Method of producing significantly pure monochloroacetic acid

FIELD: chemistry.

SUBSTANCE: invention relates to use of a loop reactor, having gas and liquid recirculation systems which are connected through the combining nozzle of a reactor ejector, in which gas and liquid circulate in a parallel stream, and the combining nozzle is formed such that, mixing power of at least 50 W/l of the liquid phase can be imparted into the liquid phase, and in which the gas recirculation system has a device for continuous removal of gaseous HCl, formed during the process, from the recirculating gas and returning unreacted hydrogen gas into the mixing nozzle of the ejector of the loop reactor, for selective catalytic hydrogenation of the liquid dichloroacetic acid to monochloroacetic acid.

EFFECT: invention relates to a continuous or periodic method of producing monochloroacetic acid containing less than 0,1 wt % dichloroacetic acid from a liquid mixture of chloroacetic acid, containing monochloroacetic acid and dichloroacetic acid, in which the mixture is mixed with a suspended hydrogenation catalyst and mixed with hydrogen gas, wherein the formed mixture reacts in said loop reactor.

15 cl, 1 dwg, 4 ex

 

The technical field to which the invention relates.

The present invention relates to the production of substantially pure monochloracetic acid (MHUC), in particular, from a liquid mixture containing monochloracetic acid and a large number of dichloracetic acid (DHOC), for example from 2 to 20 wt.%, and, depending on the circumstances, trichloroacetic acid.

Prior art

Monochloracetic acid required for the synthesis of many basic chemical products, in particular for the pharmaceutical or cosmetic industry. On an industrial scale monochloracetic acid is usually produced by direct chlorination of acetic acid, however, these responses inevitably leads only to not purified product containing, in addition to desirable monochloracetic acid, a large number of dichloracetic acid and sometimes trichloroacetic acid, and the residual acetic acid. In particular, it was found that it was virtually impossible to avoid the formation of problematic byproduct dichloracetic acid. The number of dichloracetic acid present in the final product varies usually from about 1 to 6%, depending on the particular used method of chlorination. However, in many industries t is some amount of impurities for monochloracetic acid is not acceptable, and so for many applications monochloracetic acid is determined that the content of dichloracetic acid product should not exceed 0.5 percent by weight and often even lower percentage.

Therefore, undesired by-products, in particular, dichloracetic acid, it is usually necessary to remove from the raw materials monochloracetic acid before further use. While acetic acid can be easily removed, e.g. by distillation, because of the proximity of the boiling points of monochloracetic acid (189°C) and dichloracetic acid (194°C) it is impossible to separate these products through distillation economically acceptable way.

In connection with the foregoing attempts were carried out to remove highly chlorinated acetic acids of the target product by recrystallization techniques or selective catalytic hydrogenation of the crude product.

Recrystallization can reduce the concentration of dichloracetic acid in a mixture of the crude product about 4 times in one stage of recrystallization, for example from about 3 percent to about 0.75 percent, so that it usually takes more than one stage to perform the normal requirements of the industry (compare, for example, U.S. patent No. 5756840). Furthermore, in addition to the necessity of passing the TLD is tadini cleaning recrystallization leads to a large number of mother liquor, containing large amounts of monochloracetic acid and about 18-40% by weight of dichloracetic acid, which is economically impossible to allocate and which, therefore, it is usually discarded as waste.

The usual method of hydrogenation (or dechlorination) of the crude mixture of mono-, di - and trichloroacetic acid in the presence of a catalyst suspended in the above-mentioned mixture, thereby selectively reducing the concentration of higher chlorinated derivatives in the above-mentioned mixture, is described, for example, in DE-A-1915037. In this way the crude mixture of acetic acid fed into the reactor and it suspendered catalyst. Then the bottom of the reactor impose an excess of gaseous hydrogen, and the crude mixture of acids with suspended therein catalytic hydrogenation circulates through the pipe leading from the upper zone of the reactor in the lower zone to achieve good mixing of the suspension of catalyst and the crude mixture of acids. The above-mentioned circuit of the crude acid also includes an outlet for the continuous removal of deklarirovannoe product monochloracetic acid which is then separated from acetic acid, if any. Escaping gas, including by - product hydrogen chloride and excess hydrogen leaves the reactor through additional labor is near, passing through a wash column in which gaseous hydrogen chloride is separated from the residual gaseous hydrogen by washing the gas mixture with water, so that the purified residual gaseous hydrogen could be returned to the reactor. However, this method of hydrogenation of the prior art has some disadvantages, the main disadvantage is that acceptable conversion dichloracetic acid in monochloracetic acid cannot be achieved without adding a special activators to the crude mixture of acids, which must be soluble in the above-mentioned mixture of Chloroacetic acid. Therefore, these activators usually you want to delete from pure product to meet the normal specifications for monochloracetic acid, thus requiring an additional step of purification, such as distillation monochloracetic acid. In addition, despite activation, as reported for the reaction required a considerable excess of hydrogen gas. As an example, approximately strategisation excess of hydrogen per dichloracetic acid present in the initial mixture, is used according to example 1 from this link. Regardless of these shortcomings, the degree of purity obtainable with conventional single-stage hydrogenation, still does not t aetsa really satisfactory.

