This invention concerns a process for the preparation of bleach activators and particularly concerns an improved process for the manufacture of bleach activators employing substantially water insoluble acid halides. In recent years, there has been considerable interest in both the detergent and disinfection industries in organic peracids, particularly in the detergent industry, on account of their bleaching properties. A significant proportion of this interest has concentrated on the identification and development of compounds which, although not themselves peracids, are hydrolysed on reaction with a peroxidic species (known as "perhydrolysis") to produce a peracid . Such compounds are commonly known as "bleach activators" or simply "activators" .

Many different structures are described in the literature as being suitable for use as activators, but generally they comprise both a carrier moiety and a leaving group, the peracid formed on perhydrolysis being derived from the carrier moiety. In many cases, the activators are prepared by reacting a compound that will form a suitable carrier moiety, commonly an acid chloride or anhydride, with a compound that will form a suitable leaving group, commonly but not exclusively a phenolsulphonate. The use of acid chlorides is generally preferred because of their lower cost compared with anhydrides. Several different processes for the production of activators have been described in the prior art. The reaction can be carried out in an organic solvent, such as those described in European Patent Application No. 0 1 20 591 and European Patent No. 0 220 826. An alternative process employing a substantially aqueous route is described in European Patent No. 0 294 073. In International Patent Application WO92/1 5556 a process is described for the production of benzoyloxybenzene sulphonates by the reaction between a phenolsulphonate and benzoyl chloride in the presence of a solvent comprising

water and one or more organic solvents chosen from ethanol, isopropanol dioxane and tetrahydrofuran The benzoyl chloride is employed without any prior dissolution in a solvent The aqueous process of European Patent 0 294 073 and the process of W092/1 5556 are particularly suited to the case where the acid chloride is either a liquid or has a relatively high solubility in water However, these processes are less suitable when the acid chloride is a solid and/or is poorly soluble in water, as is particularly the case when the peracid it is desired to produce by perhydrolysis is a relatively hydrophobic peracid Hydrophobic peracids are particularly those meeting the criterion for the log partition coefficient between water and n-octanol at 21 °C outlined in European Patent Application No 0 1 20 591 Particularly desirable hydrophobic peracids include pernonanoic acid and percarboxy tπmellitimides.

The processes described above notwithstanding, it remains desirable to identify additional or alternative processes for the preparation of activators It is particularly desirable to identify a process for the preparation of activators from acid chlorides that gives improved performance with solid and/or poorly water soluble acid chlorides compared with the aqueous processes of the prior art.

During the course of the studies leading to the present invention, it was surprisingly found that an improved process for the production of activators from solid or poorly water soluble acid chlorides could result if the acid chloride was dissolved in a ketone solvent prior to reaction with the carrier molecule.

It is an object of the present invention to provide an additional or alternative process for the manufacture of peracid activators

It is a second object of certain aspects of the present invention to provide a process for the preparation of activators from acid chlorides that gives improved yields with solid and/or poorly water soluble acid chlorides compared with the aqueous processes of the prior art According to the present invention, there is provided a process for the manufacture of a peracid activator by reacting an acid halide or anhydride with an aqueous dispersion of an aryl hydroxy sulphonate in the presence of an alkali in a reaction vessel, characterised in that the acid halide or anhydride is dissolved in a water-miscible hydroxyl-free solvent prior to introduction into the reaction vessel .

The process of the present invention allows the advantages of addition in liquid form of solid acid halides or anhydrides to the reaction

vessel and can offer the additional advantage for such acid halides or anhydrides of improved yields compared with addition in solid form

The solvent employed to dissolve the acid halide or anhydride prior to introduction into the reaction vessel in the process according to the present invention is a water-miscible hydroxyl-free solvent Examples of such solvents include water miscible ketones, sulphoxides, amides, nitrites and cyclic ethers, preferably ketones It will be recognised that mixtures of the solvents can be employed, depending for example, on the solubility of the acid halide or anhydride, but usually a single compound is employed as solvent. Preferably, the solvent(s) employed is/are substantially free of water.

