Method of obtaining monochloracetic acid

FIELD: chemistry.

SUBSTANCE: invention relates to chemical technology and specifically to methods of producing monochloroacetic acid used in production of carboxymethylcellulose, pharmaceutical preparations, pesticides and ethylene diamine tetraacetic acid. The method of producing monochloroacetic acid involves crystallisation in a solvent and separation of monochloroacetic acid crystals from the mother solution through filtration, extraction of the solvent from the mother solution and returning to the crystallisation step, where the solvent used is carbon tetrachloride or perchloroethylene as commercial-grade as well as recycled, wherein crystallisation is carried out for 6-8 hours at weight ratio of molten crude monochloroacetic acid : solvent equal to 1:2-2.5. The initial crystallisation temperature is 38°C and the final crystallisation temperature is equal to 0±5°C.

EFFECT: improved process of producing monochloroacetic acid which is expressed in intensification of the crystallisation process, improvement of quality factors of monochloroacetic acid and improved technical and economical factors of production.

4 cl, 1 tbl, 8 ex

 

The invention relates to chemical technology, and in particular to methods of allocation of monochloracetic acid (MHUC)used in the production of carboxymethyl cellulose, pharmaceutical drugs, pesticides, ethylenediaminetetraacetic acid.

Monochloracetic acid, obtained by the chlorination of acetic acid (CA) in the presence of catalysts (acetylchloride, acetic anhydride), contains as impurities convertible acetic acid and the products deeper chlorination (di - and trichloroacetic acid).

The removal of impurities can be done in two basic methods crystallization and hydrogenation.

The process of obtaining MHUC, including stage hydrogenation of impurities (di - and trichloroacetic acids), are well represented [U.S. Patent No. 3304325, Germany No. 1816931, CL. SS 51/42, 1976, the Federal Republic of Germany patent No. 1668023, CL. SS 51/42, 1973].

According to the description it can be carried in the gas and liquid phases in the presence of stationary or suspended catalyst based on noble metals of group VIII of the periodic Table, among which the priority is given to metallic palladium on inert carriers. The process is conducted in a temperature range from 60°C to 240°C and a large excess of hydrogen, sometimes under pressure. The disadvantages of this method of obtaining MJUK superior quality content is chloroxylenol acid (DHOC) < 0,5%) is the use of expensive palladium catalyst, the possibility of its pitch, which limits its service life, difficulty of regeneration. In addition, eat MJUK per unit volume of the catalyst is small, which requires the use of large contact apparatus with a well-organized system of heat removal. Stringent temperature conditions of the process with an extremely high corrosional environments require the use of expensive equipment using silver or bimetal steel - silver.

The allocation method monochloracetic acid crystallization is implemented in an industrial environment [Oshin L.A. Industrial organochlorine products. The Handbook. - M.: Chemistry, 1978].

In many industries, the crystallization of the raw MJUK carried out in the bulk reactor jacketed for cooling. The heat removed by the water flow and the concentration of solid phase in suspension regulate the mixing of the reaction mass obtained after chlorination of acetic acid mother liquor from stage filtration. The temperature of the suspension gradually lowered from 70°C to 20°C. due to incrustation of the surface of the mold crystallization time, the content of DHOK in the finished product reaches 2%, bldg 1%, and the removal of the product does not exceed 300 kg from 1 m3the working volume of the reactor.

Of the local way of so-called thermal crystallization of the reaction mass MJUK [Source data Institute "Synthesis" for the design of technical re-equipment of production MHUC, Moscow, 1983]. The process is carried out in molds-heat exchangers tubular type.

Significant disadvantages of such crystallization are extremely high cost of manufacturing molds and their complexity; as materials for equipment in this case you can only use graphite or titanium. The method requires the permanence of the reaction mixture composition and precise temperature regulation; is accompanied by the formation of two Queen cells (warm and cold), one of which is in the recycling, the second requires an additional circuit for recycling.

It should also be noted that the method of thermal crystallization MJUK does not allow to concentrate DHUK to a concentration that is optimal for its further processing.

There is a method of allocating commodity MJUK from the reaction mixture [U.S. Patent No. 3365493, CL. 260-539, 1968], obtained by chlorination of glacial acetic acid containing 90-99% MHUC, 0-5% DHUK, less than 1% in the share capital and 0.01-0.5% of water, diluted with an inert solvent (methylene chloride) in a weight ratio of 1:5. Contents MJUK in the selected crystals is in the range of 0.2-0.5%, but this result is achieved by the use of the initial reaction mixture with a very low content of impurities that when the chlorination of acetic acid to provide extremely the ore, taking into account recycling the mother liquor such a composition is not a real number related to MJUK impurities, especially DHUK and the criminal code.

