RU2641302C1 - Method for obtaining dimethyldisulfone - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: electrolysis is carried out in aqueous solutions of dimethylsulfone in an alkaline medium in the anode compartment of the diaphragm electrolyser in the range of densities of the anode current of 0.1-0.3 A/cm², then the solution of anolyte is cooled to T=5-8°C to the formation of crystals.

EFFECT: absence of water-soluble by-products in the electrooxidation process of aqueous solutions of dimethylsulfone in an alkaline medium to produce dimethyldisulfone.

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Description

The invention relates to a technology for producing sulfur-containing organic compounds, in particular, to the synthesis of dimethyldisulfone. Dimethyldisulfone (1,2-dimethyldisulfone-1,1,2,2-tetraoxide) is a colorless crystalline substance that is used in pharmaceuticals for the manufacture of drugs, organic synthesis as an inhibitor of oxidation and protection of functional groups, household chemicals for the synthesis of surfactants.

A known method of producing disulfones [Chichibabin A.E. The main principles of organic chemistry. Publishing house 6. M .: Goskhimizdat. T. 1 S. 234] the oxidation of thiocetals.

The disadvantages of this method is that this method produces acyclic disulfones, a multi-stage process, the use of toxic reagents and a low yield of the final product.

There is also known a method [Eurasian patent No. 019538 B1 from 04/30/2014, Cl. A01N 25/06, A01N 41/10, A01N 59/10, A01N 59/16, A01P 1/00. Composition for surface sterilization // Andersen Bjerg Marit, Berg Eric Edwin]. In this method, a mixture of disulfones of various compositions is obtained from a mixture of hydrogen peroxide and dimethyl sulfone.

The disadvantages of this method are the explosive composition of the mixture, the complexity of the separation formed of various disulfones.

The method closest in essence is the method [RF patent No. 2554880 C1. Cl. С07С, dated June 2, 2015. A method for producing methanesulfonic acid. // Khidirov Sh. Sh., Akhmedov MA, Rabadanov M.Kh.] by electrolysis in the anode compartment of a diaphragm electrolyzer from concentrated aqueous solutions of 0.2-1.6 M dimethyl sulfone at high anode current densities 0.12-0 , 2 A / cm ² .

The disadvantages of this method are the small yield of dimethyldisulfone and the difficulty of its separation from methanesulfonic acid.

The objective of the invention is to increase the productivity of the synthesis of dimethyldisulfone and the efficiency of the method.

The technical result consists in the absence of water-soluble by-products in the process of electrooxidation of aqueous solutions of dimethyl sulfone in an alkaline medium to obtain dimethyldisulfone.

The essence of the proposed method is that the electrolysis is carried out in aqueous solutions of dimethyl sulfone in an alkaline medium in the anode compartment of the diaphragm electrolyzer within the anode current densities of 0.1-0.3 A / cm ² , then the anolyte solution is cooled to T = 5-8 ° C to form crystals.

The invention is illustrated by examples.

Example 1

The electrolysis was carried out in a diaphragm electrolyzer with a cation exchange membrane brand - MKF. The anode is platinum, S = 2 cm ² , the cathode is graphite. 50 ml of 0.1 M NaOH are poured into the anode compartment of the electrolyzer and 1.88 g of dimethyl sulfone are dissolved in it, and a 0.1 M NaOH solution is dissolved in the cathode compartment.

The main product of electrosynthesis at an anode current density ( ia ) of 0.1 A / cm ² is dimethyldisulfone (CH ₃ S (O) ₂ -S (O) ₂ CH ₃ ).

After electrolysis, the anolyte solution was cooled to T = 5-8 ° C to isolate crystals of CH ₃ S (O) ₂ -S (O) ₂ CH ₃ . The isolated crystals were repeatedly washed with cold distilled water to pH 7, then dried in a desiccator over concentrated sulfuric acid and weighed on a laboratory balance.

The yield of dimethyldisulfone was 80% of the mass.

Example 2. Carried out analogously to example 1. An aqueous solution containing 3.76 g of dimethyl sulfone against 0.1 M NaOH at an anode current density of 0.1 A / cm ² was subjected to electrolysis.

