RU2121479C1 - Method of treating reaction mixture during sorbose acetonation - Google Patents

Abstract

FIELD: agriculture. SUBSTANCE: claimed method comprises neutralizing reaction mixture during sorbose acetonation with alkaline agent and subsequently demineralizing said mixture. Alkaline agent includes aqueous potassium hydroxide solution and demineralization is carried out quantitatively by direct crystallization of potassium sulfide resulting from aqueous acetone solution. Differences in the nature of sodium and potassium cations make potassium sulfate insoluble in aqueous acetone medium and leads to complete deminiralization of reaction mixture. This enables one to improve quality of the desired product such as diacetone-L-sorbose, to exclude additional stage of processing aqueous solution of mineral salts, removing water and separating them from monoacetone-L-sorbose solution. Use of potassium hydroxide for neutralization of reaction mixture in placed of potassium hydroxide solution makes it possible to prepare as one of products commercial potassium sulfate which is more preferable ecologically since potassium sulfate is in great demand as potassium fertilizer in agriculture. EFFECT: enhanced efficiency. 1 ex, 1 tbl

Description

 The claimed technical solution relates to the field of organic chemistry, and in particular to a method for producing 2,3; 4,6-diacetone-L-sorbose (DAS).

 From the scientific and technical literature, there are known methods for treating the reaction mass obtained after acetonation of sorbose according to the acid variant by neutralizing it with alkaline agents, in the role of which is an aqueous solution of caustic soda, and only with O.L. Schneidman has a reference to an unknown manuscript where potash is used as an alkaline agent, but the conditions for the process with his participation are not described.

 Further processing of the reaction mixture is usually associated with the distillation of acetone and the release of DAS.

Based on the information available in the literature, methods for processing the reaction mass in the process of acetone sorbose can be divided into the following groups:
- processing the reaction mass by neutralization followed by alkaline isolation of DAS;
- treatment of the reaction mass by neutralization followed by extraction of DAS, before the start of which partial demineralization of the reaction mass is carried out by cooling it and separating part of the precipitated crystalline sodium sulfate;
- processing the reaction mass by neutralization followed by extraction of DAS, before which water is added to the reaction mass to reduce the concentration of mineral salts so that sodium sulfate does not fall out of the reaction mass, or is ensured by observing certain temperature conditions;
- carrying out the process of acetonation with a catalytic amount of sulfuric acid, followed by neutralization of the reaction mixture with a solution of caustic soda (L.O. Shnaidman. Production of synthetic ascorbic acid (vitamin C) .- M .: Pishcheprom, 1948, p. 125, 128, 132-140 ; VN Bukin. Vitamins. - M.: Pischeprom, 1940; The latest methods for producing vitamin C. Cescosl. Farmac, 1968, 15, No. 7, pp. 376-381 (Czech); Japanese Pat. 16 E 44, No. 15415, claimed 25.04.66, published on July 9, 69 .; Japanese Pat. Cl. 16E44, No. 15416, declared July 25, 66, published on July 9, 68; A.S. N 943244 , CCCP, application form 10.06.79., Published in BI No. 26 for 1982. Method for the preparation of diacetone-L-sorbo PS; L.E. Burova, V.V. Zarutsky, V.V. Depleyskaya and others. Improvement of the technology for diacetone-L-sorbose production / Proceedings of the Ministry of Medical Industry, - Part 1, 1986 - pp. 13-16; I.A. Shaps, A.B. Letunova et al. Some improvements in the technology for diacetone-L-sorbose production / ibid., Pp. 70-73; I.E. Vasilieva, G.T. Turbovsky, T.A. Kudryavtseva "Chemistry and production technology of ascorbic acid" - M .: - Minmedprom - 1990 - Part 1, p. 102-106; Kristallinskaya R.G. Development of a method for producing diacetonsorbose with maximum yield. - In the book. : Vitamins in theory and practice. - vol. 3, - L .: - Pishchepromizdat. - from. 78-87; Levi S., Spirov G., Pencheva E.F. Investigation of the process of acid-catalytic acetonation of L-sorbose to DAS.- Chem.pharm. Journal., 1978, N 9 .; Industrial regulations for the production of ascorbic acid Kalinin Vitamin Plant N 12-38. - 1978; Industrial technological regulations for the production of ascorbic acid. / PO Marbiofarm.-Yoshkar-Ola - 1986; Industrial process regulations for the production of ascorbic acid. / All-Union Industrial Association "Soyuzlexintez" - Leningrad - PFHO Pharmakon - 1979; Industrial technological regulations for the production of medical ascorbic acid / OJSC "Vostokvit" - Biysk - 1996).