Ketones that can be employed as solvent in the process according to the present invention include acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone and N-methylpyrrolidinone. Preferably, the ketone is acetone

Sulphoxides that can be employed as solvent in the process according to the present invention include dimethylsulphoxide and sulpholane.

Amides that can be employed as solvent in the process according to the present invention include dimethylformamide and dimethylacetarnide Nitrites that can be employed as solvent in the process according to the present invention include acetonitπle.

Cyclic ethers that can be employed as solvent in the process according to the present invention include tetrahydrofuran and dioxane Acid halides or anhydrides, preferably acid chlorides, that can be employed in the process according to the present invention can be either solid or liquid, and can be either relatively soluble in water or relatively poorly soluble. In certain preferred embodiments of the present invention, particularly advantageous results have been achieved employing solid acid chlorides that are poorly water soluble. Examples of acid chlorides that can be employed include nonanoyl chloride, adipoyl chloride, nonanedioic acid chloride, dodecanedioic acid chloride, ethylene di-imidotπmellitic acid chloride, benzoyl chloride, 4,4'-sulphonyl bis-benzoyl chloride, sulphonimido benzoyl chloride, N-alkyl sulphonimidobenzoyl chlorides, including N-propyl sulphonimidobenzoyl chlorides, iso- and sec- N-butyl sulphonimidobenzoyl chlorides, N-peπtyl sulphonimidobenzoyl chlorides and N-heptyl sulphonimidobenzoyl chlorides, alkyimidotπmellitic acid chloride, alkylimidotπmellitic acid chlorides including isoamylimidotπmellitic acid

chloride, N-propylimidotπmellitic acid chloride iso- and sec- N butylimidotπmellitic acid chloride, N-pentylimidotπmellitic acid chloride and N-heptylimidotπmellitic acid chloride, and phthahmido alkanoyl chlorides, including particularly phthahmido caproyl chloride Anhydrides that can be employed include the anhydride equivalents of the acid chlorides listed hereinabove, but it will be recognised that in many cases, the choice of an anhydride will be less favoured on account of their generally higher cost

Aryl hydroxy sulphonates that can be employed in the process according to the present invention can be either substituted or unsubstituted on the aryl group Where the aryl group is substituted, the substιtuent(s) can be at any position on the aryl group Examples of substituents that can be present include short chain alkyl groups such as methyl or ethyl groups In many embodiments, the aryl hydroxy sulphonate is not substituted It will be recognised that the sulphonate group can be either ortho-, eta- or para- to the hydroxy group of the hydroxy sulphonate. Preferably, the sulphonate group is para- to the hydroxy group In most embodiments, the aryl group is selected from benzyl groups and naphthyl groups, and is preferably a benzyl group The sulphonate can be introduced in the form of a free acid which is subsequently neutralised by the alkali in the reaction vessel, or as an alkali metal or ammonium salt, and is preferably a sodium salt The most preferred aryl hydroxy sulphonate is sodium p-phenolsulphonate

The uCid chloride or anhydride can be dissolved in the solvent shortly or immediately before introduction into the reaction vessel However, it will be recognised that it is possible if desired for the dissolution to take place a significant time prior to introduction, for example several hours or more The dissolution can be effected by stirring the acid chloride or anhydride and the ketone in a suitable vessel Depending on the natures of the acid chloride or anhydride and the solvent, the dissolution can take place at ambient temperature, such as from about 1 5 to about 30 °C, or can take place at elevated temperature such as up to about 50° C to increase the rate of dissolution

The concentration of acid halide or anhydride in the solution produced by dissolution in the solvent prior to introduction into the reaction vessel can vary over a wide range up to the maximum solubility in the particular solvent and is chosen at the discretion of the user considering factors such as the desired space yield of the process, the solubility of the acid halide or anhydπαe and the nature of the solvent In many

embodiments of the present invention, the concentration is in the range of from about 20% to about 75 % w/w, particularly from about 25 % to about 50% w/w

