JPH07144102A - Method for crystallizing organic chemicals - Google Patents

Abstract

PURPOSE:To perform crystallization excelling in an aptitude for production even with a general-purpose device by first adjusting the supersaturation of organic chemical solution to crystallize flat crystals and then lowering the temp. to continue the crystallization of the flat crystals while the composition of solvent is changed. CONSTITUTION:A crystallizer 20 is provided with a kettle 22, an agitating blade 24 equipped with a bar blade, and a baffle 26 almost in the shape of F. When an organic chemical, such as a cyanic coupler, is dissolved in a good solvent, such as ethyl acetate and is fed into the kettle 22 and a poor solvent, such as methanol, is gradually added to it under agitation while the liquid temp. maintained, mainly flat crystals begin to crystallize by supersaturation. Next, while another poor solvent, such as water, is added to lower the saturation solubility of the flat crystals in the organic chemical by changing the solvent composition the temp. is lowered to continue the crystallization of the flat crystals. In this process, the agitating speed of the agitator 24 is adjusted to make the crystallized flat crystals in a complete floating state. After that, the mixture is cooled and separated into the crystals and mother liquor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystallization method for cooling an organic chemical solution to precipitate crystals of the organic chemical dissolved in the organic chemical solution.

[0002]

2. Description of the Related Art In the production of industrial chemicals, pharmaceuticals, foods, etc., solution refining cannot provide a sufficient refining effect, and therefore a crystallization step is provided to ensure the quality of the final product.

A conventional crystallization method used in this crystallization step is shown in FIG. 3 as a solubility curve graph.
The crystallization operation line in FIG. 3 is a schematic one, but as shown in the figure, conventionally, an organic chemical solution was prepared by dissolving an organic chemical in a good solvent, and then cooled to lower the liquid temperature. To generate lumpy crystals beyond the metastable region and the flattened region,
The organic chemical solution was cooled so as to pass through the lump crystal region as it was, and lump crystals were deposited.

This massive crystal has a crystal structure that is suitable for production because solid-liquid separation is easy in the next step and the crystallization speed is fast, but on the other hand, since the crystal is heavy, it seems to be a Faudler type as shown in FIG. With such a small stirring blade 2, the precipitated massive crystals could not be suspended, and the degree of supersaturation inside the tank 4 became nonuniform as shown in FIG. 6 (A), and as shown in FIG.
In the upper part of the tank 4 having a higher degree of supersaturation, finally, a large amount of fine needle-like crystals having poor filterability are deposited, resulting in a slurry having extremely poor fluidity (FIG. 6 (B)).

In order to prevent this, the stirring efficiency is high, the supersaturation degree in the tank 4 can be made uniform, and only massive crystals can be deposited. An apparatus dedicated to crystallization equipped with No. 6 is required, which imposes great restrictions on the equipment that can be used for crystallization.

[0006]

The present invention has been made in view of the above facts, and it is possible to obtain crystals having good filterability and a slurry having good fluidity even if the stirring efficiency is low,
Accordingly, it is an object of the present invention to provide a crystallization method capable of performing crystallization with excellent production suitability even in a general-purpose device.

Another object is to provide a method for obtaining crystals which can be easily taken out by using a general-purpose kettle having a Faudler blade that can be used for reaction and concentration, without using an anchor blade with high efficiency stirring. is there.

[0008]

Means for Solving the Problems As a result of intensive studies and research to achieve the above-mentioned object, the present inventor has found that by precipitating flattened crystals, crystallization with excellent production suitability can be performed even in a general-purpose apparatus. I found it.

That is, according to the invention described in claim 1, a crystallization starting step of adjusting the supersaturation degree of the organic chemical solution so that the flat crystals are mainly deposited, and the crystallization starting step is provided subsequent to the crystallization starting step. While changing the solvent composition so as to reduce the saturated solubility of this organic chemical solution, by lowering the temperature of this organic chemical solution, mainly having a crystallization step to continue the precipitation of flat crystals, the crystallization starting step and Through the crystallization step provided subsequently to this, there is provided a method for crystallization of an organic chemical by precipitating a crystal of the organic chemical by stirring this organic chemical solution so that the flow of the precipitated flat crystals is in a completely floating state. It

The present invention is a very effective method for purifying the produced organic chemical in the final step of producing the organic chemical. Examples of organic chemicals to which the method of the present invention is applied include cyan couplers, magenta couplers, colorants for normal photography represented by yellow couplers, colorants for instant photography, antifoggants, and the like. Not limited, low melting point (mp is preferably 0 to 50 ° C)
The organic compounds can be widely applied.

According to the method of the present invention, first, the degree of supersaturation of the organic chemical solution is adjusted so that mainly flat crystals are precipitated (crystallization initiation step). This adjustment may be performed by any method. For example, after dissolving an organic chemical in a good solvent to form an organic chemical solution, a poor solvent is added to the organic chemical solution to adjust the supersaturation degree of the organic chemical solution. A method of adjusting so that flattened crystals are mainly deposited may be mentioned.