Therefore, it was also proposed to combine catalytic hydrogenation, followed by a stage of recrystallization. As an example, U.S. patent No. 5756840 discloses a method of obtaining high-quality monochloracetic acid in the presence of a suitable catalyst by hydrogenation of a mixture of monochloracetic and dichloracetic acid in the absence of solvent, followed by subsequent crystallization from the melt. The hydrogenation is carried out through a fixed catalyst in a tubular reactor. In the example at the stage of hydrogenation of the content of dichloracetic acid in a mixture of mono-/dichloracetic acid could be reduced from about 3.1 percent by weight to 0.04 percent by weight, and further in a subsequent stage of recrystallization to 0.01 percent by weight. Although, as disclosed method is applicable to mixtures containing up to about 50 percent by weight of dichloracetic acid, such amount specified impurities requires a double pass through a stage of hydrogenation before the crystallization of the melt, and the method is not economical. In addition, the amount of hydrogen gas used according to this document, is also quite high, and according to the examples use 7-143-fold excess of hydrogen in comparison with the stoichiometric quantity.

Disclosure sown the STI inventions

The aim of the present invention is to provide a simple way to eliminate the drawbacks associated with prior technology for the purification of mixtures of monochloracetic acid and highly chlorinated derivatives of acetic acid, in particular the above-mentioned disadvantages.

It has been unexpectedly discovered that the disadvantages of the prior processing technology can be overcome if for selective catalytic hydrogenation of dichloracetic acid in monochloracetic acid is used loop reactor: the reactor, which contains a system of recirculation of the gas and the liquid, combined through the mixing nozzle of the ejector, and the reactor in which the gas and the liquid circulating in the parallel flow, and the specified mixing nozzle is formed so that the liquid phase can be power mixing at least 50 W/l of liquid phase.

It was also found that the use of a loop reactor according to the invention is particularly advantageous for the production of substantially pure monochloracetic acid from a mixture containing monochloracetic acid, dichloracetic acid, e.g., in the amount of 2-40 wt.% and optional trichloroacetic acid.

Accordingly, the present invention relates also to a new method for the production of substantially cystosonography acid from a liquid mixture, containing monochloracetic acid and dichloroquinone acid, especially in the amount of 2-40 wt.%, where the mixture of Chloroacetic acid, then mixed with suspended hydrogenation catalyst, is mixed with gaseous hydrogen and the resulting mixture is reacted in the reactor; a method which is characterized in that the reactor is a loop reactor containing recirculation systems gas and liquid combined using a mixing nozzle of the ejector; a reactor in which the gas and the liquid circulating in the parallel flow and mixing power introduced into the liquid phase is at least 50 W/l of liquid phase.

For the purposes of the present invention preferably is understood that the term "substantially pure" refers to the product monochloracetic acid containing less than 0.1 wt.% dichloracetic acid, more preferably less than 0.05 wt.%, most preferably less than 0.02 wt.% dichloracetic acid. It is preferable that the specified "substantially pure" monochloracetic acid also does not contain trichloroacetic acid, i.e. the proportion of trichloroacetic acid is below detection limits.

Loop reactor used according to the present invention, preferably is a so-called "Advanced Buss Loop Reactor", or the like is Oh, as described, for example, in Peter Cramers and Christoph Selinger: "Advanced hydrogenation technology for fine chemical and pharmaceutical applications" PHARMACHEM, June 2002, in which the reagents recycle the path using the pump, and the reaction is carried out in the injector nozzle in the reactor, providing a very effective mixing of the gas/liquid/solids. This type loop reactor substantially optimizes and intensifies the process of dehydrohalogenating compared to conventional technologies. For this circuit the specified loop reactor comprises a mixer highly efficient gas-emitting device containing in its upper end nozzle of the Venturi type, through which the recycle mixture of acids, optionally together with fresh liquid mixture of acids, and contains glands suspended catalyst in the reactor, and which provides a high-speed jet mentioned liquid mixture, which, in turn, ensures the absorption of the reaction gas in gazootsasyvajushchuju the camera, which is connected to the reactor through a gas-liquid ejector and surrounds the specified nozzle, thus providing a very intensive mixing of the fluid and gas.

