyl-methoxy, most preferably methoxy, one of R3" and R4" is hydrogen or methyl, the other being hydrogen, R5 is Cm~4, preferably C1~2, alkyl, unsubstituted or mono-substituted by phenyl or alkoxy(Cl~4)carbonyl, and R9'' is C1~4alkyl, preferably methyl or ethyl, and A0 is a non-chromophoric anion R5" in formula I", and R5 in formulae I and I' is most preferably methyl, ethyl, benzyl or alkoxy(C1 2)-carbonyl methyl.

As examples of non-chromophoric anions AO may be given methyl, ethyl and propyl sulphate anions and the chloride, bromide, p-toluene-sulphonate, chlorozincate and benzene-sulphonate anions. As will be appreciated, however, the anion may be any of those conventionally used in the optical brightener art.

The invention also provides a process for the production of compounds of formula I, characterised by a). reacting a compound of formula II,

with a compound of formula III,

where Y is chlorine or bromine, preferably chlorine, or b). oxidising a compound of formula V

wherein either (i) P is -XH and Q is H, and U and T form a direct bond between the atoms to which they are attached, or (ii) P and Q, together, form -X-, and U and T are both hydrogen, in case (i) the compound optionally being in protonised or quaternised form, or (c) obtaining a compound of formula I, in which Rs is other then phenyl, by alkylation of a compound of formula IV,

in which R1", R20, R30 and R40 each have a significance of R1, R2, R3 and R4, respectively, or one or more thereof signifies hydroxy, the alkylation being carried out with an alkylation agent which yields a Cl~,alkyl, unsubstituted or mono-substituted by hydroxy, cyano, phenyl, C24alkenyl, carboxy, alkoxy-(CI~4)carbonyl or -CONlR6R7, alkylating group when R1", R20, R30 and R40 have significances or R1, R2, R3 and R4 respectively or with an alkylating agent which yields a Cl~4alkyl, unsubstituted or mono-substituted by phenyl, alkoxy(C14)-carbonyl, cyano, carboxy or -CONR6R7, alkylating group when one or more of Rl to R40 is hydroxy, simultaneous alkylation of said hydroxy group taking place in the latter case, and where desired, converting any compound of formula I, obtained in free base form, into acid addition salt or quaternary ammonium salt form.

Process a). is suitably carried out in an inert polar solvent, such as in water, ethanol, methanol, isopropanol, cellosolve, dimethylformamide or mixtures thereof. A suitable reaction temperature is -50" to + 1500C, preferably 0 to 100"C. The reaction is suitably carried out in the presence of a base such as sodium carbonate, acetate, hydroxide pr methoxide, potassium hydroxide, triethylamine or pyridine.

Process b). is suitably carried out in an inert solvent, e.g. water, ethanol, acetone, acetic acid, dimethylformamide, xylene, chlorobenzene, carbon tetrachloride, chloroform or pyridine. Suitable oxidizing agents include air, manganese dioxide, lead tetraacetate, sodium hypochlorite, nitrobenzene and chloranil. A suitable reaction temperature is from 0 to 2000C, preferably 20 to 1500C.

Process (c) is suitably carried out in an inert solvent, such as chloroform, trichoroethylene, benzene, toluene, chlorobenzene, dioxan, dimethylformamide, methanol, ethanol, propanol, cellusolve or water. The alkylating agent is, of course, dictated by the desired significance of R5 in the resulting compounds formula I, and the desired significance of Rl to R4 when one of R, to R4 in compound IV is hydroxy, and is chosen accordingly. As examples of alkylating agents may be given dimethyl and diethyl sulphate, alkyl halides such as methyl, ethyl. and propyl iodide and butyl bromide, methyl p-toluenesulphonate, benzyl choride, ethylene oxide, ethylbromoacetate, allyl chloride, acrylonitrile and acrylamide. The reaction is preferably carried out in the presence of a base, such as sodium, potassium or calcium carbonate or hydroxide, calcium or magnesium oxide, magnesium hydroxide, triethylamine or benzyltrimethylammonium hydroxide. A suitable reaction temperature is from -50" to +200"C, preferably 0 to 1000C. As will be appreciated, during such alkylation any carboxy group present in the molecule will likely be alkylated. Where such occurs, hydrolysis of the ester group can subsequently be effected.