The yield of dimethyldisulfone was 78% of the mass.

Example 3. Carried out analogously to example 1. An aqueous solution containing 5.64 g of dimethyl sulfone at an anode current density of 0.2 A / cm ² was subjected to electrolysis.

The yield of dimethyldisulfone was 82% of the mass.

Example 4. Carried out analogously to example 1. An electrolysis was subjected to an aqueous solution containing 7.52 g of dimethyl sulfone at an anode current density of 0.3 A / cm ² .

The yield of dimethyldisulfone was 68% of the mass.

Example 5. Carried out analogously to example 1. An aqueous solution containing 9.54 g of dimethyl sulfone at an anode current density of 0.3 A / cm ² was subjected to electrolysis.

The yield of dimethyldisulfone was 65% of the mass.

The results of similar examples at various anode current densities are given in the table.

It can be seen from the table that the highest yield of dimethyl sulfone in a substance occurs at an anode current density of ia = 0.2 A / cm ² . Apparently, at ia > 0.2 A / cm ² , the reaction of anodic oxygen formation predominates.

In FIG. 1 shows the stationary polarization curves of a smooth platinum electrode in a 0.1 M NaOH solution (1) and in the presence of dimethyl sulfone in an amount of 1.88 g (2); 3.76 g (3); 5.64 g (4); 9.4 g (5). Potential sweep speeds of 2 mV / s. According to the stationary polarization curves, in comparison with the background curve 1, it is seen that, within the anode current densities of 0.1-0.3 A / cm ² , the oxygen evolution is suppressed due to the adsorption of dimethyl sulfone molecules on a platinum electrode.

The essence of the process of formation of dimethyldisulfone in an aqueous solution of alkali is as follows. Known adsorption on platinum and platinum metals of organic substances containing more than one carbon atom, accompanied by the breaking of C-C bonds and the dimerization of radicals formed during the destruction.

In the case of dimethyl sulfone, a similar cleavage of C-S bonds occurs with the formation of methyl sulfo group and methyl radicals. It should be noted that the average C-S bond cleavage energy (255 kJ / mol) is almost 1.5 times less than the C-C bond energy (347 kJ / mol). Therefore, when certain anode current densities are reached, the С-S bond is broken with the formation of methyl and methyl sulfonic radicals.

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Methylsulfonic radicals readily dimerize to form stable dimethyldisulfone molecules and are desorbed into the bulk of the solution.

также связываются с ОН-радикалами, образующимися при разряде гидроксид ионов.Methyl radicals

also bind to OH radicals formed during the discharge of hydroxide ions.

Methanol molecules on the surface of the platinum anode are chemisorbed to form particles of the СОН composition.

Particles of COH _{ads are} oxidized with the formation of CO ₂ , as in the complete oxidation of CH ₃ OH according to the equation [Electrode processes in solutions of organic compounds. / Ed. Damaskina B.B. M .: Publishing. Mosk. un-that. 1985. S. 11]:

The formation of carbon dioxide CO ₂ in the anode compartment is proved by gas chromatography.

In FIG. Figure 2 shows the images of dimethyldisulfone crystals taken in the field of view of the reflected light of the Mikmed-6 microscope at magnifications of 10 (a) and 40 (b) times.

The proposed method has several advantages:

- simplification of the processes of separation of the main product - dimethyldisulfone;

- productivity increase;

- the purity of the resulting final product is due to the absence of by-product formation processes associated with the dehydrogenation and hydrogenation of dimethyl sulfone molecules in the region of oxygen evolution potentials;

- the method is environmentally friendly due to the lack of release of toxic and harmful substances;

- simplicity of technology and equipment, low level of capital and operating costs.

Claims (1)

A method of producing dimethyl disulfone by electrolysis of an aqueous solution of dimethyl sulfone in an acidic medium, characterized in that the electrolysis is carried out in aqueous solutions of dimethyl sulfone in an alkaline medium in the anode compartment of the diaphragm electrolyzer within anode current densities of 0.1-0.3 A / cm ² , then anolyte solution cooled to T = 5-8 ° C until crystals form.

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