United States Patent to 11 Patent Number: 4,510,100 Plattner Et Al
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United States Patent to 11 Patent Number: 4,510,100 Plattner et al. (45) Date of Patent: Apr. 9, 1985 (54) PROCESS FOR THE PRODUCTION OF Primary Examiner-Nicky Chan 2-AMINO-1-NAPHTHALENESULFONC Attorney, Agent, or Firm-Joseph G. Kolodny ACID 75) Inventors: Eric Plattner, Seltisberg; Sebastian (57) ABSTRACT Stäubli, Magden; Fred von Kaenel, The invention relates to an improved process for the Seltisberg, all of Switzerland production of 2-amino-1-naphthalenesulfonic acid (To 73 Assignee: Ciba Geigy Ag, Basle, Switzerland bias acid). This improved process makes it possible to obtain Tobias acid which has only a very low content of 21) Appl. No.: 559,149 2-aminonaphthalene and in high space-time yield. The 22 Filed: Dec. 7, 1983 process starts from 2-hydroxynaphthalene and com prises the following main reaction steps: Related U.S. Application Data (a) the sulfonation of 2-hydroxynaphthalene to 2 hydroxynaphthalene-1-sulfonic acid (oxy-Tobias 63 Continuation of Ser. No. 352,730, Feb. 26, 1982, aban doned. acid) with chlorosulfonic acid, in an inert organic solvent; 30 Foreign Application Priority Data (b) the neutralization of the liberated hydrochloric acid Dec. 20, 1979 (CHJ Switzerland ....................... 1135/79 and excess chlorosulfonic acid still present in the reaction medium and conversion of the 2-hydrox 51 Int. Cl. ............................................ C07C 143/60 ynaphthalene-1-sulfonic acid obtained into the corre 52 U.S. Cl. ............. ... 260/508; 260/509 sponding ammonium salt with ammonia; 58) Field of Search ................................ 260/508, 509 (c) conversion of the 2-hydroxy group into the 2-amino 56) References Cited group by the Bucherer reaction; and FOREIGN PATENT DOCUMENTS (d) the subsequent precipitation of the Tobias acid with dilute sulfuric acid. 2001637 2/1979 United Kingdom ................ 260/508 2001640 2/1979 United Kingdom ................ 260/508 2001644 2/1979 United Kingdom ................ 260/508 7 Claims, 1 Drawing Figure REACTION SCHEME hNorgonic in CISOHorganic in Sowet sovert SULFONATION DESORPTION OF HC ordonic solvent orconic solver SOLAON OF TOBASACD U.S. Patent Apr. 9, 1985 4,510,100 REACTION SCHEME HN in CISO3H in Organic Organic SOV ent SOwent I- SULFONATION HC DESORPTION OF HC solution NEUTRALISATION I I PHASE rqanic IV SEPARATION SOWentSis Removal of HN Orgonic OrganicSOvent by extraction SOvent V Stripping off Of SOI went SOvent t NH3 OTSSolution NH4. Solution VI bisulfite AM NATON Solution NOOH Solution StrippingA. off NH3 VI of NH3 extract of VII Removal of AN AN by extraction solventvent precipitation H2SO2SV4 DX OF SEAS ASE SO2 DESORPTION X OF SO2. SOLATION XI OF TOBASACD 4,510,100 1. 2 tion into Tobias acid, but the yields of salts are only 85 PROCESS FOR THE PRODUCTION OF to 90% of theory and the reaction times of 4 to 6 hours 2-AMNO-1-NAPHTHALENESULFONIC ACID lead to poor space-time yields. A process for the production of Tobias acid is de This is a continuation of application Ser. No. 352,730, scribed in U.S. Pat. No. 2,058,911, which process con filed Feb. 26, 1982, now abandoned. sists in removing 2-aminonaphthalene by extraction The present invention relates to an improved process with a water-immiscible organic solvent such as mono for the production of 2-amino-1-naphthalenesulfonic chlorobenzene or dichlorobenzene, from a product acid (Tobias acid). This improved process for the pro solution obtained in an amination reaction, and acidify duction of Tobias acid makes it possible to obtain a 10 ing the resultant purified aqueous solution of the sodium product having a very low content of 2-aminonaphtha salt of Tobias acid until acid to Congo red (pH 3) at a lene, and is distinguished by high space-time yields. temperature of about 45 C., affording a Tobias acid The process of this invention for the production of which is suitable for use as an intermediate for obtaining Tobias acid starts from 2-hydroxynaphthalene, and pigment dyes. This procedure is extremely complicated comprises the following main reaction steps: 15 and leads to losses in yield. (a) the sulfonation of 2-hydroxynaphthalene to 2 The production of Tobias acid having a low content hydroxynaphthalene-1-sulfonic acid, hereinafter re of 2-naphthylamine also forms the subject matter of ferred to as oxy-Tobias acid, with chlorosulfonic acid, German Offenlegungsschriften Nos. 2831 956, 2 831 in an inert organic solvent 965, 2831966, 2831992, 2831993,2831994 and 2831 (b) the neutralisation of the liberated hydrochloric 20 995. In these processes, an attempt is made to solve the acid and excess chlorosulfonic acid still present in the problem of producing Tobias acid having a low content reaction medium and conversion of the 2-hydroxynaph of 2-naphthylamine by inhibiting the 2-naphthylamine thalene-1-sulfonic acid obtained into the corresponding which allegedly forms by decomposition of