The conversion of the free base forms of compounds of formula I into acid addition salt or quaternary ammonium salt form may be carried out in conventional manner, employing conventional protonating or quaternising agents. As examples of quaternising agents may be given dimethyl and diethylsulphates, methyl, ethyl and propyl bromides, methyl p-toluenesulphonate, ethylene oxide, benzyl chloride, ethylchloroacetate, allyl bromide, bromo-acetic acid, chloro-acetamide and chloro-N,N-dimethylacetamide. Suitable protonating agents include mineral and organic acids. Suitable solvents for the quaternisation or protonisation include trichloroethylene, toluene, chlorobenzene, dioxan, dimethylformamide, methanol, ethanol and water. A suitable reaction temperature is from 0 to 1500C, preferably 20 to 1000C. Preferably at least one equivalent of protonating or quaternisation agent is employed. If desired, and where the quaternating group is the same as Rg, the quaternisation can be carried out simultaneously with process c). i.e. alkylation and quaternisation being effected at the same time, employing, for example, an excess of the alkylating agent. In this case, a base, e.g. as set out for process c)., is preferably employed.

As will be appreciated, interconversions from one compound of formula I to another may be carried out, e.g. by conversion of carboxy or nitrile group(s) into ester and amide group(s), by conversion of nitrile, amide and ester group(s) into carboxy group(s) and interconversion of the anions in the protonated and quaternised compounds.

The resulting compounds of formula I may be isolated and purified in conventional manner.

The compounds of formulae II to V are either known or may be obtained from available starting materials in analogous manner to similar known compounds. For example, the compounds of formula IV are conveniently prepared in analogous manner to compounds I, e.g. in analogy to process a)., but employing starting materials having hydrogen in place of R5.

The compounds of formula I are optical brightening agents, being especially indicated for use in the brightening of substrates, preferably textile substrates, comprising or consisting of polyacrylonitrile polymers or acrylonitrile copolymers, such co-polymers, for example, consisting of more than 80-95% acrylonitrile copolymerised with 20 to 5% vinyl acetate, vinyl pyridine, vinyl chloride, vinylidene chloride or acrylic acid, acrylic ester, methacrylic acid or methacrylic ester.

The compounds of formula I may be applied in conventional manner to such substrates which may, for example, be in fibre, filament, woven, knitted, non-woven etc. form, e.g.

from an aqueous bath, preferably under acid conditions, and in the presence or absence of chlorite bleach. The amount of brightener used, based on the weight of the substrate is generally in the range of from 0.001 to 0.5%, preferably 0.01 to 0.2%. The compounds in protonated or quaternated form, particularly those of formula I', have good watersolubility and have notable stability to bleaching agents such as sodium chlorite and metabisulphite. The brightenings obtained generally have good light fastness properties.

The compound of formula I may also be used in the mass brightening of textile filaments, e.g. by incorporation in spinning melts or solutions.

The following Examples illustrate the invention.

Example 1 (process c) 2-Trichloromethylbenzimidazole (36.6g) and 2-amino-5-methoxyphenol (24.2g) were stirred together in 95% ethanol (300 ml). Triethylamine (47.9g) was added dropwise to the stirred mixture over a period of 15 minutes, keeping the temperature below 30"C by external cooling. The solution was then stirred at 20-250C for a further 2 hours. Water was then added and the mixture stirred for 30 minutes. The precipitated oil solidified and was filtered off, dried and crystallised from acetone and then n-butanol. 10g of the resultant fawn coloured solid was mixed with anhydrous potassium carbonate (5.2g), sodium iodide (5.7g), benzyl chloride (3.3g) acetone (50 ml) and dimethylformamide (20 ml) and the mixture stirred and heated under reflux for 4' hours. The resultant mixture was filtered hot and the filtrate cooled to OOC. The precipitate was filtered, washed with acetone and dried to give a compound of formula

as a fawn coloured solid.

Example 2 - 11 The compounds listed in the following table were prepared by a procedure similar to that described in Example 1 but employing the appropriate starting materials and reagents.

