Correspondingly, the present process describes the preparation of divinyl stilbene compounds of formula in which X represents Y represents hydrogen, Cl-C4alkyl, halogen, SO3M or C02M; R, is hydrogen; C1-C18-alkyl oder C2-C, 8-alkenyl which is unsubstituted or substituted by cyano, halogen, C1-C5-akylthio,C1-C5-aloxy,amino,C1-C5-mono--SH, alkylamino, C1-C5- dialkylamino or carboxy; mono-, di-or trihydroxy-C,-C5-alkyl; a radical of formula amino; C,-C5-monoalkylamino; C1-C5-dialkylamino ; phenyl or phenyl-C1-C3-alkyl which is unsubstituted or substituted by one or more Cl-C5- alkyl, C1-C5-alkoxy, hydroxy, carboxyl, cyano, sulfo or halogen; R2 and R3 independently represent hydrogen, Cl-C 5-alkyl which is unsubstituted or substituted by cyano,-SH, C1-C5-alkiylthio, C,-C5-alkoxy or carboxy; hydroxy-C1-C5- alkyl; mono-or di-C1-C5-alkylamino-C1-C5-alkyl ; phenyl or phenyl-C1-C3-alkyl which is unsubstituted or substituted by one or more C1-C5-alkyl, C,-Cs-alkoxy, hydroxy, cyano, SO3M or carboxy, or R2 and R3, together with the nitrogen atom connecting them, form a 5-or 6- membered heterocyclic ring; R4 is hydrogen, C,-Cs-alkyl, C,-CS-alkoxy, hydroxy, cyano, sulfo or halogen; M is hydrogen, an alkaline or alkaline earth metal cation or a cation formed from an amine; m, is a number from 1 to 5; and n, is a number from 1 to 3, characterized by a) diazotisating an amine of formula wherein Z represents bromine, iodine or-NHCORs, R5 being hydrogen or C1-C4-alkyl and Y is as previously defined, b) reacting 2 moles of the resulting diazonium salt with 1 mole of ethene in a solvent and in the presence of a palladium catalyst and an inorganic salt to yield a compound of formula wherein Y and Z are as previously defined, and c) subsequently reacting the compound of formula (3) with a compound of formula X-CH=CH2 (4) in a solvent and in the presence of a catalyst, an inorganic salt and, optionally, a ligand forming compound, X being as previously defined, or, alternatively, d) reacting one mole of the diazonium salt from step a) with one mole of a compound of formula (4) in a solvent and in the presence of a palladium catalyst and an inorganic salt to yield a compound of formula and e) subsequently reacting 2 moles of the compound of formula (5) with one mole of ethylene in a solvent and in the presence of a catalyst, an inorganic salt and, optionally, a ligand forming compound, X, Y and Z being as previously defined.

The present process is particularly suitable for the preparation of compounds of formula (1) in which Y represents hydrogen or S03M, R, is hydrogen; C1-C18-alkyl or C2-C4-alkenyl which is unsubstituted or substituted by by cyano, halogen, S03M,-SH, C1-C5-alkylthio, C1-C5-alkoxy, or hydroxy; phenyl which is unsubstituted or substituted by one or more C1-C5-alkyl, C1-C5-alkoxy, hydroxy, carboxyl, cyano, sulfo or halogen; R2 and R3 independently represent hydrogen, Cl-C 5-alkyl which is unsubstituted or substituted by cyano, halogen, S03M,-SH, C1-C5-alkylthio, C1-C5-alkoxy or hydroxy; phenyl or phenyl-C1-C3-alkyl which is unsubstituted or substituted by one or more C,-C5-alkyl, C1-C5-alkoxy, hydroxy, cyano, S03M or carboxy and M is Li, Na, K, Ca, Mg, ammonium, quaternary ammonium with C1-C8-alkyl groups, primary, secondary or tertiary ammonium with C,-Cg-alkyl groups or mono-, di-or triethanolamino.

The present process is most especially suitable for the preparation of compounds of formula (1) in which Y is hydrogen or S03M, Ri, R2 and R3 being, independently, hydrogen, Cl-C5- alkyl or phenyl and M representing K or Na, those in which X is-CN and Y is hydrogen and for those compounds in which X represents Y is hydrogen or S03M, Y is hydrogen or S03M, R1, R2 and R3 independently representing hydrogen, d-Cg-afkyi or phenyl and M is K or Na.

