JP4961821B2 - Method for producing 1,2,3-propanetricarboxylic acid plate crystal - Google Patents

Description

  The present invention relates to a method for producing a 1,2,3-propanetricarboxylic acid plate-like crystal, and more specifically, a high-purity 1,2,3-polyamide by crystallization from a 1,2,3-propanetricarboxylic acid aqueous solution. The present invention relates to a method for producing propanetricarboxylic acid as a plate-like crystal having excellent filtration separation characteristics.

  In recent years, 1,2,3-propanetricarboxylic derivatives (particularly amide compounds) have attracted attention as resin additives that improve the transparency, crystallinity and rigidity of polyolefin resins (see Patent Documents 1 to 3).

The following are typical examples of methods for producing 1,2,3-propanetricarboxylic acid and triesters thereof.
(A) A method in which diethyl maleate and diethyl malonate are reacted in the presence of a sodium ethylate catalyst, and the resulting Michael adduct is hydrolyzed in an aqueous hydrochloric acid solution and decarboxylated (see Non-Patent Documents 1 and 2). ).
(B) A method in which citric acid triethyl ester is hydrogenated in a tetrahydrofuran solvent at 175 ° C. and 10 bar in the presence of a CuO—Al 2 O 3 catalyst (see Patent Document 4). (C) A method of oxidizing 2- (2′-butenyl) succinic acid with nitric acid in the presence of a catalyst (see Patent Document 5).

  Assuming industrial production of 1,2,3-propanetricarboxylic acid, any of the above-described production methods can be carried out from an aqueous solution containing 1,2,3-propanetricarboxylic acid after completion of the reaction. In order to isolate 3-propanetricarboxylic acid and finally obtain it as a product, a crystallization operation is indispensable.

  However, in any of the above methods, when 1,2,3-propanetricarboxylic acid crystals are obtained from a 1,2,3-propanetricarboxylic acid aqueous solution by a crystallization method, the solubility at room temperature is large. In addition, a large amount of 1,2,3-propanetricarboxylic acid cannot be obtained. Therefore, in order to compensate for this defect, it was necessary to perform crystallization from a high concentration 1,2,3-propanetricarboxylic acid aqueous solution or to perform excessive cooling.

  As a result of the inventors preliminarily performing crystallization by air cooling under high concentration conditions with stirring or without stirring, needle-like crystals precipitate all at once in the entire aqueous solution, making it difficult to perform stirring and solid-liquid separation. I understood it. In addition, the solubility of 1,2,3-propanetricarboxylic acid at room temperature (for example, about 38% by weight at 25 ° C.) is very large, and thus the mother liquor on the obtained crystal surface is removed after crystallization and filtration. It was also found that when rinsing with water to reduce the yield, the productivity was significantly worsened.

  It has been described so far that water can be used as a solvent in the recrystallization of 1,2,3-propanetricarboxylic acid (see Non-Patent Document 2). However, this document makes no mention of recrystallization conditions in the case of using water, and the purity and crystal shape of the crystals obtained. In addition, the fact is that the crystallization method has not been actively used industrially due to the above problems. Until now, it has not been known that 1,2,3-propanetricarboxylic acid plate-like crystals can be obtained by crystallization from an aqueous 1,2,3-propanetricarboxylic acid solution, and the production conditions are of course described at all. Was not suggested.

Org. Syn. Coll. Vol. 1,272 Org. Syn. Coll. Vol. 1,523 Japanese Patent No. 3401868 Japanese Patent Laid-Open No. 7-242610 WO00 / 52089 JP-A-6-192167 French Patent No. 1515153

  An object of the present invention is to provide a method for producing high-purity 1,2,3-propanetricarboxylic acid as a plate-like crystal having excellent filtration separation characteristics by a crystallization operation.

  In view of the present situation, the present inventors have intensively studied to solve the above problems, and as a result, while stirring a 1,2,3-propanetricarboxylic acid aqueous solution having a specific concentration at a specific stirring speed, specific conditions are satisfied. By cooling and crystallizing under the above, it has been found that 1,2,3-propanetricarboxylic acid plate-like crystals having excellent filtration separation characteristics and high purity can be obtained with good yield, and the present invention has been completed.

  That is, the present invention provides the following method for producing 1,2,3-propanetricarboxylic acid plate crystals.

  [Item 1] In crystallization of 1,2,3-propanetricarboxylic acid from a 1,2,3-propanetricarboxylic acid aqueous solution, an aqueous solution having a 1,2,3-propanetricarboxylic acid concentration of 45 to 60% by weight is obtained. In the temperature range of 60 ° C. to 30 ° C., crystallization is performed under conditions where the stirring Reynolds number is 3,000 to 20,000 and the cooling rate is 15 ° C./hour or less. Propane tricarboxylic acid plate crystal production method.

  [Item 2] The production method according to Item 1, wherein the aqueous solution is further seeded with a seed crystal.