The deficiencies noted are not allow to recognize the proposed method of production MJUK suitable for industrial applications.

There is a method of crystallization of harmacy containing MHUC, in an organic solvent [RF Patent №2084443, CL. SS 53/16, 51/43, 01D 9/02, 1997]. As solvents it is proposed to use two connections - chloroethyl and halon-113. The crystallization is conducted at a weight ratio of the starting components 1:1 in two stages, the first crystallization raw, the second mother liquor. On both levels is the washing of the crystals used solvent. The method allows to obtain MJUK with contents DHUK 0,12-0,2% on the first stage and 0.65 to 0.45% on the second. The main drawback of this process is the use of expensive solvents, their huge losses due to the large volatility (boiling point chloroethyl +12,3°C, HADOPI-113 -47,5°C), complex technical solutions for the development of the method of their capture.

The closest in technical essence to the present invention is a method of crystallization of harmacy containing MHUC, in an organic solvent (Patent GB 949393, publ. 12.02.64.), which consists in adding to the said mixture of a chlorinated hydrocarbon having not more on the two carbon atoms, cooling the resulting mixture from +20 to -5°C for crystallization monochloracetic acid from the mixture. The number of added chlorinated hydrocarbons should be sufficient to get easily agitated mixture after crystallization. Then separate the crystals from the mother liquor and carry out the recycling, if necessary, all the mother liquor to the majority of the initial mixture in at least one cycle, until the percentage of dichloracetic acid in the mother liquor after separation of the crystals it will be at least equal percentage monochloracetic acid ibid (preferably 10-50 wt.%) and after that recycling is part described the mother liquor.

The disadvantage of this method is the presence in the process of a significant number of circulating mother liquor, which must be periodically output and disposed of, resulting in the loss with him a substantial amount of MHWC. All this greatly complicates the technological process and reduces its technical and economic indicators. In addition, it turns out monochloracetic acid is of low quality.

The technical result of the present invention is to improve the process of obtaining MHUC, reflected in the intensification of the crystallization process, improve the quality of MHWC and ysenia technical and economic indicators of production.

The technical result is achieved by obtaining monohloruksusnoj acid, comprising the crystallization of the solvent and separation of monochloracetic acid crystals from the mother liquor by filtration, removing the solvent from the mother liquor and returning to the step of crystallization, the solvent used carbon tetrachloride or perchlorethylene as commodity and regenerated, and crystallization was carried out for 6-8 hours at a weight ratio of the melt of raw monochloracetic acid: solvent 1:2-2,5, with initial crystallization temperature of 38°C, end 0±5°C.

The mother liquor is subjected to washing with water in a weight ratio of 10-15:1, followed by separation from the aqueous acid layer and returning the solvent to the stage of crystallization.

The aqueous acid layer is evaporated to a residual moisture content of not more than 1.5 wt.%, and then crystallized in the used solvent to obtain technical, product, containing monochloracetic acid of at least 95 wt.%. This crystallization is subjected to raw monochloracetic acid or its mixture with technical monochloracetic acid evolved at the stage of disposal of liquor.

The proposed method allows to obtain MJUK high quality and increase production output, and both peivate simple automated way of regeneration of the solvent and its further use in the process, with almost no losses.

The proposed method is illustrated by the following examples.

Example 1. In the reactor volumetric type, equipped with a reflux condenser, a thermometer and a shirt for heat, pour 200 g of carbon tetrachloride and metered with stirring 100 g of melt monochloracetic acid raw with a temperature of 70°With the following composition, wt.%: MJUK - 90,60, DHUK - 5,1, MC - 3,6, water - 0,5, other admixtures to 0.15. The rate of dosage provides the temperature of the crystallization mass not exceeding 50°C. Upon cooling, maintain a temperature differential between the contents of the reactor and the coolant is not more than 5°C. the crystallization Process starts at a temperature of 38°C. the stage of expansion of the crystal takes 6 hours, during which time the reaction mass is then cooled to a temperature of +5°C.

