Method of producing pure isophthalic acid and by-products from isomers of cymene and diisopropylbenzene

FIELD: chemistry.

SUBSTANCE: invention relates to organic and petrochemical synthesis, specifically to the technological process of producing pure isophthalic acid and by-products - terephthalic and formylic acid through oxidation of isomers of cymene or diisopropylbenzene with an oxygen-containing gas in an acetic acid medium in the presence of a catalyst which contains salts of heavy metals and halide compounds at high temperature and pressure to a defined degree of conversion of the said isomer mixtures to isophthalic acid and by-products, followed by separation and purification of pure isophthalic acid and by-products through re-crystallisation in water, where isomers of cymene or diisopropylbenzene are oxidised in two steps at temperature 120-140°C at the first step and 150-160°C at the second step, in conditions where concentration of the Co-Mn catalyst increases in steps in the range 1300-1800 ppm (0.130-0.180%) at the first step, 1800-2400 ppm (0.180-0.240%) at the second step, promoted by halide compounds, reducing pressure in the range 0.9-1.6 MPa with pressure fall gradient between the steps in the range 0.2-0.6 MPa; purification and separation of the reaction mass obtained after oxidation, separation of the solid crystalline product and washing with acetic acid, carrying out re-crystallisation in water with preliminary holding of the aqueous suspension of the isophthalic acid and terephthalic acid mixture at temperature 225-235°C for 10-15 minutes and successive step-by-step extraction of the desired products and by-products: at 150-190°C - extraction of solid terephthalic acid to obtain aqueous mother solution, and at 60-80°C - extraction of solid isophthalic acid form the said mother solution and washing the extracted isophthalic acid with 2-2.5-fold amount of water to obtain isophthalic acid with the following qualities: chromaticity, °H, ≤10 - m-carboxybenzaldehyde [M-CBA], %, ≤0.002 - m-toluic acid [M-TA], %, ≤0.005 - benzoic acid [BA] %, ≤0.005.

EFFECT: efficient method of producing pure isophthalic acid.

2 cl, 2 tbl, 17 ex

 

The invention relates to organic and petrochemical synthesis, specifically to the process of obtaining pure isophthalic acid (CIFC) and related products - terephthalic (TFA) and formic (MK) acids by liquid-phase catalytic oxidation of a mixture of meta - and para - isomers of zimola or diisopropylbenzene About2gas in the acetic acid medium, followed by separation and purification of reaction products.

Net IFC is used to produce polyesters, which, in turn, used for the production of coatings, paints, reinforced plastics, packaging and bottles (polyethylene terephthalate - PET) for food and technical purposes. In addition, net IFC as co monomer or intermediate used for the manufacture of durable and low-toxic insulating varnishes, fibers with high chemical and thermal resistance, color-forming components for imaging films, synthetic leather, polymer concretes, and other products. Purified terephthalic acid or a mixture thereof with isophthalic acid in a ratio of 1:0,02÷0,1 as a byproduct formed during the oxidation of the residual p-zimola in a mixture of m-, p-timolol widely used in the industrial production of PET in the manufacture of packaging and bottles for food purposes.

Murav the other acid, a conjugate formed by oxidation of the isopropyl substituent m-, p - zimola, used in the textile industry in the manufacture of Bates and dyeing wool and cotton yarn from acidic baths, and is used in various fields of technology: as a coagulating agent in the production of natural rubber; in medicine for formirovaniya amines; as a source of raw material for various salts (formate), such as copper formate, used for purification of gas mixtures of carbon monoxide, salts of cobalt and Nickel as catalysts; in the food industry as a preservative; in the production of aromatic substances, volatile solvents and other

Known methods for producing IFC used in industry, based on 2-stage processes, including usually the so-called SD-way oxidation individual m-xylene in the liquid phase of the solvent (usually CH3COOH) air with obtaining technical IFC, which mostly clear method of hydrogenation of impurities in the aqueous solution in the presence of a palladium catalyst deposited on a carbon carrier (Pd/C) ([1] - U.S. patent No. 5110984, 1992, [2] - RF application No. 95117934).

These methods are effective industrial syntheses clean (purified) IFC, but they are based on the use as feedstock clean m-Xylo is and with a basic substance content ≥99.5%pure. The receipt of raw materials to the specified quality is associated with considerable costs allocation of m-xylene from a mixture of xylene isomers, which affects the value of the IFC in the share of raw material costs.

The known method of synthesis of isophthalic and related terephthalic acid from the fraction of isopropyltoluene (simola)obtained by the alkylation of toluene with propylene [the United Kingdom Patent No. 833357, 1960]. Isomers of timolol oxidized by air in the acetic acid medium in the presence of manganese acetate and ammonium bromide at a temperature of 180°C. the oxidation Time of 4 hours. Solid acid is separated by filtration, followed by washing the solid residue with acetic acid. Gas-vapor mixture from the reactor is brought out through a cold trap, and then the resulting acetic acid condensate is mixed with a wash with acetic acid. From flooded acetic acid distilled water and a concentrated CH3COOH again sent to the oxidation reactor.

The resulting mixture of aromatic acids are first separated phthalic acid contained in the mixture in small quantities, by heating the mixture of acids to the formation of the anhydride of phthalic acid. The latter is separated from the mixture by evaporation. The remaining binary mixture of ISO - and terephthalic acids separated by extraction with acetic acid or atrificial methane is scrap with getting dimethylsulfate (SIAS) and dimethyl terephthalate (DMT). The resulting esters separated by distillation.

The main disadvantage of the proposed method is complicated isomer separation benzylcarbamoyl acids (BDK). So, for the Department of phthalic acid is required to heat the entire mixture BDK to a temperature ≥200°C with the conversion of phthalic acid in a relatively volatile phthalic anhydride. This allows you to separate it by evaporation of the remaining mixture IFC-TPA. However, this requires higher temperature (240°C), which are present in the mixture BDK impurities, in particular, carboxybenzaldehydes, ketones and others, in conditions of oxygen deficiency may be in the presence of even small quantities of catalyst catalytic thermal destruction. Remaining after removal of phthalic anhydride mixture IFC-TPA is recommended to divide by extraction with acetic acid or rectification of their methyl esters. In the first case, the extraction process requires their dissolution. It is known that they are sparingly soluble in acetic acid and water. For example, for dissolving TFA in 30%aqueous suspension require a temperature of 286°C, and in the case of IFC is not lower than 240°C. Although in acetic acid their solubility is slightly higher at high temperature 240-286°C in the presence of the residual in the solution of the catalyst itself acetic Ki is the lot may be subjected to thermal decomposition (in normal conditions it is stable up to 300°C).

In another proposed embodiment of this patent, the separation of a mixture of IFC and TPA in the form of their methyl esters requires a process of esterification with methanol and subsequent technological operations distillation of the excess methanol, the separation of SIAS and DMT with further separate them by crystallization, extraction and drying. This leads to the need for additional process steps, which complicates the process.