  [Item 3] The method according to Item 1 or 2, wherein the plate-like crystal has an average particle size in the range of 50 to 500 μm.

  [Item 4] The item 1, wherein a mother liquor obtained by solid-liquid separation after crystallization of 1,2,3-propanetricarboxylic acid plate crystals is reused as an aqueous 1,2,3-propanetricarboxylic acid solution. The manufacturing method in any one of -3.

  [Item 5] The above aqueous solution is obtained by reacting (i) maleic acid diester and malonic acid diester in the presence of an alkali catalyst to obtain a Michael reaction adduct, and then removing the used alkali catalyst and obtaining (ii) Item 5. The production method according to any one of Items 1 to 4, which is a reaction aqueous solution obtained by hydrolyzing the obtained Michael reaction adduct in the presence of an acid catalyst.

  [Item 6] The item 5 above, wherein the mother liquor obtained by solid-liquid separation after crystallizing the 1,2,3-propanetricarboxylic acid plate crystal is used for the hydrolysis reaction at the stage (ii) in the item 5. The manufacturing method as described in.

  By the production method of the present invention, 1,2,3-propanetricarboxylic acid can be obtained as plate crystals. Such plate crystals have good solid-liquid separability and can reduce the adhesion rate of the mother liquor in which impurities are dissolved to the crystals, so that high-purity 1,2,3-propanetricarboxylic acid can be obtained.

  The best mode for carrying out the present invention will be described in detail below.

[1,2,3-Provantricarboxylic acid]
There is no particular limitation on the method for producing 1,2,3-propanetricarboxylic acid (hereinafter abbreviated as “PTC”) according to the present invention, and it may be produced by any method. Specifically, in addition to the conventionally known methods exemplified in the above (a) to (c), (d) 2- (2′-alkenyl) succinic acid is treated with hydrogen peroxide in the presence of a phosphorus / tungstic acid catalyst. Examples of the method include oxidative cleavage, but are not limited thereto.

A production example of PTC by the production method (a) will be described below.
(A) The production method includes a Michael addition step in which a maleic acid diester and a malonic acid diester are subjected to an addition reaction in the presence of a base catalyst such as an alcoholate in a solvent or without solvent to obtain a corresponding tetraester, and the obtained tetra The hydrolysis step comprises hydrolysis of an ester in the presence of an acid catalyst to obtain PTC.

  Maleic acid diesters and malonic acid diesters are compounds that can be easily obtained by an esterification reaction of each acid and an alcohol in accordance with a conventionally known method, in addition to obtaining commercially available products.

  As maleic acid diesters, dimethyl maleate, diethyl maleate, di-n-propyl maleate, diisopropyl maleate, di-n-butyl maleate, di-sec-butyl maleate, di-n-pentyl maleate, di-maleate Maleic acid diesters of maleic acid such as hexyl and straight-chain or branched alcohols having 1 to 6 carbon atoms are preferred. Among them, diethyl maleate and dimethyl maleate are preferred because they are easily available industrially. Dimethyl acid is preferred.

  Malonic acid diesters include dimethyl malonate, diethyl malonate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, di-sec-butyl malonate, di-n-pentyl malonate, di-n-malonate. -Malonic acid diesters of malonic acid such as hexyl and linear or branched alcohols having 1 to 6 carbon atoms are preferable, and among them, diethyl malonate and dimethyl malonate are preferable in terms of industrial availability, especially Dimethyl malonate is recommended.

  The amount of malonic acid diester used is preferably 0.5 to 2 mol, preferably 0.8 to 1.2 mol, more preferably 0.95 to 1.05 mol, per mol of maleic acid diester. .

  Examples of the base catalyst used in the Michael addition step include alcoholates such as sodium methylate, sodium ethylate and potassium t-butylate, sodium hydroxide, potassium hydroxide, sodium amide, sodium hydride and the like. Of these, alcoholate is preferable in view of reactivity, and sodium methylate or sodium ethylate is particularly preferable. These alcoholates can be used alone or in combination of two or more. The amount to be used is preferably 0.01 to 10 mol%, more preferably 0.5 to 5 mol%, based on malonic acid diester.

  A solvent may or may not be used, but it is more preferable to carry out without a solvent because it is advantageous in terms of production and economy. When a solvent is used, aromatic hydrocarbons such as toluene and benzene, alcohols such as methanol, ethanol and isopropyl alcohol, ethers such as dioxane and tetrahydrofuran, N, N-dimethylformamide, dimethyl sulfoxide and the like can be used. In particular, ethanol, toluene, N, N-dimethylformamide is preferable. There is no restriction | limiting in particular in the amount of solvent, and if it is 1-10 times weight, it is enough.

  In the reaction, malonic acid diester, a base catalyst, and a solvent as necessary are added. After the temperature is raised to a predetermined reaction temperature, maleic acid diester is dropped at a rate that can suppress the temperature rise due to heat generation, and then the predetermined reaction temperature is reached. Therefore, it is preferable to proceed with heating and stirring for a predetermined time.