Here, "predominantly precipitating flattened crystals" to "mainly continue to precipitate flattened crystals" means that the flattened crystals occupy 60% or more, preferably 80% or more of the precipitated crystals.

Also, good solvent and poor solvent are well known terms to those skilled in the art, and a good solvent means a solvent having a large ability to dissolve a solute, and conversely, a poor solvent has a small ability to dissolve a solute.
Or, it means a solvent having almost no such ability. Typically,
A solvent that dissolves 5 g or more, preferably 20 g or more of a solute in 100 g of a solvent at 40 ° C. is a good solvent, and a solvent that also dissolves 10 g or less, preferably 1 g of a solute in 100 g of a solvent is a poor solvent.

Ethyl acetate is a good solvent for many photographic reagents. Similarly, methanol, ethanol and water are poor solvents. In the present invention, two poor solvents can be used in combination.
The poor solvent used in combination may be added sequentially or may be mixed in advance and used. Further, a combination that forms a uniform solution even after adding a poor solvent is preferable.

The degree of supersaturation of the organic chemical solution is 3 or more and 3
It is preferable to adjust the value to 0 or less. here,
Supersaturation refers to the ratio of the absolute value of the solution concentration to the saturation concentration.

Then, according to the method of the present invention, the temperature of the organic chemical solution is lowered while changing the solvent composition so as to reduce the saturated solubility of the organic chemical solution, and mainly the filterability and the agitability are obtained. Of good flattened crystals is continued (crystallization step). The saturated solubility of the organic chemical solution may be lowered by any method, for example, water is added to the organic chemical solution whose supersaturation is adjusted by adding a poor solvent to the organic chemical solution using a good solvent as a solvent. A method of gradually adding to change the solvent composition in a homogeneous system can be mentioned.

The flattened crystals thus precipitated are agitated in a completely floating state during the crystallization starting step and the crystallization step so that the supersaturation degree of the organic chemical solution in the apparatus does not become nonuniform.
As used in the text, the completely floating state means that crystals are 1 at the bottom of the tank.
It means a stirring state in which it does not stay for 2 seconds or more.

When the crystallization method of the present invention is carried out on a large scale, appropriate stirring conditions can be determined based on the stirring conditions of the crystallization experiment using a small-scale experimental apparatus. For example, Hyakunaga et al., "Agitation Effect on Particle Size Analysis in Crystallization of Phenoxyacetic Acid Compounds"
Volume 0, No. 2, published in 1984) is effective for the scale-up method using the Z factor. In this method, the minimum stirring condition that satisfies the perfect suspension condition, which is calculated under the geometrically similar scale-down condition, is first calculated. Next, the stirring rotation speed under the scaled-up condition can be obtained by making the Z factor values the same.

The present invention will be described below with reference to examples.
They are merely examples and the present invention is not limited thereto.

[0020]

【Example】

Example 1 First, the method of the present invention was carried out in a flask experiment in order to take out crystals of a cyan coupler (1) having the following structural formula I.

[0021]

[Chemical 1] As an experimental apparatus, a 500 ml separable flask having a flask diameter of 80 mm and a small Faudler blade having a stirring blade of 45 mm were used.

79 g of the cyan coupler (1) was placed in the separable flask containing 43 ml of ethyl acetate.
After being charged, the mixture was heated to 40 ° C and dissolved. Then
192 ml of methanol (poor solvent) was added to this solution at a liquid temperature of 4
The mixture was gradually added while stirring at 0 ° C. Further, seed crystals were added to this solution, and 213 ml of water (another poor solvent) was added with stirring, and the temperature was lowered to 20 ° C over 4 hours. In this process, flattened crystals were observed to be deposited, so that the deposited flattened crystals were in a completely floating state.
The stirring speed was adjusted. The stirring speed at this time is 400 rp
It was m. In addition, the temperature starts to drop from 40 ° C to 20 ° C.
The degree of supersaturation was 20 to 25.

After reaching 20 ° C, stirring was continuously maintained for 1 hour, and the temperature was rapidly lowered to 5 ° C to secure the crystallization yield.

The slurry thus obtained had good fluidity. Then, the crystallized product and the mother liquor were separated by filtration.

The crystallization product was a flat crystal of 5 μm × 30 μm, and the crystallization yield was 92%. The above crystallization method was applied to production.

The kettle used was made of 4000 liter glass lining, and the stirring blade was a Faudler type stirring blade having a blade diameter of 900 mm. A schematic structure of a crystallizer 20 equipped with this kettle and a stirring blade is shown in FIG.