The resulting suspension is filtered on a centrifuge, separating of 78.5 g of crystalline MJUK composition, wt.%: MJUK - 99,5, DHUK to 0.2, of the criminal code to 0.08, water - 0,16, other admixtures - 0,06.

The yield of purified acid 86,21%, in addition, received 221,5 g of the filtrate, to which poured 22 g of water. After mixing and sludge allocate to 200.3 g of carbon tetrachloride (Chu) and 43.2 g of aqueous acid layer. Chu return in the loop for carrying out the subsequent crystallization, and from the aqueous acid layer otparivat of 25.9 g of water. To dehydrated draught poured 3.5 g of Cho and carry out the crystallization in the above-described mode. After filtering receive 9.00 g technical MJUK composition, wt.%: MJUK - 96,1, DHUK - 3,05, MC - 0,46, water - 0,32, other impurities of 0.07, which is used when carrying out the subsequent crystallization.

Example 2. In the conditions of example 1 on the crystallization load of 200 g of regenerated carbon tetrachloride, 91 g of a melt of raw sugar and 9 grams of technical monochloracetic acid compounds mentioned in example 1.

The resulting solution is cooled from a temperature of 50°C to -5°C for 8 hours. After filtration of the suspension get 82.3 g crystalline MJUK composition, wt.%: MJUK - 99,1, DHUK - 0,45, MC - 0,11, water - 0,25, other impurities of 0.01. The yield of purified acid - 89,5%.

To 217,7 g of mother liquor added 22 g of water, after separation of the layers get 200,5 g Chu and 39,1 g aqueous acid layer from which otparivat of 25.1 g of water mixed with acetic acid. To the dehydrated residue poured 30 g Cho and conduct crystallization. After filtering receive 6,66 g technical MJUK composition, wt.%: MJUK - 95,9, DHUK - 3,3 bldg 0,50, water - 0,19, other admixtures - 0,12.

From the presented examples, it follows that the conduct of the crystallization of harmacy, consisting of MHUC, DHOK and the criminal code, in the environment of carbon tetrachloride or perchlorethylene allows you to get MJUK content not less than 99,0% when the content of DHOK of 0.2-0.5%. Experimental data are presented in table 1.

The proposed modes is cristallization are optimal, as they provide a high quality and output of the target MJUK. The decrease in the crystallization temperature leads to the increase of the content of DHOK in a marketable product, and its increase to decrease output. The influence of the amount of solvent used in the same way.

1. The method of obtaining monochloracetic acid, comprising the crystallization of the solvent and separation of monochloracetic acid crystals from the mother liquor by filtration, removing the solvent from the mother liquor and returning to the step of crystallization, in which the solvent used carbon tetrachloride or perchlorethylene as commodity and regenerated, characterized in that the crystallization was carried out for 6-8 hours at a weight ratio of the melt of raw monochloracetic acid:solvent 1:2-2,5, with initial crystallization temperature of 38°C, end 0±5°C.

2. The method according to claim 1, wherein the mother liquor is subjected to washing with water in a weight ratio of 10-15:1, followed by the separation of the solvent from the aqueous acid layer and its return to the stage of crystallization.

3. The method according to claim 2, characterized in that the aqueous acid layer is evaporated to a residual moisture content of not more than 1.5 wt.%, and then crystallized in the used solvent with what rucenim technical product containing monochloracetic acid of at least 95 wt.%.

4. The method according to claim 3, characterized in that the crystallization is subjected to raw monochloracetic acid or its mixture with technical monochloracetic acid evolved at the stage of disposal of liquor.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of obtaining monochloracetic acid (MCA) and can be used in chemical industry. MCA is an essential product in production of carboxymethyl cellulose, various pesticides and medicinal agents. The method involves a step for chlorinating acetic acid with molecular chlorine in a bubbling reactor in the presence of a homogeneous catalyst, hydrogenolysis of chlorination products in the presence of a fixed-bed catalyst based on palladium and extraction of the end product through rectification under vacuum, where the hydrogenolysis step is carried out in film mode with direct-flow movement of liquid and gas.

EFFECT: lower consumption indices of raw material, higher quality of the obtained MCA and increased amount of recycled material.

