The method of obtaining naphthalene-2,6-dicarboxylic acid

 

(57) Abstract:

Use: in the production of aromatic dicarboxylic acids, in particular in a method of producing 2,6-dicarboxylic acid for the production of polymeric materials. The inventive product, naphthalene-2,6-dicarboxylic acid, BF C12H9O4chroma 841 - 1260° Hazen. Reagent 1: 2,6-dimethylnaphthalene. Reagent 2: oxygen-containing gas. Reaction conditions: in the presence of a catalyst containing Nickel at a ratio of g atoms of Ni : ( Co + Mn ) : Br= (0,05 - 0,5) : 100 : (50 - 100), under heat and pressure. table 1.

The invention relates to a method for producing naphthalene-2,6-dicarboxylic acid (2,6-NIR), which is widely used as a monomer in polymer chemistry: introduction naphthalene cycle gives polymeric materials of high heat - resistance, fire resistance, radiation resistance. Manufactured on the basis of 2,6-NIR of specialone, films and coatings used in the electronics, electrical engineering, electronics and other industries.

A method of obtaining 2,6-NIR oxidation of 2,6-dimethylnaphthalene (2,6-DMN) at a temperature of 125-130aboutC and a pressure of 2-4 bar in acetic acid medium in the presence of catalysis the mash by distillation formed during the reaction water. To improve the efficiency of the process prior to distillation formed during the reaction water, the reaction mixture is treated with potassium permanganate at 80-100aboutWith used in quantities of from 9.1 to 25% by weight of catalyst and 2-5% by weight of the feedstock. In this way we obtain a final product - 2,6-NIR purity 85%, yield 72% of theoretical.

The disadvantages of the method in addition to the relatively low yield of 2,6-NIR and low quality of the target product, you should also include the use as an oxidizer oxygen, duration periodically feature of the process, the complexity of the technology through the use of for activation of recovered catalyst expensive potassium permanganate (1).

The closest in technical essence and the achieved effect is a method for 2,6-NIR liquid-phase oxidation of 2,6-dimethylnaphthalene (2,6-DMN) in acetic acid oxygen-containing gas in the presence of a catalyst system containing cobalt, manganese and bromine at 160-250about[2]. In the original reaction mixture support:

the concentration of 2,6-DMN not more than 1 mol per 100 mol of acetic acid;

the concentration of cobalt, manganese, bromine is not less than 0.02 g-atom of each element is Noah acid not less than 7 moles per 1 mole of the resulting 2,6-NIR.

In a continuous oxidation process thus receive the 2,6-NIR with access 84-96 mol.%, containing as an impurity 6-formyl-2-naphthoic acid (6-f-NC) in an amount of 0.05-0.2%. Output in mol.%, this 6-methyl-2-naphthoic acid (6-m-2N) is 0.1-0.2%, trimellitic acid (TMK) - 3,0-5,0%.

The disadvantage of this method is the formation in the specified quantities of intermediate products of the oxidation of 2,6-dimethylnaphthalene and in particular the product of cleavage of the naphthalene nucleus trimellitic acid, which leads to loss of catalyst activity due to the formation of salts of heavy metals (cobalt, manganese) TMK precipitated and contaminating the final product. The obtained 2,6-natalijagolosova acid usually has a color ranging from yellowish-brown to dark brown.

In the known method the appearance of colored impurities and loss of solvent of acetic acid is also due to its oxidative cleavage. However, these phenomena are not characterized by quantitative indicators.

Typically, an alkyl group, linked to the naphthalene ring, oxidized with greater difficulty than an alkyl group that is associated with the benzene ring. On the other hand, the very naftalina the'alene using known catalysts, suitable for the oxidation of alkyl benzenes in normal conditions, has not led to the formation of 2,6-NIR satisfactory quality, due to insufficient oxidation of the methyl groups, excessive cleavage naphthalene ring and undesirable coloring of the product. Especially in the case of 2,6-dimethylnaphthalene attempts to oxidize both methyl groups to carboxylic groups, without destroying naphthalene ring, associated with more difficulties in comparison with the oxidation of other isomers dimethylnaphthalene.

The aim of the invention is to increase the efficiency of the process of obtaining 2,6-naphthaleneboronic acid and improving the quality of the target product.

This goal is achieved by liquid-phase oxidation of 2,6-dimethylnaphthalene oxygen-containing gas in an acetic acid medium at elevated temperature and pressure in the presence of a catalyst containing cobalt, manganese, bromine and compounds of Nickel with a ratio of g atoms of Ni:(Co+Mn):Br, equal(0,05-0,5):100:(50-100) respectively.

The new method is a catalyst composition, comprising various compounds of Nickel (oxide, hydroxide= salt of aliphatic and aromatic acids, Nickel, passing under the reaction conditions is.