To simplify the technology of isophthalic acid methods, according to which a mixture of m-, p-timolol pre-separated by rectification method using columns, at least with 150 plates at reflux from 40 to 150 [UK Patent No. 1408058, 1975]. The proposed allocation method m-zimola of the isomeric mixture of timolol is energy intensive due to the extremely high reflux ratio and material-intensive because of the large number of plates (150). These negative factors, due to the close boiling points of the meta - and prisonerof of simola (∆TKip.≤2°C), making this stage is not cost effective and technically complex.

In the well-known [the United Kingdom Patent No. 1336726, 1974] method selective adsorption on a molecular sieve selected from the alkylate liquid binary mixture of m-, p-timolol passed through a layer of molecular sieve type X or Y, for example H for about the Jena salts VA and K. Isomer of sorbed zimola replaced by desorbent, for example benzene or toluene. The proposed circuit model of the rolling layer, which includes 4 zones sorbent, series-connected, which serves the initial mixture and desorbent, take the extract and the raffinate. The inlet and outlet holes in the 4 zones are cyclically, the extract and the raffinate is distilled off with the release of the m-zimola and p-zimola. However, the scheme sorption separation of the considered mixtures is relatively bulky properities (cyclic) process and requires quite clean on the physico-chemical composition and stable shared mixtures. In addition, it is necessary to periodically perform processing operations on restoration (regeneration) of the sorbent, desorbent ensuring regulatory permissible emissions into the atmosphere, which complicates the separation scheme and leads to an increase in production costs to a level commensurate with the cost of separation of the mixture IFC-TPA by recrystallization in solvents or other methods, i.e. without the use of pre-separation of a mixture of meta and para isomers of zimola.

Known oxidation individual timolol to the appropriate BDK more simple scheme according to the method [V. Ovchinnikov, Vinylacetal, S. Gittes, "Chemistry and technology of monomers", Proceedings of VNIIM, Vol.3, issue 3, Tula, 172, s]. Terephthalic acid is produced by liquid-phase catalytic oxidation of individual p-zimola air in the environment of acetic acid with the yield of the target product ~70% of theory. The process is carried out in one stage at a temperature of 150-160°C at a pressure of 20 kg/cm2in the presence of Co-Mn-Br catalyst, the content of components which constitutes, g-mol/mol p-zimola:

With+2- 0,00625; Mn+2- 0,00625; Br-- 0,02335.

The main disadvantage of the single-stage method for the oxidation of an individual isomer of zimola, for example p-zimola to TPA is the low yield of the target product, not exceeding 70% of theory.

There are also known methods of obtaining isophthalic and terephthalic acids from isomers diisopropylbenzene, usually synthesized by the alkylation of benzene with propylene.

Thus, according to the Dutch patent [Holland Patent No. 108519, 1964] a mixture of IFC-TPA receive liquid-phase oxidation of binary mixtures of meta - and para - isomers of diisopropylbenzene (DIPR) air in the environment of CH3COOH in the presence of Co-Mn catalyst. In continuous mode, the process is carried out at 120-150°C and a pressure of 2.8 kg/cm2for 1.5-3 hours. The resulting crude mixture IFC-TPA can be divided by the known methods, for example, with application of the process of recrystallization in a suitable solvent or by distillation their dimethyl EPE is s after the esterification selected BDK methanol. The treatment processes, IFC and TPA in this way will not be considered. The distinctive feature of this method of obtaining IFC-TPA is carrying out the reaction at relatively low temperatures of 120-150°C in the presence of Co-Mn catalyst, providing along with the main reaction leading to the formation of the BDK, the occurrence of concomitant oxidation of a metal of groups of the isopropyl substituents to formic acid, which as phthalic acid, is a valuable product for various industrial syntheses.

However, the proposed method is oxidation of isomers diisopropylbenzene to IFC-TPA provides only technical (wet) mixture BDK.

Of the many methods of separation and purification IFC-TPA closest to the technical essence and the achieved results is an improved method of separating isomeric phthalic acids - IFC-TPA-FC obtained by liquid-phase oxidation of isomeric mixture of dialkylphenols, in particular of xylene isomers, the method of fractional crystallization in aqueous solution [U.S. Patent No. 3082250, 1963].

The essence of this method is the following. A mixture of phthalic acids are separated from oxidate, consisting mainly of oxidation products of dialkylphenol and solvent (CH3COOH), a method of crystallization and subsequent filtration. Next, receiving the hydrated precipitate was washed with pure SN 3COOH to remove residual solution containing the catalyst and partially dissolved impurities (mainly intermediate products). Dissolution BDK carried out by dissolving in water with sequential removal of individual solutions of acids. By varying the temperature parameters and the selection of appropriate concentrations of a mixture of phthalic acid in a solvent (N2(O) may achieve acceptable separation of phthalic acid.

The use of fractional dissolution 3-component mixture BDK and their subsequent separation by crystallization from individual solutions are certainly possible, and this method is implemented on an industrial scale. However, given the inevitable cocrystallization of BDK and contained impurities, including isomers Truelove acids, carboxybenzaldehydes and others, will need to carry out the process in several stages, which leads to considerable complication of the scheme of separation of phthalic acid by the proposed method.

The aim of the proposed method is to increase the output IFC and related products (TFA and formic acid) in the oxidation of mixtures of isomers zimola and diisopropylbenzene, as well as improving the efficiency of the separation of phthalic acid and its treatment with achievement of higher quality of target products.

This goal before thetsa fact, what isomeric mixture of m-, p-zimola and m-, p-diisopropylbenzene containing 70-96% m-zimola or m-diisopropylbenzene, oxidized in two stages in terms of increasing the degrees of concentration of Co-MT catalyst in the limit of 1200-2600 ppm promoted with a halogen compound, a temperature in the range of 120-165°C and discrete (stepwise) lowering the pressure in the range of 1.6-0.9 MPa, with the gradient of the decreasing difference between the levels of 0.2-0.6 MPa in such a way that on the first stage of the process is carried out at a temperature of 120-140°C, a pressure of 1.4 to 1.6 MPa the concentration of m-, p - dialkylphenol 14-18%, the total concentration of Co and MP 0,130÷0,180% (1300÷1800 ppm) at a ratio of Co:MP=1:0,8÷1,2 with the addition of equimolar amount of halogen in the form of Nug or mixture (NWG • Hcl) for 90-120 minutes before reaching 90-98% conversion of the initial mixture of m-, p-zimola or m-, p-diisopropylbenzene in oxygen-containing compounds and the establishment of oxidation products stationary concentration of the mixture IFC-TPA 15-22%, after which the resulting reaction mixture (oxidat-1) are oxidized at the second foot when reduced to 0.9-1.4 MPa pressure and at increased up to 0,180÷0,240% (1800-2400 ppm) concentration-MP catalyst and high atomic ratio of the catalyst to halogen is from 1:1 to 1:1,3, the reaction continues 40-60 minutes before reaching the oxidation products of the concentration of the mixture IFC-TPA 94-99,5% and total concentration of elapsed is cnyh compounds (in terms of m, p-diisopropylbenzamide) 0,3-0,7%, after which the reaction mass of the second stage (oxidat-2) is removed from the reaction zone, cooled to 90-116°C, produce a solid phase, which after washing with acetic acid at elevated temperature dried to constant weight and the dry mixture BDK suspended in water in the ratio: BDK:N2O=1:2÷2,5.