  The reaction temperature is usually in the temperature range of 0 ° C. to 100 ° C., preferably in the range of 20 ° C. to 80 ° C. When the temperature is less than 0 ° C., the reaction is delayed, and when it exceeds 100 ° C., by-products are formed. The reaction yield of the target compound tends to decrease.

  The reaction time may vary depending on the type of malonic acid diester and maleic acid diester, the amount and concentration of the catalyst, the reaction temperature, and the like, but is usually 1 to 30 hours, preferably about 2 to 10 hours.

  The reaction can be carried out in the air, but from the viewpoint of safety, the reaction is preferably carried out in an inert gas atmosphere such as nitrogen or argon.

  After the completion of the Michael addition reaction, neutralization, water washing or water washing is performed to remove the used base catalyst, and then the tetraester obtained by distilling off the solvent under normal pressure to reduced pressure is the raw material for the next hydrolysis step. Can be used as is. In particular, when the reaction is carried out without a solvent, it is only necessary to carry out neutralization, washing with water or washing with water, and the efficiency of the process can be improved. Further, if necessary, the obtained tetraester may be distilled under reduced pressure and used as a raw material for the hydrolysis step.

Next, it describes about the hydrolysis process of the obtained tetraester.
Since the hydrolysis reaction is an equilibrium reaction, it is usually advantageous to carry out the distillation while distilling off the produced alcohol to the outside of the reaction system. Therefore, it is preferable to carry out the hydrolysis reaction while continuously or intermittently adding an amount of water corresponding to the amount of distilled water containing the produced alcohol. The decomposition ends.

  The acid catalyst used for the hydrolysis reaction is preferably an organic sulfonic acid, and examples thereof include p-toluenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, and benzenesulfonic acid. Generally, p-toluenesulfonic acid is used. Used.

  Other acidic catalysts, for example, strong acids such as phosphoric acid, sulfuric acid, hydrochloric acid, Diaion SK1BH (trade name, manufactured by Mitsubishi Chemical Corporation), Amberlite IR-120B (trade name, manufactured by Rohm and Haas) Nafion NR-50 A strongly acidic ion exchange resin such as (trade name, manufactured by DuPont) can also be used.

  The amount of the acid catalyst used is 0.1 to 10% by weight, preferably 0.5 to 8% by weight, more preferably 1 to 5% by weight, based on the tetraester. When the amount is less than 0.1% by weight, the hydrolysis reaction rate is slow. On the other hand, when the amount exceeds 10% by weight, a rate increase corresponding to the amount added cannot be obtained, which is not economical.

  The amount of water used in the hydrolysis reaction is usually preferably 0.5 to 20 times equivalent, preferably 0.5 to 10 times equivalent, more preferably 0.5 to 5 times equivalent to the tetraester. It is.

  As reaction temperature, it is 50-150 degreeC normally, Preferably it is 90-110 degreeC. The reaction time varies depending on other reaction conditions, but is usually 3 to 30 hours, preferably 10 to 25 hours.

  Crude PTC crystals may be isolated from the aqueous solution containing PTC thus obtained after completion of hydrolysis by distilling off the solvent or the like. However, the aqueous solution containing PTC is used as it is for the present invention. You can also

Next, a manufacturing example of PTC by (d) manufacturing method will be described below.
(D) The production method comprises peroxidation of 2- (2′-alkenyl) succinic acid or its anhydride in water or a solvent miscible with water, using tungstic acid, molybdic acid, and their heteropolyacid as a catalyst. This is a method for producing PTC by oxidation with hydrogen.

  The heteropolyacid here is a condensed acid composed of two or more oxygen acids, the polyacid atoms are tungsten and molybdenum, and the heteroatoms are P, As, Si, Ti, Co, Fe, Examples include B, V, Be, I, Ni, Ga, and the like. The amount of catalyst used is selected from a wide range as long as it is an amount effective for exhibiting catalytic activity. However, from the viewpoint of the reaction rate and the cost of the catalyst, 0.01 to 30% by weight based on 2- (2′-alkenyl) succinic acid in terms of free acid (tungstic acid, molybdic acid or their heteropolyacid), 1 to 10% by weight is recommended.

  As the reaction solvent, water, an organic solvent miscible with water, for example, alcohol having 1 to 4 carbon atoms, dioxane, tetrahydrofuran, dimethylformamide or the like may be used alone, or may be used in combination with water as long as a uniform phase is maintained. Is possible. Of these, water, a water-miscible solvent having 1 to 4 carbon atoms, or a mixed solvent thereof is preferable, and water is particularly preferable.

  Although it does not specifically limit as a density | concentration of the substrate at the time of reaction, The range of 2-70 weight% is preferable, and the range of 15-60 weight% is more preferable. By carrying out the reaction within such a range, the target product tends to be obtained with high yield and high purity.