 The method of processing the reaction mixture using alkaline isolation of DAS allows to isolate DAS in the form of a precipitate, which, however, is contaminated due to the adsorption of impurities by the main product — its purity does not exceed 70% of the basic substance. This fact indicates the high solvating ability of sodium sulfate, present as a by-product in the reaction mass with respect to DAS.

 The method of processing the reaction mixture with subsequent extraction of DAS gives a cleaner product. But in order to reduce the share of mineral impurities and make it difficult to transfer together with DAS (due to the formation of strong solvates) to the organic layer, the reaction mass after distillation of acetone must be diluted with some water to reduce the concentration of sodium sulfate in the mass or to carry out the process at a temperature that ensures homogeneous state of the mass entering the extraction. This technique allows you to get a cleaner solution of DAS in an organic solvent, but complicates the further processing of the water-mineral layer remaining after extraction, since there is a need for a stage of distillation of water from a solution of sodium sulfate.

 Carrying out the process of acetonation with a catalytic amount of sulfuric acid followed by neutralization with a sodium hydroxide solution can reduce the concentration of sodium sulfate in the reaction mass and, accordingly, obtain a cleaner target product, however, this method is associated with the need to continuously remove significant amounts of reaction water from the reaction sphere by distillation with vapors acetone and its absorption on the developed surface of the adsorbent-desiccant, for example zeolite, which further requires the stage of its regeneration, Anna considerable energy costs and a high risk - the use of high temperatures.

 The method of processing the reaction mixture by neutralization followed by extraction of DAS, before which partial demineralization of the reaction mixture is carried out, also reduces the content of impurities in the DAS solution after extraction, but does not solve the problem, since a significant amount of sodium sulfate remains in the reaction mass due to its high solubility in water and acetate solution as well.

 According to this method, the reaction mass after the sorbose acetonation reaction containing DAS, monoacetone-L-sorbose (MAC) and sulfuric acid in an aqueous acetone medium is treated with an aqueous solution of caustic soda to a slightly alkaline reaction at a temperature of 6-9 degrees Celsius. In this case, the sodium sulfate formed partially precipitates as a crystalline product, which is separated from the liquid phase by centrifugation.

 Next, the water-acetone solution obtained after separation of sodium sulfate is sent to distill off the acetone and the condensation products of acetone. In this case, a significant amount of water is added to the reaction mass.

 The syrupy product remaining after acetone distillation contains diacetone-L-sorbose, monoacetone-L-sorbose, sodium sulfate and other mineral impurities that enter the reaction mixture with sulfuric acid.

 DAS is recovered from the syrup-like product obtained by distillation by extraction with an organic solvent. At the same time, part of the mineral impurities passes into the crude organic layer together with DAS in accordance with their distribution coefficients between the layers, thereby polluting the main product (mineral impurities remain in the DAS after distillation of the organic solvent). The low quality of the DAS solution further affects the stage of its oxidation, reducing the yield of the target product, diacetone-2-keto-L-gulonic acid.

 This method of processing the reaction mass, as the closest to the claimed technical solution, is selected as a prototype (L.O. Schneidman. Vitamin production. - M.: Food industry, 1973).

 The objective of the proposed technical solution is to improve the quality of diacetone-L-sorbose, improving the process by eliminating the stages of distillation of water from a solution of mineral salts and separating them from a solution of monoacetone-L-sorbose, improving the environmental characteristics of the process.

 The essence of the claimed technical solution lies in the fact that in the method of treating the reaction mass after sorbose acetonation in the acid version using neutralization with an alkaline agent and its subsequent demineralization, an aqueous solution of potassium hydroxide is used as the alkaline agent, and demineralization is carried out quantitatively by direct crystallization of the resulting potassium sulfate from water-acetone solution.