Mentioned mixing device that mixes the gas and liquid phase and maintains the catalyst in a suspended form, made a particularly high mixing power the spine in the liquid phase, usually at least 50 W/l of liquid phase, preferably from 50 to 2000 W/l of liquid phase, in particular from 100 to 500 W/l of liquid phase.

This method of operation is a significant cause of the above advantages over conventional methods of hydrogenation, which is used only conventional mixing capacity from 0.1 to 10 W/l of liquid phase.

Advanced loop reactor, is applicable for the present invention typically contains a gas recirculation circuit connecting the free space of the reactor with ghatotkacha camera in the upper part of the reactor. Unreacted hydrogen in the free space above the product with hydrogen chloride which is formed during the reaction dehalogenase circulates through the circulation loop of the gas sucked through the suction self-priming nozzle. Accordingly, in the circuit of the gas does not require additional compressor or other gas-lift system. This continuous recirculation gas is one of the reasons for very efficient use of raw materials of hydrogen gas according to the present invention, so as to avoid having to use a large stoichiometric excess of hydrogen, which are known from the prior art. Usually the molar amount of water used is an ode to exceed the molar amount of dichloracetic acid and trichloroacetic acid, if there is one) from 0 to about 60 percent, preferably from 0 to 10 percent. However, according to the present invention, the stoichiometric excess of hydrogen is not required.

The method of hydrogenation can mainly be carried out under a pressure of from 0 to 10 barg. ("bar excess pressure" corresponds to the absolute pressure of from 1 to 11 bar), preferably from 0 to 3 barg.

The reaction temperature is preferably from 130 to 170°C., more preferably 140 to 155°C.

The catalysts used for the method of the invention, are preferably noble metals deposited on an inert carrier. For example, gidrirovanie is done using existing industrial heterogeneous catalysts of the noble metal preferably with 1-5% palladium or platinum deposited on activated carbon, the concentration of catalyst is from 0.05 to 1.00 wt.%, preferably from 0.1 to 0.4 wt.%, based on the total amount of raw material. The catalysts used according to this invention, are prepared in the usual way.

In a particularly preferred method of the invention the spent catalyst after hydrogenation is separated from the product and reuse in the next batch with the addition of from 1 to 10% of fresh catalyst in the calculation of the original number rolled is atora. As a result of this practical implementation of the General process flow of the catalyst is in a low range from 80 to 125 g/tonne crude mixture of Chloroacetic acid. It was also found that a mixture of spent catalyst and fresh catalyst shows improved selectivity for the product, then there is a lower tendency to excessive hydrogenation of monochloracetic acid in acetic acid. Given the above, other specific variant of realization of the method according to the present invention is a method, which is described earlier in this document, in which the catalyst of the first hydrogenation after use, remove, add fresh catalyst in the amount of 1-10 percent of the catalyst originally used for the first hydrogenation and subsequent hydrogenation using this mixture and used fresh catalyst, and so forth, if desired.

The recirculated fluid relating to the loop reactor preferably includes a heat exchanger, in particular a shell-and-tube heat exchanger for temperature control. This external heat exchanger is, for example, advantage, because its effectiveness is not limited by the size of the reactor that would be the case with traditional coil or other surface is of teploobmena, built into the reactor (although they will also work). Another advantage of the external heat exchanger is that available is the full surface of the heat exchanger, even if the reactor is operated only with a reduced volume of liquid.

In a particularly preferred variant of the method of the present invention, the gas recirculation system includes a device for the continuous removal of gaseous HCl formed during the hydrogenation, from the flow of recirculating gas and return substantially only unreacted hydrogen gas in the ejector mixing nozzle loop reactor. Thus, it is possible to effect recirculation of hydrogen and at the same time to avoid the adverse effects of HCl on hydrogenation. The removal of hydrogen chloride by using adsorption columns, integrated in-line recirculation gas to the loop reactor, provides a significant advantage for the reaction, because to ensure the best performance dehydrohalogenation, because of the equilibrium, it is advantageous to maintain the content of hydrogen chloride in the gas phase at a very low level.

Gaseous HCl is preferably absorb water in a conventional absorption column. For this purpose, the gas mixture is preferably passed through one or settlement shall egovernance refrigerators, which cools the gas and entrained by the flow of organic matter condensed and returned to the autoclave. The cooled gas mixture enters the absorption column, in which the content of hydrogen chloride is completely absorbed water. Purified hydrogen is absorbed back into the loop reactor and reused for dehydrohalogenation, and the organic phase preferably again returns to the loop reactor. The absorption due to the above mentioned self-priming nozzle is sufficient as the driving force for the circulation of gas in if you have enabled this separation of hydrogen chloride.