Amines of formula (2) utilise in step a) of the process are preferably those in which Z represents bromine, iodine or acetylamino.

The diazotisation step a) of the process is carried out in the presence of a strong mineral acid and a diazotising reagent. Suitable strong mineral acids are, for example, hydrochloric acid, sulphuric acid, methane sulphonic acid or tetrafiuoroboric acid, sulphuric acid being particularly preferred, whilst suitable diazotising reagents are, for example, sodium nitrite, lower alkyl i. e. C1-C6-alkyl nitrites or nitrosyl sulphuric acid, sodium nitrite being especially suitable. The temperature at which the diazotisation reaction is carried out is dependent on the amine of formula (2), but, in general, lies within the range of between-10 and 30°C,-5 to 25°C or 0 to 25°C being preferred.

The palladium (II) compound used as a catalyst in steps b), c), d) and e) of the process is PdCl2, PdBr2, Pd (N03) 2, H2PdC14, Pd (OOCCH3) 2, [PdCI4] Na2, [PdC14] Li2, [PdC14] K2, palladium (II) acetylacetonate, palladium (II) dibenzylideneacetone (dba) or solvates thereof, <BR> <BR> <BR> dichloro- (1, 5-cyclooctadiene) palladium (l ), dichlorobis- (acetonitrile) palladium (II), dichlorobis- (benzonitrile) palladium (II),-allylpalladium (II) chloride dimer, bis-(z-methallyl palladium (II) chloride) or-allylpalladium (II) acetylacetonate, Pd (dba) 2, Pd (dba) 3. solvent Pd2 (dba) 3, Pd2 (dba) 3. solvent or PdC12 being preferred.

The quantity of palladium catalyst used is in an amount of 0.01 to 5 mole %, based on the diazonium salt, preferrably 0.1 to 1%.

Ligand-forming compounds which may be used in steps c) or e) of the process are, for example, phosphines having the formula PR6R7R8 or R6R7P-Q-P R6R7, whereby R6, R7 and R8 independently represent alkyl, cycloalkyl or aryl, which may be substituted by halogen, hydroxy, alkoxy, sulphonate or carboxy groups and Q represents linear or branched, substituted or unsubstituted C2-C12-alkylene, 1,2- or 1,3-C4-C8-cycloalkylene, 1,2- or 1,3- heterocycloalkylene with 5 or 6 ring members and 0 or N as the heteroatom or ferrocenyl, triphenyl phosphine being preferred.

Steps b), c), d) and e) of the process may be effected in water as solvent or may be conducted in a two-phase solvent system comprising water and a water-immiscible organic solvent such as halogenated hydrocarbons in the presence of a phase transfer catalyst.

Alternatively, an organic solvent may be employed, whereby the organic solvent is one or more of an alcohol; ketone; carboxylic acid; sulfone; sulfoxide; N, N-tetrasubstituted urea; N- alkylated lactam or N-dialkylated acid amide; ether; aliphatic carboxylic acid ester or lactone; nitrile; and a glyme.

The inorganic salt used in steps b), c), d) and e) of the process is a Li-, Na-, K-, NH4-, Mg-or Ca--salt of a carboxylic acid, preferably lithium-, potassium-or sodium acetate, bicarbonate or carbonate, whereby sodium or potassium acetate, or sodium or potassium bicarbonate are especially suitable, the inorganic salt being used in excess.

Reaction steps b) and e) of the process involve the use of gaseous ethylene and are carried out in an inert atmosphere, preferably of nitrogen and at pressure of between 1 and 10 bar, preferably of between 1 and 5 bar and most preferably at a pressure of between 1 and 2 bar.

The reaction steps b) and d) of the process are carried out at a temperature of between 10 and 100°C, preferably at between 10 and 60°C and most preferably at between 10 and 40°C, whilst steps c) and e) are advantageously performed at a temperature of between 100 and 160°C, in particular, at between 120 and 140°C.

A further aspect of the invention is represented by novel divinyl stilbene compounds of the formula in which R2 and R3 are as previously defined and especially those in which R2 and R3 represent hydrogen or C,-Cs-alkyl, further compounds of the formula in which X and M are as previously defined, especially compounds in which M represents hydrogen, sodium or potassium and X is a group of the formula wherein R2 and R3 represent hydrogen or C,-C5-alkyl and, thirdly, a compound of the formula C1-C18-Alkyl are straight chain or branched residues such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec. butyl, tert. butyl, amyl, isoamyl or tert. amyl, hexyl. heptyl, octyl, isooctyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl or octadecyl.