They are of formula

Example X Rx Ry Rz Rq R5 Physical appearance 2 0 H H OCH3 H CH3 pale fawn solid 3 0 H H CH3 H CH2Ph colourless solid 4 S H H OCH3 H CH3 pale yellow solid 5 0 CH3 H CH3 H CH2Ph white solid 6 0 CH3 H CH3 SO2CH3 " " 7 0 H H CH3 SO2CH3 CH2Ph 8 0 H OCH3 H H CH3 pale yellow solid 9 0 H OCH3 H H CH2-CH=CH2white solid 10 0 H H OCH3 H CH2CO2ET 11 0 H Cl OCH3 H CH3 11a 0 CH3 H CH3 H CH2CO2Et white solid lib 0 H H OCH3 CH3 CH3 11c 0 H H OCH3 Cl CH3 lid 0 H H OCH3 H CH2CO2CH3 " " 11e 0 H H OEt H CH3 Ph = phenyl Et = ethyl Example 12 (quaternisation) The compound described in Example 1 (5.4g) was mixed with dioxan (100 ml) and dimethyl sulphate (1.9g) and the mixture heated under reflux for 1 hour then cooled to 20 C and filtered to give a compound of formula

as a pale yellow solid.

Example 13 Compounds of the following table were also prepared by a procedure similar to that described in Example 12 but employing appropriate starting materials. They are of formula

Ex. X Rx Ry Rz Rq R9 R5 Anion e Physical Appearance 14 O H H CH3 H CH3 CH2Ph CH3SO40 colourless solid 15 0 H H OCH3 H CH3 CH3 CH3SO40 pale yellow solid 16 S H H OCH3 H CH3 CH3 CH3SO40 yellow solid 17 0 CH3 H CH3 H CH3 CH2Ph Cl- white solid 18 0 CH3 H CH3 SO2CH3CH3 CH2Ph CH3SO4- white solid 19 0 H H CH3 SO2CH3CH3 CH2Ph CH3SO4e' white solid 20 O H OCH3 H H CH3 CH3 CH3SO4 pale yellow solid 21 0 H H OCH3 H CH3 CH2CH=CH2 CH3SO4- white solid 22 0 H H OCH3 H CH3 CH2CO2Et CH3SO40 pale yellow solid 23 0 H Cl OCH3 H CH3 CH3 CH3SO4e pale yellow solid 24 O H H OCH3 H C2H5 CH2CO2Et CH3SO4e pale yellow solid 25 O H H OCH3 H CH3 C2H4CN CH3SO4 pale yellow solid 26 0 H H OCH3 H CH3 C2H4CO2CH3 ZnCl4- pale yellow solid 26a O CH3 CH3 H CH2CO2Et CH2CO2Et Br- pale yellow solid Ex. X Rx Ry Rz Rq R., R5 Anion 8 Physical Appearance 26b O CH3 H CH3 H CH2CO2Et CH2Ph BrO pale yellow solid 26c O CH3 H CH3 SO2CH3 CH2CO2Et CH2Ph BrO pale yellow solid 26d O H H OCH3 CH3 CH3 CH3 CH3SO46 pale yellow solid 26e O H H OCH3 Cl CH3 CH3 CH3SO4e' pale yellow solid 26f O H H OCH3 H CH2CO2CH3 CH3 -. CH3SO46 pale yellow solid 26g O H H OC2H5 H CH3 CH3 CH3SO4e' pale yellow solid Ph = phenyl Et = ethyl Example 27 (process c) with simultaneous quaternisation) 2-Trichloromethylbenzimidazole (23.6g) and 1-amino-2-hydroxynaphthalene hydroch loride (19.6g) were stirred together in 2-ethoxyethanol (100 ml) whilst triethylamine (40.4g) was added dropwise with external cooling to keep the temperature of the reaction mixture below 30"C. The mixture was stirred at ambient temperature for a further 17 hours and poured into water (500 ml). The precipitate was filtered, dried and crystallised from dioxan.

7 g of the resultant fawn coloured solid was stirred in dioxan (30 ml) together with magnesium oxide (0.5g) and dimethyl sulphate (6.2g). The mixture was heated to reflux, stirred under reflux for 17 hours, cooled to 20"C and filtered. Crystallisation of the crude solid product from isopropanol gave a compound of formula

as a yellow coloured solid.

Example 28 (process c)) 6-Hydroxy-2(2')-benzimidazolyl benzoxazole (100 g), ethyl bromoacetate (166.3g), anhydrous potassium carbonate (55.0 g) and acetone (600 ml) were stirred together under reflux for 3 hours. The solution was then filtered hot to remove inorganic salts and 300 ml of acetone distilled out. The solution was then cooled to 0 C and the precipitated solid filtered off and dried to give a compound of formula

as a write solid.

