The method of obtaining 2,5-biphenyldicarboxylic acid

 

(57) Abstract:

The invention relates to a method for producing monomer, in particular 2,5-biphenyldicarboxylic (filteredfiles) acid, which can be used together with other aromatic acids and dialami for the production of thermotropic liquid crystal polyesters (TICP) for industrial use.

The purpose of the invention is to increase the output and quality of 2,5-biphenyldicarboxylic acid, which is achieved by alkylation of p-xylene by cyclohexanol, followed by dehydrogenation of the resulting cyclohexyl-p-xylene oxidation of 2,5-dimethylbiphenyl and further selection of the target product, the distinguishing feature of which is that the oxidation of 2,5-dimethylbiphenyl carried out in the liquid phase with oxygen or air in the acetic acid medium under initial concentration of 2.5-dimethylbiphenyl (0.1 to 1.0 mol/l in the presence of a catalyst system containing cobalt acetate, manganese acetate, sodium bromide in a molar ratio of(5,0-50,0):(1- 2,5):(5,0-50,0) at a temperature of 80-110oC for 3-6 h with further crystallization, after make clean received 2.5 - biphenyldicarboxylic acid dissolved in aqueous ammonia is slotow. table 1.

The invention relates to a method for producing 2,5-biphenyldicarboxylic (filteredfiles) acid, which can be used in conjunction with other aromatic acids and dialami as a monomer for the production of thermotropic liquid crystal polyesters (TICP) for industrial use. For such a fully (or almost fully) aromatic polymers at temperatures above their melting point characteristic anisotropic phase with low viscosity, so that they can be converted into products with high mechanical characteristics.

Known [1] the method of synthesis of isomer filteredfiles-3,4-biphenyldicarboxylic acid oxidation of 3,4-dimethylbiphenyl oxygen at a temperature of 95oC in acetic acid medium and in the presence of a catalytic system consisting of cobalt acetate and sodium bromide.

The disadvantages of this method are low yield and quality filteredfiles acid containing up to 5-10% of impurities (mainly lactancia).

Closest to the proposed is [2] the method of obtaining 2,5-biphenyldicarboxylic acids by alkylation of p-xylene with cyclohexanol in the presence of 93-95% sulfur is formed cyclohexyl-p-xylene at a temperature of 250-280oC in the presence of a catalyst of platinum or palladium on aluminum oxide, the oxidation of 2,5 - dimethylbiphenyl parchment potassium in a solution of pyridine and the selection of the target product, including the distillation of pyridine and water, acidification of the residue, filtering, washing and drying the obtained precipitate.

This method has many disadvantages from the point of view of practical applications, in particular the use of expensive oxidizing agent, the low yield of the target product at the stage of oxidation, the difficulties in the separation of the product from manganese dioxide and irrational use of the latter.

The problem solved by the invention is to increase the output and quality of 2,5-biphenyldicarboxylic acid.

We propose a method of obtaining 2,5-biphenyldicarboxylic acids by alkylation of p-xylene cyclohexane, followed by dehydration of the resulting cyclohexyl-p-xylene, liquid-phase oxidation of 2,5 - dimethylbiphenyl with a further selection of the target product, a distinctive feature, which is that the oxidation of 2,5-dimethylbiphenyl carried out with oxygen or air in the acetic acid medium under initial concentration of 2.5-dimethylbiphenyl 0.1 to 1.0 mol/l, Yarnykh ratio 5,0-50,0 1-2,5 5,0-50,0 respectively at a temperature of 80-110oC for 3-6 h, and the selection of the target product is carried out with the help of crystallization, after which the dedicated 2.5-biphenyldicarboxylic acid is dissolved in aqueous ammonia and planted the resulting ammonium salt of dioxane with its subsequent dissolution in water and acidification.