  The stoichiometric amount of hydrogen peroxide required for this reaction is 4 moles per mole of 2- (2′-alkenyl) succinic acid, but usually 4 to 12 moles, preferably 6 to 10 moles. Is desirable. The concentration of hydrogen peroxide in the reaction mixture can be selected from a wide range. The lower limit is that the concentration of the catalyst obtained by oxidizing 2- (2′-alkenyl) succinic acid is sufficient to restore the oxidation ability with hydrogen peroxide, and even if it is very dilute, avoid a decrease in reaction rate. Although not possible, the oxidation reaction proceeds. In addition, there is no particular upper limit, and a considerably high concentration may be used. However, from the viewpoint of improving the reaction rate and reducing the production cost using a low concentration of hydrogen peroxide, 0.1 mmol / L to 12 mol / L, preferably 10 mmol / L to 8 mol / L. L is advantageous. Hydrogen peroxide is usually supplied in the form of a 5 to 60% by weight aqueous solution, and any concentration of hydrogen peroxide can be used, but 40 to 60% by weight hydrogen peroxide is preferred.

  Examples of the reaction temperature include a temperature range of usually 20 to 150 ° C., preferably 60 to 130 ° C., from the viewpoint of the reaction rate. The reaction can be carried out under normal pressure, under pressure or under reduced pressure. From the viewpoint of the reaction rate and from the viewpoint of preventing or suppressing the decomposition of hydrogen peroxide, the reaction is preferably performed at 60 to 130 ° C, preferably 80 to 100 ° C, particularly at the reflux temperature.

  The reaction time may vary depending on the type of 2- (2′-alkenyl) succinic acid, the concentration of the catalyst and hydrogen peroxide, the reaction temperature, whether or not the organic monocarboxylic acid produced as a by-product is distilled off, etc. It is in the range of 50 hours, preferably 5 to 25 hours, more preferably 6 to 20 hours.

  Moreover, it is preferable to distill off the aliphatic monocarboxylic acid by-produced out of the reaction system. The method is not particularly limited, but a method of evaporating and distilling out of the system together with water is simple and preferable.

  The reaction may be carried out under normal pressure or reduced pressure, and may be carried out in either a continuous or batch manner. The reaction can also be carried out in the air, but from the viewpoint of safety, it is preferably carried out in an inert gas atmosphere such as nitrogen or argon.

  Crude PTC crystals may be isolated from the aqueous solution after completion of the oxidation reaction containing PTC thus obtained by distilling off the solvent or the like, and the aqueous solution containing PTC can be used in the present invention. Can also be provided.

  In the above production methods (a) and (d), the aqueous solution obtained after the completion of the reaction is preferable in that it can be used as it is, and in particular, the aqueous reaction solution obtained by the production method (a) is a PTC plate obtained. It is particularly preferred in terms of crystal yield, purity and hue.

  Moreover, the aqueous solution containing PTC obtained by methods other than the above-exemplified methods (a) and (d) can be used in the present invention. These aqueous solutions can also be decolorized using activated carbon before crystallization. The amount used is preferably in the range of 0.01 to 20 parts by weight, more preferably in the range of 0.1 to 10 parts by weight, and still more preferably in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of PTC. is there. The treatment temperature is usually in the range of 100 ° C. from the lowest temperature at which crystals do not precipitate from the obtained reaction aqueous solution, and preferably in the range of 50 ° C. from the lowest temperature at which crystals do not precipitate. The treatment time is usually in the range of 1 minute to 10 hours, but is not particularly limited as long as a decoloring effect is obtained. The crude PTC means that the purity is 75% by weight to less than 95% by weight.

[Crystallization of PTC]
The concentration of the PTC aqueous solution in the present invention is 45 to 60% by weight, preferably 45 to 55% by weight. If it is less than 45% by weight, needle-like crystals with poor filterability are likely to be produced, and the working efficiency and the purity of the target product tend to be deteriorated. On the other hand, if it exceeds 60% by weight, the slurry concentration increases, so stirring. Solid-liquid separation becomes difficult, and the purity of the target product tends to decrease, which is not preferable. When the product obtained as an aqueous solution of PTC after completion of the reaction is used as it is as in the production methods (a) and (d) above, water is appropriately added under normal pressure or reduced pressure so as to be within the above concentration range. It is necessary to crystallize after adjusting by evaporating and concentrating or adding water.

  In order to improve the production rate of plate crystals, it is preferable to completely dissolve the PTC needle crystals before crystallization. Therefore, it is recommended to heat the PTC aqueous solution to 60 ° C. or higher, preferably 70 ° C. or higher, particularly preferably 90 ° C. or higher. After the PTC needle-like crystals are dissolved, the plate-like crystals can be preferentially precipitated by crystallization at a predetermined cooling rate and stirring conditions.

