Patent ID: 8715746
Filing Date: 2014-05-06
Classification: A61K,A61P,C01B,C01P,Y10T

Abstract:
1. A method for preparing pharmaceutical grade sodium thiosulfate pentahydrate comprising: a) contacting sodium sulfite with sulfur in an aqueous solvent at a temperature of between about 90° C. and about 110° C., wherein the pH after about 4 hours of the resulting mixture is from about 7 to about 9; b) cooling the mixture to between about 15° C. and about 25° C.; c) adding a base to the mixture until the pH of the mixture is basic; d) filtering the mixture to yield a solution; e) distilling the solution at between about 50° C. and about 100° C. to a gravity of between about 1.20 to about 1.70; f) contacting the solution with activated carbon at between about 45° C. and about 55° C.; g) filtering the solution to remove the activated carbon; h) cooling the solution to between about 15° C. and about 25° C. and adding a seed crystal of sodium thiosulfate pentahydrate; i) cooling the solution to between about 0° C. and about 10° C. and filtering the solution; and j) drying the sodium thiosulfate pentahydrate at about 35° C. until the water content of the sodium thiosulfate pentahydrate is between about 34% weight and about 36.8% weight.