PROCESS FOR PRODUCING TAURINE

Abstract

There is disclosed a process for producing taurine by decomposing ammonium taurinate to taurine and ammonia. Ammonium taurinate is prepared by the hydrogenation of ammonium 2-nitroethanesulfonate, by the reaction of aziridine with ammonium bisulfite, or by mixing alkali taurinate with an ammonium salt selected from the group from ammonium isethionate, ammonium bisulfite, ammonium sulfite, ammonium sulfate, ammonium bisulfate, ammonium chloride, ammonium bromide, ammonium nitrate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium carbonate, ammonium bicarbonate, ammonium carboxylate, ammonium alkyl sulfonate, ammonium aryl sulfonate, and a mixture of two or more thereof.

Claims

1. A process for producing taurine which comprises decomposing ammonium taurinate to taurine and ammonia by heating and removing ammonia.

2. The process according to claim 1, wherein ammonium taurinate is prepared by reducing ammonium 2-nitroethanesulfonate.

3. The process according to claim 1, wherein ammonium taurinate is prepared by catalytic hydrogenation of ammonium 2-nitroethanesulfonate.

4. The process according to claim 1, wherein ammonium taurinate is prepared by mixing alkali taurinate or a mixture of alkali taurinate, alkali ditaurinate, and alkali tritaurinate with ammonium isethionate.

5. The process according to claim 1, wherein ammonium taurinate is prepared by mixing alkali taurinate or a mixture of alkali taurinate, alkali ditaurinate, and alkali tritaurinate with an ammonium salt selected from the group of ammonium bisulfite, ammonium sulfite, ammonium sulfate, ammonium bisulfate, ammonium chloride, ammonium bromide, ammonium nitrate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium carbonate, ammonium bicarbonate, ammonium carboxylate, ammonium alkyl sulfonate, ammonium aryl sulfonate, and a mixture of two or more thereof.

6. The process according to claim 1, wherein ammonium taurinate is prepared by the reaction of aziridine with ammonium bisulfite, ammonium sulfite or a mixture of ammonium bisulfite and ammonium sulfite.

7. The process according to claim 1, wherein the decomposition of ammonium taurinate is performed at a temperature from 60 C. to 150 C. at reduced, normal, or increased pressure.

8. The process according to claim 1, wherein the yield of taurine from ammonium taurinate is from 90% to quantitative.

9. The process according to claim 4, wherein alkali taurinate is lithium taurinate, sodium taurinate, or potassium taurinate.

10. The process according to claim 5, wherein alkali taurinate is lithium taurinate, sodium taurinate, or potassium taurinate.

Description

DESCRIPTION OF THE DRAWINGS

[0067] FIG. 1 illustrates one embodiment of a flowchart for producing taurine from ammonium isethionate.

[0068] FIG. 2 illustrates one embodiment of a flowchart for producing taurine from aziridine.

EXAMPLES

[0069] The following examples illustrate the practice of this invention but are not intended to limit its scope.

Example 1

[0070] To a 2-L autoclave are added 1200 mL of 24% ammonia solution, 296 g of sodium isethionate, and 2 g of sodium hydroxide. The solution is heated to 260 C. for 2 hours under autogenous pressure. After cooling, 286.2 g of ammonium isethionate is added and ammonia is removed by boiling to bring the pH of the solution to pH 6.5. After heating to remove excess ammonia, concentrating and cooling to room temperature, a suspension of crystalline taurine is obtained. Taurine is recovered by filtration and dried to 189.3 g. Taurine is recovered in a yield of 75.7%.

Example 2

[0071] To the mother liquor of Example 1 is added 340 g of gaseous ammonia and total volume is adjusted to 1500 mL with deionized water, followed by addition of 12.4 g of sodium hydroxide. The solution is placed in a 2-L autoclave and is subjected to ammonolysis reaction and treatment with ammonium isethionate as described in Example 1.

[0072] Taurine, 241.2 g after drying, is obtained in a yield of 96.2% on the basis of ammonium isethionate used.

Examples 3 to 7

[0073] The mother liquor after isolation of taurine, after being saturated with ammonia, is repeatedly subjected to the ammonolysis reaction in the presence of 15 g of sodium hydroxide 5 times for an overall yield of taurine of 96.4% on the basis of ammonium isethionate used.

Example 8

[0074] To 240 g of a 50% solution of ammonium bisulfite was added dropwise 143.6 g of a 35% aqueous solution of aziridine, prepared by distilling a sodium hydroxide solution of 2-aminoethylsulfonate ester, while the temperature was maintained between 35 to 45 C. The initial pH of ammonium bisulfite was at 4.6 and the final pH of the solution became 9.8. After being stirred at the same temperature for 2 additional hours, the solution was heated to reflux to decompose ammonium taurinate to taurine and ammonia. After cooling, taurine crystallized from the solution and the pH of the crystalline suspension became 6.5.

[0075] After filtration and drying, 108 g of taurine was obtained as a white crystalline solid and 14 g of taurine remained in the mother liquor. The total yield was 97.6% on the basis of aziridine.

Example 9

[0076] To 1 L flask were added 500 mL of deionized water, 172 g of ammonium 2-nitroethanesulfonate, and 10 g of Raney Ni. The flask was mounted to a Parr shaker and purged with hydrogen three times and the hydrogenation was continued until no more absorption of hydrogen was observed. The suspension was filtered to remove Raney Ni catalyst to provide a clear solution, which was heated to boiling to a total volume of about 500 mL. No ammonia was observed to escape at the end of boiling and the pH of the solution was 6.8. Upon cooling, massive crystallization of taurine was obtained. After filtration and drying, 114 g of taurine was obtained as white crystalline material and 9 g of taurine remained in the mother liquor. The overall yield of taurine from ammonium 2-nitroethanesulfonate was 98.1%.

[0077] It will be understood that the foregoing examples, drawing, and explanation are for illustrative purposes only and that various modifications of the present invention will be self-evident to those skilled in the art. Such modifications are to be included within the spirit and purview of this application and the scope of the appended claims.