  After dissolving the needle-like crystals of PTC, crystallization is performed while gradually cooling. Therefore, crystallization can be started from any temperature of 60 ° C. or higher (preferably 60 to 90 ° C., particularly preferably 60 to 70 ° C.). Further, the addition of a PTC plate crystal as a seed crystal is recommended as a preferred method because the formation of the plate crystal is promoted by addition. The temperature at which the seed crystal is added is not particularly limited as long as it is not lower than the temperature at which the PTC crystal starts to precipitate and does not dissolve (preferably 60 to 70 ° C.), and the addition amount is not particularly limited. However, 0.1 to 5% by weight, preferably 0.1 to 1% by weight, more preferably 0.1 to 0.3% by weight based on the total amount of PTC dissolved in the aqueous solution is recommended. Is done.

  The cooling rate is 15 ° C./hour or less, preferably 4 to 10 ° C./hour, and particularly preferably 5 to 8 ° C./hour. The slower the cooling rate, the more the production and growth of plate crystals are promoted, while the productivity tends to decrease.

Further, the stirring speed in the present invention is preferably in the range of 3,000 to 20,000, and 8,000 to 18,000 in stirring Reynolds number. If it is less than 3,000, the liquid flow rate in the crystal boundary film becomes a laminar flow, so that the crystal growth is inhibited. On the other hand, when it exceeds 20,000, the generated crystals are not preferable because the frequency of collision between the crystals or between the crystals and the stirring blade increases and the plate-like crystals are crushed. The stirring Reynolds number in the present invention is a dimensionless number defined by Re = ρd ² n / μ, ρ is the density (kg · m ⁻³ ) of the PTC aqueous solution used for crystallization, and μ is its viscosity. (Kg · m ⁻¹ · s ⁻¹ ), d represents the diameter (m) of the stirring blade, and n represents the rotational speed (1 / s ⁻¹ ). The viscosity was measured using an E-type viscometer.

  Moreover, the stirring method is not particularly limited, but a rotating method using a stirring blade or the like is usually used. Examples of the shape of the stirring blade include radial flow blades such as a disc turbine type, paddle type, curved blade fan turbine type, and arrow blade turbine type, and axial flow blades such as a propeller type, an inclined paddle type, and a fiddler type. However, it is not limited to these. In addition, a paddle type having a special shape can also be used, for example, a large two-paddle blade (trade name “Full Zone” manufactured by Shinko Pantech), a paddle blade having a grid-like slit (manufactured by Sumitomo Heavy Industries, Ltd.) The trade name “Max Blend”) and the like can also be suitably used.

  In the present invention, a PTC plate crystal can be preferentially produced by maintaining the above-described cooling rate and stirring rate conditions for a PTC aqueous solution having a prescribed concentration from 60 ° C. to 30 ° C. When crystallization is started from a temperature higher than 60 ° C., the cooling rate and the stirring rate specified in the present application are not necessary in the cooling process up to 60 ° C., but the crystallization is performed under the conditions specified in the present application. It is desirable.

  Cooling may be continued after reaching 30 ° C. or lower, and it is usually desirable to cool to about 10 to 25 ° C. Cooling below 10 ° C increases the crystal yield, but conversely increases the slurry concentration, making it difficult to transfer and solid-liquid separation of the slurry, resulting in a decrease in production efficiency and a decrease in the PTC purity obtained. is there. Even when the aqueous solution of PTC reaches 30 ° C. or lower, it is preferable to continue cooling at a predetermined cooling rate of the present application. However, crystallization continues even without cooling, and a large crystal is obtained by providing a so-called aging period. Can grow into. As the aging time, 3 to 12 hours, preferably 4 to 8 hours are recommended. A longer ripening time is preferable because the crystal grows and is easily taken out as a large plate crystal. In addition, as a stirring speed when crystallization is continued even when the temperature reaches 30 ° C. or lower, the above-described stirring Reynolds range is preferable, but a stirring Reynolds number lower than that may be used for the purpose of preventing crystal breakage.

  After the crystallization is completed, the PTC can be separated from the mother liquor by a solid-liquid separator, for example, a centrifuge, a filter press, a Nutsche, etc., but a centrifuge is preferred industrially. The separated PTC crystals have a very high solubility in water (for example, 40 g at room temperature / 100 g of water), and since the PTC yield is reduced by rinsing with water to remove the adhered mother liquor containing impurities, tin It is preferable to dry as it is.

  It is important that the PTC crystal obtained by the crystallization method of the present invention is a plate crystal having an appropriate size. The average particle size of the plate-like crystal of the present invention is within the range of 50 to 500 μm, and the filtration time can be remarkably shortened by making the crystal shape plate-like, and it is difficult to produce fine powder, so the load of the separation process is increased. It is reduced and it is easy to obtain high-purity PTC.