C,-C5-Alkoxy or d-Cs-atkytthio may be straight chain or branched residues such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec. butoxy, tert. butoxy, amyloxy, isoamyloxy or tert. amyloxy or methylthio, ethylthio, n-propylthio, isopropylthio, n-butylthio, tert. butylthio or amylthio.

C2-C,8-Alkenyl represent, for example, allyl, methallyl, isopropenyl, 2-butenyl, 3-butenyl, isobutenyl, n-penta-2,4-dienyl, 3-methylbut-2-enyl, n-oct-2-enyl, n-dodec-2-enyl, isododecenyl or n-octadec-4-enyl.

Examples of C,-Cs-monoalkylamino or C1-C5-dialkylamino are methylamino, ethylamino, propylamino, butylamino, or pentylamino or dimethylamino, diethylamino, dipropylamino, dibutylamino or dipentylamino.

When the substituents R2 and R3 together with the nitrogen atom connecting them form a heterocyclic ring, this may be a pyrrolidine, piperidine, pipecoline, morpholine, thiomorpholine, piperazine, N-alkylpiperazine such as methylpiperazine, N-phenylpiperazine or N-alkylimidazoline ring. Preferred saturated heterocyclic residues are pyrrolidino, piperidino or morpholino.

Halogen may be chlorine, bromine or iodine, but is preferably chlorine.

When M represents an alkaline or alkaline earth metal these are preferably Li, K, Na, Ca or Mg, whilst when M represents a cation formed from an amine these may be NH4, mono-, di-, tri-or tetramethylammonium, mono-, di-, tri-or tetraethylammonium, mono, di-, tri-or tetra-n- or isopropylammonium, mono, di-, tri-or tetra-n-, sec-or t-butylammonium, mono-, di-or triethanolammonium, mono-, di-or tri-n-or isopropanolammonium, mono-, di-or tri-n-sec- or t-butanolammonium, morpholinium, piperidinium or pyrrolidinium.

In dissolved or finely divided states, the brighteners obtained by the above process display a more or less pronounced fluorescence. They are therefore used, according to the invention, for optically brightening synthetic or natural organic materials.

Examples of such materials which may be mentioned, without the review given below being intended to express any limitation thereto, are textile fibres from the following groups of organic materials, insofar as optical brightening thereof enters into consideration: (a) Polyamides which are obtainable as polymerisation products by ring opening, for example those of the polycaprolactam type, (b) polyamides which are obtainable as polycondensation products based on bifunctional or polyfunctional compounds capable of undergoing a condensation reaction, such as hexamethylenediamine adipate, (c) branched or especially linear polyesters and blends thereof and (d) natural textile organic materials of animal or vegetable origin, for example based on cellulose or proteins, such as cotton or wool, linen or silk.

The organic materials to be optically brightened can be in diverse stages of processing and are preferably finished textile products. They can, for example be in the form of hank goods, textile filaments, yarns, twisted yarns, nonwovens, felts, textile fabrics, textile composites or knitted fabrics.

The brighteners defined above are of particular importance for the treatment of textile fabrics. The treatment of textile substrates is advantageously carried out in an aqueous medium in which the particular optical brighteners are present in a finely divided form (suspensions, so-called microdispersions and in some cases solutions). Dispersing agents, stabilisers, wetting agents and further auxiliaries can optionally be added during the treatment.

The treatment is usually carried out at temperatures of from about 20° to 140°C, for example at the boiling point of the bath, or in the region thereof (about 90°C). For the finishing, according to the invention, of textile substrates it is also possible to use solutions or mulsions in organic solvents, as are used in dyeing practice in so-called solvent dyeing (pad-thermofix method and the exhaustion dyeing process in dyeing machines).

The optical brighteners which can be used according to the present invention can also be employed, for example, in the following use forms: (a) In mixtures with so-called"carriers", wetting agents, softeners, swelling agents, antioxidants, light stabilisers, heat stabilisers and chemical bleaching agents (chlorite bleach and bleaching bath additives).

(b) In mixtures with crosslinking agents and finishing agents (for example starch or synthetic finishing agents) and also in combination with very diverse textile finishing processes, especially synthetic resin finishes (for example crease resistant finishes such as"wash-and- wear","permanent press"and"no-iron"), and also flame resistant finishes, soft handle finishes, anti-soiling finshes or anti-static finishes or antimicrobial finishes.