Oxidation of 2,6-DMN carried out at a temperature of 180aboutC and a pressure of 20 kg/cm2in a reactor made of titanium, equipped with a stirrer, a reflux condenser, a sampler, a device for control and regulation of temperature, pressure and air flow. The original reaction mixture, containing in its composition 2,6-DMN, acetic acid, water, acetates of cobalt and manganese at a certain ratio of cobalt to manganese, ammonium bromide, compounds of Nickel continuously metered into the reactor. The oxidation is carried out in the presence of Nickel compounds with a ratio of g atoms of Ni:(Co+Mn):Br, equal(0,05-0,5):100:(50-100) respectively. Air from the compressor through the filters from the oil through the pressure regulator, is fed into the reaction zone. The exhaust from the reactor gases pass into the condenser, where the condensation of the vapors of acetic acid and water, which are in the form of phlegmy returned to the reactor. The number of flue gases from the reactor is controlled by a counter, the contents of oxygen and carbon oxides continuously determine the current analyzers.

The resulting reaction mixture at a flow continuously directed to a collection of oxidate under pressure reactor.

After completing the process the th and liquid parts. The precipitate 2,6-naphthaleneboronic acid washed on the filter consistently hot acetic acid and water, dried and analyzed: the content of organic compounds by means of gas-liquid chromatography; the content of the colored impurities - spectrophotometric method for the indicator colour in Hazen units. Separately analyze the filtrate for the determination of outputs 6-methyl-2-naphthoic acid and trimellitic acid. The yield of 2,6-naphthalene-dicarboxylic acid 96,6 mol.%. Obtained under these conditions, the product contains a small number of 6-formyl-2-naphthoic acid (0.02 to 0.06 wt.%) - product of incomplete oxidation of 2,6-dimethylnaphthalene and colored impurities (700-900 units Hazen). Output 6-methyl-2-naphthoic acid is less than 0.01 mol.%, trimellitic acid and 0.40 to 0.75 mol.%. Loss of acetic acid are 152-156 kg per 1 ton of 2,6-NIR. Their readings of gas analyzers for CO and CO2rely on the reactions of oxidative degradation:

CH3COOH + 1,5 O2->> CO+CO2+ 2H2ABOUT

Reducing the loss of acetic acid while improving the quality of the target product is achieved by carrying out the oxidation process in the presence of Nickel compounds with a ratio of g-foamy in the oxidation of 2,6-dimethylnaphthalene, allows to obtain 2,6-NIR with high output and minimum content of impurities, and with minimal loss of acetic acid due to thermo-oxidative degradation.

It is established that the deviation from the ratio of components of the catalytic system Ni:(CO+Mn):Br, equal(0,05-0,5):100:(50-100) (in g-atoms) in the oxidation of 2,6-dimethylnaphthalene in one direction or another leads to deterioration of quality indicators 2,6-NIR and efficiency of the process:

increasing the concentration of 6-formyl-2-naphthoic acid (example 1,5);

increases the amount of colored impurities (example 1,5);

increasing the output side of the reaction product from the oxidation trimellitic acid (example 1,5);

increased loss of acetic acid due to its thermo-oxidative degradation (example 1,5).

P R I m e R 1. Oxidation of 2,6-dimethylnaphthalene carried out at 180aboutC and a pressure of 20 kg/cm2in a reactor made of titanium working capacity of 0.9 liters equipped with a stirrer, a reflux condenser, a sampler, a device for control and regulation of temperature, pressure and air flow. The initial reaction mixture composition, wt.%: 81,0 (2,92) 2,6-DMN; 2622 (94,48) acetic acid; 37,5 (1,35) water, 28 (1.0) tetrahydrate acetates of cobalt and Margo plunger pump continuously metered into the reactor at 430 g/H. Air from the compressor through the filters from oil and carbon dioxide, through the pressure regulator serves in an area with a speed of 5.6 nl/min Exhaust from the reactor gases pass into the condenser, where the condensation of the vapors of acetic acid and water, which are in the form of phlegmy returned to the reactor. The number of flue gases from the reactor is controlled by a counter, the contents of oxygen and carbon oxides continuously determine the current analyzers. The resulting reaction mixture at a flow continuously directed to a collection of oxidate under pressure reactor.

After the process is complete, the contents of the reactor and the collector is cooled to 90aboutAfter discharge pressure unload on the filter, where it is separated into solid and liquid parts. The precipitate 2,6-NIR washed on the filter consistently hot acetic acid and water, dried and examined for the content of organic compounds by means of gas-liquid chromatography; the content of the colored impurities - spectrophotometric method for the indicator colour in Hazen units at a wavelength of 450 nm. Separately analyze the filtrate for the determination of outputs 6-methyl-2-naphthoic acid and trimellitic acid. The result DMN at various initial concentrations of acetate tetrahydrate Nickel ceteris paribus process.

Examples 6-9 characterize the outputs of 2,6-NIR and its quality under different concentrations of bromine compounds, comparative examples 10-12 show that in the absence of the Nickel output of the final product decreases and the quality of 2,6-NIR.

The proposed method of producing 2,6-naphthaleneboronic acid has the following advantages.

Improves the quality of the product. Obtained under these conditions, the target product contains a small number of 6-formyl-2-naphthoic acid (0.02 to 0.06 wt. percent, from 0.05 to 0.2% in the prototype; 6-methyl-2-naphthoic acid is less than 0.01 mol.% compared to the 0.1-0.2% in the prototype; output trimellitic acid and 0.40 to 0.75 mol.% compared with 3.0 to 5.0% in the prototype.