Differences from the prototype
1. In the claimed technical solution to neutralize the reaction mass, a solution of potassium hydroxide is used, and not a solution of caustic soda. The use of caustic potassium solution at the stage of processing the reaction mixture obtained after acetone sorbose is not reported in the scientific and technical literature. It is only known to use potassium hydroxide solution at the stage of DAS oxidation. At first glance, the use of caustic potassium solution to neutralize should have led to the same result as in the case of caustic soda. However, differences in the nature of sodium and potassium cations provide significant differences in the behavior of sodium and potassium salts. Due to this circumstance, the solubility of potassium sulfate in water is almost five times lower than that of sodium sulfate. These relative differences in solubility are enhanced with respect to the water-acetone solution.

 2. Differences in the nature of sodium and potassium cations, ensuring the insolubility of potassium sulfate in an aqueous-acetone medium, lead to a quantitative precipitation of potassium sulfate from the reaction mass immediately after its neutralization. In the prototype, part of the sodium sulfate also falls out of the reaction mass, but a significant part of it remains in solution, contaminating the main reaction product, DAS, during further processing of the reaction mass.

 3. Thus, the use of a solution of caustic potassium instead of caustic soda leads to complete demineralization of the reaction mass, which, after distillation of acetone, enters the stage of extraction of DAS with an organic solvent.

 However, the absence of mineral salts in the reaction mass does not affect the completeness of the extraction of DAS with an organic solvent, since the extraction is carried out in the presence of alkali, which sufficiently facilitates the redistribution of DAS between the layers in favor of the organic layer - the yield of DAS is at least 80%, the purity of the product is the level of 98-99% for the main substance.

Positive effect
1. The use of a demineralized aqueous-acetone solution of DAS with an admixture of MAS obtained after neutralization of the reaction mass with a solution of potassium hydroxide further eliminates the additional step of processing an aqueous solution of mineral salts with distillation of water and separating them from the MAS solution.

 2. The exclusion of mineral salts from the process allows to reduce the proportion of mineral impurities in the main product - DAS, sent to the oxidation stage, that is, to increase the purity of the product, which further improves the yield and quality of diacetone-2-keto-L-gulonic acid.

 3. The use of caustic potassium instead of caustic soda allows one to obtain, as one of the products of the process, a marketable form of potassium sulfate, which is more preferable than sodium sulfate from an environmental point of view, since potassium sulfate is currently in higher demand and has wider areas applications, the main of which is its use as a potash fertilizer in agriculture (large-capacity consumer).

 Disposal of sodium sulfate is currently problematic.

 The invention is illustrated by the following examples.

 Example 1. 3500 ml of acetone is loaded into the reactor and cooled to zero degrees Celsius. After that, 300 g of sorbose are loaded into the reactor with stirring. At the end of the loading of sorbose into the reactor, 200 ml of sulfuric acid are metered with cooling at such a rate that the temperature in the reaction mass does not exceed 8 degrees Celsius. At the end of the dosage, sorbose is aged for an hour at a temperature of minus 12 degrees Celsius. Next, the reaction mass is neutralized with a 20% aqueous solution of potassium hydroxide at a temperature of not more than 20 degrees Celsius until a slightly alkaline reaction. The precipitated crystalline potassium sulfate is separated, washed with acetone, squeezed and dried. Receive 612.4 g of potassium sulfate, which in its quality meets the requirements for mineral fertilizers.

 The aqueous-acetone solution of DAS with an admixture of MAC after distillation of acetone and removal of the condensation products of acetone is directed to extraction. The extraction of DAS is carried out with toluene in an amount of 1347 ml. At the end of the extraction, 1735 ml of desalted water are added to the toluene layer containing DAS, and toluene is distilled off with steam. After distillation of toluene, an aqueous DAS solution is obtained containing 359 g of DAS with a basic substance content of 99%.

 Other examples are tabulated.

 The claimed technical solution is supposed to be implemented in the conditions of production of OJSC "Vostokvit" (Biysk).

Claims (1)

 A method of processing the reaction mass of the process of sorbose acetonation by neutralizing it with an alkaline agent followed by demineralization, characterized in that an aqueous solution of potassium hydroxide is used as the alkaline agent, and demineralization is carried out quantitatively by direct crystallization of the formed potassium sulfate from an aqueous acetone solution.

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