The resulting aqueous suspension is heated to 225-235°C, kept at this temperature for 10-15 minutes, then cooled to 150-190°C and the resulting intermediate suspension secrete TPA, which after washing the heated water output stage drying and packing of known techniques, and the mother liquor after separation of TPA (leachate - 1) is cooled to 60-80°C and formed from the main suspension was isolated by the IFC, which after washing the heated water in the ratio: IFC:N2O=1:2÷2,5 subjected to drying and filling of the known methods of obtaining IFC the following qualities:

- chromaticity, °N, ≤10

- m-carboxybenzene [M-KBA], %, ≤0,002

- m-tolarova acid [M-TC], %, ≤0,005

benzoic acid [Bq], %, ≤0,005

The invention is illustrated by, but is not limited to the following examples.

Example 1

For oxidation of the used fraction of m-, p-timolol the following composition,%:

m-timal -81,01

p-timal -19,97

other products -0,02.

In a separate narabotany experiments sod is neigh m-zimola in the alkylate was increased to 96% method parallelomania.

In book 1 prepare the first batch of the original reaction mixture (IRS), for which it loads 337 ml (289 g) accumulated mixture of m-, p-zimola containing ~80% m-zimola and ~20% p-zimola, 20 ml (20 g H2O), 1287 ml (1475) acetic acid, 7.5 g of acetate tetrahydrate, 7.5 g of acetate tetrahydrate MP and 11 g of 40%aqueous solution NVG.

The resulting mixture is heated to 60-70°C. after dissolution of the catalyst pump metering pump into the reactor 400 ml of IRS, which in a stream of nitrogen at a pressure of 1.6 MPa heated to 125°C. On attainment of this temperature shut off the flow of nitrogen into the reactor and discharge air in an amount to provide the content of O2in the exhaust not more than 5 volume%. The start of the reaction and its flow is determined by the absorption of oxygen and indications of the concentrations of CO2and CO in the exhaust gases on the gas analyzers.

After establishing a stable temperature and absorption Of2serves the IRS in the amount of 8.3 ml/min (0.5 l/ h), providing a residence time in the reaction zone 90 minutes. The reaction products (oxidat 1) flow into the reactor-deciliter II stage, running under the same pressure of 1.6 MPa. The additional oxidation process in mode 2 nd step is carried out in semi-continuous mode in the same reactor by entering solution Co-Mn-Br catalyst in acetic acid of the same concentration is the ratio of its components, as in the original reaction mixture. At the same time reduce the pressure 1.6 MPa to 1.0 MPa, and increase the reaction temperature to 160°C. the oxidation Reaction continued for 40 minutes until reduced absorption of oxygen in autothermal mode. Temperature oxidation 160±1°C and the associated content of co and CO2in the exhaust gases is supported by the pressure change ±0,015 MPa.

The resulting reaction mass (oxidat 2) is cooled to 115°C, separated from her solid crystalline products, washed heated to 110°With acetic acid in the ratio of crystalline products:CH3COOH=1:2,5, and then dried to constant weight and subjected to analysis.

Obtained in the 2nd stage the product has the following quality indicators:

Σ [TC+kumanova to-TA], %0,18
Σ [KBA+Operator], %0,21
Σ[side and other products]% 0,36
Chromaticity, °N26

For the implementation of the processes of division IFC and TPA and cleanup solvent used water.

Charged to the reactor 20%aqueous suspension of a mixture of IFC-TPA granted the military as a precipitate from the reaction mass of 2-stage oxidation after washing with acetic acid. In a stream of nitrogen, the suspension is heated to 232°C at a pressure of 3.0 MPa and kept at this temperature for 15 minutes, then reduce temperature to 190°C by evaporation of water by lowering the pressure of the reaction mass is maintained at this temperature for 12 minutes, and the resulting suspension produce a solid residue TPA, which after washing with water and drying has the following quality indicators:

Σ [TC]+[BK], %0,009
Σ [KBA+acetylbenzoic acid (ACBK)], %0,002
[IFC], %the 3.8
Chromaticity, °N9,0

The aqueous mother liquor (filtrate 1) is cooled to 80°C, allocate the resulting solid (crystal) phase IFC, washed her method repulpable hot water in the ratio of IFC:N2O=1:2.5 and after separation and drying achieve the following indicators selected and purified IFC:

The total yield of the target product IFC stages of oxidation, separation and purification amounted to 91.1%, a co-product of TPA 94,8%.

The conditions and results of the first and subsequent examples are shown in tables 1 and 2.

Example 2. The experience is conducted under the conditions of example 1 with the only difference that the oxidation process at the second stage is carried out in a continuous mode with the air in the reactor at time I and II steps on 65 minutes and maintaining the total time of the sample 130 minutes.

At the stage of oxidation obtained the following results.

Total concentration IFC-TPA in the oxidation products of the first stage of 22.5% at conversion degrees m-, p-timolol in oxygenated compounds, including IFC-TPA, 96,3%.

The percentage of total IFC-TPA in oxidation products selected from oxidate 2 reactor of the second stage, 99,48% with the color index 16°N, the total output IFC-TPA at the stage of oxidation in two stages 95,5% and concomitant product - formic acid - 70.2 per cent.

In the process of separation and purification of the mixture IFC-TPA in the conditions of example 1 (table 2) obtained the following quality indicators net IFC and related product TFA.

[m-TK+BK], %0,005
[m-KBA], %0,002
Chromaticity, °N6,0
/tr>
The quality of IFCQuality TFK
[m-TK+BK], %0,004Σ. [t-TC]+[BK], %0,07
[m-KBA], %0,0015Σ. [KBA+Operator], %0,0018
[IFC], %3,6
Chromaticity, °N5,0Chromaticity, °N9,0

Total yield IFC on stage oxidation and separation of mixtures IFC-TPA with their cleaning amounted to 91.6%, and byproduct - TPA - 94,6%.

Example 3. The experience is conducted under the conditions of example 1, with the only difference that the concentration of Co-Mn catalyst at the I and II stages of oxidation lower by 1.3 times, and the reaction temperature increased at 5°C. the Mode separation and purification of the mixture IFC-TPA remain at the same level of experience 1.

