KR820001173B1 - Method for refining saccharin sodium - Google Patents

Abstract

Na saccharin, contaminated with 2-MeC6H4SO2NH2, was dissolved in H2O and extd. countercurrent with methylene chloride for 3 hr with repeated evapn. of the methylene chloride to give Na saccharin contg. < 1 ppm 2-MeC6H4SO2NH2.

Description

Method of Purifying Crucine-Sodium

A device diagram for practicing the method of the present invention.

The present invention relates to a method for purifying crude carbohydrate-sodium impure by organic matter.

Since the saccharin-sodium synthesis method of Falber-Gremsem uses toluene as a starting material to obtain saccharin-sodium in an impure state by organic compounds, chemically reacting these impurities to precipitate or crystallize them Tried. However, this is not satisfactory in purity of saccharin-sodium and is a significant expense.

If the high purity can be obtained by improving the method of the above-mentioned aspect in this invention, this method can be implemented at low cost also for large scale industrial use.

The method of the present invention allows the 30-60% (preferably 40%) of aqueous solution of crude caro-sodium adjusted to pH4.5-6.0 (preferably pH5.0-5.5) to vertically position chloride It is characterized by extracting countercurrent to methylene. Where percentages are based on crystal weight.

Since impurities derived from synthesis are water-soluble, most of these organic impurities, especially foods, are associated with methylene chloride because ortho-toluene-sulfonamide has a relatively high division ratio with respect to saccharin-sodium. It can be dissolved at a high rate, where it can be separated and converted to methylene chloride by these countercurrent extraction methods, and then the separated methylene chloride can be easily separated by distillation. Zaccharin-sodium is practically insoluble in methylene chloride, water dissolves in methylene chloride in an extremely limited range, and therefore negligible small amounts of saccharin-sodium dissolved in water can pass through methylene chloride. In other words, methylene chloride can be dissolved in a limited range in an aqueous solution of saccharin-sodium. Therefore, even in purified, concentrated or crystallized saccharin-sodium, methylene chloride is finally below 1 ppm.

For large scale industrial use, it is necessary to stir the relevant liquids very vigorously and, in accordance with the method of the present invention, flow them through a flow barrier plate, in particular through a sieve or packing material placed in countercurrent, in an intermittent manner so as to pass countercurrent to each other. Obtained by emulsifying the prepared liquid. Intermittent flow is good for 100-200 intermittent vibrations, and the optimum vibration frequency and amplitude are visually observed through the droplet structure formed in the flow barrier plate, for example through the glass wall of the extraction tower, and then the distribution of droplets becomes single and delicate. The frequency and amplitude can be adjusted up to and measured easily by trial and error. In this case, the fact that equilibrium is not maintained until 1-2 hours must be calculated.

The countercurrent extraction of the liquids involved together is preferably carried out at a temperature of 15-22 ° C. (preferably 20 ° C.).

It is preferable that the liquid passage amount of methylene chloride, which is optimum in yield, price, and purity compared to the liquid passage amount of the crude solution, is 2-3 times the liquid passage amount of the crude solution (2.5 times in the case of 40% crude solution). Countercurrent extraction can be carried out in stages in extraction towers connected in multiple orders. But the cost to the device is reduced by using a unique extraction tower. If the only extraction tower in the continuous process is insufficient, the crude solution and methylene chloride can be subjected to countercurrent extraction in a closed circuit. However, the crude solution can be flowed in a continuous manner, or only methylene chloride can be circulated to flow again through the same extraction column. When methylene chloride circulates and flows, the methylene chloride is purified by distillation when the methylene chloride returns, and thus it is particularly bonded for extraction. In this case, purification by distillation can be carried out in each cycle or in each n-cycle because it depends on the saturation of methylene chloride with orthotoluene-sulfonamide.

Anti-extraction is repeated until the content of organic impurities of saccharin-sodium that can be crystallized from an aqueous solution is 1 ppm or less.