In a more specific embodiment, the aforementioned variety of ways in the specified process receive water hydrochloric acid as the second useful product. This product aqueous hydrochloric acid can be used directly for many purposes, i.e. it is a commercial product, normally does not require additional processing, such as further purification.

According to the invention, for example, the crude mixture monochloracetic acid, dichloracetic acid and acetic acid, containing 3-4% by weight of dichloracetic acid, can gidrirovaniya in the above-mentioned conditions with the formation of a product containing a maximum of 0.0 wt.% dichloracetic acid or also less, than this number. However, as already mentioned above, this technology is also fully adaptable for cleaning by dehalogenase mixtures Chloroacetic acid, containing a much higher concentration of dichloracetic acid, for example, the mother liquor from stage crystallization monochloracetic acid, "residual mixture containing monochloracetic acid, dichloracetic acid and acetic acid and, for example, contains approximately 18-40 wt.% dichloracetic acid, which can easily be converted into a final mixture containing ≤0.02 percent by weight of dichloracetic acid in a single stage hydrogenation. This is especially surprising and important advantage of the present invention compared with the known methods, which are usually used at least two-stage hydrogenation to convert a mixture of Chloroacetic acid with a relatively high concentration of dichloracetic acid, suitable for industrial applications product monochloracetic acid.

This high efficiency together with a particularly high selectivity of the hydrogenation process according to the present invention, which is further increased with the use of the catalyst, makes it possible that the reaction product obtained in the single-stage p is acesse hydrogenation, according to the present invention should not normally be subjected to additional purification stages to suit all normal industrial criteria of purity for monochloracetic acid.

The method of the present invention may be carried out periodically and continuously. Both options produce qualitatively superior monochloracetic acid at lower investment and operating costs.

A continuous process according to the invention is particularly preferred, for example, because of its generally superior performance. During continuous operation of the process according to the invention, the recirculated fluid mainly contains a built-in cross flow filter for extracting suspended catalyst from the product monochloracetic acid, continuously emerging from the reaction system. A suitable filter cross flow has such a form as, for example, shell-and-tube heat exchanger, but is equipped with a porous sintered metal cassettes. The reaction slurry (the mixture of acids and catalyst) circulates from the beginning to the end of the inner part of the cartridge filter, and the filtrate is collected in the annular space of this filter. From time to time the filter surface should be re-cleaned withheld catalyst, for example, with the aid of the completion of the washing procedure of the reverse flow.

As mentioned previously herein, the method dehalogenase or hydrogenation according to the present invention is carried out with particular advantage in an improved ejector loop reactors, similar advanced "Buss loop reactor is used to effect the hydrogenation of liquids, in which suspended heterogeneous catalyst for the formation phase of the suspension. To further illustrate describes a suitable device, accompanied by reference to Figure 1.

The installation includes the autoclave (1), the reaction pump (2), a heat exchanger for the liquid phase (3), the mixing nozzle (4) for absorption and dispersion of hydrogen in a liquid reaction mixture, which is continuously circulated between the reaction the autoclave (1) and heat exchanger (3) under the action of the reaction of the pump (2). Hydrogen (11) when the controlled pressure is supplied to the mixing nozzle (4). Gases in the free reactor space above the product circulated through the gas recirculation circuit, being extended by suction self-priming nozzle. Fascinated with the flow of organic matter are condensed (13) and returned to the reactor. Hydrogen chloride formed during the hydrogenation, is absorbed in the absorption column (10) with the use of technical water (12). Purified hydrogen sucks is I'm back (7) in the reactor and reused. Clean monochloracetic acid may be removed through line (8).

EXAMPLE 1

The hydrogenation mixture of 35.0 wt.% dichloracetic acid. Used a loop reactor with a mixer Venturi and is additionally equipped with a refrigerator and the absorption column, integrated internal gas network, as shown in the drawing. Filled with an inert gas loop reactor with a working volume of 15 liters made 19 kg molten mixture containing 35 wt.% DHUK and 65 wt.% MJUK. Powered reactionary pump and through the gateway of catalyst added to 0.032 kg of a commercially available palladium catalyst on a carbon carrier (5% Pd on coal). Powered integrated absorption of HCl, filled with water. The reactor was filled with hydrogen and then the reaction mixture was heated to 155°C. the hydrogen Pressure in the loop reactor was increased to 3 barg.) and began hydrogenation by opening the source of hydrogen supply pressure-controlled. During the reaction gas from the space above the product in the reactor, consisting mainly of hydrogen chloride and hydrogen, continuously passes through the internal system of absorption, in which hydrogen chloride is removed from the hydrogen by absorption, and the purified hydrogen is returned to the reactor. After 200 minutes of consumption of the hydrogen reduced the elk, and the reaction was continued for further 10 minutes, after which the reactor was cooled to 70°C. the Reactor razgermetiziruetsya and purged with nitrogen. The total consumption of hydrogen was 1213 N. The obtained product was analyzed by HPLC and it was found that the composition is a 96,57 wt.% MHUC, 0.02 wt.% DHUK and 3,41 wt.% acetic acid.