Synthesis of 2,5-biphenyldicarboxylic acid in accordance with the present invention it is proposed to carry out in three stages: first the alkylation of p-xylene (I) cyclohexanol in the presence of sulfuric acid, the second liquid-phase dehydrogenation of the resulting cyclohexyl-p-xylene (II) heterogeneous catalysts 2.5-dimethylbiphenyl (III), the final stage is the oxidation of (II) 2.5-biphenyldicarboxylic acid (IV).

The best conditions for the synthesis of (II) are the following: temperature 8-11oC, the molar ratio (I):cyclohexanol:sulfuric acid 3:1:3, duration of response 1-5 h (mainly 3 to 4 hours). A byproduct of the reaction is of DICYCLOHEXYL-p-xylene, which can find an independent application in the synthesis of LC polymers.

The dehydrogenation reaction (II) preferably takes place in the liquid phase at temperatures of 250-350oC (better 300-320oC) in the presence of 30-70% (ogicheskom the implementation process may 3-5-fold use of the catalyst without deterioration process indicators.

The main product of the oxidation reaction is 2,5-biphenyldicarboxylic acid. It precipitates upon cooling the reaction mixture to 20-25oC. Intermediate reaction products-monocarboxylic (2-methylbiphenyl-5-carboxylic 5-methylbiphenyl-2-carboxylic acid remain in the filtrate. This solution, which also contains a mixture of catalysts can be used for further oxidation. Due to the specific structure of the original hydrocarbon (III) by-products of the reaction are fluorenone-3-carboxylic acid (VII) and lactancia (VIII). Both of these compounds crystallize with 2,5-biphenyldicarboxylic acid, their presence affects the performance of the target product. To obtain the acid required for TGCP quality proposed cleaning method and its treatment with an aqueous solution of ammonia, based on the insolubility ammonium salt of 2,5-biphenyldicarboxylic acid in 1,4-dioxane, followed by dissolving the selected salt in water and acidification of the resulting solution with hydrochloric acid.

Example 1. Stage alkylation is carried out, cooling until 11oC of 234.2 g of p-xylene in a mixture with 217,1 g of 96% sulfuric acid with vigorous stirring was added dropwise within 1 h 74,6 g cyclohexane is a thief alkali, again water, dried over calcium chloride, dispersed over the vacuum, highlighting 86,6 g cyclohexyl-p-xylene (taken cyclohexanol 62,2%)

For the implementation stage dehydrogenation 100 g of cyclohexyl-p-xylene and 50 g of catalyst (palladium on aluminium oxide) is heated at a temperature of 310oC for 10 hours Upon completion of the reaction products of the dehydrogenation is subjected to fractional distillation under vacuum, receiving and 83.3 g of 2,5-dimethylbiphenyl (output 86,7%), which is a colorless liquid with a boiling point of 123oC (9 mm RT.cent.).

For carrying out oxidation reactions 14,9500 g of cobalt (II) acetate; 6,1800 g of sodium bromide; 0,7364 g of manganese (II) acetate (molar ratio of 20:20:1); 545,5 g of acetic acid and ice to 81.28 g of 2,5-dimethylphenyl heated to a temperature of 95oC and serves oxygen at a speed of 0.18 m3/H. the Reaction is performed for 4 h, then the mixture is cooled to room temperature, filtered off the precipitated crystals of 2,5-biphenyldicarboxylic acid, washed with water, dried at 80oC. Get 80,52 g acid, which was subjected to purification to obtain a product that meets the requirements to source products for polymeric materials.

For this 80,52 g acid rastvorilsya, the precipitate is filtered off, washed with dioxane. To obtain the acid is dissolved in 300 ml of water and add hydrochloric acid to pH 2. The precipitation of 2.5-biphenyldicarboxylic acid is filtered off, washed with water, dried at 80oC. Gain of 62.5 g of 2,5-biphenyldicarboxylic acid (input was 57.9% of theoretical).

Example 2 (for comparison).

In examples 2-7 stage alkylation, dehydrogenation and cleaning carried out as in example 1.

