JPS5988465A - Separation of indole - Google Patents

Abstract

PURPOSE:To carry out the chromatographic separation of indole from an organic mixture containing indole and methylindole, by using a zeolite having specific pore size and containing silver as major part of the substitution cation, and acetonitrile as a developer. CONSTITUTION:Indole is separated from an organic mixture containing indole and methylindole and composed of C, H, O and N (e.g. coal tar fraction) by chromatography using a zeolite having pore size of >=6Angstrom and containing silver as the major part of the substitution cation (e.g. X type or Y type zeolite), and acetonitrile and/or propionitrile as a developer. USE:Raw material of perfume, dye, drug, essential amino acid, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for chromatographically separating indole from a mixture of similar compounds using a specific zeolite and a developing agent.

Indole is useful as a raw material for perfumes, dyes, medicines, etc., and in recent years has been in the spotlight, particularly as a raw material for essential amino acids. Indole is found in coal tar, jasmine oil, neroli oil, rotten protein, etc. Among them, indole is found in coal tar, which is produced in large quantities industrially.

0.2-0.5 fold fl'! It is said that the fraction with a boiling point range of 220-270°C obtained by distilling this contains 1.5-4.5% by weight.

In the conventional chromatographic separation technology, as a method for separating indole from the above coal tar fraction, JP-A No. 56-6
A method is known that uses a Y-type zeolide substantially substituted with lithium and/or sodium and anisole as a developing agent, as disclosed in Japanese Patent No. 5868. However, in this method, indole and naphthalene, thionaphthene, 1-methylnaphthalene, 2-methylnaphthalene,
It acts as a fraction of biphenyl, dimethylnaphthalene, acenaphthene, diphenylene oxide, and fluorene, but it is a fraction of methylindole and indole, which have a similar structure to indole.111I1. It is difficult. As a result of intensive research by the present inventors to solve this problem, we used a zeolite with an aperture diameter of about 6A or more and in which most of the substituted cations are sister, and acetonitrile and/or pyrovionitrile as a developing agent. It is only in this configuration of the present invention that the object can be achieved.

Although this is not a technology directly related to the present invention, in a zeolite equilibrium adsorption test, a special technique is to adsorb a toluene solution of indole and 2-methylnaphthalene onto a zeolite whose cation is silver, and to exfoliate both with acetonitrile. It is known from Japanese Patent Publication No. 56-65868. However, it has become clear that acetonitrile has the ability to strip off all of the indole and 2-methylnaphthalene systems, and this shows that it can be used as a developing agent for indole and methylindole systems, which are different in chromatographic separation. It is unpredictable that acetonitrile will work.

One example is coal tar fraction. The content of methyl indole may be 1% by weight or more.

Good results are obtained even with less than 1% by weight.

This means that if methylindole cannot be chromatographically separated, even if the initial methylindole content is low, the chromatographic
This is because after treatment, the indole fraction is concentrated and becomes a non-negligible amount. The effective methylindole content to which the present invention is applied is 0.01% by weight or more. Preferably it is 0.1 weight or more.

A wide variety of zeolites are known, both naturally occurring and artificially synthesized. However, not all of these zeolites are effective as the adsorbent for separating indole according to the present invention, and those having an opening diameter larger than the molecular size of indole, that is, about 68 or more, are effective. As a zeolite with an aperture diameter of approximately 68 or more.

X type, Y type, L type, Omega type, Faujasite.

There is a ZSM group represented by mordenite and ZSM-5. If we plan from an industrial perspective,
X 71; which is produced on a scale of ! I-type zeolite and Y-type zeolite are the most preferred suction C1 agents.

For X-type zeolite, oxide display: Na, O・M2O
3.2.58i0. -6) 120, unit cell constant display:
NaB6 [: (AIOs)ss(SiO□),.

6]・264I-I20, density: 1.93 y7 company,
Unit cell constant: 25.02-24.86A, void lft: o, soα°, opening diameter: 12cm-7,
4A, 6-membered ring-2, 2A, speed 1" diameter: 8. It is a zeolite characterized by IA.