In some cases methylene chloride contains acidic impurities, and in order to remove them from the countercurrent extraction, 0.2-1.0% (preferably 0.5%) of potassium carbonate is added to the methylene chloride during distillation. Since potassium carbonate binds with acidic impurities, these acidic impurities do not pass through the effluent.

The method of the present invention can be used for crude caro-sodium dissolved in a crude solution, and for this dissolution it is preferable to use desalted water, and the acid salt can be used to adjust the pH value. In addition, the method of the present invention can also be used for crude sodium-sodium prepared by a known synthesis method, for example, Maumi's method, in particular for crude sodium-sodium synthesized by the Falberg-Remsen method. In the crude solution form, it is advantageous to adjust the pH value and the concentration of the crude solution to use the crude aqueous solution of saccharin-sodium obtained by the saccharin-sodium synthesis method by the Falberg-Remsen method as the crude solution. In this case, it is not necessary to determine the aqueous solution of crude carbohydrate-sodium produced by the Falberg-Remsen method, and the purified saccharin-sodium according to the method of the present invention should be determined after concentration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will be described in detail with reference to the implementation of the method of the present invention.

The device is equipped with three storage tanks (1), (2) and (3), a separation tank (4), a control tank (7) equipped with a stirrer (5) and a heater (6), a heater (10), and (11). Two evaporators (8) and (9), a crystal tank (14) equipped with a cooling jacket (12) and an agitator (13), two condensers (15) and (16), an intermittent flow generator (17) and Extraction tower 19, separator 20, dryer 21 and two pumps 23, 24 provided with a sieve 18, which is a flow barrier plate.

The extraction tower is composed of a glass tube 22 located vertically of 7 m in length, on which 70 plates 18 are installed at right angles to the flow. The inner cross section of the glass tube is circular and the diameter is 225 mm. Separation vessels 30 and 31 are provided at the upper and lower portions of the glass tube, and a connector 32 is installed at the bottom of the lower separation vessel 31. The connector is intermittently driven by an eccentric driver 29. The pressure direction of the bellows-type pump 28 which is possible is open | released. Vibration frequency can be adjusted by the handle 25 to the intermittent flow of 100-200 per minute, the stroke of the bellows-type pump 28 can be adjusted to 20-300cc by the handle 26. As a result of the operation of the bellows-type pump 28, intermittent flow appears on the liquid column of the glass tube 22, and its components intermittently flow through the body plate 28 and are emulsified. The desired purification is achieved by a very strong emulsification, and the optimum amplitude and vibration frequency using the handles 25 and 26 are obtained by trial and error. The conditions selected in the operation described below are adjusted to 150 pulses per minute and a pumping force of 40 cc. The rest of the apparatus will be described according to the operation steps described below.

Fill the crude tank (7) with a crude aqueous solution of saccharin-sodium obtained by synthesizing Zaccharin-sodium by the Falberg-Remsen method, and adjust the pH to pH 5 by adding hydrochloric acid which is constantly stirred with a stirrer (5), Moreover, the temperature is adjusted to 20 degreeC with the heater 6. The contents of the adjustment tank 7 are finished and continuously readjusted to pH 5 and a temperature of 20 ° C., and the adjusted content of the adjustment tank is a crude solution. The crude solution contains 40 kg of crystalline saccharin-sodium per 100 kg of solution, and the crude solution is circulated in the extraction tower 19 from the bottom to the top by a combination pump 23 at a flow rate of 354 liters per hour. The solution is supplied to the storage tank 2 in purified form.

The methylene chloride purified by distillation is charged to the storage tank 1, and the methylene chloride of the storage tank 1 maintains the temperature at 18 DEG C, and is combined with the combined pump 24 at the top to the bottom at a flow rate of 885 liters per hour. Furnace flows through the extraction column (19). In other words, it flows countercurrently to the crude solution and is supplied to the still 8. The two liquids flowing opposite to each other in the extraction tower 19 are mixed into the emulsion under the action of the plate 18 and the intermittent pressure treatment by the intermittent flow generator 17, and since the specific gravity is different from each other, the crude solution is separated into the emulsion at the top. And methylene chloride is separated from the emulsion at the bottom.