The aqueous dispersion of aryl hydroxysulphonate can be produced by stirring a mixture of water and the aryl hydroxysulphonate The weight ratio of water to aryl hydroxysulphonate in the dispersion can vary over a wide range, but in many embodiments is in the range of from about 0 5 . 1 to about 1 5 : 1 , and is preferably from about 1 . 1 to about 5 1 The aqueous dispersion also comprises an alkali, commonly an alkali metal hydroxide. Preferably, when an alkali metal hydroxide is present, the alkali metal corresponds to that of the aryl hydroxysulphonate In many embodiments, the alkali metal hydroxide is sodium hydroxide The mole ratio of alkali in excess of that required to neutralise any free sulphonic acid : aryl hydroxysulphonate is often from about 0.9 1 to about 2 1 , preferably from about 1 . 1 to about 1 .5 : 1

In the process according to the present invention, the mole ratio of acid halide or anhydride to aryl hydroxysulphonate is often at least about 0.75 : 1 , and is unlikely to be greater than about 2 ^• 1 . In many embodiments, the mole ratio is selected in the range of from about 0.8 1 to about 1 .4 : 1 .

It will be recognised that the weight ratio of solvent employed to dissolve the acid halide or anhydride to water in the aqueous dispersion of aryl hydroxysulphonate can very widely depending for example on the nature of the reagents. In many embodiments, the weight ratio of solvent to water is chosen to be from about 5 1 to about 1 . 5, preferably from about 3 : 1 to about 1 : 3. In certain preferred embodiments, the weight ratio of solvent to water is chosen to be such that the activator produced is substantially insoluble in the reaction mixture, thereby causing it to precipitate This can reduce or eliminate the need for extractive or evaporative techniques to obtain the product on completion of the reaction period .

The temperature at which the reaction is carried out is commonly ambient temperature or less, often from about 0° C to about 25 °C and preferably from about 2°C to about 1 0°C When a sub-ambient reaction temperature is employed, a coolant at the appropriate temperature is usually employed . Examples of suitable coolants include water and glycol

The introduction of the solution of acid halide or anhydride into the reaction vessel containing the aqueous dispersion of the aryl

hydroxysulphonate can be achieved in a number of ways The introduction can be achieved in a single dose, but it will be recognised that on account of the exothermic nature of the reaction between the acid halide or anhydride with the aryl hydroxysulphonate, this can produce a significant rise in temperature and should therefore be avoided except in the case of very small scale preparations or those where extremely effective cooling is available to control the temperature rise In many embodiments, the introduction takes place over an extended period , for example from about 30 minutes to several hours, particularly from about 45 minutes to 2 hours The introduction can take place continuously throughout this period or may take place in the form of a number of discrete additions throughout the introduction period The rate of addition is usually controlled to maintain the reaction temperature at or around the desired reaction temperature, particularly in the case of reactions at sub-ambient temperatures, where the exothermic nature of the reaction is balanced with the cooling employed

On completion of the introduction of the solution of the acid halide or anhydride, the reaction is commonly maintained at the reaction temperature with stirring for a reaction period which may vary from about 30 minutes to several hours, for example 5 hours, depending on the reagents and conditions employed . In many embodiments, the reaction period is from about 1 hour to about 3 hours

The activators produced by the process according to the present invention can be separated from the reaction mixture on completion of the desired reaction period by conventional means well known to those skilled in the art In many embodiments the activators are solids and therefore can relatively simply be separated from the reaction medium, for example by filtration If desired, the activator so obtained can be washed to remove any contaminants, for example any unreacted reagents Washing can be effected with water, preferably cooled to reduce the extent of dissolution of the activator, or with a suitable volatile organic solvent Preferably, the activator is washed with a solvent of the type used to dissolve the acid halide or anhydride

The process can be operated as a batch process, but it will also be recognised that the process can be operated continuously, for example employing feeds of reagents to a reactor from wnich product a product stream is removed, the relative flow rates and reactor dimensions being arranged to give the desired reaction/residence time

Solvent recovered in the product separation stage can be recycled , and re-employed to dissolve further acid halide or anhydride, or may be disposed of in a suitable manner.

