MXPA96002606A - Method for preparing acids 4-alkyl-2-hydroxy-3,5-dichlorobencensulfoni - Google Patents

Abstract

The present invention relates to a method for preparing 4-alkyl-2-hydroxy-3,5-dichlorobenzenesulfonic acids by sulfonation of 4-chloro-3-alkylphenol and followed by chlorination of the 4-alkyl-2-hydroxy-5-chlorobenzenesulfonic acid present in the mixture of acetic acid reaction, characterized in that the chlorination is carried out by adding, to the reaction mixture, salts of the hypochlorous acid and / or chloric acid and, if necessary, hydrochloric acid or its

Description

METHOD FOR PREPARING 4-ALOUIL-2-HYDROXY-3, 5- DICHLOROBENCENSÜLPHONIC ACIDS DESCRIPTION OF THE INVENTION The invention relates to a method for preparing 4-alkyl-2-hydroxy-3,5-dichlorobenzenesulfonic acids by the sulfonation of 4-chloro-3-alkylphenol and by chlorination of 4-alkyl-2-hydroxy-5-hydroxy -chlorobenzene sulfonic acid present in an acid reaction mixture. The 4-alkyl-2-hydroxy-3,5-dichlorobenzenesulfonic acids prepared by the method according to the invention are valuable raw materials in preparing photographic chemicals, when the sulphonic acid group is replaced with a nitro group. This substitution reaction can be performed in a known manner, by adding nitric acid, to the chlorination reaction mixture without the need to isolate the dichloro compound between the steps. The method according to the invention can be described by the following reaction sequence: 4-chloro-3-alkylfluorol 4-alkyl-2-idroxy-5-acid 4-alkyl-2-hydroxy-3,5-chlorobenzis-sulfonic acid dlchlorobepcepsulfonic acid The alkyl is preferably methyl, ethyl or isopropyl. It is already known to sulfonate 4-chloro-3-alkylphenol using different sulfonation reagents. In the method according to U.S. Patent 5 136 109 and corresponding EP 473 464 application, sulfonation is carried out using chlorosulfonic acid in an organic solvent after which water is added to the reaction mixture and The chlorination of 4-alkyl-2-hydroxy-5-chlorobenzenesulfonic acid is carried out using a compound of hydrochloric acid and hydrogen peroxide with or without a catalyst, so that the chlorine needed in the chlorination is generated in ßi tu in the reaction mixture. The sulfonation has also been carried out using an excess amount of concentrated sulfuric acid, as described in the application JP 61-57536 and by the sulfuric anhydride complex as described in US Pat. No. 3,903,178. of chlorine and sulfuryl chloride in chlorination is described in several publications such as EP 473 464 which uses these chlorination reagents in the comparison. The known methods mentioned in the above are functional as such but have disadvantages. When elemental chlorine and sulfuryl chloride are used for chlorination, only half of the available chlorine is used. In addition to this, an equivalent amount of hydrogen peroxide is generated as a by-product and an equivalent amount of sulfur dioxide is generated from sulfuryl chloride. To handle these gases, a separate equipment is necessary, in such a way that the gases are not emitted to the environment. When hydrogen peroxide is used, no byproducts are generated since because of hydrogen peroxide and hydrochloric acid (in an excess amount) they are added as an aqueous solution, it carries water to the reaction mixture and in addition, this method requires special provisions to safely handle hydrogen peroxide. None of the methods mentioned in the above uses the residual sulfuric acid of the sulfonation. The object of the present invention is to provide a method for preparing 4-alkyl-2-hydroxy-3,5-dichlorobenzenesulfonic acids by sulfonation of 4-chloro-3-alkylphenol and by chlorination of 4-alkyl-2-acid. hydroxy-5-chlorobenzenesulfonic acid present in the obtained acid reaction mixture, in such a way that the chlorination reagents can be used as effectively as possible, while the residual sulfuric acid, present in the acid reaction mixture, obtained as a result of sulfonation, it can also be used. According to the present invention, the chlorination is carried out by adding, to the acidic reaction mixture, salts of hypochlorous acid and / or doric acid and when necessary, hydrochloric acid or its salt. The chlorination reagent of this form is generated in itself in the reaction mixture by the oxidizing effect of the hypochlorous acid and / or doric acid salts when using the acidity of the reaction mixture and the chlorine in the oxidation reagent. When chlorate is used, the chloride ions in the reaction mixture are also used. Chloride ions can also be used when they are obtained from salts, so that the cationic portions neutralize some of the excess acid in the mixture. Accordingly, a source of cheap chloride can be used in the method, for example, sodium chloride whose chlorine is used in chlorination, while sodium neutralizes sulfuric acid.