4 cl, 1 dwg, 1 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention refers to organic chemistry, to chlororganic technology, specifically to advanced method of chloroacetic sodium salt production allowing for high quality with minimum power inputs. Method of chloroacetic sodium salt production (Na-CA) is characterised by that dry initial components that are soda ash (Na2CO3) and chloroacetic acid (CA) are continuously dispensed in stoichiometric ratio to desintegrator or dismembrator with linear speed of disk pins 30-150 m/s, where exposed to mechanochemical influence. Thereafter produced Na-CA is continuously supplied to drying. Produced in offered method Na-CA completely meets quality requirements of standard documents.

EFFECT: high quality products with minimum power inputs.

7 cl, 2 dwg, 3 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention pertains to the perfection of the method of obtaining monochloracetic acid from chlorine and acetic acid in the presence of a catalyst through reactive distillation. The given method and the device for reactive distillation are much less complex than known reactors.

EFFECT: invention allows to obtain monochloracetic acid with a low content of over-chlorinated products.

11 cl, 1 tbl, 1 dwg, 1 ex

FIELD: organic chemistry.

SUBSTANCE: invention relates to method for purification of monochloroacetic acid from dichloroacetic acid impurities. Claimed method includes hydrogenolysis in presence of hydrogen in film regime at 135-145°C in cascade of sequentially bonded reactors with fixed bed of heterogeneous catalyst namely palladium on activated carbon. Preferably reactor cascade with intermediate cooling with cold flow of monochloroacetic acid as cooling agent is used.

EFFECT: simplified process; product of improved quality.

3 cl, 7 ex, 3 dwg

FIELD: industrial organic synthesis.

SUBSTANCE: process is accomplished via catalytic chlorination of acetic acid at elevated temperature involving as catalyst crude acetyl chloride obtained as by-product in oxyethylidenediphosphonic acid synthesis at acetic acid-to-crude acetyl chloride weight ratio 1:(0.1-0.4). Crude acetyl chloride is employed either individually or in the form of acetic acid solution with content of principal solution no less than 90 wt %.

EFFECT: reduced level of dichloroacetic acid in final product and enabled utilization of chemical production waste.

2 cl, 6 ex

FIELD: industrial organic synthesis.

SUBSTANCE: two-stage process of production of monochloroacetic acid comprises acetyl chloride preparation stage and second stage wherein acetyl chloride is converted into desired product. Acetyl chloride is obtained via chlorination of acetic anhydride in continuous mode. Second stage is also carried out continuously in two steps involving recycling of acetyl chloride and acetic acid. Acetyl chloride is first chlorinated in UV activated chlorine flow in hydrodynamic mixing chamber to form nonochloroacetyl chloride. In the second step, nonochloroacetyl chloride recovered from reaction mixture is vaporized and fed into hydrodynamic mixing chamber to be mixed with 99.9% acetic acid. Resulting reaction mixture, containing monochloroacetic acid and acetyl chloride, is passed to heat exchanger at 80°C, wherein acetyl chloride is separated in thin layer from condensed monochloroacetic acid and returned to the first step.

EFFECT: increased productivity of process due to accelerated chlorination operation.

5 cl

The invention relates to the industrial production monochloracetic acid
The invention relates to the production of trichloroacetic acid (THUK), which is obtained by the oxidation of mixtures hlorosoderzhashie

The invention relates to the field of technology organochlorine compounds, and in particular to a method for producing sodium salt of monochloracetic acid used in the production of monochloracetic acid used in the production of sodium salt of carboxymethyl cellulose, dyes, herbicides, vitamins b6and medicines

FIELD: chemistry.

SUBSTANCE: invention relates to a method of preparing a sodium formate-containing composition with formic acid content of not less than 35 % of the total weight of the said composition, in which a) a stream of formic acid with formic acid content of not less than 74 wt % is provided; b) a stream of formic acid from step a) together with sodium formate-containing streams from step f) and step h) are taken to the crystallisation step where an aqueous solution is obtained at high temperature, where the said solution has molar ratio HCOOH:Na[HCOO] greater than 1.5:1 and molar ratio HCOOH: H2O equal to at least 1.1:1; c) at the crystallisation step the aqueous solution from step b) is crystallised to obtain a stream which contains a solid phase and a mother solution; d) the stream obtained from step c) is taken to a separation step on which the solid phase is separated from the mother solution to obtain a stream which contains sodium diformate and a stream which contains a mother solution; e) the stream which contains the mother solution from step d) is divided into two parts; f) one part of the stream from step c) in form of a portion (A) is returned to step b); g) the other part of the stream from step e) in form of a portion (B) together with the stream, including a base, which contains sodium is taken to a neutralisation step to obtain a mixture which contains sodium formate, and where portions of the mother solution (A) and (B) complement each other to 100 wt %, and the weight ratio of portion (A) of the mother solution to portion (B) lies between 20:1 and 1:10; and b) the sodium formate-containing mixture from step g) and optionally from step h), if necessary after its withdrawal, is taken to the concentration step in form of a stream where a portion of water contained in that stream is released, where after separation of the portion of water a stream which contains sodium formate is obtained, which is directly returned to step b) or crystallised at the second crystallisation and separation step, and the obtained liquid phase is taken to the concentration step h) in form of a stream, and the solid phase is taken in form of a stream to step b). The obtained product can be used in industrial production, especially at relatively low temperatures.