(c) As additives to various soaps and washing agents.

(d) In combination with other substances having an optical brightening action.

If the brightening process is combined with textile treatment or finishing methods, the combined treatment can in many cases advantageously be effected with the aid of corresponding stable formulations which contain the compounds having an optical brightening action in a concentration such that the desired brightening effect is obtained.

In certain cases, the full effect of the brightener is achieved by an after-treatment. This can be, for example, a chemical treatment (for example acid treatment), a thermal treatment (for example heat) or a combined chemical/heat treatment.

The amount of the optical brighteners to be used according to the invention, relative to the material to be optically brightened, can vary within wide limits. A distinct and durable effect can already be achieved with vary small amounts and in certain cases, for example, with amounts of 0.03% by weight. However amounts of up to about 0.5% by weight can also be used. For most cases of interest in practice, amounts of between 0.05 and 0.5% by weight relative to the material to be brightened, are preferably of interest.

The optical brighteners are also especially suitable as additives for washing baths or to industrial and household washing agents and they can be added in various ways. They are appropriately added to washing baths in the form of their solutions in water or organic solvents or also in a state of fine division as aqueous dispersions or slurries. They, or their components, are advantageously added to household or industrial washing agents at any phase of the manufacturing process of the washing agent, for example to the so-called "slurry"prior to spray-drying of the washing powder or during the preparation of liquid washing agent combinations. The compounds can be added both in the form of a solution or dispersion in water or other solvents and also without auxiliaries in the form of a dry brightener powder. However, they can also be sprayed, in the dissolved or pre-dispersed form, onto the finished washing agent.

Washing agents which can be used are the known mixtures of detergent substances, such as, for example, soap in the form of chips and powders, synthetic products, soluble salts of sulphonic acid half-esters of higher fatty alcools, arylsulphonic acids, which are substituted by higher alkyl and/or polysubstituted by alkyl, carboxylic acid esters with alcools of medium to higher molecular weight, fatty acid acylaminoalkyl-or aminoaryl-glycerol- sulphonates, phosphoric acid esters of fatty alcools and the like. So-called"builders"which can be used are, for example, alkali metal polyphosphates and alkali metal polymeta- phosphates, alkali metal pyrophosphates, alkali metal salts of carboxyethylcellulose and other"soil redeposition inhibitors", and also alkali metal silicates, alkali metal carbonates, alkali metal borates, alkali metal perborates, nitrilotriacetic acid, ethylenediamine-tetraacetic acid and foam stabilisers, such as alkanolamides of higher fatty acids. Furthermore, the washing agents can contain, for example: antistatic agents, superfatting skin protection agents, such as lanolin, enzymes, antimicrobial agents, perfumes and dyestuffs.

The brighteners have the particular advantage that they are also effective in the presence of active chlorine donors, such as, for example, hypochlorite and can be used without substantial loss of the effects in washing baths with non-ionic washing agents, for example alkylphenol polyglycol ethers. Also in the presence of perborate or peracids and activators, for example tetraacetylglycoluril or ethylenediamine-tetraacetic acid are the new brighteners very stable both in pulverulent washing agent and in washing baths.

The brighteners according to the invention are added in amounts of 0.005 to 2% or more and preferably of 0.03 to 0.5%, relative to the weight of the liquid or pulverulent ready-to-use washing agent. When they are used to wash textiles made of cellulose fibres, polyamide fibres, cellulose fibres with a high grade finish, wool and the like, wash liquors which contain the indicated amounts of the optical brighteners according to the invention impart a brillant appearance in daylight.

The washing treatment is carried out, for example, as follows: The indicated textiles are treated for 1 to 30 minutes at 5° to 100°C and preferably at 25° to 100°C in a wash bath which contains 1 to 10 g/kg of a composite washing agent containing builders and 0.05 to 1% relative to the weight of the washing agent, of the brighteners claimed. The liquor ratio can be 1: 3 to 1: 50. After washing, the textiles are rinsed and dried in the customary manner. The wash bath can contain, as a bleach additive, 0.2 gui of active chlorine (for example in the form of hypochlorite) or 0.1 to 2 g/l of sodium perborate.