The results were achieved at the stage of oxidation.

The conversion of a mixture of p-, m-zimola in oxygen-containing compounds in the first stage is 90.2%, stage II - quantitatively (100%); concentration mixtures IFC-TPA in the reaction products isolated from Okidata-1, reached 15.1 percent, from Okidata-2 was 94,52% with the color index 28 °N; output mixture IFC-TF is - 92,0%, formic acid - 60,4%.

Results in phase separation of the mixture IFC-TFA and purification of selected products.

The quality of the purified IFKQuality companion product - TFK
[m-TK+BK], %0,010Σ. [TC]+[BK], %0,013
[m-KBA], %0,002Σ. [KBA+Operator], %0,0025
[IFC], %a 3.9
Chromaticity, °N8,0Chromaticity, °N10,0

Total yield of purified IFC stages of oxidation, separation and purification of the mixture by 90.2%, and the total output of the accompanying product - TPA - 93.9 per cent.

This shows that with decreasing concentration With-MP catalyst and the temperature increase in the limits somewhat reduced output IFC (from 95.1 to 92,0%), increased content of impurities (intermediate and side connections of 0.36% to 4,89%).

At the stage of the division and cleaning quality indicators purified IFC and related product TPA - approach quality limit values suitable for use in the manufacture of polyethylene terephthalate (PET) or a mixture of polyethylenterephtalate (PET-MF) according to the color index (8°N and 10°N, respectively) and on the content of m-KBA (0,002%) and KBA (0,0025%), respectively.

Example 4. The experience is conducted under the conditions of example 2, with the only difference that at the stage of oxidation the concentration of a mixture of m-, p-zimola in the environment CH3COOH increase from 16% to 18%, flushing isolated from oxidate 2 mixture IFC-TPA carried out by its repulpable in acetic acid at elevated temperature (165°C)and the allocation washed IFC-TPA is carried out at 115°C.

Separation and purification IFC-TFA in water is performed in the mode example 2.

At the stage of separating and washing the mixture IFC-TFA experience is conducted under the conditions of example 2 (table 2) with the only difference that the temperature of the suspension increases from 230°to 235°C and holding time of 10 min the solution is cooled to a temperature filtration -1 - 180°C.

When the foregoing conditions of example 4 (table 1, 2) obtained the following results.

At the stage of oxidation: conversion of a mixture of m-, p-zimola at the first stage of oxidation 90%;

additional oxidation of oxalate at the second stage, followed by washing the selected oxidation products of acetic acid at elevated temperature (165°C) results in the technical mixture IFC-T Is For the following qualities:

Σ[IFC+TFA],%99,37
Σ[isomers TC and Kumanovo acid], %0,18
Σ[isomers KBA and acetylbenzoic acid], %0,16
Σ[other intermediates and
products], %0,29
Chromaticity, °N27

Further separation of the resulting mixture and purification of the selected IFC and TFA method step of crystallization in aqueous solution leads to the production of products with the following quality indicators (table 2):

The quality of IFCQuality companion product - TFK
[m-TC and BC], %0,012Σ. [TC]+[BK], %,014
[m-KBA], %0,0021Σ. [KBA+Operator], %0,002
Chromaticity, °N7,0[IFC], %4,6
Chromaticity, °N9,0
Output IFC - 91.3%of associated product - TPA - 94,5%

Example 5. The experience is conducted under the conditions of example 1, with the only difference that, as a promoter, a mixture of HBr and Hcl in the ratio of 1:1 while maintaining the total concentration of the halogen ion on the same level of example 1 (0,312%).

Result. When replacing half of the bromine to chlorine, is used as a promoter Co-Mn catalyst, the qualitative indicators of the mixture IFC-TPA at the stage of oxidation of a mixture of m-and p-timolol, and their total output are almost on the same level as example 1, which allows to partially use Hcl as a promoter 1 as a cheaper and affordable product.

At the stage of separation of the mixture IFC-TFA and purification obtained the following results:

The quality of IFCQuality companion product - TFK
Σ[m-TC and BC], %0,008 Σ. [TC]+[BK], %0,009
[m-KBA], %0,0021Σ. [KBA+Operator], %0,0022
Chromaticity, °N9,0[IFC], %as 4.02
Chromaticity, °N10
The output of the IFC is to 91.1%, a companion product - TPA - 94,1%

Example 6 (comparative). The experience is conducted under the conditions of example 2, with the only difference that the temperature oxidation of a mixture of m-, p-timolol in reactors I and II levels set on the same low level of 130°C.

The following results are obtained.

At the stage of oxidation in the reactor of the first stage at time of 65 minutes, the conversion of m-, p-timolol in the intermediate oxygen-containing compounds, as well as in IFC-TPA reaches of 96.2%. The total concentration of IFC and TPA in oxidation products selected from oxidate 1, is 23.6%. These results are consistent with example 2.

Further oxidation of oxalate-1 in the reactor of the second stage at a temperature of 135°C and enter it advanced solution With and MP catalyst and Br (in the form of a 40%aqueous HBr) zadarmo is prohibited; oxygen uptake is suspended and the main reaction products after 65 minutes of additional oxidation are intermediate and side connections. Qualitative indicators mixture of oxidized products isolated from oxidate 2 reach values:

Σ[IFC+TFA], %30,09
Σ[isomers TC and Semenovich acid], %46,1
Σ[isomers KBA and acetyl benzoic acid], %14,0
Σ[other including products], %10,9
Color selected from oxidate -2 solid
(crystal) a mixture of products, °N196

The total yield IFC-TPA on the original mixture of m-, p-simola is only 39.4 per cent, formic acid, or 30.2%.

The reason for low quality mixture IFC-TPA and small of their release are: 1) the accumulation of oxidation products is relatively stable at 130-135°C hydroperoxide isomers of zimola, decomposition (transformation) which leads to the formation of isomers of cresol - inhibitors of the oxidation reaction; 2) reduction of the reactivity of the intermediate connection is on (isomers mixture Truelove, Semenovich, acetylbenzoic acids and other carboxyl-containing compounds), which in conditions of low temperature 130°C not undergo further oxidative transformation.

Example 7 (comparative). The experience is conducted under the conditions of example 2, with the only difference that the process of oxidation of a mixture of m-, p-timolol carried out in one step at an elevated temperature of 160°C.

Results

1. Increased more than three times the accumulation in the exhaust CO2and that indicates the ascending side of oxidative processes decarbonylation and decarboxylation of the intermediate oxygen-containing compounds, the initial m-, p-timolol and solvent.

2. Increased chromaticity crude mixture IFC-TPA from 16°N to 170°H, isolated from oxidate, as a consequence, increased more than 10 times the content of the oxidation products side colored compounds: achieved in example 2 - 0,24%, 7 comparative example is 2.46%.