EFFECT: improved method of preparing a sodium formate-containing composition with formic acid content of not less than 35% of the total weight of the said composition; obtained product has antibacterial activity and is used in preservation for example, as well as for acidification of animal and plant material.

16 cl, 5 dwg, 7 ex, 8 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to a carboxylic acid synthesis method. The invention specifically relates to a method for synthesis of carboxylic acids through oxidation of a hydrocarbon with oxygen or an oxygen-containing gas, and more specifically to oxidation of cyclohexane to adipinic acid. According to the invention, the method involves a step for oxidising the hydrocarbon and at least one step for extracting the formed dicarboxylic acids from the reaction medium and, in known cases, return unconverted hydrocarbon and oxidation by-products such as ketones and alcohols which may be formed to the reaction. The disclosed method also includes a step for conversion, separation or extraction of α,ω-hydroxycarboxylic compounds formed during oxidation. This step for conversion, separation or extraction of α,ω-hydroxycarboxylic compounds involves oxidation of medium containing the said compounds in order to convert them to dibasic acids.

EFFECT: design of an efficient method of obtaining carboxylic acids.

16 cl, 10 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of purifying carboxylic acid from a mixture which contains one or more carboxylic acids selected from a group consisting of terephthalic acid, isophthalic acid, orthophthalic acid and their mixtures, and also contains one or more substances selected from a group consisting of carboxybenzaldehyde, toluic acid and xylene. The method involves: bringing the mixture into contact with a selective solvent for crystallisation at temperature and in a period of time sufficient for formation of a suspension of a complex salt of carboxylic acid with the selective solvent for crystallisation without complete dissolution of the complex salt of carboxylic acid; extraction of the complex salt and decomposition of the complex salt in the selective solvent for crystallisation in order to obtain free carboxylic acid. The mixture containing unpurified carboxylic acid is brought into contact with the selective solvent for crystallisation in order to form a suspension of a complex salt of carboxylic acid with the selective solvent for crystallisation. The complex salt is extracted and, if desired, processed for extraction of free carboxylic acid.

EFFECT: methods are especially suitable for purifying aromatic dibasic carboxylic acids such as terephthalic acid, and also enables reduction of the degree of contamination of phthalic acids with carboxybenzaldehyde isomers.

22 cl, 3 tbl, 1 dwg, 3 ex

FIELD: process engineering.

SUBSTANCE: invention relates to removal of impurities and mother solution and wash filtrate extraction from oxidising reactor discharge flow formed in synthesis of carboxylic acid, usually, terephthalic acid. Proposed method comprises: (a) directing oxidised flow in zone of enrichment by solid particles to settle solid particles and form dumping flow suspension via cooling it, adding settling agent, removing solvent or combining said cooling and adding; (b) separating dumping flow suspension in separation zone to form filter pad and mother solution and forced flushing of said filter pad at high pressure in said separation zone by flushing fluid flow comprising water and, not obligatorily, solvent to form washed pad. Note here that said separation zone comprises at least one filter device operated at pressure and comprising at least one filter cell. Note also that said filter cell accumulates layer of filter pad with depth of at least 0.635 cm (0.25 inch), "c" directing at least a portion of flushing filtrate and at least a portion of mother solution to oxidising zone.

EFFECT: higher efficiency.