6-Hydroxy-2(2')-benzimidazolyl benzoxazole was prepared by a procedure similar to that described in Example 1, above, but employing the appropriate starting materials.

Example 29 By proceeding as described in Example 28, but employing benzyl chloride in place of ethyl bromoacetate the compound of formula

is obtained as a white solid.

Example 30 (quarternisation) The compound described in Example 28 (4.5 g) was mixed with dioxan (25 ml) and dimethyl sulphate (1.48 g) and the mixture heated under reflux for 2 hours, then cooled to 20"C and filtered to give the compound of formula

as a white solid.

Example 31 Following the procedure described in Example 30, but employing the compound of Example 29 in place of the compound of Example 28, there is obtained the compound of formula

as a pale yellow solid.

Example 32 (process c)) 2-Trichloromethylbenzimidazole (36.6g) and 2-amino-5-methoxy phenol (24.2 g) were stirred together in 95% ethanol (300 ml), triethylamine (47.9 g) was added dropwise to the stirred mixture over a period of 15 minutes, keeping the temperature below 30"C by external cooling. The solution was then stirred at 20-25"C for a further 2 hours. Water was then added and the mixture stirred for 30 minutes. The precipitated oil solidified, and was filtered off and crystallised from acetone and then butanol. 13.05 g of the resultant fawn coloured solid was stirred under reflux in dioxan (50 ml) with acrylonitrile (9 g) and benzyl trimethyl ammonium hydroxide 40% W/W aqueous solution (0.5 ml) for 17 hours. The solution was then cooled to 40"C and added to 100 cc of water. The precipitated solid was filtered, washed with water and dried to give the compound of formula

as a fawn coloured solid.

Example 33 The compound of formula

was obtained as a white solid in a similar way to the compound described in Example 32 but using methyl acrylate instead of acrylonitrile.

Example 34 The compound of formula

was obtained as a white solid in a similar way to the compound described in Example 1, but using appropriate starting materials and reagents.

Example 35 The compound of formula

was obtained as a pale yellow solid in a similar way to the compound described in Example 12 but using appropriate starting materials and reagents.

Example 36 (process a)) 1-Methyl-2-trichloromethylbenzimidazole (2.5 g) and 2-amino-5-methoxyphenol (1.4 g) were stirred together in 95% ethanol (25 ml) and triethylamine (1 g) added dropwise to the stirred mixture, keeping the temperature below 30"C by external cooling. The mixture was then heated to the boil and stirred under reflux for 2 hours. The mixture was then cooled to 20"C, filtered and the solid washed with water and dried to give the compound described in Example 2 as a pale fawn solid.

Example 37 (protonation) The compound described in Example 2 (5 g) was stirred in water (25 ml) and concentrated hydrochloric acid (36% w/w) (5 g) was added. The mixture was heated to the boil to give a clear solution and then the solution was cooled to 20"C. The resulting solid precipitate was filtered off and washed with a little 20% w/w hydrochloric acid solution and dried to give the compound of.formula

as a pale yellow solid.

Example 38 (process b)) 2-Hydroxy-4-methoxy-Nj(1,3-dimethylbenzimidazoliumyl)-2-methylidenj anilinemethosulphate (7.5 g) was stirred in glacial acetic acid (25 ml) and manganese dioxide (2.25 g) added. The mixture was warmed to reflux and stirred under reflux for 30 minutes and then screen to remove excess manganese dioxide. The solution was evaporated, to remove acetic acid and water (20 ml) added. The mixture was warmed until a clear solution was obtained and then the solution cooled to 20"C and the precipitate filtered, washed with a little water and dried at 80"C to give the compound described in Example 15 as a pale yellow solid.