For carrying out oxidation reactions 1,6000 g of cobalt (II) acetate, 0,0900 g of sodium bromide (molar ratio 7:1); of 101.5 g of acetic acid ice and 10.2 g of 2,5-dimethylbiphenyl heated to 95oC and serves oxygen at a speed of 0.02 m3/H. the Reaction is carried out for 8 h, then the mixture is cooled to room temperature, filtered off the precipitated crystals of 2,5-biphenyldicarboxylic acid, washed with water, dried at 80oC. Obtain 6.6 g of the acid (yield of 48.7% of theoretical), which contains 94,4% of the basic substance, and a 4.9% compound (VIII) and 0.7% (VII).

Example 3. For carrying out oxidation reactions 12,4500 g of cobalt (II) acetate; 5,1500 g of sodium bromide; 1,2250 g of manganese (II) acetate (molar ratio 10:10:1); with a speed of 0.06 m3/H. the Reaction is carried out for 7 h, after cooling, separating the precipitated crystals of 2,5-biphenyldicarboxylic acid. Gain of 22.8 g of the product.

Example 4. To bring the oxidation reaction is heated to a temperature of 110oC 2,4900 g of cobalt (II) acetate; 0,5150 g of sodium bromide; 0,1225 g of manganese (II) acetate (molar ratio of 20:10:1); 83,22 g of acetic acid and ice 13,65 g of 2,5-dimethylbiphenyl, serves oxygen at a speed of 0.03 m3/H. the Reaction is carried out for 3 hours, you get a 2.5-biphenyldicarboxylic acid with a yield of 86.4% of the content of the basic substance in which 88%

Example 5. 2,5-Biphenyldicarboxylic acid is obtained, oxidizing 68,25 g of 2,5-dimethylbiphenyl in 414 g of acetic acid at 95oC in the presence of 12,4500 g of cobalt (II) acetate; 5,1500 g of sodium bromide; 0,275 g of manganese (II) acetate (molar ratio of 50:50:1); air consumption 0.6 m3/h, reaction time 5 hours While getting 60,96 g (yield 67.2 per cent) of 2,5-biphenyldicarboxylic acid.

Example 6. To 12,4500 g of cobalt (II) acetate; 5,1500 g of sodium bromide; 1,2250 g of manganese (II) acetate (molar ratio 10: 10: 1) was added 848,5 ml (890,2 d) acetic acid of ice and 91 g of 2,5-dimethylbiphenyl, the mixture is heated to 95o

Example 7. To a solution of 93,3750 g of cobalt (II) acetate; 38,6250 g of sodium bromide and 0,6125 g of manganese (II) acetate (molar ratio of 150:150:1) in 231 g (220 ml) of acetic acid add ice to 136.5 g of 2,5 - dimethylbiphenyl and heat the mixture to 95oC. Set the oxygen flow rate 0.30 m3/h and carry out the reaction for 4 h are 44,28 g (yield of 22.4) filteredfiles acid, while also formed 76% of monocarboxylic acids.

As follows from the above examples adherence to the stated conditions can achieve the goal of the invention. Going beyond the stated intervals or absence among the components of the catalytic system of the manganese (II) acetate reduces the product yield.

The polyester obtained from 2,5-biphenyldicarboxylic (filteredfiles) acid and hydroquinone FTG first patented by DuPont [3] According to given data, the fiber of this thermoplastic has a very low mechanical properties (see table 1). However, data on method of preparation and purity filteredfiles acid in the patent is not given. For comparison, the table presents data on the properties of FGF synthesized from hydroquinone and 2,5-biphenyldicarboxylic kislitsa different ways of processing of thermoplastics by extrusion, molding can also produce prepregs. FGF has excellent fibre-forming ability can be subjected to significant draw the hood. The measured mechanical properties of cast samples of FGF polymer: strength 8010 MPa and the modulus of elasticity 5400400 MPa when the discontinuous elongation 2%

References

1. Koshel, N. and other Studies in the field of synthesis of polycarboxylic acid of biphenyl. I. Synthesis of biphenyl-3,4-dicarboxylic acid liquid-phase oxidation of 3,4-dimethylbiphenyl Body. chemistry, so-24, vol. 7, S. 1499-1504, 1988