Preferably, sodium or potassium chlorate or hypochlorite is used as the chlorination reagent. In addition, one or more of the following may be added to the reaction mixture: eodium chloride, potassium chloride, calcium chloride, aluminum chloride, and iron chloride. The invention is described in detail with the help of the examples, which do not mean that they limit the scope of the invention. Isolation of the product, 4-alkyl-2-hydroxy-3,5-dichlorobenzenesulfonic acid, is usually impractical because nitration can be carried out in the chlorination mixture and the isolation could only cause reduced performance. For the analyzes, the product was isolated only in examples 2a and 12 and the isolated products were used as reference substances for the analysis of the other examples. The yield is measured from 3-alkyl-4-chlorophenol. All percentages are given in% by weight, if not stated otherwise.

Example 1 Preparation of the starting material (alkyl = ethyl) by sulfonation with fuming sulfuric acid. 47. 0 g of 3-ethyl-4-chlorophenol are dissolved in 120 ml of 1,2-dichloroethane. 82 g of 30% fuming sulfuric acid are added to the mixture for one hour and the temperature is maintained at 20-25 ° C. The mixture is stirred for 2 hours at this temperature. According to a liquid chromatogram, the initial material has reacted completely. The mixture of 4-ethyl-2-hydroxy-5-chlorobenzenesulfonic acid is used as the starting material in the subsequent reactions.

Examples 2a and 2b Chlorination by hydrochloric acid and chlorate salt. a) 31.3 g of 3-ethyl-4-chlorophenol are dissolved in 1,2-dichloroethane and sulfonated in the form according to Example 1. 20 ml of water and 73 g of 30% hydrochloric acid and 53 g of 20% NaC103 solution is added to the mixture for 45 minutes at approximately 20 ° C. According to the liquid chromatographic analysis, the chlorination is complete. 50 ml of water are added to the mixture and the precipitate is filtered and washed with dichloroethane. 26.6 g of the dry precipitate are obtained and contain 81% of the 4-ethyl-2-hydroxy-3,5-dichlorobenzenesulfonic acid, R N 13 C (DMSO solvent and reference 39.5): 12.2 (CH 3); 24.7 (CH2); 121.4 (C-3); 122.3 (C-5), 125. 3 (C-6); 130 4 (C-1); 141. 2 (C-4); 148 7 (C-2); IR: 3376, 1404, 1251, 1211, 1133, 1048, 1041 (and sodium sulfate 1186). The rest of the precipitate was sodium sulfate. b) 4 ml of water and then 5 ml of 37% hydrochloric acid are added to the reaction mixture (55 g) of Example 1, keeping the mixture below 30 ° C. Gradually 52.7 g of a 7% KC103 solution is added to the mixture, maintaining the temperature at about 25 ° C. After 2.5 hours, 80% of the initial material has reacted. 1.2 g of 37% hydrochloric acid are added to the mixture and the stirring is continued overnight, after which the yield of 4-ethyl-3-hydroxy-3,5-dichlorobenzenesulfonic acid was 97%.

Example 3 Chlorination by sodium chloride and sodium chlorate. 4 ml of water and then 23.4 g of 20% NaCl solution are added to the reaction mixture (55 g) of Example 1, keeping the temperature below 30 ° C. The mixture is diluted with 20 ml of water. 21.3 g of the 20% NaC103 solution are added to the mixture, maintaining the temperature at approximately 30 ° C. After stirring overnight at room temperature, the yield of the chlorine mixture was 98%.

Example 4 Chlorination by potassium chloride and potassium chlorate. 4 ml of water and 29.8 g of the 20% KCl solution and then 70 g of 7% KC103 solution are added to the mixture of Example 1 at a temperature of 25 ° -40 ° C. The mixture did not mix well and reacted slowly. After mixing overnight, the conversion was 73%. 13 ml of 37% hydrochloric acid are added to the mixture and the stirring is continued for 3.5 hours at 40 ° C, after which the yield of the dichloro mixture was 92%.