44 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: method involves, for example: (a) evaporation of said oxidised discharge stream, containing terephthalic acid, metallic catalyst, impurities, water and solvent, in the first zone of an evaporator to obtain a vapour stream and a concentrated suspension of the discharge stream; and (b) evaporation of the said concentrated suspension of the discharge stream in the second zone of the evaporator to obtain a stream rich in solvent and a high-concentration suspension of the discharge stream, where the said second zone of the evaporator has an evaporator operating at temperature ranging from 20°C to 70°C, where from 75 to 99 wt % of the said solvent and water is removed by evaporation from the said oxidised discharge stream at step (a) and (b); (c) the said high-concentration suspension of the discharge stream is filtered in a zone for separating solid products and liquid to form a filtered product and a mother liquid; (d) washing the said filtered product using washing substances fed into the said zone for separating solid products and liquid to form a washed filtered product and washing filtrate; and dehydration of the said filtered product in the said zone for separating solid products and liquid to form a dehydrated filtered product; where the said zone for separating solid products and liquid has at least one pressure filtration device, where the said pressure filtration device works at pressure ranging from 1 atmosphere to 50 atmospheres; (e) mixing water and optionally extractive solvent with the said mother liquid and with all of the said washing filtrate or its portion in the mixing zone to form an aqueous mixture; (f) bringing the extractive solvent into contact with the said aqueous mixture in the extraction zone to form a stream of extract and a purified stream, where the said metallic catalyst is extracted from the said purified stream.

EFFECT: improved method of extracting metallic catalyst from an oxidised discharge stream obtained during production of terephthalic acid.

36 cl, 3 dwg, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of separating a mixture of naphthenic acids. The method is characterised by that, an aqueous solution a mixture of sodium salts of naphthenic acids - naphthenic soap, with concentration of 3 to 5 M is treated with 3 to 5 M sulphuric acid with control of the pH of the medium. For each unit change of pH value, the precipitated complex of naphthenic acid and its sodium salt is separated from the reaction mass, after which each fraction of the product is dissolved in a fivefold amount of water to decompose the formed complex, and then treated with 3 to 5 M sulphuric acid to pH 1-2 and naphthenic acids are separated from the aqueous solution to obtain fractions of naphthenic acids with dissociation constant pKa=8±1.

EFFECT: formation of complexes of naphthenic acids with their sodium salts for separation of a mixture of naphthenic acids with similar chemical and physicochemical properties.

1 ex

FIELD: chemistry.

SUBSTANCE: crystalline calcium salt of gluconic acid or its compound with excipients is processed in grinding activator devices, or to a value of supplied specific energy of not more than 10.4 kJ/g and achieving amorphous-crystalline state, or to a value of specific energy of not less than 10.5 kJ/g and achieving amorphous state. The obtained substances are analysed using X-ray diffraction, infrared, NMR, EPR spectroscopy, mass- and chromatography-mass spectrometry and differential thermal analysis.

EFFECT: mechano-activated amorphous and amorphous-crystalline compounds and compositions are used as active compounds for making pharmaceutical preparations.

13 cl, 10 dwg, 12 ex

FIELD: chemistry.

SUBSTANCE: sodium hydroxide solution is added to a technical mixture of benzoic and cinnamylic acid, obtaining a precipitate. Water is added to obtain a homogeneous solution. The obtained technical mixture of sodium salts of benzoic and cinnamylic acid with composition ranging from 2:1 to 1:2 and overall concentration ranging from 3 to 5 M is then mixed with sulphuric acid with concentration ranging from 3 to 5 M. Addition of sulphuric acid is stopped at pH of the medium between 8 and 9, and the precipitated complex of cinnamylic acid with its sodium salt is filtered from the reaction mixture, dissolved in excess amount of water to dissolve sodium salt of cinnamylic acid. Cinnamylic acid precipitates, and is further treated with sulphuric acid with concentration ranging from 3 to 5 M to pH between 1 and 2. The precipitated crystals of cinnamylic acid are separated; the reaction mixture remaining after separation of the complex is mixed with a solution of sulphuric acid with concentration ranging from 3 to 5 M until pH between 1 and 2. As a result, crystalline benzoic acid forms.

EFFECT: formation of complexes of carboxylic acids with their sodium salts for separating components of a mixture of carboxylic acids with similar chemical and physico-chemical properties.