3. The total yield of the crude mixture IFC-TPA decreased from 95.5% to 86.9%.

4. At the stage of separation obtained in one step oxidation mixture IFC-TFA and purification of separated products as IFC in terms of color exceeds more than 5 times the acceptable norm: reached 67°N, an acceptable rate of ≤10°N.

The main reason for the unsatisfactory quality of IFC in terms of color and low wychodzenia and associated (TFA) products, in conditions of high temperature 160°C primary products of oxidation of the isopropyl group m-, p-timolol (isomers hydroperoxides, aldehydes and ketones) little resistant and thermal decomposed by oxidative degradation with the formation and accumulation of active radical, including ion-radical compounds, further transformation which prevails in the reaction of oxidative condensation with the formation of high-boiling, mostly painted, connection - alkyl-, hydroxy-, keto - and carboxyprothrombin biphenyl, benzophenone, fluorenone and other products and oxidation products with a smaller number of substituents, such as benzoic the acid.

Example 8 (comparative). The experience is conducted under the conditions of example 1, with the only difference that at the stage of oxidation using a catalyst with a low ratio of cobalt to manganese:Mn=1:2 while maintaining the total concentration.

The results obtained.

At the stage of oxidation decreased the content of CO2and CO in the exhaust gases 1, 2 times;

[CO2] from 1.8% about. to 1.3% vol., [WITH] with 0.3% about. 0.1% vol., that indicates a decrease in the secondary processes of oxidative decarboxylation and decarbonylation.

However, along with the slowdown of adverse reactions, decreased the conversion of m-, p-timolol at the I and II levels from 96% to 935% and from 100% to 98.2 per cent, respectively, as well as the content of the mixture IFC-TPA in the oxidation products with 99,25% to 96.8 per cent. Output IFC-TPA decreased from 95.1% to 90.6%of. At the stage of separation IFC-TFA and purification of the quality of IFC in terms of color exceeded the acceptable rate more than 2 times (26°N, valid normoblastic ≤10°N), and the content of intermediate compounds, such as m-KBA, IFC after washing exceeded the permissible rate of 1.8 times (0,0045%valid 0,0025%). Total yield IFC stages of oxidation, separation and purification decreased by 3.2%to 91.1% to 87.9%.

Example 9. The experience is conducted under the conditions of example 1, with the only difference that the use of catalyst with a high ratio of cobalt to manganese:Mn=2:1 while maintaining the total concentration.

The results showed that the qualitative indicators crude mixture IFC-TPA obtained at the stage of oxidation, and purified IFC and related product of TPA at the stage of separation and purification surpass the quality of IFC's experience 1 and is within the limits of normovolaemia requirements for purified IFC and TPA. At the same time, the yield of the target (IFC) and associated (TPA) product has slightly decreased by only 0.4%, as a consequence moderately increased decarboxylation and decarbonylation intermediates by using a more active binary mixtures with a high content of Co in the Co-Mn-Br catalyst.

Example but carried out in the conditions of example 9, the only difference that the total concentration of Co-Mn catalyst in the reaction mixtures of I and II degree of oxidation is reduced by 30% while maintaining the ratio of Co:Mn=2:1 and the concentration of bromine, as in example 9, stage I 0,240%, stage II 0,312%.

The results obtained.

At the stage of oxidation is reached the output of the technical mixture is 95.6% for its quality, suitable for separation and purification of the proposed method.

ΣIsom.[TC+kumanova acid], %0,21
ΣIsom.[KBA+Operator], %0,19
Σ[Bq and other by-products.], %0,57
Chromaticity, °N20

At the stage of separation of the technical mixture IFC-TFA and purification divided BDK obtained purified IFC and the accompanying product TFA following qualities:

[m-KBA], %
The quality of IFCQuality companion product - TFK
Σ[m-TK+BK], %0,006Σ. [TC]+[BK], %0,012
0,002Σ. [KBA+Operator], %0,0024
Chromaticity, °N6,0[IFC], %3,7
Chromaticity, °N9

The total stages of oxidation, separation and purification) output IFC of 92.6%, a co-product of TPA 93,0% spent on raw materials - mixture of isomers zimola.

Example 11 (comparative). The experience is conducted under the conditions of example 1 with the only difference that the concentration of bromine in the I and II stages of oxidation, reduce twice, i.e. increase the ratio of [Co+Mn]:VG 1:1÷1.3 to 1:0,5÷0,65.

The obtained result.

The conversion of m-, p-zimola decreased from 100% to 98.3%of the indicator color of the crude mixture IFC-TPA increased from 26°N to 45°N (declining almost 2 times), yield a crude mixture IFC-TPA decreased from 95.1% to 92.2 per cent i.e. by 2.9%.

At the stage of separation of the mixture IFC-TFA and purification qualitative indicators purified IFC and related product TFA exceed the maximum permissible values for chrominance at 4°n of the KBA at 0.0015% (15 ppm).

Example 12 (comparative). The experience is conducted under the conditions of example 4 with the only difference that at the stage of oxidation Konzentrat the Yu m, p-zimola in the original reaction mixture increases from 18% to 20%, and at the stage of separation of the mixture IFC-TPA concentration aqueous suspension increase from 26.5% to 27%.

The results obtained.

At the stage of oxidation of the quality of the crude mixture IFC-TPA reaches the boundary of the indicators for which it is suitable for further separation and cleaning:

ΣIsom.[TC+cumin. acid], %0,26
ΣIsom. [KBA+Operator],%0,23
Σ[PAPR],%0,40
Chromaticity, °N29

At the stage of separation of the mixture of raw IFC-TFA and purification of separated products when the concentration of the aqueous suspension 27% qualitative indicators of the target product is purified IFC and concomitant product - TPA - exceed permissible values.

The quality of IFCQuality companion product - TFK
Σ[m-TK+BK], %0,20Σ. [TC]+[BK], %0,010
[m-KBA], %0,005Σ. [KBA], %0,006
Chromaticity, °N12[IFC], %4,0
Chromaticity, °N12

Example 13 (comparative). The experience is conducted under the conditions of example 1, with the only difference that the oxidation of a mixture of m-, p-timolol carried out at a pressure in the first stage of 0.3 MPa, at the second stage of 0.9 MPa, corresponding to the vapor pressure of the reaction mixtures at a temperature of 130°C (stage I) and 160°C (stage II), and the exposure time of the water suspension of a mixture of IFC-TFA at a temperature of 232°C was reduced from 15 minutes to 9 minutes.

The results obtained.

At the stage of oxidation, the color of the technical mixture IFC-TPA increased from 26°N to 47°N.

After the separation of the technical mixture and cleaning the indicator color of the target product IFC and related product TFK has exceeded the allowable value (≤10°N) and amounted to 14 °N and 16 °N, respectively.