2. Auth. St. USSR N 1133259 class. C 07 C 63/331.

3. U.S. patent N 42949555.

The method of obtaining 2,5-biphenyldicarboxylic acids by alkylation of p-xylene by cyclohexanol, followed by dehydrogenation of the resulting cyclohexyl-p-xylene and liquid-phase oxidation by heating 2,5-dimethylbiphenyl with a further selection of the target product using acidification, characterized in that the oxidation of 2,5-dimethylbiphenyl carried out with oxygen or air in the acetic acid medium under initial concentration of 2.5-dimethylbiphenyl 0.1 to 1.0 mol/l in the presence of a catalyst system containing cobalt acetate, manganese acetate and Brangelina the target product is carried out with the help of crystallization, then dedicated 2.5-biphenyldicarboxylic acid is dissolved in aqueous ammonia and planted the resulting ammonium salt of dioxane with its subsequent dissolution in water and acidification.

 

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FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a continuous method for preparing highly pure terephthalic acid. Method involves oxidation of p-xylene with oxygen-containing gas in acetic acid medium in the presence of catalyst comprising heavy metal salts, such as cobalt and manganese and halide compounds under increased pressure and temperature up to the definite degree of conversion of para-xylene to terephthalic acid at the first step and the following two-step additional oxidation of prepared reaction mixture and isolation of the end product. Mixing time of reagents is <25 s, oxidation at the first step is carried out at temperature 180-200°C up to conversion degree of p-xylene 95%, not above, oxidation at the second step is carried out at temperature 175-185°C and before feeding to the third step of oxidation the reaction mass is heated to 200-260°C, kept for 8-12 min and oxidized at temperature 180-200°C in the presence of catalyst comprising Ni and/or Zr salts additionally. As halide compounds method involves using XBr or XBr + XCl wherein X is H, Na, Li followed by isolation of solid products of oxidation after the third step and successive treatment with pure acetic acid and water in the mass ratio terephthalic acid : solvent = 1:3. Invention provides intensification of process and to enhance quality of terephthalic acid.

EFFECT: improved method for preparing.

1 tbl, 1 dwg, 14 ex

FIELD: industrial organic synthesis.

SUBSTANCE: aromatic carboxylic acid is obtained via liquid-phase oxygen-mediated oxidation of initial aromatic mix containing benzene bearing two or three oxidizable substituents in its ring or naphthalene bearing at least one oxidizable substituent in its ring in reaction medium containing initial aromatics, promoter, heavy metal-based catalyst, and solvent containing benzoic acid and about 5 to about 60 wt % water, percentage of solvent in reaction medium ranging from 1 to 40 wt %. Oxidation proceeds in reaction zone of double-phase stream reactor under reaction conditions to produce high-pressure emission gas at 160-230°C in first part of reaction zone and at 180-260°C in second part of reaction zone, while at least part of aromatic acid produced crystallizes from reaction medium in reaction zone. According to second embodiment of invention, aromatic carboxylic acid production process comprises (i) providing reaction mixture containing initial aromatic compound, heavy metal-based catalyst, bromine source, and solvent containing benzoic acid and water, initial aromatic compound being benzene bearing two oxidizable alkyl substituents in m- and/or p-positions of its ring or naphthalene bearing oxidizable alkyl substituents in its ring, percentage of solvent in reaction medium ranging from 1 to 40 wt %; (ii) bringing at least part of reaction medium into contact with oxygen-containing gas in first continuously stirred mixing reactor at 160-230°C to form first high-pressure gas stream and product containing crystalline aromatic dicarboxylic acid in liquid medium containing the same, heavy metal-based catalyst, bromine, water, benzoic acid, intermediate oxidation products, and by-products; and (iii) sending thus obtained product to second continuously stirred mixing reactor, wherein second high-pressure gas stream is formed and at least part thereof contacts with oxygen-containing gas at 180 to 260°C to produce aromatic dicarboxylic acid.