Example 5 Chlorination by sodium hypochlorite. ml of water and 85 g of sodium hypochlorite solution, containing 10% active chlorine, are added to the reaction mixture (55 g) of Example 1 at about 40 ° C for 2 hours. Shortly after it was finished adding, the yield of the dichloro mixture was 95%.

Example 6 Preparation of the starting material (alkyl = ethyl) by sulfonation with sulfuric acid. 31. 3 g of 3-ethyl-4-chlorophenol are added to 118 g of 98% sulfuric acid and stirred for 1.5 hours at ° C. 40 ml of water are added to the mixture and the resulting 4-ethyl-2-hydroxy-5-chlorobenzenesulfonic acid mixture is used in the subsequent chlorination examples.

Example 7 Chlorination by hydrochloric acid and sodium chlorate. 6. 5 g of 30% hydrochloric acid and then 9.3 g of 20% sodium chlorate solution are added to the sulfonation solution (38 g) of Example 6 for two hours, maintaining the temperature at about 40 ° C. After the addition was complete, the yield of 4-ethyl-2-hydroxy-3,5-dichlorobenzenesulfonic acid was 94%.

Example 8 Chlorination by sodium chloride and sodium chlorate. . 7 g of the 20% sodium chloride solution and then 10 g of the 20% sodium chlorate solution are added to the sulfonation solution (38 g) of Example 6 at 40 °. After 3 hours, the yield of the dichloro derivative was 95%.

Example 9 Chlorination by sodium hypochlorite. ml of water and 57 g of sodium hypochlorite solution containing 10% of the active chlorine are added to the sulfonation solution (38 g) of Example 6 at about 40 ° C. After three hours, the yield of the dichloro compound was 94%.

Example 10 Chlorination by calcium chloride and sodium chlorate. g of the 15% calcium chloride solution and g of the 20% sodium chlorate solution are added to the sulfonation solution (38 g) of Example 6. The temperature is maintained below 40 ° C. After two hours, the yield of the dichloro mixture was 92%.

Example 11 Reference test for hydrochloric acid and sodium perchlorate. g of water and 7.9 g (7 ml) of hydrochloric acid 37%, are added to the mixture (55 g) of Example 1 at a temperature below 40 ° C. The 8.7% sodium perchlorate solution (5.62 g, 0.04 mol) is added to the mixture at 35 ° C. The initial material has not reacted all at this temperature for two and a half hours.

Example 12 Preparation of the starting material (alkyl = methyl) and chlorination by hydrochloric acid and sodium chlorate. 28. 8 g of 4-chloro-3-methylphenol are dissolved in 60 ml of 1,2-dichloroethane and 57.7 g of 30% fuming hydrochloric acid, added to the mixture for two hours, maintaining the temperature at 20 ° -25 ° C. After one hour of stirring, the starting material had reacted completely and 20 ml of water was added to the mixture for half an hour and then 73 g of 30% hydrochloric acid was added in 15 minutes at about 20 ° C. 53 g of the 20% NaCl03 solution are added to the mixture in 70 minutes at 25 ° C. According to a liquid chromatographic analysis, the sulfonic acid had reacted completely and 50 ml of water was added to the mixture and the precipitated product was washed with dichloroethane and water and 27.4 g of the precipitate were recrystallized from water (165 ml). The purity of the dry precipitate was 98% (as determined by NMR): 13 C NMR (DMSO solution and ref 39.5): 17.8 (CH3); 122.1; 123.1; 125.2; 130.1; 136. 2; 148.6 (carbons of the benzene ring). IR: 3191, 1444, 1345, 1269, 1131, 1048, 749, 606.