Qualitative indicators IFC as well as the accompanying product TFA content of intermediate compounds (isomers Truelove and Semenovich acids, isomers KBA) are extremely let the th interval.

Example 14 (comparative). The experience is conducted under the conditions of example 2, with the only difference that at the stage of separation of the mixture IFC-TFA its aqueous solution, heated to 230°C, cooled in the first case (a) up to 210°C, followed by separation of the solid crystalline phase TFA filtration method, and in the second case, b) up to 160°C.

The results:

a) at elevated temperature (210°C) allocation of TPA significant part in dissolved form goes with the filtrate, which reduces the sharpness of separation of a mixture of IFC and TPA. In isolated from the filtrate crystalline IFC after cooling, the aqueous suspension of up to 90°C contains more than 3% TFA;

b) at low temperature (160°C) allocation of TPA significant portion of isophthalic acid cocrystallized with TPA, which led to the decrease of the yield of the target product by 3.5% and increased content included in the selected side product of TPA from 3.6% to 14%.

Example 15. Oxidation of a mixture of m-, p-diisopropylbenzene containing 80% m-diisopropylbenzene and 20% p-diisopropylbenzene, conducted in the conditions of example 1, with the only difference that the temperature at the I and II levels decreased by 10°C to 120°C and 150°C respectively, and the time (duration) of the reaction was increased to 30 min for each step.

The obtained result.

At the stage of oxidation yield crude mixture IFC-TPA was 94,1% quality indicators suitable d is I the separation and purification of the proposed method.

ΣIsom.[TC+kumanova acid], %0,21
ΣIsom.[KBA+Operator],%0,23
Σ[Bq+other side products]% 0,32
Chromaticity, °N28

At the stage of separation and purification the following as the target (IFC) and associated (TFA) products:

The quality of IFCQuality companion product - TFK
Σ[m-TK+BK], %0,009Σ isomer. [TC+BK], %0,011
Σ[m-KBA+m-ACBK], %0,0018Σ. [KBA+Operator], %0,0024
Chromaticity, °N7[IFC], %3,7
Chromaticity, °N9

Sum the ary output IFC and TPA stages of oxidation, separation and purification accounted for 91.3% and 93.6%, respectively.

Example 16. The experience is conducted under the conditions of example 15 with the only difference that the temperature of the oxidation on the I and II levels increased at 5°C, and the residence time (duration of response) at each stage is reduced by 10 minutes, up to 110 min and 60 min, respectively.

At the stage of separation of the technical mixture IFC-TFA and purification of the lower limit temperature of crystallization and the selection of TPA was reduced by 5°C from 190°C. to 185°C.

The results obtained.

At the stage of oxidation is reached the output of the technical mixture IFC-TPA - 95.2 per cent in case of qualitative indicators, suitable for separation and purification.

ΣIsom.[TC+kumanova acid], %0,18
ΣIsom.[KBA+Operator], %0,21
Σ [Bq+other side products]% 0,30
Chromaticity, °N24

At the stage of separation of the technical mixture IFC-TFA and purification of separated products quality indicators received IFC and related TFA meet the requirements of treated products:

The quality of IFC Quality companion product - TFK
Σ [m-TK+BK], %0,005Σ. [TC+BK], %0,012
Σ [m-KBA+m-ACBK], %0,002Σ. [KBA+Operator], %0,0024
Chromaticity, °N6[IFC], %3,0
Chromaticity, °N10

The total yield IFC stages of oxidation, separation and purification amounted to 92.1%, and the yield associated TPA 93.9 per cent.

Example 17. Experience the oxidation of m-, p-diisopropylbenzene carried out in the conditions of example 10 in the oxidation of m-, p-zimola with the only difference that instead of the mixture of isomers zimola containing 80% meta-zimola and 20% para-zimola, use a mixture of isomers diisopropylbenzene containing 80% m-diisopropylbenzene and 20% p-diisopropylbenzene.

The results obtained.

At the stage of oxidation of the output of the technical mixture IFC-TPA accounted for 93.4% of the quality indicators that are acceptable for subsequent separation and purification of products developed by the JV is soba:

ΣIsom.[kumanova acid], %0,28
ΣIsom.[KBA+Operator], %0,24
[BK+other FOB. cont.], %0,31
Chromaticity, °N27

At the stage of separation and purification of the quality of IFC and associated TPA has reached the limit value for use as the co monomer in the production of PET film destination (for packaging and packaging materials).

The quality of IFCQuality companion product - TFK
Σ[m-TK+BK],%0,01Σ-, m-isomer. [TC+BK], %0,014
Σ[m-KBA+m-ACBK],%0,0023Σ-, m-isomer. [KBA+Operator], %0,0025
Chromaticity, °N9[IFC], %3,2
Chromaticity, °N10

The results of oxidation of m-, p - diisopropylbenzene to IFC-TPA, as well as separation and purification of oxidation products showed their identity with the results achieved in the oxidation of m-, p - timolol found in the conditions of catalytic oxidation and purification of the reaction products.

As in the case of oxidation of isomers zimola, when using isomers of diisopropylbenzene reduced by 30% concentration of Co and mn catalyst at an elevated ratio With:MP=1,3:1 is the maximum allowable minimum concentration for both dialkylphenols.

The comparison of the conditions and results of examples 1,2 oxidation of isomers zimola and examples 15, 16 and oxidation of isomers diisopropylbenzene to IFC-TPA (table 1), as well as the conditions and results of cleaning and isomers benzylcarbamoyl acids of examples 1, 2 and 15, 16 (table 2) showed that the developed method is more versatile as used techniques, and the possibility of using more advanced sources of hydrocarbon raw material for the synthesis of monomers and polymers based on them.

1. The way recip is of pure terephthalic acid by oxidation of isomers zimola or diisopropylbenzene oxygen-containing gas in an acetic acid medium in the presence of a catalyst, including heavy metals and halide compounds at elevated temperature and pressure to a degree of conversion of these isomeric mixtures of isophthalic acid and related products with subsequent separation and purification of IFC and related products by recrystallization in water, characterized in that the isomers zimola or diisopropylbenzene oxidized in two stages at a temperature in the 1st stage of 120-140°C, on the 2nd stage at 150-160°C in terms of increasing the degrees of concentration of Co-MT catalyst within 1-tier 1300-1800 million-1(0,130-0,180%), 2-tier 1800-2400 million-1(0,180-0,240%), promoted by compounds of halogen, lower pressure in the range of 0.9-1.6 MPa with the gradient of the decreasing difference between the levels in the range of 0.2-0.6 MPa; purification and separation was obtained after oxidation of the reaction mixture, separation from her crystalline solid product and washing with acetic acid, carried out by recrystallization in water with pre-exposure water suspension of a mixture of IFC-TFA at a temperature 225-235°C for 10-15 min and sequential manual selection of the target and related products: at 150-190°C - allocation of solid TPA obtaining aqueous mother liquor, and 60-80°C - allocation of solid IFC from the specified stock solution, followed by rinsing highlighted the Oh IFC 2-2,5-fold amount of water.