  The average particle size of the plate-like crystals in the present specification and claims is obtained by taking a drop of crystallization slurry on a slide glass plate, covering it with a cover glass, and taking a photograph with an optical microscope. This is a value calculated by measuring the major axis of at least 10 particles selected at random using the manual measurement mode of the analysis software (manufactured by Mitani Corporation, trade name “Win ROOF”). Also, the aspect ratio was calculated from the ratio with the minor axis measured at the same time.

  In the present specification, “plate-like” is a crystal having a small aspect ratio, and specifically, an average value of values obtained by dividing the major axis (maximum diameter) of each crystal by the minor axis (minimum diameter) is 1 to 1. 5 things. If this value exceeds 5, it becomes “needle”. Therefore, the PTC of the present invention is plate-shaped, that is, the average value of the value obtained by dividing the major axis of the individual crystal by the minor axis is 1 to 5, and more preferably 1 to 3.

  After crystallization, since the mother liquor obtained by solid-liquid separation contains unprecipitated PTC, a predetermined amount of crude PTC or an aqueous solution thereof is added to the mother liquor, and adjusted to a predetermined concentration. Crystallization can be performed and the mother liquor can be recycled. Moreover, it can also be reused as an oxidation reaction reaction solvent in the production method (d).

  In particular, since the mother liquor obtained by crystallization after hydrolysis of the tetramethyl ester in the above production method (a) contains an acid catalyst in addition to PTC, it is again subjected to the hydrolysis reaction of the tetramethyl ester. It is preferable in terms of environment and economy.

  The PTC thus obtained is easy to handle industrially in large quantities because it has a good crystal shape, fluidity, and is stable with few fine powders that make the working environment worse. Moreover, the purity of PTC is 95 to 99% or more, and it can be sufficiently used as an acid component of industrial raw materials, for example, 1,2,3-propanetricarboxylic acid amide derivatives, without further purification.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In addition, the gas chromatography analysis (GC analysis) and the high performance liquid chromatography analysis (HPLC analysis), and the average particle diameter and aspect ratio of the PTC crystal in the following production examples were performed according to the conditions shown below.

  Dimethyl maleate and dimethyl malonate are subjected to an addition reaction in the presence of a sodium methylate catalyst, the used alcoholate catalyst is removed, and then the resulting Michael adduct is hydrolyzed in the presence of a p-toluenesulfonic acid catalyst. The aqueous reaction solution obtained by decarboxylation was prepared by the method described in Production Example 1 below.

  Preparation of aqueous reaction solution obtained by oxidative cleavage of 2- (2′-alkenyl) succinic acid with hydrogen peroxide in the presence of a phosphorus / tungstic acid catalyst, and then removing by-product caproic acid under reduced pressure or normal pressure Was prepared by the method described in Production Example 2.

(1) HPLC analysis (Michael addition)
Column: SHIMADZU SCR ODS-2 ID 6.0 mm x length 150 mm
Mobile phase: acetonitrile: water = 35: 65 (vol / vol)
Flow rate: 1 ml / min Temperature: 40 ° C
Detection: UV210nm and UV265nm

(2) HPLC analysis (hydrolysis)
Column: SHIMADZU SCR 101-H inner diameter 7.9 mm x length 300 mm
Mobile phase: 5 mmol / l Perchloric acid aqueous solution Flow rate: 0.8 ml / min Temperature: 40 ° C.
Detection: UV210nm

(3) GC analysis (oxidation reaction)
Device: SHIMADZU GC-14B
Column: DB-1701 2.5mmx30m 0.25μm
Column temperature: 100-300 ° C (10 ° C / min)
Flow rate: 1 ml / min Split: 1/30
Septum: 10 ml / min Injection temperature: 300 ° C
Detection temperature: 300 ° C

(4) Measurement of PTC particle size The average particle size of PTC was measured by the following method.
After completion of crystallization, a drop of crystallization slurry was collected on a slide glass plate, covered with a cover glass, and photographed with an optical microscope. The major axis and minor axis of at least 10 or more randomly selected particles were measured from the obtained image in a manual measurement mode of analysis software (manufactured by Mitani Corporation, trade name “Win ROOF”). The average particle diameter was the average value of the major axis. A numerical value obtained by dividing the major axis by the minor axis was taken as the aspect ratio.

[Production Example 1]
(1) Michael addition process
A glass 3000 ml four-necked flask equipped with a thermometer, dropping funnel, thermometer, condenser with condenser, and stirring device was charged with 782 g (5.9 mol) of dimethyl malonate and 28% sodium methylate (methanol solution). 56.9 g (5 mol% / dimethyl malonate) was charged, and after raising the temperature to 50 ° C., 814 g (5.6 mol) of dimethyl maleate was added dropwise over 1.0 hour, followed by stirring with heating at the same temperature for 3 hours. Next, after cooling, the organic layer was washed with 400 g of ion exchange water to remove the alkali catalyst used, and then 1560 g of a tetramethyl ester of Michael adduct was obtained. As a result of GC analysis, the reaction rate was 100% and the selectivity was 98.5%.