According to a preferred aspect of the present invention, there is provided a process for the manufacture of a bleach activator by reacting an acid halide or anhydride with an aqueous dispersion of sodium phenolsulphonate in a reaction vessel, characterised in that the acid halide or anhydride is dissolved in acetone prior to introduction into the reaction vessel, the aqueous dispersion additionally contains sodium hydroxide in a mole ratio to sodium phenolsulphonate of from 1 : 1 to 1 .5 : 1 , the weight ratio of acetone to water is from 3 : 1 to 1 : 3 and the mole ratio of acid halide or anhydride to sodium phenolsulphonate is 0.8 : 1 to 1 .4 : 1 .

Having described the invention in general terms, specific embodiments thereof are described in greater detail by way of example only.

Example 1

3.5g sodium hydroxide and 1 3.5g sodium phenolsulphonate dihydrate were added to 30g demineralised water in a 250ml 3 necked flask and cooled to 5 °C with an ice bath. 1 2.5g nonanoyi chloride was dissolved in 1 5g acetone and also cooled to 5 °C with an ice bath. The solution of nonanoyi chloride in acetone was added with stirring to the 3-necked flask dropwise via a dropping funnel over an addition period of 1 hour. The temperature was maintained at ca. 5 °C throughout the addition by control of the addition rate. The reaction was maintained at 5 °C for a further 2 hours after completion of the addition. The reaction mixture was filtered at 5 ° C, and the product washed with water and then with 50mls acetone.

Analysis of the product showed it to be sodium nonanoyloxybenzenesulphonate in a yield of 76% based on the weight of acid chloride employed, and having a purity of 79.7% .

Example 2

7.44g sodium hydroxide and 24.4g sodium phenolsulphonate dehydrate were added to 53.5g demineralised water in a 500ml 3 necked flask and cooled to 5 °C with an ice bath. 32g N-isoamylimidotrimellitic acid chloride was dissolved in 75ml acetone at 40° and allowed to cool to ambient temperature. The solution of acid chloride in acetone was added with stirring to the 3-

necked flask dropwise via a dropping funnel over an addition period of 1 hour The temperature was maintained at < 1 0°C throughout the addition by control of the addition rate The reaction was maintained at ca 5 ° C for a further 1 hour after completion of the addition The reaction mixture was filtered at 5 ° C, and the product washed with water and then acetone

Analysis of the product showed it to be sodium N- isoamylimidotrimel toyloxybenzenesulphonate, having the chemical structure

NaSθQ-Ph-O C ^J l l

0

in a yield of 90.1 % based on the weight of acid chloride employed, and having a purity of 100%.

Example 3 1 1 .5g sodium hydroxide and 47.8g sodium phenolsulphonate dehydrate were added to 1 07.5g demineralised water in a 1 1 3 necked flask and cooled to 5 °C with an ice bath. 60g N-isoamylimidotπmellitic acid chloride was dissolved in 1 50ml acetone at 40° and allowed to cool to ambient temperature The solution of acid chloride in acetone was added with stirring to the 3-necked flask dropwise via a dropping funnel over an addition period of 1 hour. The temperature was maintained at ca. 5 °C throughout the addition by control of the addition rate. A further 30g water was added to facilitate stirring and the reaction maintained at 5 °C for a further 1 .5 hours after completion of the addition. The reaction mixture was filtered at 5 ° C, and the product washed with water and then with acetone

Analysis of the product showed it to be sodium N isoamylimidotπmellitoyloxybenzenesulphonate in a yield of 86 7% based on the weight of acid chloride employed, and having a purity of 1 00%