2. The method according to claim 1, characterized in that the feedstock used isomeric mixture of m-, p-timolol or m-, p-aminobutiramida benzene containing 70-96% m-zimola or m-diisopropylbenzene.



 

Same patents:

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: chemistry.

SUBSTANCE: invention relates to a method of preparing a dry residue of aromatic dicarboxylic acid containing 8-14 carbon atoms, suitable for use as starting material for synthesis of polyester, where the said method involves the following sequence of stages, for example: (a) oxidation of aromatic material in the oxidation zone to obtain a suspension of carboxylic acid; (b) removal of impurities from the suspension of aromatic dicarboxylic acid in the liquid-phase mass-transfer zone where at least 5% liquid is removed, with formation of a residue or suspension of aromatic dicarboxylic acid, and a stream of mother solution, where the liquid-phase mass-transfer zone includes a device for separating solid substance and liquid; (c) removal of residual impurities from the suspension or residue of aromatic dicarboxylic acid obtained at stage (b) in the zone for countercurrent washing with a solvent to obtain a residue of aromatic dicarboxylic acid with the solvent and a stream of mother solution together with the solvent, where the number of steps for countercurrent washing ranges from 1 to 8, and the countercurrent washing zone includes at least one device for separating solid substance and liquid, and the said solvent contains acetic acid, (d) removal of part of the solvent from the residue of aromatic dicarboxylic acid together with the solvent obtained at stage (c) in the zone for countercurrent washing with water to obtain a residue of aromatic dicarboxylic acid wetted with water and a stream of liquid by-products together with the solvent/water, where the number of countercurrent washing ranges from 1 to 8, and the countercurrent washing zone includes at least one device for separating solid substance and liquid, where stages (b), (c) and (d) are combined into a single liquid-phase mass-transfer zone, and directing the residue of aromatic dicarboxylic acid wetted with water directly to the next stage (e), (e) drying the said residue of aromatic dicarboxylic acid wetted with water in the drying zone to obtain the said dry residue of aromatic dicarboxylic acid suitable for synthesis of polyester, where the said residue wetted with water retains the form of residue between stages (d) and (e).

EFFECT: design of an improved version of the method of preparing dry residue of aromatic dicarboxylic acid.

21 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: invention refers to the improved method for oxidising of aromatic hydrocarbon such as para-xylol, meta-xylol, 2,6-dimethylnaphthalene or pseudocumene with forming of corresponding organic acid. The oxidation is implemented by the source of molecular oxygen in liquid phase at temperature range from 50°C to 250°C in the presence of catalyst being a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon. The invention refers also to the catalytic system for obtaining of organic acid by the liquid-phase oxidation of aromatic hydrocarbons representing: a) oxidation catalyst based on at least one heavy metal representing cobalt and one or more additive metals being selected from manganese, cerium, zirconium, titanium, vanadium, molybdenum, nickel and hafnium; b) bromine source; and c) unsubstituted polycyclic aromatic hydrocarbon.

EFFECT: activation of the aromatic hydrocarbons oxidation increasing the yield of target products and allowing to decrease the catalyst concentration and the temperature of the process.

45 cl, 4 tbl, 16 ex

The invention relates to an improved method of reducing the content of 4-carboxybenzene in the production of terephthalic or 3-carboxymethylthio in the production of isophthalic acid, comprising: (a) dissolving crude terephthalic acid or crude isophthalic acid in a solvent at a temperature of from 50 to 250With obtaining a solution; (b) crystallization of the purified acid from this solution by reducing the temperature and/or pressure; (C) the Department specified crystallized terephthalic acid or isophthalic acid from the solution; (d) adding an oxidant to the reactor oxidation carboxyanhydride for oxidation specified filtered solution of stage (C), leading to the transformation of 4-carboxybenzene or 3-carboxymethylthio in terephthalic acid or isophthalic acid; (e) evaporating the solvent from this solution from step (d); (f) cooling the concentrated solution from step (e) for crystallization additional quantities of purified terephthalic acid or isophthalic acid and filtering the specified slurry and recycling the most part, the mother liquor from step (f) in the devices is

The invention relates to an improved process for the preparation of terephthalic and isophthalic acids

The invention relates to an improved method for producing isophthalic acid used in copolymerization ways of producing fibers, films, plastic bottles and structures made of polyester resin, which consists in the oxidation of metaxalone in the reaction solvent to obtain a liquid dispersion

The invention relates to an improved method for producing isophthalic acid, which is an important monomer and intermediate in polymer chemistry for the production of chemical fibers, polyester films, varnishes, dyes, plastics

FIELD: chemistry.

SUBSTANCE: invention relates to methods of producing aromatic carboxylic acids. The method involves the following, for example: bringing material which contains at least one substituted aromatic hydrocarbon, in which the substitutes can be oxidised to carboxyl groups, with oxygen gas in a liquid-phase oxidation reaction mixture which contains monocarboxylic acid as a solvent and water, in the presence of a catalyst composition meant for oxidising the substituted aromatic hydrocarbon to an aromatic carboxylic acid, containing at least one heavy metal, in a reaction section at high temperature and pressure sufficient for preservation of the liquid-phase oxidation reaction mixture and formation of an aromatic carboxylic acid and impurities containing by-products of the reaction, dissolved or suspended in the liquid-phase oxidation reaction mixture and a high-pressure vapour phase which contains a solvent - monocarboxylic acid, water and small quantities of the initial aromatic hydrocarbon and by-products of oxidation of the initial aromatic hydrocarbon and the solvent - monocarboxylic acid; moving the high-pressure vapour phase from the reaction section to a separation section in which the solvent - monocarboxylic acid, water and oxidation by-products are separated into at least one first liquid phase rich in the solvent - monocarboxylic acid and at least one second liquid phase rich in water, and at least one second high-pressure vapour phase stripped of the solvent - monocarboxylic acid, which contains water vapour, so that by-products of oxidation of the initial aromatic hydrocarbon are preferably in the first liquid phase and by-products of oxidation of the solvent - monocarboxylic acid are preferably in the second high-pressure vapour phase; and removal from the separation section in separate streams of the first liquid phase which is rich in the solvent - monocarboxylic acid, and the second liquid phase rich in water, which contains less than 5 wt % solvent - monocarboxylic acid and by-products of its oxidation, and the second high-pressure vapour phase which virtually contains less than 2 wt % by-products of oxidation of the initial aromatic hydrocarbon.

EFFECT: invention relates to an apparatus for producing aromatic carboxylic acids.