The 2-hydroxy-4-methoxy-N-[(1 ,3-dimethylbenzimidazoliumyl)-2-methylidenejaniline methosulphate used in the above example was prepared as follows: 2-Amino-5-methoxyphenol (50.5 g) was added to isobutanol (200 ml) and 2dichloromethylbenzimidazole hydrochloride (86 g) and the mixture stirred at 20-250C as triethylamine (110 g) was added dropwise over a period of one hour. The mixture was stirred at 20-25 C for sixteen hours, the solid filtered off, washed with isobutanol and then water and dried at 80"C to give 2-hydroxy-4-methoxy-N-(benzimidazolyl-2-methylidene)aniline as a pale fawn coloured solid. 2-Hydroxy-4-methoxy-N-(benzimidazolyl-2methylidene)-aniline (13.4 g) and magnesium oxide (2.0 g) were mixed in 1,2dichloroethane (50 ml). The mixture was stirred and heated to the boil and dimethyl sulphate (13.9 g) added dropwise to the refluxing mixture over 30 minutes. The mixture was stirred at reflux for a further 2 hours, then cooled to 20"C and filtered. The solid was washed with 1,2-dichloroethane and dried at 70"C to give 2-hydroxy-4-methoxy-N[(l,3- dimethylbenzimidazol umyl)-2-methylidenej-anillne methosulphate as a yellow solid.

Application Examples A). A 5 gram piece of polyacrylonitrile was entered at 40"C into 200 mls of a solution containing 5 milligrams of the compound described in Example 12 and 100 milligrams of formic acid. The temperature of the bath was raised to 90-950C during 30 minutes then maintained at 90-950C for a further 60 minutes. The fabric was rinsed well in hot then cold demineralised water and dried at 80 C. The treated piece was brilliantly white compared to the untreated fabric. Similar results were obtained when the compound of Example 12 was replaced by the compound of Example 30.

B). A 5 gram piece of polyacrylonitrile was entered at 400C into 200 mls of a solution containing 10 milligrams of the compound described in Example 15, 400 milligrams of sodium chlorite, 400 milligrams of a phosphate based buffer salt and sufficient formic acid to adjust the pH of the bath to 3.5. The temperature of the agitated bath was increased to 90-95"C during 30 minutes and maintained at 90-950C for a further 60 minutes. The piece was then anti-chlored for 10 minutes in 200 mls of a solution containing 400 milligrams of sodium metabisulphite, well rinsed with demineralised water and finally dried at 800C under tension. The treated piece was brilliantly white compared to the untreated material. Similar results were obtained when the compound of Example 15 was replaced by the compound of Example 31.

WHAT WE CLAIM IS: 1. A compound of formula I,

where either, Rl, R2,

Claims (45)

**WARNING** start of CLMS field may overlap end of DESC **. dimethylbenzimidazol umyl)-2-methylidenej-anillne methosulphate as a yellow solid. Application Examples A). A 5 gram piece of polyacrylonitrile was entered at 40"C into 200 mls of a solution containing 5 milligrams of the compound described in Example 12 and 100 milligrams of formic acid. The temperature of the bath was raised to 90-950C during 30 minutes then maintained at 90-950C for a further 60 minutes. The fabric was rinsed well in hot then cold demineralised water and dried at 80 C. The treated piece was brilliantly white compared to the untreated fabric. Similar results were obtained when the compound of Example 12 was replaced by the compound of Example 30. B). A 5 gram piece of polyacrylonitrile was entered at 400C into 200 mls of a solution containing 10 milligrams of the compound described in Example 15, 400 milligrams of sodium chlorite, 400 milligrams of a phosphate based buffer salt and sufficient formic acid to adjust the pH of the bath to 3.5. The temperature of the agitated bath was increased to 90-95"C during 30 minutes and maintained at 90-950C for a further 60 minutes. The piece was then anti-chlored for 10 minutes in 200 mls of a solution containing 400 milligrams of sodium metabisulphite, well rinsed with demineralised water and finally dried at 800C under tension. The treated piece was brilliantly white compared to the untreated material. Similar results were obtained when the compound of Example 15 was replaced by the compound of Example 31. WHAT WE CLAIM IS:

1. A compound of formula I,

where either, Rl, R2, R3 and R4, independently, are hydrogen, C1~4alkyl, Cl~,alkoxy, halogen, cyano, carboxy, alkoxy(Cl~4)carbonyl, -CONR6R7, -SO2NR6R7, -SO2R8, alkyl(C14)carbonyloxy, or C14alkoxy monosubstituted by phenyl, alkoxy (Cl~4)carbonyl, cyano, carboxy or -CONR6R7, with the proviso that a maximum of one of R1 and R2 and a maximum of one of R3 and R4 can signify a group selected from cyano, carboxy, alkyl (C14)carbonyloxy, -CONR6R?, -SO2NR1 and -S02R8, or one or both pairs Rl and R2, and R3 and R4, are on adjacent carbon atoms and form a fused benzene ring, any pair not forming a ring being as defined above, R5 is C1~4alkyl, unsubstituted or mono-substituted by hydroxy, cyano, phenyl, C24al- kenyl, and carboxy, C1~4alkoxycarbonyl or -CONR6R7; or unsubstituted phenyl, R6 and R7, independently, are hydrogen or C1~4alkyl, R8 is C1~4alkyl, and X is O or S, in free base, acid addition salt or quaternary ammonium salt form.