salts of ammonium salt with ammonia; oxy-Tobias acid or Tobias acid. As in this case too the (c) conversion of the 2-hydroxy group into the 2 25 entire process is concerned with the formation of the amino group by the Bucherer reaction; and less soluble alkali metal salts of oxy-Tobias acid, it has (d) the subsequent precipitation of the Tobias acid not yet proved possible to find a wholly satisfying solu with dilute sulfuric acid. tion, especially as regards the space-time yield, which is The Bucherer reaction is usually employed in the of such importance for large-scale production. production of Tobias acid by amination of alkali metal 30 Accordingly, the present invention has for its object salts of 2-hydroxy-1-naphthalenesulfonic acid on an to provide a novel process for the production of 2 industrial scale. A small number of by-products are amino-1-naphthalenesulfonic acid that does not have formed in this reaction. One of these by-products is the disadvantages of the known processes. This object is 2-aminonaphthalene, which is a carcinogen. accomplished by means of an improved process for the The Occupational Safety and Health Administration 35 production of 2-amino-1-naphthalenesulfonic acid (To (OSHA) has issued regulations which only permit the bias acid), by reacting a suspension of 2-hydroxynaph handling of substances containing 2-aminonaphthalene thalene, in a water-immiscible organic solvent, with if the content of this latter is 0.1% by weight or less (see: chlorosulfonic acid, under anhydrous conditions and in The Federal Register 39, No. 20, Part III, pp. the temperature range from about 0° C. to 10 C., to 3756-3797 (1974) and “The Control of Industrial Blad 40 give 2-hydroxy-1-naphthalenesulfonic acid (oxy-Tobias der Tumours', Scott and Williams, Brit. J. Industrial acid), removing HCl from the reaction mixture by de Medicine 14, pp. 150-163 (1957). Tobias acid produced sorption in vacuo and, by addition of aqueous ammonia on a large scale has therefore had to be subjected to solution and water, converting the reaction mixture into elaborate after treatments in order to meet this require a two-phase mixture consisting of an organic and an ment, or else production would have had to cease. Sur 45 aqueous phase, separating the resultant ammoniacal prisingly, it has now been found that Tobias acid con aqueous phase and extracting it with a water-immiscible taining only very insignificant amounts of 2-naphthyla organic solvent to remove 2-naphthol and stripping off mine, which lie far below the required limits, is obtained the residual organic solvent in the aqueous phase in by conducting the entire reaction to result in the forma vacuo, treating the extracted aqueous layer, under pres tion of the more readily soluble ammonium salts instead 50 sure, with ammonia and SO2 donors and heating it, of the formation of alkali metal salts in the intermediate stripping off NH3 from the aqueous reaction mixture steps. containing the ammonium salt of Tobias acid thereby The better solubility of the ammonium salt of oxy obtained and extracting the product solution with a Tobias acid permits the batches to be carried out in water-immiscible organic solvent, acidifying the ex higher concentrations than with alkali metal salts, 55 tracted aqueous suspension of Tobias acid at elevated whereby-as already mentioned-better space-time temperature, removing SO2 from the suspension by yields are obtained and, in connexion therewith, better desorption, cooling to 30° C., and collecting the prod utilisation of the investment required, of energy, and of uct by filtration, and, if desired, drying it, which process ecological measures, to mention only a few advantages. comprises The production of alkali metal salts of oxy-Tobias 60 (a) introducing into a suitable reaction vessel, simulta acid by sulfonation of 2-hydroxynaphthalene with neously and continuously, separate streams of a 20-30% chlorosulfonic acid is known. Attention is drawn in suspension of 2-hydroxynaphthalene in a water-immis particular here to U.S. Pat. No. 1,716,082 and Fierz cible organic solvent which is inert to chlorosulfonic David and Blangey, "Fundamental Processes of Dye acid, and of chlorosulfonic acid which may be diluted Chemistry” (Interscience Publishers Inc., New York, 65 with the same solvent, in the temperature range from 1949, pp. 199-200). -10° to +10 C., in such concentration and at such a The process of U.S. Pat. No. 1,716,082 results in rate of addition that an anhydrous reaction mixture oxy-Tobias acid salts which can be converted by amina having a molar ratio of chlorosulfonic acid to 2-hydrox 4,510,100 3 4 ynaphthalene of about 0.90 to about 1.05 to 1, prefera zene, but preferably dichloroethane. Suitable extract bly 0.95 to 1.05 to 1, is obtained, and leaving the reac ants for use in the reaction are aromatic hydrocarbons tion mixture for about 10 to 150 minutes in the reaction such as toluene, xylenes, or ethylbenzene, as well as the vessel, same solvents mentioned above.