This crystallizer 20 is equipped with the above-mentioned kettle 22 and the agitator 24 equipped with the above-mentioned three Faudler blades (rod-shaped blades).
And a baffle 26 having a substantially F-shaped cross section that is inclined upward. An opening 22B is formed substantially at the center of the ceiling 22A of the kettle 22, and the Faudler blade of the agitator 24 is held in the kettle 22 through the opening 22B. The rotation speed of the stirrer 24 is 95 rpm at maximum and 27 at minimum.
Variable speed of rpm is possible. Ceiling 22A
An opening 22C is also formed in the vicinity of the outer circumference, and the baffle 26 is held in the hook 22 through the opening 22C. Around the side wall 22D and bottom surface 22E of the shuttle 22,
A cooling bath 28 for cooling the solution in the pot 22 is formed, and the cooling bath 28 is filled with the cooling liquid 30.
A coolant inlet 28A for entering the inside and a coolant outlet (not shown) for discharging the coolant 30 are formed. The cooling liquid inlet 28A and the cooling liquid outlet are connected to a heat exchanger (not shown) via a pipe (not shown), and the cooling liquid 30 circulates between the heat exchanger and the cooling tank 28. Bottom 22E of the hook 22
A discharge port 22F for discharging the slurry obtained by cooling the solution is formed in a substantially central portion of the, and the discharge of the slurry is adjusted via the valve 32. The crystallizer 20 includes a solution port for injecting a solution into the other pot 22 and a thermometer for controlling the temperature in the pot 22. Further, the clearance between the stirring blade of the stirrer 24 and the deepest central part of the bottom of the kettle is 80 mm, which facilitates the floating of the crystals retained at the bottom.

In this example, brine was used as the cooling liquid. 780 kg of the above cyan coupler (1) was placed in a kettle 22 charged with 426 liters of ethyl acetate, and then dissolved while stirring while maintaining the liquid temperature at 40 ° C. Then, 1919 liters of methanol was gradually added to this solution while stirring while maintaining the liquid temperature at 40 ° C. Furthermore, seed crystals were added to this solution, and 2132 liters of water was added with stirring, and the temperature was lowered to 20 ° C. over 4 hours. The flat crystals precipitated in this process were adjusted to a stirring speed that was a complete floating condition. This stirring speed is
It was 48 rpm. After reaching 20 ° C, stirring was continuously maintained for 1 hour, the temperature was rapidly lowered to 5 ° C, and then the crystals and the mother liquor were separated by filtration with a centrifuge.

At this time, the slurry had a good fluidity, and the crystallized product was the same flat crystal as in the flask.

FIG. 2 shows a solubility curve and a crystallization operation line schematically represented. The solubility curve shown by the broken line in the figure represents the solubility curve of the solution before the addition of the poor solvent and is shown by the solid line. The solubility curve represents the solubility curve after adding the poor solvent, and the solubility curve shown by the broken line is lowered to the solubility curve shown by the solid line to facilitate the crystallization operation in the flat crystal region.

Example 2 Even when the cyan coupler (2) having the following structural formula II was crystallized under the same scale-up conditions as in Example 1, flat crystals with good filterability could be obtained. .

[0032]

[Chemical 2] Example 3 Even when the cyan coupler (3) having the following structural formula III was crystallized under the same scale-up conditions as in Example 1, flat crystals with good filterability could be obtained.

[0033]

[Chemical 3] Example 4 Even when the magenta coupler intermediate having the following structural formula IV was crystallized under the same scale-up conditions as in Example 1, flat crystals with good filterability could be obtained.

[0034]

[Chemical 4]

[0035]

EFFECTS OF THE INVENTION By using the crystallization method of an organic chemical according to the present invention, it is possible to obtain crystals having good filterability and a slurry having good fluidity even if the stirring efficiency is low. In addition to being able to perform excellent crystallization, it is possible to establish a scale-up method applicable from experimental equipment to manufacturing equipment.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a crystallizer according to the present invention.

FIG. 2 is a diagram showing a model of crystal form control in the crystallization method of the present invention.

FIG. 3 is a diagram showing a model of crystal form control in a conventional crystallization method.

FIG. 4 is a diagram showing a state of crystallization in a conventional crystallization method, in which (A) shows a state in which massive crystals have started to be deposited,
(B) shows the state at the end of crystallization.

FIG. 5 is a diagram showing a model of crystal form control when a Faudler type stirring blade is used in a conventional crystallization method.

FIG. 6 is a diagram showing a state of crystallization when a Faudler-type stirring blade is used in a conventional crystallization method,
Shows the state where the agglomerates started to precipitate, and (B) shows the state at the end of crystallization.

[Explanation of reference numerals] 20 crystallizer 22 kettle 24 stirrer (Faudler type) 28 cooling layer

Claims (3)

[Claims] 1. A crystallization starting step of adjusting the supersaturation degree of an organic chemical solution so that mainly flat crystals are precipitated, and a saturated solubilization of the organic chemical solution provided subsequent to the crystallization starting step is lowered. While changing the solvent composition, by lowering the temperature of this organic chemical solution, there is a crystallization step that mainly continues the precipitation of flat crystals, and through the crystallization initiation step and the crystallization step that is subsequently provided, precipitation A method for crystallizing an organic chemical, characterized in that the organic chemical solution is stirred so that the flow of the flattened crystal is completely suspended. 2. An organic chemical solution is prepared by dissolving an organic chemical in a good solvent, and then a poor solvent is added to the organic chemical solution to adjust the supersaturation degree of the organic chemical solution so that mainly flat crystals are precipitated. The method for crystallization of organic chemicals according to claim 1, characterized in that 3. The crystallization method of an organic chemical according to claim 2, wherein the degree of supersaturation after adjustment is 3 or more and 30 or less.