EXAMPLE 2

Hydrogenation of a mixture containing 3.0 wt.% dichloracetic acid

Used the same reactor as in example 1, for the hydrogenation of a mixture containing 3.0 wt.% DHUK, of 95.4 wt.% MJUK and 1.2 wt.% of acetic acid. Filled inercom loop reactor made of 19 kg of a mixture of the composition. Powered reactionary pump and through the gateway of the catalyst was added 0.019 kg of a commercially available palladium catalyst on a carbon carrier (5% Pd on coal). Powered integrated absorption of HCl, filled with water. The reactor was filled with hydrogen and then the reaction mixture was heated to 150°C. the hydrogen Pressure in the loop reactor was increased to 3 barg.) and began hydrogenation by opening the source of hydrogen supply pressure-controlled. During the reaction gas from the space above the product in the reactor, consisting mainly of hydrogen chloride and hydrogen, continuously passes through the internal system of absorption, in which chlorite is th hydrogen is removed from the hydrogen absorption, and the purified hydrogen is returned to the reactor. After 110 minutes, the consumption of hydrogen is decreased, and the reaction continued for the next 10 minutes, after which the reactor was cooled to 70°C. the Reactor razgermetiziruetsya and purged with nitrogen. The total consumption of hydrogen was only 104 N. The obtained product was analyzed by HPLC and it was found that the composition is a 97,94 wt.% MHUC, 0.01 wt.% DHUK and 2.05 wt.% acetic acid.

EXAMPLE 3

Hydrogenation under normal conditions a mixture containing 4.0 wt.% dichloracetic acid

Used the same reactor as in example 1, for the hydrogenation of a mixture containing 4.0 wt.% DHUK, br93.1 wt.% MHUC, 2.5 wt.% acetic acid and 0.4 wt.% water. Filled with an inert gas loop reactor was placed 19 kg molten mixture of the composition. Powered reactionary pump and through the gateway of the catalyst added 0,076 kg of a commercially available palladium catalyst on a carbon carrier (5% Pd on coal). Powered integrated absorption of HCl, filled with water. The reactor was filled with hydrogen and then the reaction mixture was heated to 145°C. Started hydrogenation by opening the source of hydrogen supply pressure-controlled. The pressure is maintained constant in the interval 0-0,2 barg. During the reaction gas from the head space of PR is the product in the reactor, consisting mainly of hydrogen chloride and hydrogen, is continuously passed through an internal system of absorption, in which hydrogen chloride is removed from the hydrogen absorption and the purified hydrogen is returned to the reactor. After 170 minutes of consumption of hydrogen is decreased, and the reaction was continued for further 10 minutes, after which the reactor was cooled to 70°C. the Reactor was purged with nitrogen. The total consumption of hydrogen was only 140 N. The obtained product was analyzed by HPLC and it was found that the composition is a 97,62 wt.% MHUC, 2,33 wt.% acetic acid and without residual DHUK (below detection limit).

EXAMPLE 4

Hydrogenation of a mixture containing 3.5 wt.% dichloracetic acid, using recycled catalyst

Used the same reactor as in example 1, for the hydrogenation of a mixture containing 3.5 wt.% DHUK, or 95.7 wt.% MJUK and 0.8 wt.% of acetic acid. Filled with an inert gas loop reactor was placed 19 kg molten mixture of the composition. Powered reactionary pump and through the gateway of catalyst added to the original number of 0.038 kg of a commercially available palladium catalyst on a carbon carrier (5% Pd on carbon). The hydrogenation conditions were identical to example 2. After 60 minutes, the hydrogenation was stopped and the contents react the RA was cooled to 70°C. The reactor razgermetiziruetsya and purged with nitrogen. The reaction mixture was filtered at 70°C in the periodic filter action to separate the catalyst from the precious metal from the product. The used catalyst was mixed with 19 kg of the molten mixture of the original product and the added addition of 1.9 g of fresh catalyst. Started a new hydrogenation according to the procedure described above.

The full cycle of hydrogenation, filtration and reuse of the catalyst was carried out up to 12 times. The selectivity of the catalyst, as measured by reduced formation of by-product acetic acid increased with the number of cycles of hydrogenation.