Increases efficiency by reducing the loss of acetic acid.

The METHOD of OBTAINING NAPHTHALENE-2,6-DICARBOXYLIC ACID by liquid phase oxidation of 2,6-dimethylnaphthalene oxygen-containing gas in an acetic acid medium in the presence of a catalyst containing compounds of cobalt, manganese and bromine, at elevated temperature and pressure followed by separation of the target product known method, characterized in that the oxidation is carried out in the presence of Nickel compounds in zootoxin the

 

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FIELD: organic chemistry, chemical technology.

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EFFECT: improved method for preparing.

1 tbl, 1 dwg, 14 ex

FIELD: industrial organic synthesis.

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EFFECT: minimized toxic methyl bromide formation.

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EFFECT: improved preparing method.

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EFFECT: improved preparing method.

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FIELD: organic chemistry, chemical technology.

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EFFECT: improved preparing method.

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

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FIELD: method and composition for selective removal of iron solvent oxide from surface of titanium parts without damaging them.

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EFFECT: possibility for selective removal of iron oxide from surface of titanium parts without damage of said parts.

18 cl, 1 dwg, 6 tbl, 14 ex

FIELD: chemical industry; petrochemical industry; methods of extraction of the unreacted xylene from the acetic acid at production of the terephthalic or isophthalic acid.

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EFFECT: the invention ensures the upgrade of the production process of regeneration of the acetic acid and the unreacted alkylbenzene using the phase of the azeotropic distillation of xylenes from the acetic acid.

8 cl, 4 tbl, 5 dwg

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to an improved method for synthesis of halogenphthalic acid. Method involves mixing from 3 to 7 weight parts of acetic acid with 1 weight part of halogen-ortho-xylene, with from 0.25 to 2 mole% of cobalt source as measured for above said halogen-ortho-xylene, with from 0.1 to 1 mole% of manganese source measured for above said halogen-ortho-xylene, with from 0.01 to 0.1 mole% of metal source as measured for above said halogen-ortho-xylene wherein this metal is chosen from zirconium, hafnium and their mixtures, with from 0.02 to 0.1 mole% of bromide source as measured for above said halogen-ortho-xylene wherein halogen-ortho-xylene is represented by the formula (IV): wherein X represents halogen atom. Method involves holding the reaction mixture under pressure 1600 KPa, not less. At temperature 130-2000C, addition of molecular oxygen-containing gas to the reaction mixture in consumption 0.5 normal m3 of gas/h per kg of halogen-ortho-xylene in the reaction mixture for time sufficient for 90% conversion of halogen-ortho-xylene to yield halogenphthalic acid. Also, invention relates to a method for synthesis of halogenphthalic anhydride by distillation and dehydration of halogenphthalic acid, and to a method for synthesis of polyesterimide that involves interaction of halogenphthalic anhydride with 1,3-diaminobenzene to yield bis-(halogenphthalimide) of the formula (II): wherein X means halogen atom, and interaction of bis-(halogenphthalimide) of the formula (II) with alkaline metal salts of dihydroxy-substituted aromatic hydrocarbon of the formula (IV): OH-A2-OH wherein A2 means a bivalent radical of aromatic hydrocarbon to yield polyesterimide.

EFFECT: improved method of synthesis.

20 cl, 2 tbl, 5 ex

FIELD: process for continuous production of terephthalic or isophthalic acid by liquid phase oxidation of respective aromatic dialkyl hydrocarbon.

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EFFECT: production of stable quality acid, rational consumption of resources, power and water for performing process.

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for purifying naphthalene carboxylic acid. Method involves contacting crude naphthalene acid with solvent used for purifying in the presence of hydrogen and catalyst that comprises a precious metal of VIII group taken among palladium, platinum and ruthenium and metal of group IVB taken among silicon, germanium, tin and lead at temperature about from 520 to 575°F. Proposed method provides preparing reduced amount of organic pollution in purified acid as compared with other methods of purification.

EFFECT: improved purifying method.

19 cl, 1 dwg, 5 tbl, 5 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: 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

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 relates to a method of processing polyethylene terephthalate wastes. The method involves ethanolysis of polyethylene terephthalate (PET), in which material containing PET reacts with ethanol. Ethylene glycol and an aromatic diethyl ester, such as diethyl isophthalate and/or diethyl terephthalate, are separated. PET or a terpolymer containing a terephthalate monomer and ethylene glycol monomers react with ethanol and ethanol, diethyl terephthalate, ethylene glycol and optionally diethyl isophthalate are separated. The separated diethyl components can undergo liquid-phase oxidation to obtain an aromatic carboxylic acid. Acetic acid can also be obtained via liquid-phase oxidation of the separated diethyl components. Aromatic carboxylic acid can be used to obtain polymers. The invention also describes apparatus for processing polyethylene terephthalate wastes. The apparatus includes a reactor, a distillation column operating at atmospheric pressure and a vacuum distillation column.

EFFECT: high efficiency of the method.

29 cl, 1 dwg, 8 tbl, 8 ex

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