2. A compound of Claim 1, wherein R1 and R2, independently, are hydrogen; C1~4alkyl; chlorine; or Cl~,alkoxy, unsubstituted or mono-substituted by phenyl, alkoxy(C14)-carbonyl, carboxy, cyano or -CONR6R7; or, together, form a fused benzene ring.

3. A compound of Claim 2, wherein one of R1 and R2 is hydrogen or Cl~,alkyl, the other C14alkyl; chlorine; or C14alkoxy, unsubstituted or mono-substituted by phenyl or alkoxy(C1 4)carbonyl.

4. A compound of any preceding Claim, wherein one of R, and R2 is hydrogen.

5. A compound of Claim 4, wherein the other of R1 and R2 is Cl~,alkoxy, -unsubstituted or mono-substituted by alkoxy(C1~4)carbonyl.

6. A compound of any preceding claim, wherein one of R3 and R4 is hydrogen or C1~4alkyl, the other being hydrogen, C1~4alkyl, chlorine or -S03Rs.

7. A compound of any preceding claim, wherein one of R3 and R4 is hydrogen.

8. A compound of Claim 7, wherein one of R3 and R4 is hydrogen, the other being hydrogen or methyl.

9. A compound of any preceding claim wherein, where the Rl/R2 or R3/R4 bearing ring is mono-substituted, the substituent is in the 6-position and wherein where either of said rings is disubstituted, one of the substituents is in the 6-position.

10. A compound of any preceding claim in acid addition salt or quaternary ammonium salt form.

11. A compound of Claim 10 in quaternary ammonium salt form.

12. A compound of formula I',

wherein R2, is C1-4alkyl; chlorine; or C14alkdxy, unsubstituted or mono-substituted by phenyl or alkoxy(C14carbonyl, R1' is H or C1~4alkyl, one of R3, and R4' is hydrogen or C1-4alkyl and the other is hydrogen, C14alkyl, chlorine or -SO2CH3, Rg is C14alkyl, unsubstituted or mono-substituted by alkoxy(C12)carbonyl, phenyl or -CONR6R7, R5 is as defined in Claim 1 and A- is a non-chromophoric anion.

13. A compound of Claim 12, wherein R1' is hydrogen.

14. A compound of Claim 12 or 13, wherein one of R3, and R41 is hydrogen.

15. A compound of Claim 14, wherein one of R3, and R4' is hydrogen, the other being hydrogen or methyl.

16. A compound of any one of Claims 12 to 15, wherein R2' is C14alkoxy, unsubstituted or mono-substituted by phenyl or alkoxy(C14carbonyl.

17. A compound of any one of Claims 12 to 16, wherein R9 is unsubstituted C1-4alkyl,

18. A compound of Claim 17, wherein Rg is methyl or ethyl.

19. A compound of any preceding claim, wherein R5 is C14alkyl, unsubstituted or mono-substituted by hydroxy, cyano, phenyl or alkoxy(C1~4)carbonyl.

20. A compound of Claim 19, wherein R5 is C1~4alkyl, unsubstituted or monosubstituted by phenyl or alkoxy(C1-4)-carbonyl.

21. A compound of Claim 20, wherein R5 is methyl, ethyl, benzyl or alkoxy(C12)car- bonyl methyl.

22. A compound of any preceding claim, wherein X is O.

23. A compound of formula I",

where R2" is C1~4alkoxy, unsubstituted or mono-substituted by phenyl or alkoxy(C1~4)carbonyl, one of R3" and R4" is hydrogen or methyl, the other being hydrogen, R5" is C1~4alkyl, unsubstituted or mono-substituted by phenyl or alkoxy(C1~4)carbonyl, R9" is Cl~4alkyl, and Ae is as defined in Claim 12.

