United States Patent (19) 11 Patent Number: 4,696,773 Lukenbach et al. 45 Date of Patent: Sep. 29, 1987 54) PROCESS FOR THE PREPARATION OF (56) References Cited SETHONCACID U.S. PATENT DOCUMENTS (75) Inventors: Elvin R. Lukenbach, Somerset; 4,499,028 2/1985 Longley .............................. 260/513 Prakash Naik-Satam, East Windsor, both of N.J.; Anthony M. Schwartz, FOREIGN PATENT DOCUMENTS Rockville, Md. 0151934 11/1981 Fed. Rep. of Germany ...... 260/513 (73) Assignee: Johnson & Johnson Baby Products Primary Examiner-Alan Siegel Company, New Brunswick, N.J. Attorney, Agent, or Firm-Steven P. Berman 21) Appl. No.: 882,660 57) ABSTRACT Fied: Jul. 7, 1986 A process for the preparation of isethionic acid involv 22 ing the reaction of sodium isethionate and hydrogen 51 Int. Cl. ............................................ C07C 143/02 chloride in an alcoholic solvent is described. (52) U.S.C. ................................................ 260/513 R 58) Field of Search ........................ 260/513 R, 513 B 3 Claims, No Drawings 4,696,773 1 2 These and other objects of the present invention will PROCESS FOR THE PREPARATION OF become apparent to one skilled in the art from the de SETHONCACD tailed description given hereinafter. FIELD OF INVENTION SUMMARY OF THE INVENTION This invention relates to a process for the preparation This invention relates to a novel process for the prep of isethionic acid involving the reaction of sodium ise aration of isethionic acid. thionate and hydrogen chloride in an alcoholic solvent. BACKGROUND OF THE INVENTION 10 DETALED DESCRIPTION OF THE This invention relates to a process for the preparation INVENTION ofisethionic acid. Isethionic acid can also be referred to The present invention relates to a process comprising as 2-hydroxyethane sulfonic acid and is of the formula reacting sodium isethionate with hydrogen chloride in HOCH2CH2SO3.H. Numerous processes have been the presence of a suitable alcohol resulting in the forma suggested in the literature for the preparation of isethi 15 tion of isethionic acid. onic acid and the related isethionate salts. This reaction should be carried out in an alcoholic A number of these methods are disclosed in C. M. solvent system wherein the alcohol is a straight or Suter, "The Organic Chemistry of Sulfur", John Wiley branched chain lower alkanol containing from 1 to 4 & Sons, Inc. New York, 1944 (reprinted 1969), pps. carbon atoms. A preferred alcohol solvent is ethanol. 130-132. An early preparation involved the action of 20 In the process of the present invention it is important sulfur trioxide upon ethyl alcohol or ether to yield ethi that anhydrous sodium isethionate and anhydrous hy onic acid which can then be hydrolyzed to isethionic drogen chloride are utilized to prevent contamination acid. The sulfonation of barium ethyl sulfate produces and insure the purity and yield of the desired product. similar results. Another preparation involves the action The reaction is preferably carried out at room tem of sulfur trioxide upon ethylene to form crystals of 25 perature but may be carried out at elevated tempera carbyl sulfate that hydrolyze first to ethionic acid and tures up to the boiling point of the solvent, if the rate of then to isethionic acid. The hydrolysis of ethionic acid reaction requires. After completion, the resultant prod to produce isethionic acid and sulfuric acid has also uct is filtered to remove the insoluble solids, and then been described in Wooten and Lloyd, J. Org. Chem. 39, the alcohol and axcess hydrogen chloride is distilled off 2112 (1974) and Weinreich and Jufreso, Bull. Soc. 30 yielding substantially pure isethionic acid. The yields Chem. France 1965 (3) 787; which indicate that the approach 100% bases on the sodium isethionate pro hydrolysis readily occurs under aqueous acid condi vided that equimolar amounts of sodium isethionate and tions. These processes all have in common the require hydrogen chloride or an excess of hydrogen chloride is ment of the use of sulfur trioxide, a violent reagent utilized. requiring careful and special handling techniques, and 35 Isethionic acid is useful in electroplating; in the manu the intermediacy of carbyl sulfate or ethionic acid, facture of inks; in the preparation of resins; as a reaction which must then be hydrolyzed in aqueous solution to catalyst, for example, isethionic acid serves as a catalyst isethionic acid resulting in the production of sulfuric in the condensation reaction of aniline with formalde acid as a by-product. Due to the use of water as a sol hyde to prepare diaminodiphenylmethanes; and as a vent the resulting isethionic acid is obtained in a dilute reagent in the preparation of surfactants which are use solution and of concentrated is obtained as the monohy ful in the formulation of personal care and cleaning