SU382603A1 - WAY OF OBTAINING DIACETON-2-KETO-1-GULONOVA - Google Patents

Description

one

The invention relates to the production of ketocarboxylic acids, in particular diacetone-2-keto-Gulonic acid, which is widely used in the synthesis of vitamin C-ascorbic acid.

A known method of producing diacetone-2 keto- /, -gulonic acid by electrochemical oxidation of diacetone-1-sorbose in an alkaline medium at a temperature not higher than 100 ° C using a nickel cathode and nickel oxide anode pr: and a current density of 0.1-20 a / dm, mainly 10 a / dm, while the interelectrode distance has no significant effect on the process.

The yield of the target product -94%. However, the productivity of the process is 0.23 g / h.

In order to intensify the process with the proposed method, the electrochemical oxidation is carried out at a current density of 20.0-100 a / dm and an interelectrode distance of 20-30 mm. This reduces the process time by 12-15 times.

In addition, it should be borne in mind that the arrangement of electrodes, i.e., coaxial (see Table 1) or plane-parallel (see Table 2), affects the efficiency of oxidation.

With a plane-parallel arrangement of electrodes with a distance between them of 32 mm, the yield of the target product at current density

12 a / dm is already 12.0% higher than pr: and coaxial arrangement, and it does not change so much with a significant increase in current density.

Table I

table 2

Note for the table. 1 and 2: 7.5 g of diacetone - /, - sorbose in 130 ml of 2% sodium hydroxide solution is used, the amount of electricity is 7.5 a hour.

From tab. With the coaxial arrangement of the electrodes with a distance between them of 5 mm, the output of diacetone-keto-1-gulon-1 1 acid drops quite significantly already at a current density of 12 a / dm.

The optimum was an interelectrode distance of 25 mm with a plane-parallel arrangement of the electrodes.

The amount of electricity passed through the current with high current densities should be 1.6-1.8 per hour per 1 g of diacetone-1.-Sorbose.

In tab. 3 shows the distance between the Mezherulech and the yield of the target product by substance n by current.

T a b l I t; j 3

 Experiments on the effect of the interelectrode distance were carried out at a low concentration of diacetone-L adsorbose (58 g / l) and the amount of electricity I per hour per I g of diacetone - /, - sortosis.

The last column for comparison presents data with the amount of transmitted electricity 1.7 per hour per 1 g of diacetone-b-sorbose and the concentration usually used in industrial conditions (100 g / l). Both of these factors contribute to an increase in the product yield by substance.

As can be seen from the table. 3, the interelectrode distance of 25 mm is optimal, and the interval of change of the interelectrode distance should be relatively narrow (20-30 mm). The dependence of the output of diacetone-2-keto-L-gulonic acid on the interelectrode distance is associated with the cumulative effect of such factors as mixing of the electrolyte in the interelectrode space, the separation of the pelvic at the electrodes, the access of the solution in the interlayer; electrolyte.

Table 4.

The effect of the amount of missed electricity on the output of diacetone-2-keto-L-salt of acid

cetone - / .- sorbose) with an interval of change in the amount of electricity of 1.5-1.7 per hour per 1 g of diacetone - / .- sorbose, whereas at current densities below 20 a / dm, the amount of electricity missed is 1 a hour on 1 g of diacetan- /.-sorbose. The latter is due to the fact that with an increase in the current density, the oxygen flow rate increases, and the amount of current per oxidation decreases.

A decrease in temperature below 50 ° C significantly slows down the process, and at temperatures above 60 ° C there is no point in leading the process, since the lero rate does not increase, but a strong evaporation of the electrolyte occurs. The duration of the process should increase at lower current densities, i.e., the productivity of the process will decrease. The duration of the process at a concentration of diacetone β-sorbose of 100 g / l is 4.5 hours for a current density of 50 a / dm. In this case, diacetone-2-keto-L-gloric acid is obtained in a yield of 94%. The productivity of the process is 3 g / h of diacetone-2-keto-Igulonic acid from 2.9 g / h of diacetone-L adsorb. At a current density of 147 a / dm, the process time is 3.2 hours, and the processing speed of the diacetone-L-coprose increases to 4 g / hour, but at a lower substance yield (87%), the diacetone-2-keto formation rate - /, -tuloic acid will be 3.9 g / hour.

The time spent with the known method is 260 hours, i.e., 65 g of diacetone-L-concentrate are processed. Upon oxidation at 10 a / dm 0.25 g / h of diacetone - /, - sorbose, 0.23 g / h of diacetone-2-keto-Igulonic acid is formed. A comparison of the known method with the proposed one shows that productivity. last higher by order.

Increasing the current density to 205 a / dm versus 105 practically does not affect the output, and therefore should be carried out at a density not higher than 100 a / dm.

Table 5

Examples: a concentration of diacetone-L-cobose is 58 g / l, a current density of 50 a / dm, an interelectrode distance of 25 mm, 2% NaOH solution.

From tab. 4 it follows that a high yield of the product by substance at high current densities, for example, at 50 a / dm, is achieved only with a 01P1 defined amount of continuous electricity (1.67 and an hour per 1 g of diaphragm ai ne: concentration of diacetone-L-coprose 100 g / l, the amount of electricity 1.7 A. hour for 1 gdiacetone-phosphorus.

At a current DENSITY of 12 a / dm, the power consumption per 1 kg of diacetone-2-keto - / .- gulon switch is 4 ket hour, and at a current density of 100 - 7.5 ket hour (cost 1.5 kopecks per 1 kW hour). Increase density

current from 12 to 100 a1dm increase the cost of electricity from 6 to 11.3 kopecks. At the cost of diadetosis-L-base 5 rubles. per kg (the consumption rate of diaceto-L-base is 1 kg per 1 kg of diacetone-2-keto-b-gulonic acid hydrate), the increase in electric power consumption will be 1% of the cost of diaceto-b-sorbose. However, the latter should be recouped by reducing capital investment during the process in an incentive-based mode.

Example. In a glass electrolyzer without a diaphragm with a nickel oxide anode and a nickel cathode, 130 ml of a 2% sodium hydroxide solution containing 13 g of diaoTOH-L-cop6o3bi is poured. The electrolysis is carried out at an anodic current density of 31.7 Idm and a temperature of 55 ° C. The amount of electricity missed is: 13 a hour. In the electrolysis process, 15 ml of a 15% sodium hydroxide solution are uniformly added to bind the resulting diacetone-2-keto-1-gulonic acid. After electrolysis the solution

ACCIDENT with cold 1: 1 HC1 so that the temperature does not exceed 5 ° C. Diaceton-2-keto-L-hydrochloric acid drop-down hydrate is filtered off. Received 13.72 g of the target product, which corresponds to the yield of the loaded diacetone sorbose 94%.

Subject invention

Claims (2)

1. A method for producing diacetone-2-KeTO-L-rylonoic acid by electrochemical oxidation of diacetone - /, - sorbose in an alkaline medium at a temperature not higher than 100 ° C using a nickel cathode and a nickel oxide anode, characterized in the process is intensified; the latter is carried out in an electrolyzer with a current density of 20.0-100 a1 dm, and an interelectrode distance of mm, followed by separation of the target product by known techniques. 2. A method according to claim 1, characterized in that the process is carried out with an interelectrode distance of 25 mm and 60 ° C.