12
The composition of the product
CycleDHUK (wt.%)MJUK (wt.%)Acetic acid (wt.%)Reaction time (min)
10,0997,532,3860
80,0798,801,1460
0,0498.921,0560

1. The use of a loop reactor containing recirculation systems gas and liquid combined by mixing nozzle ejector reactor in which the gas and the liquid circulating in the parallel flow and the mixing nozzle is formed so that the liquid phase can be introduced by mixing capacity of at least 50 W/l of liquid phase, and in which the gas recirculation system contains a device for the continuous removal of gaseous HCl formed in a process of recirculating gas and returning the unreacted hydrogen gas in the mixing ejector nozzle loop reactor for the selective catalytic hydrogenation of liquid dichloracetic acid in monochloracetic acid.

2. The method of obtaining monochloracetic acid containing less than 0.1 wt.% dichloracetic acid from a liquid mixture of Chloroacetic acid, monochloracetic acid and dichloracetic acid, in which the mixture is mixed with suspended hydrogenation catalyst, is mixed with hydrogen gas, with resultant mixture is reacted in a loop reactor containing gas recirculation system and a liquid, the joint through the m mixing nozzle of the ejector, in which the gas and the liquid circulating in the parallel flow and mixing power introduced into the liquid phase is at least 50 W/l of liquid phase, and formed in the process model HC1 gas is continuously removed from the recirculating gas in said gas recirculation system, and unreacted hydrogen gas is returned to the mixing ejector nozzle loop reactor.

3. The method according to claim 2, in which gaseous HCl is absorbed by water in the absorption column, preferably after the liquid phase, is carried out with recirculating gas has been removed in the cooling device of the recirculating gas to return to the loop reactor.

4. The method according to claim 2 or 3, wherein as the second product is hydrochloric acid.

5. The method according to claim 2 or 3, in which gaseous hydrogen is used in molar excess of the number of dichloracetic acid at from 0 to 60%.

6. The method according to claim 2 or 3, wherein the recirculation system fluid comprises a heat exchanger.

7. The method according to claim 2 or 3, wherein the hydrogenation carried out under a pressure of from 0 to 10 barg.

8. The method according to claim 2 or 3, wherein the hydrogenation is carried out at a temperature of from 130 to 170°C.

9. The method according to claim 2 or 3, wherein the stirring power is introduced into the liquid phase, is in the range from 50 to 2000 W/l of liquid f is PS.

10. The method according to claim 2 or 3, wherein the reaction product is extracted from the loop reactor, is not subjected to further stages of purification to remove residual dichloracetic acid.

11. The method according to any of claim 2 to 3, in which the catalyst of the first hydrogenation after using extract, add fresh catalyst in the amount of 1-10% of the amount of catalyst originally used for the first hydrogenation, and a mixture of used and fresh catalyst is used for further hydrogenation.

12. The continuous method according to any of claim 2 to 11.

13. Periodically operating the method according to any of claim 2 to 11.

14. The continuous method according to item 12, in which the recirculated fluid contains a built-in cross flow filter for extracting suspended catalyst from the product monochloracetic acid coming out of the reaction system.

15. The method according to claim 2, in which a liquid mixture of Chloroacetic acid contains monochloracetic acid and 2-40 wt.% dichloracetic acid.



 

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FIELD: organic chemistry.

SUBSTANCE: invention relates to new method for production of m- or p-substituted α-arylalkanecarboxylic acids of general formula I

from respective α-hydroxylated derivatives using inexpensive reagents and without converting of any reducible groups such as ester or ketone ones in side chains. In formula R is hydrogen, C1-C6-alkyl; R1 is hydrogen, linear or branched C1-C6-alkyl, phenyl, p-nitrophenyl, alkali or earth-alkali cation or cation of pharmaceutically acceptable ammonia salt: A is C1-C4-alkyl, aryl, optionally substituted with one or more alkyl, hydroxy, etc., aryloxy, arylcarbonyl; A is in m- or p-sites; P - linear or branched C1-C6-flkyl, phenyl, nitrophenyl. Claimed method includes the next steps: a) converting of compounds of formula II to compound of formula III either by reaction of II with compound of formula in presence of organic or inorganic base or by reaction of II with thiophene of formula and followed by reaction of obtained product with HNRaRb, wherein Ra andRb are as defined above; b) thermal rearrangement of III to form IIIb ; c) catalytic dehydration of IIIb to form IIIc ; and d) optional hydrolysis of IIIc to obtain target compound of formula I. Also are disclosed new compounds of formulae III and IIIb.

EFFECT: new α-arylalkanecarboxylic acids and intermediates thereof.