The brighteners according to the invention can also be applied from a rinsing bath with a "carrier". For this purpose the brightener is incorporated in a soft rinsing agent or in another rinsing agent, which contains, as the"carrier", for example, polyvinyl alcool, starch, copolymers on an acrylic basis or formaldehyde/urea or ethylene-urea or propylene-urea derivatives, in amounts of 0.005 to 5% or more and preferably of 0.2 to 2%, relative to the rinsing agent. When used in amounts of 1 to 100 mi, and preferably of 2 to 25 mi, per litre of rinsing bath, rinsing agents of this type, which contain the brighteners according to the invention, impart brillant brightening effects to very diverse types of treated textiles.

A further application of the compounds of the invention is for the brightening of paper, either in the pulp mass during paper manufacture or in the size-press, which has been described in British Patent Specification 1, 247,934, or preferably in coating compositions. When brighteners of the present invention are employed in such formulations papers brightened with them exhibit a very high degree of whiteness.

Furthermore, the compounds of the invention are useful for the mass whitening of synthetic fibres and plastics as described in"Fluorescent Whitening Agents", R. Anliker and G. Muller, Georg Thieme Publishers Stuttgart, 1975, pages 65-82.

The compounds obtained by the process of the present invention are particularly advantageous in that they exhibit not only extremely high whitening ability, but, in addition, in many cases highly desirable water solubilities and also possess excellent white aspects in the solid state.

The following Examples serve to illustrate the invention; parts and percentages are by weight, unless otherwise stated.

A. Preparative Examp) es Example 1 To 50g. of water and 150g. of ice, 34.4g. of 4-aminobromobenzene and 28g. of 96% sulphuric acid are added with stirring and the mixture stirred for a further 30 minutes below 0°C. At the same temperature, 29.0g. of 50% aqueous sodium nitrite solution are added dropwise over 30 minutes and the mixture then stirred for a further 1 hour, the temperature being maintained below 10°C by cooling. After this time the nitrite excess is checked and, if necessary, neutralised by the addition of a small amount of 4-aminobromobenzene.

To the diazonium salt solution 200ml. of ethanol are added dropwise with stirring over 10 minutes at 20°C. 60.6g. of sodium acetate are then added, the mixture stirred until it is homogenous and then transferred to a pressure reactor. After the addition of 0.4g of palladium (dba) 2 the vessel is flushed with nitrogen for 5 minutes and ethene is then introduced to a pressure of 1 to 2 bar. Reaction is then continued at 18-25°C for 10 hours, ethene being constantly introduced, after which time the pressure is released. The resulting white to grey suspension is filtered, washed with water and dried to yield 30g. of 4,4'- dibromostilbene which is used directly for the final step.

30g. of 4,4'-dibromostilbene are stirred into 240ml. of dimethylformamide and 20g. of ethyl acrylate added followed by 34g. of sodium acetate and 0.1 g. of triphenylphosphine. The mixture is heated to 120°C when vigorous gas evolution begins and maintained at this temperature for 20 hours. After heating to reflux, 2.0g. of active charcoal are added, the solution clarified and then cooled to 15°C when crystallisation takes place. The precipitated product is separated by filtration, washed and dried to yield 26g. of the compound of formula (9).

Example 2 A 4-necked flask equipped with stirrer and heating/cooling bath is charged with 200moi. of glacial acetic acid and 35.4g of 97% 4-aminobromobenzene stirred in. 25.4g. of 100% sulphuric acid are added dropwise, the well-stirred pale suspension cooled to 10°C and 39.5g. of a 36% solution of sodium nitrite in water added dropwise over 1 hour, the temperature being maintained below 15°C by cooiing. The temperature is then raised to 20°C and the mixture stirred for a further 5 hours to complete reaction. The nitrite excess is removed by the addition of some sulphamic acid and the reaction mixture used directly for the next step.

To this reaction mixture 60g. of acetic anhydride are added dropwise to reduce the water concentration, the temperature being maintained below 20°C by cooling. After stirring for 20 minutes, 36.8g. of anhydrous sodium acetate are slowly added followed by 0.3g of palladium (dba) 2. After flushing with nitrogen, ethene is introduced to a pressure of 1 to 2 bar.

The temperature rises to 30°C over 2-3 hours, after which time no remaining diazonium salt can be detected. The reaction mass is filtered to yield 50g. of moist filter cake which is used directly for the next step.