24. A compound of Claim 23, wherein R2" is methoxy or alkoxy(C1-2)carbonyl,

25. A compound of Claim 24, wherein R2" is methoxy.

26. A compound of any one of Claims 23 to 25, wherein R5 is Cl~2alkyl, unsubstituted or mono-substituted by phenyl or alkoxy(C1-4)carbonyl.

27. A compound of any one of Claims 23 to 26, wherein R9, is methyl or ethyl.

28. A compound of any one of Claims 23 to 27, wherein R5" is methyl, ethyl, benzyl or alkoxy(C1~2)carbonyl methyl.

29. A compound of Claim 1, as described in any one of the Examples, other than Examples 12, 15, 22, 26d and 30.

30. A compound of formula

where AQ is as defined in Claim 12.

31. A compound of formula

where AV is as defined in Claim 12.

32. A compound of formula

where AO is as defined in Claim 12.

33. A compound of formula

where A0 is as defined in Claim 12.

34. A compound of formula

where A0 is as defined in Claim 12.

35. A compound of any one of Claims 30 to 34, wherein AO is CH3SO4-.

36. A compound of Claim 1, wherein Rt, R2, R3 and R4 are other than C14alkoxy mono-substituted by phenyl alkoxy(C14)-carbonyl, cyano, carboxy or -CONR6R,.

37. A compound of Claim 12, wherein R,' is hydrogen, R,' is C1-4alkyl, C,~4alkoxy or chlorine, one of R3' and R4' is hydrogen and the other is hydrogen, C14alkyl, chlorine or -SO2CH3 and R9 is C1-4alkyl, unsubstituted or mono-substituted by C1-alkoxy-carbonyl.

38. A compound of Claim 12, wherein R1' is hydrogen, R2 is C~4alkoxy, mono-substituted by phenyl, alkoxy(C1-4)-carbonyl, carboxy, cyano or -CONR6R7, one of R3, and R4' is hydrogen and the other is hydrogen, C1-4alkyl, chlorine or -SO2CH3 and R9 is C1-4alkyl, unsubstituted or mono-substituted by C~alkoxy-carbonyl.

39. A compound of Claim 3S wherein R2, is C14alkoxy, mono-substituted by phenyl or C1 4alkoxy-carbonyl.

40. A process for the production of a compound as claimed in Claim 1, comprising a). reacting a compound of formula II,

with a compound of formula III,

where Y is chlorine or bromine, or b). oxidising a compound of formula V

wherein either (i) P is -XH and Q is H, and U and T form a direct bond between the atoms to which they are attached. or (ii) P and 0 together, form -X-,and U and T are both hydrogen. in case (i) the compound opti:irlally being in protonised or quaternised form, or c). obtaining a compound of formula I, in which R5 is other then phenyl, by alkylation of a compound of formula IV,

in which R10, R20, R30 and R40 each have a significance of R1, R2, R3 and R4, respectively, or one or more thereof signifies hydroxy, the alkylation being carried out with an alkylation agent which yields a C1~4alkyl, unsubstituted or mono-substituted by hydroxy, cyano, phenyl, C2~4alkenyl, carboxy, alkoxy-(C1~4)carbony1 or -CONR6R7, alkylating group when R1 , R2 , RX and R40 have significances of R1, R?, R3 and R4, respectively, or with an alkylating agent which yields a C1~4alkyl, unsubstituted or mono-substituted by phenyl, alkoxy(C1~4)-carbonyl, cyano, carboxy or -CONR-6R7, alkylating group when one or more of R1" to R40 is hydroxy, simultaneous alkylation of said hydroxy group taking place in the latter case, and, where desired, converting any compound of formula I, obtained in free base form, into acid addition salt or quaternary ammonium salt form.

41. The process of Claim 40, substantially as hereinbefore described with reference to any one of the foregoing Examples 1 to 38.

42. A compound as claimed in Claim 1, whenever obtained by the process of Claim 40 or 41.

43. A process for optically brightening a substrate comprising or consisting of polyacrylonitrile or acrylonitrile copolymer, comprising applying thereto, as optical brightening agent, a compound of any one of Claims 1 to 39 and 42.

44. A process according to Claim 43, substantially as hereinbefore described, with reference to either of the foregoing Application Examples A and B.

45. A polyacrylonitrile or acrylonitrile copolymer substrate whenever brightened by the process of Claim 43 or 44.