(2) Hydrolysis step 500 g of tetramethyl ester obtained by the above method in a glass 1000 ml four-necked flask equipped with a dropping funnel, a distillation tube, a thermometer and a stirrer, 125 g of distilled water and p-toluenesulfonic acid monohydrate 20.0 g of Japanese product was added, and hydrolysis was performed at 100 ° C. While adding the same amount of distilled water as the distilled water (approx. 120 ml / hour) as appropriate, the PTC conversion rate in the reaction system was analyzed by high performance liquid chromatography to follow the hydrolysis process. The conversion to PTC in the reaction system did not increase 16 hours after the start of hydrolysis, and 604 g of hydrolysis reaction solution was obtained. The reaction rate at this time was almost 100%, and the selectivity was 97.4%.

[Production Example 2]
To a glass 5000 ml four-necked flask equipped with a stirrer, thermometer, dropping funnel and condenser water separator, 650.1 g (3.0 mol) of 2- (2′-octenyl) succinic anhydride and water 1953 g was added and heated to 100 ° C. for 30 minutes in a nitrogen atmosphere to obtain a hydrous acid, then cooled to 70 ° C., 29.9 g of phosphorus / tungstic acid was added as a catalyst, and 200 g of 60% hydrogen peroxide was added dropwise. After reacting at 70 ° C. for 2 hours, the temperature was raised to reflux temperature, and 1900 g of 60% hydrogen peroxide was added dropwise over 10 hours while evaporating and distilling off by-product caproic acid together with water. The reaction was allowed for 5 hours. At that time, the separated caproic acid was distilled out of the system with a water separator, and the reaction was carried out while returning only water to the system. After the reaction, water was distilled off to obtain 738 g of a crude reaction solution. The reaction rate at this time was almost 100%, and the selectivity was 70.9%.

[Example 1]
Into a glass 1000 ml separable flask equipped with a thermometer, a condenser, a decanter, and a stirrer equipped with a full-zone stirring blade having a blade diameter of 7 cm, 550 ml of the reaction aqueous solution prepared in Production Example 1 having a PTC content of 50% by weight was added. In addition, the mixture was cooled from 60 ° C. to 25 ° C. at a cooling rate of 6 ° C./hour while stirring at a Reynolds number of 16,000. 0.5 g of PTC seed crystals (plate crystals) at 60 ° C. (0.2% by weight based on PTC content) was added. After reaching 25 ° C., it was further continued for 12 hours. After suction filtration, 178.1 g of white solid was obtained. The purity by HPLC analysis was 99.2% (yield 64%). The obtained PTC crystal was a plate crystal having an average particle diameter of 120 μm and an aspect ratio of 1.8.

[Example 2]
The reaction solution produced in the same manner as in Production Example 1 was heated to 100 ° C. under normal pressure, water was removed as the solvent, and the PTC content was changed to 60% by weight. 253.7 g of solid was obtained. The purity by HPLC analysis was 99.4% (yield 76%). The obtained PTC crystal was a plate crystal having an average particle diameter of 250 μm and an aspect ratio of 2.2.

[Example 3]
The reaction solution was prepared in the same manner as in Production Example 1 except that 680 g of a reaction solution having a PTC content of 45% by weight was added by adding 130 g of water as a solvent, and the same procedure as in Example 1 was carried out. Got. The purity by HPLC analysis was 99.2% (yield 46%). The obtained PTC crystal was a plate crystal having an average particle diameter of 210 μm and an aspect ratio of 1.3.

[Example 4]
The same procedure as in Example 1 was carried out except that the reaction solution prepared in the same manner as in Production Example 1 was used and the stirring Reynolds number was 8200, to obtain 136.1 g of a white solid. The purity by HPLC analysis was 99.2% (yield 49%). The obtained PTC crystal was a plate crystal having an average particle diameter of 180 μm and an aspect ratio of 2.1.

[Example 5]
Using the filtered mother liquor obtained in Example 1, a hydrolysis reaction was carried out in the same manner as in Production Example 1 to obtain a 1,2,3-propanetricarboxylic acid-containing hydrolysis reaction solution. Crystallization was performed in the same manner as in Example 1 to obtain 224.2 g of a white solid. The purity by HPLC analysis was 96.2% (yield 78%). The obtained sintered PTC crystal was a plate-like crystal having an average particle size of 85 μm and an aspect ratio of 1.3 and having very good filterability.

[Example 6]
Using the same apparatus as in Example 1, the reaction solution prepared in Production Example 2 was heated to 100 ° C. under normal pressure, and water as a solvent was distilled off. 550 ml of a reaction aqueous solution concentrated to a PTC content of 50% by weight was added, and the mixture was cooled from 60 ° C. to 25 ° C. at a cooling rate of 6 ° C./hour while stirring at a stirring Reynolds number of 10,000. 0.2 g of PTC seed crystals (0.2 wt% based on PTC content) was added at 60 ° C. After reaching 25 ° C., the mixture was further stirred for 12 hours. After suction filtration, 186 g of a white solid was obtained. The purity by HPLC analysis was 90.2% (yield 61%). The obtained PTC crystal was a plate-like crystal having an average particle diameter of 110 μm and an aspect ratio of 1.4.