The 50g. of moist 4,4'dibromostilbene obtained as described above are stirred into 240g. of dimethylformamide and 12g of acrylonitrile added. After the further addition of 38g. of sodium hydrogen carbonate and 0.1 g of triphenylphosphine the mixture is heated to 140°C when vigorous gas evolution commences which later subsides. After a reaction time of 5 hours, the mixture is heated to reflux, treated with 2g. of active charcoal and the solution clarifie. On cooling to 15°C the crystallised product is separated by filtration, washed and dried to yield 24g of the compound of formula (10).

Example 3 To 50g. of water and 150g. of ice 30.4g. of 4-aminoacetanilide and 28g. of 96% sulphuric acid are added with stirring and the mixture stirred for a further 30 minutes below 0°C. At the same temperature, 29.0g. of 50% aqueous sodium nitrite solution are added dropwise over 30 minutes and the mixture then stirred for a further 1 hour, the temperature being maintained below 10°C by cooling. After this time the nitrite excess is checked and removed by the addition of some sulphamic acid, the solution then being used directly for the next step.

To the above diazonium salt solution, 200ml. of ethanol are added dropwise over 10 minutes at 10°C. 60.6g. of sodium acetate are then added, the mixture stirred until it is homogenous and then transferred to a pressure reactor. After the addition of 0.4g of palladium (dba) 2 the vessel is flushed with nitrogen for 5 minutes and ethene is then introduced to a pressure of 1 to 2 bar. Reaction is then continued at 10-25°C for 10 hours, ethene being constantly introduced, after which time the pressure is released. The resulting white to grey suspension is filtered with suction and washed with water to yield 60g. of moist filter cake containing 4,4'-bisacetamidostilbene which is used directly for the next reaction step.

The moist filter cake obtained above is slurried in 200ml. of water, 30g. of 36% aqueous sodium hydroxide solution added and the mixture stirred for 2 hours at 80°C. Sulphuric acid is then added to pH 8 and the precipitated 4,4'-diaminostilbene filtered, washed and dried.

A 500ml. 4-necked flask equipped with stirrer and heating/cooling bath is charged with 220ml. of glacial acetic acid and 19.1g of 4,4'-diaminostilbene stirred in. 10.4g. of methane sulphonic acid are then added dropwise, the well-stirred pale slurry cooled to 10°C with an ice bath and 20.5g of a 36% solution of sodium nitrite in water added dropwise over 1 hour with cooling below 15°C. The temperature is then raised to 25°C and the mixture stirred for a further 5 hours after which time the nitrite excess is removed by the addition of some sulphamic acid.

To this mixture 60g. of acetic anhydride are added dropwise with cooling below 20°C. After stirring for a further 20 minutes, 36.8g. of sodium hydrogen carbonate are slowly added, the foaming being maintained under control. 0.3g of a 20% solution of palladium chloride in 20% hydrochloric acid followed by 20.0g. of acrylic acid dimethylamide are then stirred in, whereby vigorous gas evolution immediately commences. The temperature rises to 50°C within 2-3 hours after which time no remaining diazonium salt can be detected. The reaction mixture is filtered with suction and the solid product recrystallised from a mixture of water and dimethylformamide to yield 30. Og of the compound of formula (11).

Example 4 A 500ml. 4-necked flask equipped with stirrer and heating/cooling bath is charged with 220moi. of water and 52.0g. of 97% 4-acetylaminoaniline-3-sulphonic acid are stirred in.

10.4g. of 100% sulphuric acid are then added dropwise. The well-stirred pale slurry is cooled to 10°C with an ice-bath and 40.5g. of a 36% solution of sodium nitrite in water added dropwise over 1 hour, the temperature being maintained below 15°C. The temperature is then increased to 25°C and reaction continued for a further 5 hours, after which time the nitrite excess is removed by the addition of some sulphamic acid.

To the above diazonium salt suspension 200ml. of ethanol are added dropwise over 10 minutes at 10°C. 60.6g. of sodium acetate are then added, the mixture stirred until it is homogenous and then transferred to a pressure reactor. After the addition of 0.4g of palladium (dba) 2 the vessel is flushed with nitrogen for 5 minutes and ethene is then introduced to a pressure of 1 to 2 bar. Reaction is then continued at 10-25°C for 10 hours, ethene being constantly introduced, after which time the pressure is released. The resulting white to grey suspension is salted out and filtered with suction to yield 60g. of moist filter cake containing 4,4'-bisactamidostilbene-3, 3'-disulphonic acid sodium salt which is used directly for the next reaction step.