Example 4

5.2g sodium hydroxide and 1 8.3g sodium phenolsulphonate dehydrate were added to 87g demineralised water in a 1 1 3 necked flask and cooled to 5 °C

with an ice bath 22g N-isoamyiimidotπmeilitic acid chloride was dissolved in 150ml tetrahydrofuran (THF) at room temperature The solution of acid chloride in THF was added with stirring to the 3-necked flask dropwise via a dropping funnel over an addition period of 1 hour The temperature was maintained at ca. 5 ° C throughout the addition by control of the addition rate The reaction temperature was allowed to reach room temperature over 1 hour after completion of the addition The reaction mixture was filtered at room temperature, and the product washed with water and then 30mls THF

Analysis of the product showed it to be sodium N- isoamylimidotπmellitoyloxybenzenesulphonate in a yield of 67.1 % based on the weight of acid chloride employed, and having a purity of > 90%

Example 5 2.1 g sodium hydroxide and 7.27g sodium phenolsulphonate dehydrate were added to 10g demineralised water in a 250ml 3 necked flask and cooled to 5 °C with an ice bath. 1 1 g ethylene di-imidotπmellitic acid chloride was warmed in 200ml dimethylformamide (DMF) until the acid chloride had dissolved The solution of acid chloride in DMF was added with stirring to the 3-necked flask dropwise via a dropping funnel over an addition period of 1 hour. The temperature was maintained at ca. 5 °C throughout the addition by control of the addition rate The reaction temperature was maintained at ca 5 °C for a further 2 hours after completion of the addition and then allowed to reach room temperature over 1 hour The reaction mixture was filtered at room temperature and the product washed with water and then 30mls acetone.

Analysis of the product showed it to be disodium ethylene di-imidotπmellitoyloxybenzenesulphonate having the chemical structure

in a yield of 71 % based on the weight of acid chloride employed , and having a purity of ca. 100% by NMR

Comparison 6

1 6g sodium hydroxide, 8 4g sodium phenolsulphonate dehydrate were added to 5g ethanol and 1 3.3g demineralised water in a 1 00ml 3 necked flask and cooled to 5 ° C with an ice bath 1 0g solid N-isoamylimidotrimellitic acid chloride was added with stirring to the 3-necked flask dropwise via a solids funnel over an addition period of 1 hour The temperature was maintained at ca 5 ° C throughout the addition by control of the addition rate The reaction was maintained at 5 °C for a further 1 hours after completion of the addition, and allowed to reach room temperature The reaction mixture was filtered at room temperature, and the product washed with 30mls demineralised water followed by 30mls acetone

Analysis of the product showed it to be sodium N- isoamylimidotπmellitoyloxybenzenesulphonate in a yield of 83 5 % based on the weight of acid chloride employed, and having a purity of 90 1 %

Comparison 7

5.2g sodium hydroxide and 1 8.3g sodium phenolsulphonate dehydrate were added to 87g demineralised water in a 1 1 3 necked flask and cooled to 5 °C with an ice bath 22g N-isoamylimidotπmellitic acid chloride was dissolved in 1 50ml ethanol at room temperature The solution of acid chloride in ethanol was added with stirring to the 3-necked flask dropwise via a dropping funnel over an addition period of 1 hour The temperature was maintained at ca 5 °C throughout the addition by control of the addition rate The reaction temperature was allowed to reach room temperature over 1 hour after completion of the addition The reaction mixture was filtered at room temperature, and the product washed with water and then with 30mls ethanol

Analysis of the product showed that no sodium N- isoamylimidotπmellitoyloxybenzenesulphonate had been produced

The results of Examples 1 - 5 (according to the present invention) show ^* hat the process of the present invention can be employed to produce activators The results of Examples 1 - 3 show that acetone can be employed as solvent for the acid chloride, the result of Example 4 shows that THF can be employed and the result of Example 5 that DMF can be employed , particularly for acid chlorides that have only limited solubility in acetone A comparison of the

results of Example 2 with the results of Comparison 6 (following the general teaching of International Application no. W092/1 5556) shows that the process of the present invention significantly increased the yield of activator with product purity at least as good as that from comparison 3. The results from Comparison 7 show that the use of a hydroxyl-containing solvent, ethanol, to predissolve the acid chloride gave no yield of activator.