6 cl, 5 ex

The invention relates to an improved method for producing a p-hydroxymandelic compounds by condensation in the water, in the presence of an alkaline agent, an aromatic compound containing at least one hydroxyl group and having a free parapolitica, with Glyoxylic acid

The invention relates to the production of amides and/or NITRILES

FIELD: organic chemistry.

SUBSTANCE: invention relates to new method for production of m- or p-substituted α-arylalkanecarboxylic acids of general formula I

from respective α-hydroxylated derivatives using inexpensive reagents and without converting of any reducible groups such as ester or ketone ones in side chains. In formula R is hydrogen, C1-C6-alkyl; R1 is hydrogen, linear or branched C1-C6-alkyl, phenyl, p-nitrophenyl, alkali or earth-alkali cation or cation of pharmaceutically acceptable ammonia salt: A is C1-C4-alkyl, aryl, optionally substituted with one or more alkyl, hydroxy, etc., aryloxy, arylcarbonyl; A is in m- or p-sites; P - linear or branched C1-C6-flkyl, phenyl, nitrophenyl. Claimed method includes the next steps: a) converting of compounds of formula II to compound of formula III either by reaction of II with compound of formula in presence of organic or inorganic base or by reaction of II with thiophene of formula and followed by reaction of obtained product with HNRaRb, wherein Ra andRb are as defined above; b) thermal rearrangement of III to form IIIb ; c) catalytic dehydration of IIIb to form IIIc ; and d) optional hydrolysis of IIIc to obtain target compound of formula I. Also are disclosed new compounds of formulae III and IIIb.

EFFECT: new α-arylalkanecarboxylic acids and intermediates thereof.

6 cl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for synthesis of alkyl(meth)acrylates which are used in synthesis of polymers and copolymers with other polymerisable compounds, involving a step for re-esterification of alkyl ester of α-hydroxycarboxylic acid with (meth)acrylic acid, accompanied by formation of alkyl(meth)acrylates and α-hydroxycarboxylic acid, and a step for dehydration of α-hydroxycarboxylic acid, accompanied by formation of (meth)acrylic acid.

EFFECT: method enables to obtain a product with high selectivity.

22 cl, 2 tbl, 2 dwg, 38 ex

FIELD: chemistry.

SUBSTANCE: invention relates to use of a loop reactor, having gas and liquid recirculation systems which are connected through the combining nozzle of a reactor ejector, in which gas and liquid circulate in a parallel stream, and the combining nozzle is formed such that, mixing power of at least 50 W/l of the liquid phase can be imparted into the liquid phase, and in which the gas recirculation system has a device for continuous removal of gaseous HCl, formed during the process, from the recirculating gas and returning unreacted hydrogen gas into the mixing nozzle of the ejector of the loop reactor, for selective catalytic hydrogenation of the liquid dichloroacetic acid to monochloroacetic acid.

EFFECT: invention relates to a continuous or periodic method of producing monochloroacetic acid containing less than 0,1 wt % dichloroacetic acid from a liquid mixture of chloroacetic acid, containing monochloroacetic acid and dichloroacetic acid, in which the mixture is mixed with a suspended hydrogenation catalyst and mixed with hydrogen gas, wherein the formed mixture reacts in said loop reactor.

15 cl, 1 dwg, 4 ex

FIELD: chemistry.