2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a thermal separation method using fractional condensation of a product-gas mixture, obtained through heterogeneous catalysed partial oxidation of propene and/or propane in gaseous phase to acrylic acid, for separating at least one mass flow, concentrated with acrylic acid, from a product-gas mixture containing acrylic acid, which involves continuous static operation of at least one device for thermal separation, containing at least one effective separation chamber with a fractionation column which has mass-transfer trays as built-in separating elements, in which the product-gas mixture is loaded, containing acrylic acid as at least one mass flow, and from which at least one mass flow containing acrylic acid is unloaded under the condition that, the overall mass flow loaded into the effective separation chamber and obtained from combining separate mass flows loaded into the separating chamber, contains X wt % components distinct from acrylic acid, the mass flow which is unloaded from the effective separation chamber with the largest content of acrylic acid, contains Y wt % components distinct from acrylic acid, ratio X:Y is ≥5, effective separation chamber, except the loading and unloading place, is bordered by a solid phase and contains, besides the mass-exchange trays as built-in separating elements in the fractionation column, at least one circulating heat exchanger, and total volume of the chamber, filled with liquid phase, is ≥1 m3, wherein temperature of the liquid phase is at least partially ≥80°C, when the effective separation chamber is divided into n separate volume elements, wherein the highest and lowest temperature of liquid phase in a separate volume element differ by not more than 2°C, and the volume element in the effective separation chamber is solid, total dwell time ttotal.

≤20 h, where A = (Ti-To)/10°C, To= 100°C, Ti = arithmetic mean value of the highest and lowest temperature of the ith volume element in the liquid phase in °C, msi = total mass of acrylic acid in the volume of the liquid phase of the ith volume element, mi = total liquid phase mass unloaded from the ith volume element, and is the sum of all volume elements i, under the condition that, volume elements i with liquid phase mass mi and as volume elements with a dead zone are also not included in the sum of all volume elements i, as well as volume elements i, which do not contain liquid phase, and total amount of liquid phase contained in volume elements with a dead zone is not more than 5 wt % of the total amount of liquid phase contained in the effective separation chamber.

EFFECT: separation of mass flow concentrated with acrylic acid.

10 cl, 12 dwg, 2 ex, 2 tbl

FIELD: chemistry.

SUBSTANCE: proposal is given of a method of removing impurities from a water mixture or purified water mixture through extraction of the water mixture or purified water mixture using an extractive solvent in the extraction zone with formation of a stream of extract and a stream of raffinate and, optionally, separation of the extract stream and the solvent rich stream in the separation zone with formation of a stream of organic impurities with high boiling point and a stream of extractive solvent.

EFFECT: provision for extracting metallic catalyst in active form, reusable at the paraxylene recycling stage.

29 cl, 2 dwg, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to a method of preparing a sodium formate-containing composition with formic acid content of not less than 35 % of the total weight of the said composition, in which a) a stream of formic acid with formic acid content of not less than 74 wt % is provided; b) a stream of formic acid from step a) together with sodium formate-containing streams from step f) and step h) are taken to the crystallisation step where an aqueous solution is obtained at high temperature, where the said solution has molar ratio HCOOH:Na[HCOO] greater than 1.5:1 and molar ratio HCOOH: H2O equal to at least 1.1:1; c) at the crystallisation step the aqueous solution from step b) is crystallised to obtain a stream which contains a solid phase and a mother solution; d) the stream obtained from step c) is taken to a separation step on which the solid phase is separated from the mother solution to obtain a stream which contains sodium diformate and a stream which contains a mother solution; e) the stream which contains the mother solution from step d) is divided into two parts; f) one part of the stream from step c) in form of a portion (A) is returned to step b); g) the other part of the stream from step e) in form of a portion (B) together with the stream, including a base, which contains sodium is taken to a neutralisation step to obtain a mixture which contains sodium formate, and where portions of the mother solution (A) and (B) complement each other to 100 wt %, and the weight ratio of portion (A) of the mother solution to portion (B) lies between 20:1 and 1:10; and b) the sodium formate-containing mixture from step g) and optionally from step h), if necessary after its withdrawal, is taken to the concentration step in form of a stream where a portion of water contained in that stream is released, where after separation of the portion of water a stream which contains sodium formate is obtained, which is directly returned to step b) or crystallised at the second crystallisation and separation step, and the obtained liquid phase is taken to the concentration step h) in form of a stream, and the solid phase is taken in form of a stream to step b). The obtained product can be used in industrial production, especially at relatively low temperatures.

EFFECT: improved method of preparing a sodium formate-containing composition with formic acid content of not less than 35% of the total weight of the said composition; obtained product has antibacterial activity and is used in preservation for example, as well as for acidification of animal and plant material.

16 cl, 5 dwg, 7 ex, 8 tbl

Up!