SU438637A1 - The method of separation of a mixture of citric and isopolymer acids - Google Patents

Description

one

The invention relates to a method for isolating and separating a mixture of citric and d-isolimic acids, widely used in various areas of the national economy.

There is a known method of extracting these acids from a cultural liquid containing equivalent amounts of d-isolimonic and citric acids by precipitating a mixture of acids from a solution in the form of barium salts, followed by treating the resulting salts with sulfuric acid. The mixture of citric and d-isolimonic acids obtained after evaporation of the aqueous solution is converted into a mixture of methyl esters with methanol IB in the presence of a catalyst — boron trifluoride etherate, followed by separation of the mixture by fractional distillation and the isolation of acids by known methods. The output of each of the acids 36-55%.

The disadvantages of this method are the use of expensive barium oxide reagent-hydrate for extracting a mixture of acids, the need for a distillation unit for separating a mixture of methyl esters, unavoidable losses of target products during fractional distillation of esters, and an insufficiently high yield of acid-acid.

The aim of the invention is to increase the yield of individual acids, simplify, reduce the cost of the process.

This goal is achieved by the fact that the mixture of acids is separated from the culture fluid in the form of calcium salts, the mixture of citric and d-isolimic acids, obtained after treatment of salts with sulfuric acid, is converted into a mixture of citric acid and lactone of d-isolimic acid by heating in vacuum at 100 ° C, the resulting mixture is treated with ethyl acetate, the precipitated citric acid is filtered off, followed by the isolation of d-isolimic acid from the mother liquor of the lactone and its conversion by the action of alkali to sodium d-isocitrate. The yield of citric acid is 76-93%, sodium d-isocitrate 75-80%.

Example 1 Concentrated hydrochloric acid was added to 1 l of culture liquid obtained by the fermentation of Candida lipolytica yeast to a pH of 1.0; yeast cells

are centrifuged off and washed with distilled water. Centrifugal together with wash water is passed through a column containing 150 vol. including cation exchanger KU-2 in H + form, for release from cations,

included in the nutrient medium Reader. The acidic eluate is evaporated at a temperature of a boiling water bath to a volume of 250 ml, and then a saturated solution of calcium hydroxide is added at 70-80 ° C, heated to

70 - SO C, to pH 9-10.

The precipitated calcium salts are separated by hot filtration, washed with moist water and an ethanol-water mixture (1: 1) and dried in air. The resulting mixture of salts is suspended in 200 ml of distilled water and with constant stirring, 49% sulfuric acid is gradually added to the suspension to pH 1-2. The precipitated calcium sulfate is filtered off and washed with water. The excess H2SO4 in the filtrate was removed by careful addition of a 5% barium chloride solution and the filtrate was evaporated in vacuo at 100 ° C to syrup.

The calcium sulphate which precipitated additionally during evaporation is filtered off, washed with distilled water, and the filtrate is again evaporated in vacuo to obtain a light yellow syrup. Then, 30 ml of toluene is added to the syrup, which is evaporated in vacuo at the temperature of the boiling bath. This operation is repeated three times. 7.0 g of a very thick yellow syrup are obtained in the residue.

To 7.0 g of the mixture was added 25 ml of ethyl acetate. On grinding, a white crystalline precipitate is separated, which is filtered and washed with ethyl acetate. 3.5 g (76%) of citric acid are obtained. Ethyl acetate is then evaporated from the filtrate and the solid residue (3.5 g) is dissolved in 10 ml of absolute ethanol. An ethereal solution of diazomethane is added to the resulting solution until slightly yellow in color. The precipitate is filtered off and recrystallized from absolute ethanol. 2.2 g (80%) are obtained.

dimethyl ether of lactone, so pl. 105-160 ° C, alo -66.9 ° (C 1.7, in acetone). 2.2 g of dimethylaminic acid dimethyl lactone ester are heated with 38 ml of 1N. sodium hydroxide solution for 45 min at 100 ° C, after which the solution is evaporated to dryness. 20 ml of absolute ethanol is added to the solid residue, the precipitate is filtered off, washed several times with absolute ethanol and then with ether. 2.52 g (78.5%) of d-isolimonic trisodium salt is obtained.

Subject invention

The method of separating the mixture of citric and d-monolone (ACID by precipitating the latter from the solution in the form of salts of metals of the P group, followed by treatment of the obtained salts with sulfuric acid, separation of the mixture and separation of individual acids, is different in that, in order to increase the yield of individual acids and simplifying the process, the mixture obtained after treatment of the salts with sulfuric acid is heated in vacuum at 100 ° C, the resulting mixture is treated with ethyl acetate, filtered

precipitated citric acid, followed by the isolation of d-isolimic acid from the mother liquor of lactone and its conversion to the sodium salt by known methods.