PROCESS FOR PREPARING L-ASCORBIC ACID

L-ascorbic acid is prepared from sodium 2-keto-L-gulonate by introducing gaseous hydrogen chloride in a molar ratio to the sodium-2-keto-L-gulonate of about 1.5 - 2.0 into a mixture composed of the sodium 2-keto-L-gulonate, ethanol and acetone in a ratio of 1 : 0.25 - 1.00 : 0.5 - 2.5 by weight at a temperature of about 25 - 75°C until precipitation of sodium chloride ends, removing the precipitated sodium chloride before L-ascorbic acid begins to crystalize out, maintaining the filtrate or supernatant at a temperature of about 25 - 75°C for a period of 5 -100 hours and cooling it to yield crystals of L-ascorbic acid as a final product. A solvent inert to the L-ascorbic acid and 2-keto-L-gulonate may be added to the filtrate or supernatant with a favorable result in obtaining a purer end product. r