EFFECT: minimized toxic methyl bromide formation.

26 cl, 2 dwg

FIELD: organic chemistry of polymers, chemical technology.

SUBSTANCE: invention relates to the improved method for preparing trimellitic acid anhydride. Method for preparing intramolecular trimellitic acid anhydride is carried out by liquid phase oxidation of pseudocumene with air oxygen for a single stage at increased temperature and pressure under conditions of countercurrent of oxygen-containing gas and reaction products in the presence of a catalyst comprising heave metal salts and halide compounds followed by distilling off a solvent and thermal dehydration of mellitic acid up to its intramolecular anhydride. Oxidation of pseudocumene is carried out in reaction volume separated for three zones wherein hydrogen bromide acid is added to each reaction zone by distributed feeding to provide the discrete increase of the HBr concentration up to [HBr] ≥ 0.052% in the first (upper) zone, [HBr] ≤ 0.09% in the middle (second) zone, and [HBr] ≤ 0.111% in the bottom third) zone. The composition of catalyst is maintained as constant in all zones in the ratio of its components in the limit Co : Mn : Ni = (0.28-0.66):1:0.04, respectively, and the process is carried out in the temperature range 160-205°C by its step-by-step increase in zones in the range: 160-180°C in the upper (first) zone, 180-190°C in the middle (second) zone, and 195-205°C in the bottom (third) zone. Invention provides improving the technological process of oxidation of pseudocumene, to improved quality of the end product and to enhance specific output of the reaction volume. Trimellitic acid anhydride is used broadly in preparing high-quality plasticizers, insulating varnishes, high-temperature polyimidoamide coatings and other polymeric materials.

EFFECT: improved preparing method.

2 tbl, 3 dwg, 16 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention elates to a method for preparing pure isophthalic acid. Method involves step-by-step oxidation of m-xylene with oxygen-containing gas in acetic acid medium in the presence of catalyst comprising heavy metal salts and halide compounds under increased pressure and temperature up to the definite degree of conversion of m-xylene to isophthalic acid and the following isolation of the end product. Oxidation of m-xylene is carried out for tree steps at discrete change of temperature by steps to side of decreasing and with the following increasing, or increasing with the following decreasing by the schedule: T1 > T2 < T3 or T1 < T2 > T3 in the temperature range 180-200°C in the presence of manganese-cobalt-bromide catalyst modified with additives of zinc and/or nickel salts in the following ratio of metals Mn : Co : Ni = 1:(0.5-2):(0.005-0.01):(0.005-0.01), respectively, in the total concentration of metals 490 p. p. m. in the reaction mass in the equimolar ratio of the amount of bromine with respect to metals and mixing time of reagents added to the reagents zone <10 s. Then oxidized compound from the 3-d step is subjected for cooling, crystalline isophthalic acid is isolated and treated successively by washing out with acetic acid at temperature 80-100°C in the mass ratio isophthalic acid : CH3COOH = 1:(2-2.5) to remove catalyst and with water at increased temperature 150-230°C in the ratio isophthalic acid : water = 1:(2-3) to remove acetic acid. Then the washed out product is isolated and dried by known procedures to obtain highly pure isophthalic acid. Method provides simplifying the process and to improve quality of isophthalic acid.

EFFECT: improved preparing method.

2 tbl, 1 dwg, 10 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for preparing dimethyl-1,5-naphthalene dicarboxylate that is used in preparing polymers based on thereof and articles made of these polymers. The economic and effective method involves the following stages: (1) dehydrogenation of 1,5-dimethyltetraline to yield 1,5-dimethylnaphthalene; (2) oxidation of 1,5-dimethylnaphthalene prepared at dehydrogenation stage to yield 1,5-naphthalene dicarboxylic acid being without accompanying isomerization stage, and (3) esterification of 1,5-naphthalene dicarboxylic acid prepared at oxidation stage in the presence of methanol to yield the final dimethyl-1,5-naphthalene dicarboxylate.