drate. Generally, these processes are not used to obtain products. isethionic acid perse but rather the hydrolysis mixture Specific embodiments of the present invention are is neutralized with alkaline earth bases such as calcium illustrated by the following representative examples. It or barium salts to precipitate the insoluble sulfate fol 45 will be understood, however, that the invention is not lowed by the addition of alkali thereby forming the confined to the specific limitations set forth in the indi isethionate salt. vidual examples, but rather to the scope of the ap U.S. Pat. No. 4,499,028 discloses a process for the pended claims. preparation of isethionic acid by treating alkali metal 50 EXAMPLE I isethionate with hydrochloric acid in aqueous medium. In a suitable reaction apparatus equipped with con This process requires excess hydrochloric acid which is denser, stirrer and cooling means and protected from not easily recovered for reuse. This process results in atmospheric moisture, are combined 78 g of dry sodium yields of about 80% isethionic acid containing alkali isethionte and 100 ml anhydrous ethanol. Excess dry metalisethionates and water. 55 hydrogen chloride gas is introduced by a suitable dis None of the methods of preparing isethionic acid persion means into the stirred mixture with cooling for disclosed in the prior art yield isethionic acid substan about hour, such that the temperature does not exceed tially free of contaminants such as chloride ion, sodium 60° C. After removal of precipitated sodium chloride by ion, sulfuric acid and water nor are they economical. filtration, the alcohol and excess hydrogen chloride are It is therefore an object of the present invention to distilled off under vacuum. The residue of 123 g of provide a novel process for the preparation ofisethionic liquid isethionic acid solidifies on cooling. It has an acid. equivalent weight (sodium hydroxide titration) of 135, It is a further object of the invention to provide a and is free of chloride ion. process for the preparation of isethionic acid which avoids undesirable contaminants. 65 EXAMPLE II It is a still further object of the invention to provide In a suitable reactor equipped with condenser, stirrer an economically desirable process for the preparation of and cooling means protected from atmospheric mois isethionic acid. ture is placed 505 g of ethanol. Dry hydrogen chloride 4,696,773 3 4 gas is introduced by a suitable dispersion means until EXAMPLE V 154 g (3.44 mole) is absorbed. In a suitable reaction apparatus equipped with stir To the above solution is added with stirring 503 g (3.4 ring, vacuum and heating utilities, and equipped with moles) of sodium isethionate in portions over 1 hour. distillation condenser are combined lauric acid (200 The mixture is stirred for an additional 30 min. It is then parts) and isethionic acid (150 parts, 20% excess). The reaction mixture is heated under < 1 mmHg pressure to filtered and the solvent removed by distillation to pro 125 C. over 2 hours, to produce lauroylisethionic acid duced 435 g ofisethionic acid (quantitative yield, equiv of 87% activity. After cooling to 75° C., the reaction alent weight 126, with negligible chloride content). 10 mass is transferred to a solution of 175 parts of trietha nolamine in 1000 parts of water. The mixture is vigor EXAMPLE III ously stirred at 45 C. to produce a homogeneous solu In a suitable reactor is placed 2-propanol (500g) and tion at pH 6.2 of the triethanolamine salt of lauroyl isethionic acid of 24.4% activity (96% conversion) HCl gas is introduced with cooling until 141 g (3.91 15 which is useful as a surfactant. moles) is absorbed. In addition to the preferred embodiments described Sodium isethionate (193g, 1.3 moles) is added, and herein, other embodiments, arrangements and varia the mixture stirred at room temperature for 16 hours. tions within the scope of the invention and the scope of the appended claims will be apparent to those skilled in After filtration and evaporation of HC/alcohol 164 g of 20 the art. isethionic acid (quantitative yield) is obtained. What is claimed is: 1. A process for the preparation of isethionic acid EXAMPLE IV under anhydrous conditions comprising contacting an In a suitable reactor are combined 1000 ml of isopro hydrous sodium isethionate with anhydrous hydrogen panol solution of hydrogen chloride (HCl content 111 25 chloride in the presence of an alcohol solvent. 2. The process of claim 1 wherein the solvent is a g, 3.08 moles) and sodium isethionate (228 g, 1.54 lower alkanol containing from 1 to 4 carbon atoms. moles). The mixture is heated at the boil for two hours. 3. The process of claim 2 wherein the solvent is etha After cooling, filtration and evaporation, 194g ofisethi nol. onic acid (quantitative yield) is recovered. 30 se k sk s s 35 40 45 50 55 60 65 .