Example 13 Preparation of the starting material (alkyl = methyl) and chlorination by aluminum trichloride and sodium chlorate. 7. 2 g- of 4-chloro-3-methylphenol are dissolved in 20 ml of 1,2-dichloroethane and 13.7 g of 30% fuming sulfuric acid are added to the mixture for about one hour keeping the temperature at 20 ° -25 ° C. After an hour, the initial material had reacted completely and 20 ml of water and 3.1 g of aluminum trichloride were added to the mixture for half an hour at approximately 20 ° C and then, 11.6 g of the 20% NaCl03 solution was added during hour and medium at about 25 ° C. After 40 minutes of stirring at 25 ° C, the intermediate sulfonic acid had reacted and 50 ml of water were added to the mixture and the phases formed were separated at 65 ° C. An 86% yield was analyzed from the aqueous phase using the reference sample obtained from Example 12.

Example 14 Chlorination by iron chloride and sodium chlorate. 7. 2 g of the 4-chloro-3-methylphenol is sulfonated and chlorinated in the manner described in Example 13, but the aluminum chloride was replaced with 3.6 g of iron chloride. A yield of 92% is obtained. As indicated by the tests, hydrochloric acid and its salts, such as NaCl, KC1, CaCl2, A1C13 and FeCl3, can be used as the source of chlorine. The salts of hypochlorous acid and doric acid, such as NaOCl, NaCl03 and KC103, can be used as the oxyacid of oxidation of chlorine. Chlorates containing chlorides as impurities can also be applied in the method, while the salt of perchloric acid NaC104 does not work in a reaction despite its high valency.

Example 15 Chlorination by hydrochloric acid and sodium chlorate ("isopropyl" alkyl) 17. 1 g of 3-isopropyl-4-chlorophenol are dissolved in 30 ml of 1,2-dichloroethane and 27.5 g of 30% fuming sulfuric acid to the mixture for one hour, maintaining the temperature at 20ß-25ßC. According to a liquid chromatographic analysis, the initial material had reacted completely after one hour of agitation. 10 ml of water are added to the mixture for 20 minutes and then 37 g of 30% hydrochloric acid for 10 minutes at about 15 ° C. 20 ml of water are added to the mixture and the precipitated product is washed with dichloromethane and water. 2-Hydroxy-4-isopropyl-3,5-dichlorobenzenesulfonic acid, isolated as the sodium salt, was dried overnight at 23 ° C and its purity was 90% (4.5% by weight of H 0) as determined by NMR: 13 C NMR (Ref. TMS 0.0) 19.1; 30.9; 121.7; 122.4; 126.5; 130.3; 143.4; 148.9. IR: 3570, 3320, 1403, 1355, 1237, 1181, 1045, 674, 641, 607, 568, 540.

Example 16 Chlorination by hydrochloric acid and sodium chlorate (10% NaCl) impure 17.1 g of 3-isopropyl-4-chlorophenol are dissolved in 30 ml of 1,2-dichloroethane and 26.7 g of the 30% fuming sulfuric acid are added to the mixture for one hour, maintaining the temperature at 20 ° -25 °. C. After 2 hours of agitation, the initial material had reacted completely. 10 ml of water are added to the mixture for 15 minutes, cooling it, and 37 g of 30% hydrochloric acid are added for one hour. Then, 20% NaCl03 solution (in a total of 27 g) is added to the mixture for one hour and 15 minutes at 25 ° C, the solution comprises 0.53 g of NaCl as an impurity (10% by weight when compared with sodium chlorate). The reaction mixture is stirred for another two hours at 25 ° C and the amount of the dichlor compound created in this way is analyzed by the use of the product of Example 15 as a standard; the yield of the non-isolated product was 70%.

Having described the invention as above, property is claimed as contained in the following:

Claims (3)

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1. . 1. A method for preparing 4-alkyl-2-hydroxy-3,5-dichlorobenzenesulfonic acids by sulfonation of 4-chloro-3-alkylphenol and by chlorination of 4-alkyl-2-hydroxy-5-chlorobenzenesulfonic acid present in a mixture of acid reaction, characterized in that the chlorination is carried out by adding, to the acid reaction mixture, salts of hypochlorous acid and / or doric acid and if necessary, hydrochloric acid or its salt.
2. 2. The method according to claim 1, characterized in that sodium or potassium chlorate or hypochlorate is used as the chlorination reagent.
3. 3. The method according to claim 1 or 2, characterized in that, in addition to the salt of the Doric acid, one or more of the following are added to the acid reaction mixture: NaCl, KCl, CaCl2, A1C13, FeCl3 and HCl.