45 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to pharmaceutical chemistry, specifically to a method of producing 1-adamantane carboxylic acid which is a basic intermediate product in production of antiviral agent ramantadin. The method of producing 1-adamantane carboxylic acid is realised through carboxylation of 1-nitroxyadamantane with methanoic acid in the presence of sulphuric acid. 1-nitroxyadamantane is dissolved in 93.0-96.0% sulphuric acid containing 0.7-1.0 moles of urea. Methanoic acid or its salt is added in amount of 1.5-2.0 mol per mole of 1-nitroxyadamantane and held at temperature 18-20°C for 4-24 hours. The reaction mass is diluted with water at temperature 90-95°C and held at temperature 80-90°C for 30-40 minutes to complete hydrolysis of the formed 1-nitrourea and 1,3-dinitrourea. Adamantane carboxylic acid is the cooled and filtered. Output of the end product with melting point of 177-180°C is theoretically equal to 90-99%.

EFFECT: design of an efficient method of obtaining 1-adamantane carboxylic acid.

3 cl, 8 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for synthesis of p-terphenyl-2',5'-dicarboxylic acid through akylation of p-xylene with a cyclohexanol alkylation agent in the presence of a catalyst - sulphuric acid and then dehydrogenation of the obtained 2,5-dicyclohexyl-p-xylene in liquid phase at atmospheric pressure and temperature 260-290°C on aluminium-palladium catalysts, with extraction of 2',5'-dimethyl-p-terphenyl during cooling and then its oxidation with oxygen in a solution of glacial acetic acid at high temperature in the presence of a dissolved cobalt-manganese-bromine catalyst and extraction of p-terphenyl-2',5'-dicarboxylic acid crystals from the reaction mixture after cooling, where alkylation is carried out in molar ratio of p-xylene, cyclohexanol and sulphuric acid equal to 2-5:2-5:2-4 and temperature 0-5°C while adding the first half of cyclohexanol and raising temperature to 10-20°C until the end of the alkylation process, and oxidation of 2',5'-dimethyl-p-terphenyl is carried out at 105-110°C.

EFFECT: method enables to increase output of the said product by several times.

3 ex

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

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: invention relates to methods of producing aromatic carboxylic acids. The method involves the following, for example: bringing material which contains at least one substituted aromatic hydrocarbon, in which the substitutes can be oxidised to carboxyl groups, with oxygen gas in a liquid-phase oxidation reaction mixture which contains monocarboxylic acid as a solvent and water, in the presence of a catalyst composition meant for oxidising the substituted aromatic hydrocarbon to an aromatic carboxylic acid, containing at least one heavy metal, in a reaction section at high temperature and pressure sufficient for preservation of the liquid-phase oxidation reaction mixture and formation of an aromatic carboxylic acid and impurities containing by-products of the reaction, dissolved or suspended in the liquid-phase oxidation reaction mixture and a high-pressure vapour phase which contains a solvent - monocarboxylic acid, water and small quantities of the initial aromatic hydrocarbon and by-products of oxidation of the initial aromatic hydrocarbon and the solvent - monocarboxylic acid; moving the high-pressure vapour phase from the reaction section to a separation section in which the solvent - monocarboxylic acid, water and oxidation by-products are separated into at least one first liquid phase rich in the solvent - monocarboxylic acid and at least one second liquid phase rich in water, and at least one second high-pressure vapour phase stripped of the solvent - monocarboxylic acid, which contains water vapour, so that by-products of oxidation of the initial aromatic hydrocarbon are preferably in the first liquid phase and by-products of oxidation of the solvent - monocarboxylic acid are preferably in the second high-pressure vapour phase; and removal from the separation section in separate streams of the first liquid phase which is rich in the solvent - monocarboxylic acid, and the second liquid phase rich in water, which contains less than 5 wt % solvent - monocarboxylic acid and by-products of its oxidation, and the second high-pressure vapour phase which virtually contains less than 2 wt % by-products of oxidation of the initial aromatic hydrocarbon.

EFFECT: invention relates to an apparatus for producing aromatic carboxylic acids.

45 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to production of ortho-substituted benzene polycarboxylic acids and their intramolecular anhydrides, particularly trimellitic acid and its anhydride, pyromellitic acid and its dianhydride. The object of invention is achieved due that the initial hydrocarbons used are tri- and tetra-alkylbenzenes which contain methyl and isopropyl, methyl and ethyl or only methyl substitutes of general formula:

a) b)

where: a) R1, R3-CH3, R2-C3H7 or -C2H5; R1, R2, R3-CH3 b) R1, R2, R3-CH3, R4-C3H7 or C2H5; R1, R3-CH3, R2, R4-C3H7 or C2H5; R1, R2, R3, R4-CH3, for example isopropyl-p-xylene, ethyl-p-xylene, pseudocumene, 5-isopropylpseudocumene, 2,5-diisopropyl-p-xylene, 5-ethylpseudocumene, durene and others. Said compounds are oxidised in three steps with concentration of the dissolved oxygen in the liquid phase of oxidation products at each step in the range of 0.11-0.15 mol/l while maintaining pressure which is 16-18, 3.6-4.16 and 1.25-1.4 times higher, respectively, in reaction zones Pizb relative vapour pressure of the liquid reaction mass Pup, while raising temperature step-by-step in the range, °C: 120-135, 140-185, 190-215, discrete increase in concentration of metal ions of a Co2+ and Mn2+ catalyst and a Br- promoter. Obtained acids undergo thermal dehydration at temperature 230-240°C. The obtained anhydride solution undergoes purification through crystallisation in two steps in naturally different individual and binary solvents. The precipitated complex salt of the intramolecular anhydride is dried at temperature ≥125°C, which ensures decomposition of the complex to form a highly pure end product.

EFFECT: high efficiency of the process and high output of the end product.

3 cl, 2 dwg, 2 tbl, 11 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method for synthesis of p-terphenyl-2',5'-dicarboxylic acid through akylation of p-xylene with a cyclohexanol alkylation agent in the presence of a catalyst - sulphuric acid and then dehydrogenation of the obtained 2,5-dicyclohexyl-p-xylene in liquid phase at atmospheric pressure and temperature 260-290°C on aluminium-palladium catalysts, with extraction of 2',5'-dimethyl-p-terphenyl during cooling and then its oxidation with oxygen in a solution of glacial acetic acid at high temperature in the presence of a dissolved cobalt-manganese-bromine catalyst and extraction of p-terphenyl-2',5'-dicarboxylic acid crystals from the reaction mixture after cooling, where alkylation is carried out in molar ratio of p-xylene, cyclohexanol and sulphuric acid equal to 2-5:2-5:2-4 and temperature 0-5°C while adding the first half of cyclohexanol and raising temperature to 10-20°C until the end of the alkylation process, and oxidation of 2',5'-dimethyl-p-terphenyl is carried out at 105-110°C.

EFFECT: method enables to increase output of the said product by several times.

3 ex

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