The moist filter cake obtained above is slurried in 200ml. of water, 30g. of 36% aqueous sodium hydroxide solution added and the mixture stirred for 2 hours at 80°C. Sulphuric acid is then added to pH 3 and the precipitated 4,4'-diaminostilbene-3, 3'-disulphonic acid filtered, washed and dried.

A 500mi. 4-necked flask equipped with stirrer and heating/cooling bath is charged with 200mut. of water and 35g. of acid are stirred in. 10.4g. of 100% sulphuric acid are then added dropwise. The well-stirred pale slurry is cooled to 10°C with an ice-bath and 39g. of a 36% solution of sodium nitrite in water added dropwise over 1 hour, the temperature being maintained below 15°C. The temperature is then increased to 25°C and reaction continued for a further 5 hours, after which time the nitrite excess is removed by the addition of some sulphamic acid.

To this mixture 90g. of acetic anhydride are added dropwise with cooling below 20°C. After stirring for a further 20 minutes, 36.8g. of sodium hydrogen carbonate are slowly added, the foaming being maintained under control. 0. 3g of a 20% solution of palladium chloride in 20% hydrochloric acid followed by 16g. of acrylamide are stirred in, whereby vigorous gas evolution immediately commences. The temperature rises to 50°C within 2-3 hours after which time no remaining diazonium salt can be detected. The reaction mixture is filtered with suction and dried under vacuum, the solid product then being recrystallised from a mixture of water and sodium chloride to yield 36. Og of the compound of formula (12).

Example 5 A 500ml. 4-necked flask equipped with stirrer and heating/cooling bath is charged with 200ml. of glacial acetic acid and 35.4g. of 97% 4-aminobromobenzene are stirred in. 25.4g. of 100% sulphuric acid are then added dropwise. The well-stirred pale slurry is cooled to 10°C with an ice-bath and 39.5g. of a 36% solution of sodium nitrite in water added dropwise over 1 hour, the temperature being maintained below 15°C. The temperature is then increased to 20°C and reaction continued for a further 5 hours, after which time the nitrite excess is removed by the addition of some sulphamic acid and the reaction mixture used directly for the next step.

To this reaction mixture 80g. of acetic anhydride are added dropwise to reduce the water concentration, the temperature being maintained below 20°C by cooling. After stirring for 20 minutes, 36.8g. of anhydrous sodium acetate are slowly added followed by 0.3g of palladium (dba) 2. After flushing with nitrogen, 18g. of acrylic acid are added. The temperature rises to 40°C over 2-3-hours, whereby vigorous gas evolution occurs. After this time no further diazonium salt can be detected. Water is then added and the precipitate containing 4- bromocinammic acid filtered off and used directly for the next reaction step.

60g. of the crude 4-bromocinammic acid obtained above are stirred into 240g. of dimethylformamide, 34g. of anhydrous sodium acetate and 0.1 g. of triphenylphosphine added and the mixture heated to 140°C. Ethene is then introduced and after 2 hours the mixture is heated to reflux, treated with 2g. of active charcoal and filtered from the insoluble residue. After cooling to 15°C the product precipitates and is seperated by filtration, washed and dried to yield 25g. of the compound of formula (8).

B. Application Examples a) Exhaust Process A polyester fabric (Terylene type 540) is treated, in a dying apparatus, at room temperature and at a liquor ratio of 1: 20, with an aqueous bath containing 0.1 % by weight of the optical brightening agent of formula (11), in finely dispersed form and in the presence of 1 g/l. of a fatty alcohol polyglycol ether as dispersing agent. The temperature is raised from room temperature to 110 over 30 minutes, held for a further 30 minutes at this temperature and subsequently cooled to 40°C during 15 minutes. The textile material is then rinsed for 30 seconds under running water and dried at 70°C.

The so-treated polyester fabric exhibits a high degree of whiteness. b) Pad-thermofixation Process A polyester fabric (Terylene type 540) is treated at room temperature by the pad-batch process with an aqueous liquor containing 1.2g/l of the optical brightening agent of formula (11), in dispersed form and in the presence of 1 g/I of an alkali salt of a sulfonated dicarboxyiic acid alkyl ester. The pinch-off effect is 65%. Subsequently, the fabric sample is dried for 30 minutes at 70°C and then thermofixed during 30 seconds at 180°C.

The so-treated polyester fabric exhibits a high degree of whiteness.