The crude solution flowing out of the top of the extraction tower passes through the storage tank (2), the crude solution purified in the storage tank (2) is supplied to the evaporator (9). The effluent of water and a small amount of methylene chloride is condensed in the condenser 16 and separated in the separating tank 4. Methylene chloride is supplied to the storage tank 1, while water is supplied to a connected synthesis apparatus of saccharin-sodium connected in series, not shown in the figure.

In the evaporator 9, the distillation residue passes through the crystallization tank, where the purified saccharin-sodium is determined and then the saccharin-sodium is separated from the mother liquor in the separator 20. The mother liquor is returned to a serially connected saccharin-sodium synthesizer, not shown, while the separated crystals are passed through a drier 21, where the crystals are dried and then discharged as final product.

The methylene chloride flowing out of the bottom of the extraction tower is purified by distillation in the evaporator (8), the distillate is condensed in the condenser (15), stored in the storage tank (3) as intermediate products and then returned to the storage tank (1). do. The distillation residue is discarded and 0.5% potassium carbonate is constantly supplied to the evaporator 8 in which a certain amount of methylene chloride is evaporated to separate any acidic impurities from the methylene chloride.

This operation yields 167 kg of crystallized saccharin-sodium per hour.

The crude solution contains 50 ppm orthotoluene-sulfonamide as impurities, and the pure saccharin-sodium obtained contains impurities of 1 ppm or less.

By modifying the above-described process, a small amount can be circulated in the crude solution filling to purify. For this purpose, the crude solution passed through the extraction column is re-adjusted in the storage tank 2 via the coupling conduit 27 shown in dotted line. Return to (7), and adjust the pH value and temperature to the minimum value in the adjustment tank (7). This is again flowed through the extraction tower by the combination pump 23 and then circulated until the desired purity is continued. The purified crude solution is then supplied from the storage tank 2 to the evaporator 9.

The circulation can be manipulated at every feed, but a continuous method is preferred. At this time, a part of the purified crude solution is returned from the storage tank (2) to the adjustment tank (7), the residue passes directly from the storage tank (2) to the evaporator (9). The loss in the adjustment tank 7 is good by supplying more fresh crude solution.

If the purity of the purified saccharin-sodium obtained is not sufficient, the amount of crude solution returned from the storage tank 2 to the control tank 7 is increased, which in turn leads to a loss of the passage in the whole plant.

The present invention will be described with reference to the following examples, which do not limit the scope of the present invention.

EXAMPLE

The crude solution consists of 500 kg of saccharin-sodium contaminated with a total of 250 g of orthotoluene-sulfonamide dissolved in 750 kg of water, using 100 liters of methylene chloride as a solvent. Both charges are circulated countercurrent for three hours to the extraction tower of the experimental plant. The experimental facility is constructed and operated in the same manner as the above-mentioned manufacturing facility. It is configured on a smaller scale than just the equipment described above. During the experimental operation, the crude solution is returned to the adjustment tank by the coupling conduit 27 in the drawing, and then flows back to the extraction tower. Methylene chloride is evaporated 3-5 times in 3 hours and the crude solution is passed through 2-3 extraction towers for 3 hours. After 3 hours, the crude solution was collected in a storage tank corresponding to the storage tank 2, and the purified crude solution was then distilled, crystallized and dried as described above in the drawing to contain 1 ppm or less of orthotoluene-sulfonamide. To obtain purified crystalline saccharin-sodium. The mother liquor remaining after the determination can be added to the next saccharin-sodium solution charge to be purified as described in the figure above.

Claims (1)

In the method for purifying crude carbohydrate-sodium purified by organic substances, methylene chloride is used for 30-60% crude aqueous solution of crude carbohydrate-sodium in vertically counterbalanced countercurrent extraction, and the countercurrent in countercurrent extraction. Method for purifying crude sodium-sodium, characterized in that the emulsification of the liquid by intermittently supplying the liquid through a flow barrier plate.

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