Y-type zeolite has oxide display: Na, 0, AI, 0
．．・4.88t 01l-8,9HtO% unit cell constant display” Na5s ((At 0x)sa (810J
, s,]・250・H,0, density=1-92 f/C
(:, , unit cell constant: 24.85~2t6i
X, void volume! 0-48C/, /C/,.

It is a zeolite characterized by aperture diameter: 12A term - 7.4X, 6-membered ring -2,2A, velocity aperture diameter: s, IX.

Therefore, the X-type zeolite and Y-type zeolite used in the present invention may be any type of X-type zeolite synthesized by a conventionally known method as long as it has the above-mentioned crystal structure. , Y-type zeolite can also be used.

In addition, in the representations of the X-type zeolite and the Y-type zeolite, Na is used during the synthesis of the zeolite mainly due to synthetic requirements.

In order to achieve the purpose of the present invention, it is necessary to substitute some or all of the cations constituting the X-type zeolite and the Y-type zeolite with a specific metal ion to exhibit a high degree of selective separation. .

The aperture diameter changes by changing the type of metal ion,
In addition, the interaction between the metal ion and the substance to be separated changes, and the selective separation properties change due to both effects.

As a measure of selective separability, the following minute 1'iiu
coefficients are used. The separation coefficient is defined as two specific components A,
What are the concentrations of the liquid phase of components A and B when a liquid containing B is brought into contact with an adsorbent and an equilibrium state is reached?

Xmu, Xs% The concentration of the adsorbed phase is Ymu, Yl, respectively.
When , the value of ′ is defined by the following formula.

Below are commercially available A, X, Y and L as experimental examples.
Type zeolite) 1 was used, the type of gold ion was changed, and the same ion exchange treatment and calcination as in Example 1 described below were carried out, followed by the following ■
0.5r of zeolite was added to each of the solution members 2f of type 2 and (2) and left in contact at 70°C for 4 hours to determine the separation factor. The results are shown in Tables 1 and 2 to explain which metal ions are preferred.

Solution (1) Solution 1 (1) In Tables 1 and 2, solution i is shown with a separation factor of 1.
(I) and (II) each adsorption capacity W1. W Maro was listed.

The adsorption capacity ridge is defined by the following formula, and the larger this value is, the higher the actual separation efficiency is, so it is preferable.

As for the performance of the adsorbent preferred below, it is preferable that both the separation coefficients of indole and 3-methylindole and indole and 2-methylindole are high, and even if only one is high, it is not preferable if the other is low. It is also necessary that the adsorption capacity be at a certain level or higher (approximately 1501nf/f-zeolite).

Note that among methylindoles, 2-methylindole and 3-methylindole are most difficult to separate from indole.

Comparing Tables 1 and 2 from the above perspective, as shown in Experimental Examples 1 to 28, silver is specifically preferable as a type of metal ion, while potassium, havidium, cesium, copper and nickel are preferable. Kaya\ preferred. Further, as the type of zeolite, X-type and Y-type zeolites are preferable from the viewpoint of adsorption capacity.

The exchange of cations is carried out by contacting the zeolite with a water-soluble charge of the ions to be exchanged, such as an aqueous silver nitrate solution.

The substituted cation used in the present invention is silver, which requires that at least 6°4 of the exchange capacity of the zeolite used be replaced with silver.

The number of cations used is preferably 0.8 times or more the number of exchangeable cations in the zeolite.

Further, the ion concentration of the solution for ion exchange is selected to be an appropriate concentration below the saturation concentration, and is usually in the range of 0.01N to 4N and below the saturation concentration. When performing ion exchange with mixed metal ions/.

Utilizing common anion solution gold.

The shapes of the X-type zeolite and Y-type zeolite used in the present invention are as described above. 1 is appropriately selected depending on the method of contacting the mixture with the zeolite. It may be in the form of powder or crushed lumps, or it may be a molded product obtained by compression molding, extrusion molding, molding with a marmerizer, molding with a spray dryer, or the like.