EFFECT: improved preparing method.

9 cl, 3 dwg, 5 ex

FIELD: chemical industry; methods of production of the purified crystalline terephthalic acid.

SUBSTANCE: the invention is pertaining to the improved method of production and separation of the crystalline terephthalic acid containing less than 150 mass ppm of the p-toluene acid in terms of the mass of the terephthalic acid. The method provides for the following stages: (1) loading of (i) para- xylene, (ii) the water reactionary acetic-acidic medium containing the resolved in it components of the oxidation catalyst, and (iii) the gas containing oxygen fed under pressure in the first zone of oxidation, in which the liquid-phase exothermal oxidization of the para-xylene takes place, in which the temperature and the pressure inside the first being under pressure reactor of the oxidization are maintained at from 150°С up to 180°С and from 3.5 up to 13 absolute bars; (2) removal from the reactor upper part of the steam containing the evaporated reactionary acetic-acidic medium and the gas depleted by the oxygen including carbon dioxide, the inertial components and less than 9 volumetric percents of oxygen in terms of the non-condensable components of the steam; (3) removal from the lower part of the first reactor of the oxidized product including (i) the solid and dissolved terephthalic acid and (ii) the products of the non-complete oxidation and (ii) the water reactionary acetic-acidic medium containing the dissolved oxidation catalyst; (4) loading of (i) the oxidized product from the stage (3) and (ii) the gas containing oxygen, into the second being under pressure zone of the oxidation in which the liquid-phase exothermal oxidization of the products of the non-complete oxidization takes place; at that the temperature and the pressure in the second being under pressure reactor of the oxidization are maintained from 185°С up to 230°С and from 4.5 up to 18.3 absolute bar; (5) removal from the upper part of the second steam reactor containing the evaporated water reactionary acetic-acidic medium and gas depleted by the oxygen, including carbon dioxide, the inertial components and less, than 5 volumetric percents of oxygen in terms of the non-condensable components of the steam; (6) removal from the lower part of the second reactor of the second oxidized product including (i) the solid and dissolved terephthalic acid and the products of the non-complete oxidation and (ii) the water reactionary acetic-acidic medium containing the dissolved oxidation catalyst; (7) separation of the terephthalic acid from (ii) the water reactionary acetic-acidic medium of the stage (6) for production the terephthalic acid containing less than 900 mass ppm of 4- carboxybenzaldehyde and the p-toluene acid; (8) dissolution of the terephthalic acid gained at the stage (7) in the water for formation of the solution containing from 10 up to 35 mass % of the dissolved terephthalic acid containing less than 900 mass ppm of the 4- carboxybenzaldehyde and the p-toluene acid in respect to the mass of the present terephthalic acid at the temperature from 260°С up to 320°С and the pressure sufficient for maintaining the solution in the liquid phase and introduction of the solution in contact with hydrogen at presence of the catalytic agent of hydrogenation with production of the solution of the hydrogenated product; (9) loading of the solution of the stage (8) into the crystallization zone including the set of the connected in series crystallizers, in which the solution is subjected to the evaporating cooling with the controlled velocity using the significant drop of the temperature and the pressure for initiation of the crystallization process of the terephthalic acid, at the pressure of the solution in the end of the zone of the crystallization is atmospheric or below; (10) conduct condensation of the dissolvent evaporated from the crystallizers and guide the condensed dissolvent back into the zone of the crystallization by feeding the part of the condensed dissolvent in the line of removal of the product of the crystallizer, from which the dissolvent is removed in the form of the vapor; and (11) conduct separation of the solid crystalline terephthalic acid containing less than 150 mass ppm of the p-toluene acid in terms of the mass of the terephthalic acid by separation of the solid material from the liquid under the atmospheric pressure. The method allows to obtain the target product in the improved crystalline form.

EFFECT: the invention ensures production of the target product in the improved crystalline form.

8 cl, 3 tbl, 2 dwg, 3 ex

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