[Comparative Example 1]
Crystallization was carried out in the same manner as in Example 1 except that 170 g of water as a solvent was added to the reaction solution produced in the same manner as in Production Example 1 and 720 g of a reaction solution having a PTC concentration of 38% was used to obtain 179.3 g of a white solid. It was. The purity by HPLC analysis was 84.7% (yield 55%). An optical micrograph of this crystal is shown in FIG. As is apparent from this photograph, the obtained PTC crystal is a needle-like crystal with poor filterability.

[Comparative Example 2]
Crystallization was performed in the same manner as in Example 1 except that the cooling rate from 60 ° C. to 40 ° C. was cooled at 20 ° C./hour, and from 40 ° C. to 25 ° C. was cooled at 10 ° C./hour. Got. The purity by HPLC analysis was 86.3% (yield 46%). Moreover, when this crystal was observed with a microscope, it was a needle crystal similar to Comparative Example 1.

[Comparative Example 3]
The procedure was the same as in Example 1 except that the stirring Reynolds number was 2,300, to obtain 172.7 g of a white solid. The purity by HPLC analysis was 83.2% (yield 52%). Moreover, when this crystal was observed with a microscope, it was a needle crystal similar to Comparative Example 1.
[Comparative Example 4]
The procedure was the same as in Example 1 except that the stirring Reynolds number was 25,000, and 169.6 g of a white solid was obtained. The purity by HPLC analysis was 89.0% (yield 55%). Moreover, when this crystal was observed with a microscope, it was a fine needle crystal.
[Comparative Example 5]
The reaction solution produced in the same manner as in Production Example 1 was heated to 100 ° C. under normal pressure, and the solvent water was distilled off to make the PTC content 65%. When the rest was carried out in the same manner as in Example 1, a highly concentrated slurry solution in which liquid transfer was difficult was obtained. Further, when this crystal was observed with a microscope, most of the needle crystals were the same as in Comparative Example 1.

  With the production method of the present invention, the crystal shape of 1,2,3-propanetricarboxylic acid becomes plate-like, whereby the filtration time can be remarkably shortened and the load on the separation process is reduced. Moreover, since the adhesion rate to the crystal | crystallization of the mother liquor in which an impurity dissolves can be reduced with improvement of separability, it became possible to manufacture highly purified 1,2,3-propanetricarboxylic acid industrially efficiently. A derivative of this, 1,2,3-propanetricarboxylic acid tris (alkyl-substituted cyclohexylamide), is useful as a resin additive to improve the transparency, crystallinity and rigidity of polyolefin resins.

1 is a view showing an optical micrograph of 1,2,3-propanetricarboxylic acid obtained in Example 1. FIG. 2 is a view showing an optical micrograph of 1,2,3-propanetricarboxylic acid obtained in Example 2. FIG. 4 is a diagram showing an optical micrograph of 1,2,3-propanetricarboxylic acid obtained in Example 3. FIG. 4 is a view showing an optical micrograph of 1,2,3-propanetricarboxylic acid obtained in Comparative Example 1. FIG.

Claims (6)

  In crystallization of 1,2,3-propanetricarboxylic acid from a 1,2,3-propanetricarboxylic acid aqueous solution, an aqueous solution having a 1,2,3-propanetricarboxylic acid concentration of 45 to 60% by weight 1,2,3-propanetricarboxylic acid plate characterized by performing crystallization under the conditions of a stirring Reynolds number of 3,000 to 20,000 and a cooling rate of 15 ° C./hour or less in a temperature range of 30 ° C. A method for producing a crystal.   Furthermore, a seed crystal is put into the said aqueous solution and it crystallizes, The manufacturing method of Claim 1 characterized by the above-mentioned.   The production method according to claim 1 or 2, wherein the plate-like crystal has an average particle diameter in the range of 50 to 500 µm.   The mother liquor obtained by solid-liquid separation after crystallization of 1,2,3-propanetricarboxylic acid plate crystals is reused as an aqueous 1,2,3-propanetricarboxylic acid solution. The manufacturing method of crab.   The aqueous solution is obtained by reacting (i) maleic acid diester and malonic acid diester in the presence of an alkali catalyst to obtain a Michael reaction adduct, and then removing the used alkali catalyst, and (ii) the obtained Michael reaction The production method according to any one of claims 1 to 4, which is a reaction aqueous solution obtained by hydrolysis of an adduct under an acid catalyst. 6. The production according to claim 5, wherein the mother liquor obtained by solid-liquid separation after crystallization of 1,2,3-propanetricarboxylic acid plate-like crystals is used in the hydrolysis reaction of step (ii) in claim 5. Method.