SUBSTANCE: invention relates to method of reverse splitting of Michael adducts, contained in fluid F with weight part ≥ 10 wt %, counted per liquid F weight, which were formed in the process of obtaining acrylic acid or its esters, in installation of reverse splitting, which includes, at least, one pump P, separation column C, which from bottom to top consists of bottom part, separating part, which is adjacent to bottom part and contains internal devices with separating effect, and head part, which follows it, in which pressure in gaseous phase decreases from bottom to top, as well as indirect heat exchanger with circulation of heat carrier UW, which has, at least, one secondary volume and, at least, one primary volume, separated from said, at least, one secondary volume by means of real separating wall D, in which fluid F with supply temperature TZ is continuously introduced into separation column C in point of supply I, which is located in said separation column C above the lowest internal device with separating effect; expenditure flow M˙ of fluid F with temperature TSU, flowing into bottom part through internal devices with separating effect, containing Michael adducts, is continuously taken away in located at the lowest level of bottom part of column C by means of pump P, in such a way that in bottom part as bottom fluid set is level S of fluid, flowing into it, which constitutes less than half of distance A, measured from point of separating column C, located at the lowest level, to lower surface of the lowest internal device with separating effect in separation column C, while in the remaining volume of bottom part, located above said level of fluid, pressure of gas GD exists, as well as, at least, one partial flow I from expenditure flow M˙* is passed through, at least, one secondary volume of indirect heat exchanger with circulation of heat carrier UW, and by indirect heat exchange with liquid heat carrier, passed simultaneously through, at least, one primary volume of said indirect heat exchanger with circulation of heat carrier UW, is heated to temperature of reverse splitting TRS, which is above temperature TSU; and from removed from, at least, one secondary volume of indirect heat exchanger with circulation of heat carrier UW with temperature TRS flow of substance M˙ in point of supply II, which is below the lowest internal element with separating effect of separation column C and above level S of bottom fluid, at least, one partial flow II is supplied back into bottom part of separation column C in such a way that said, at least, one partial flow II in bottom part of separation column C is not directed on bottom fluid, and, at least, from one of two flows M˙, M˙* discharged is partial flow as residual flow on condition that temperature of reverse splitting TRS is set in such a way that, on one hand, in the process of passage of, at least, one secondary volume of indirect heat exchanger with circulation of heat carrier UW, at least, part of Michael adducts, contained in, at least, one partial flow I, are split with formation of respective to them products of reverse splitting, as well as, on the other hand, at least, one partial flow II, supplied back into separation column C, under existing in bottom part in point of supply II gas pressure GD, is boiling, and gaseous phase, which is formed in the process of boiling, containing, at least, partial amount of product of reverse splitting, is supplied into head part of column C as gas flow G, containing product of reverse splitting, following decreasing towards head part of column C gas pressure, and said gas flow G by direct and/or indirect cooling is partially condensed still in head part of separation column C and/or being discharged from head part of separation column C, condensate, formed in this process is, at least, partially returned to separation column C as reflux fluid, and gas flow, remaining in the process of partial condensation, is discharged, with pump P representing radial centrifugal pump with semi-open radial working wheel. Coefficient of efficiency Q of claimed method constitutes at least 20%.

EFFECT: improvement of method.

14 cl, 9 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to improved method of obtaining terephthalic acid, including a) interaction of 2,5-furanedicarboxylic acid, 2,5-furane dicarboxilate or their mixture with ethylene in presence of solvent with formation of bicyclic ether at temperature in the interval from 100°C to 250°C and pressure in the interval from approximately 10 lb/sq.inch (about 68.95 kPa) to 2000 lb/sq.inch (about 13.79 MPa) and b) dehydration of bicyclic ether.

EFFECT: method ensures effective obtaining terephthalic acid with reduced amount of admixtures, coloured admixtures and carbon oxides, which are formed in industry in case of liquid-phase oxidation of methyl-substituted benzoles, or without said admixtures at all.

16 cl, 1 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to method of producing α, β ethylenically unsaturated carboxylic acid or its ester, such as methacrylic acid or its alkyl ethers, for example, methyl methacrylate. Method involves stages of interaction of formaldehyde or suitable source thereof with carboxylic acid or its ester, for example, propionic acid or its alkyl ethers, in presence of catalyst and optionally in presence of alcohol, selected from C1-C30 alkanol, including aryl-alcohols. Catalyst contains group II metal phosphate crystals, having rod- or needle-like morphology. Phosphate can be hydroxyapatite, pyrophosphate, hydroxyphosphate, PO42- phosphate or their mixture. Metal of group II can be selected from Ca, Sr, Ba or mixtures thereof, for example hydroxyapatite strontium and calcium hydroxyapatite. Invention also relates to catalyst system containing crystalline metal phosphate catalyst and catalyst carrier. Metal phosphate has rod- or needle-like morphology.

EFFECT: technical result is high selectivity of product.

19 cl, 10 tbl, 24 ex

FIELD: chemistry.

SUBSTANCE: invention relates to methods of producing acrylic acid, acrylic acid derivatives or mixtures thereof, where, in particular, method includes a step of bringing into contact a flow containing hydroxypropionic acid, hydroxypropionic acid derivatives or mixture thereof, with catalyst containing (a) at least one anion of condensed phosphate, which is selected from a group consisting of formulae (I), (II) and (III), where n is equal to at least 2 and m is at least 1; and (b) at least two different cations, wherein said cations include: (i) at least one univalent cation and (ii) at least one polyvalent cation; catalyst is substantially neutrally charged; additionally molar ratio of phosphorus and said at least two different cations is 0.7-1.7, to obtain acrylic acid, acrylic acid derivatives or mixtures thereof as a result of contact with said catalyst.

EFFECT: methods for catalytic dehydration of hydroxypropionic acid, hydroxypropionic acid derivatives or mixtures thereof into acrylic acid, acrylic acid derivatives or mixture thereof are carried out with high output and selectivity and without significant conversion into undesirable by-products, such as acetaldehyde, propionic acid and acetic acid.

35 cl, 4 tbl, 15 ex

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