Next, the developing agent is zeolite 1? must be selected appropriately, taking into consideration the high exchange rate. In the present invention,
Since the substituted metal ion of zeolite is zeolite, it is essential to use acetonitrile and/or propionitrile as a developing agent.

In order to separate indole using the adsorbent and developing agent of the present invention, commonly used adsorption separation operations, ie, batch chromatographic separation method and continuous chromatographic separation method, are applied. The batch chromatographic separation method herein refers to the following operations.

First, a developing column filled with adsorbent to the required length is first filled with the developing agent, and a mixture containing indole and methyl indole or this mixture is dissolved in a suitable solvent, and a filtrate solution is fed into the specified F11 from one end. Then, an adsorption zone is formed in the developing tower. Next, a predetermined amount of developing agent is introduced from the rear of the mixture, and the developing agent moving from the rear completely removes the adsorption zone, and each component is moved forward while opening the mixture.
-ru. Each component in the mixture begins to separate in the developing column depending on the difference in adsorption power. Then, in the darkest region where indole and methylindole have sufficiently separated, the indole-rich region is extracted. Alternatively, it is also possible to measure the indole concentration in the entire part of the market (where indole is not completely separated from other components) before and after feeding the mixture, and then feeding the mixture again and recovering the indole concentration.

Continuous chromatographic separation is a method in which the mixture inlet is moved to an appropriate position in the adsorption zone according to the advancing speed of the adsorption zone separated into each component as it progresses in the developing column, and the This is a method to achieve a steady state and continuously separate indole and methylindole by extracting methylindole and an indole-rich liquid from each position and replenishing the insufficient developing agent from an appropriate position outside the adsorption zone. .

In both batch and continuous processes, the product is usually obtained in a state dissolved in a developer, but the developer of the present invention and indole have considerably different boiling points and can be separated by simple distillation.

Next, the operating conditions will be explained using a batch chromatographic separation method as an example.

The length of the developing column is required to be 5 m or more to sufficiently separate indole and methyl indole, and preferably 8 m or more. If it is less than sm, separation of indole and methylindole will be insufficient, and highly pure indonyl cannot be recovered at a high recovery rate.

Furthermore, since conventional chromatographic separation technology uses a developing column at the However, in the present invention, by using a developing column with the above-mentioned length, these separations can be improved and highly purified indole can be recovered at a high recovery rate.

In the prior art, silk in the mixture alternately fed with the developing agent was used in an amount of about 0.1 to 0.2 parts by weight of the amount of packed zeolite, but in the present invention, the content of methyl indole is 1.
When using a mixture with a weight of less than 14 h, the indole content in the row is about 0.15~0, srib (phase part, preferably is 0.2 to 0.6 heavy chain parts, which is larger than conventional values, and 1
The amount of mixture processed per batch, and therefore the yield of indole 111, is larger than that of the prior art, which is efficient.

Separation is good if the feeding amount is less than this range, but
It is economically disadvantageous because the amount recovered is small. Moreover, if the feeding amount is larger than this range, the separation will be poor, the recovery rate will deteriorate, and the amount recovered will also decrease, which is not preferable.

The flow rate of the mixture and developing agent in the developing tower is approximately 2 m/hr.
-io yrL/hr is desirable. This is the conventional technology
Compared to around m/hr, it is much faster, the amount of processing per hour increases, and it is more efficient.

The temperature at which the mixture and the developing agent are brought into contact with the zeolite must be at least a temperature at which the mixture does not solidify, and specifically preferably at room temperature or higher. Further, the upper limit of the temperature is preferably about 130° C. or lower, taking into consideration the boiling point of the developing agent.

According to the present invention, it is possible to separate indole and methyl indole, which has been difficult with conventional chromatographic separation using zeolite, and has great industrial significance.

Examples of the present invention and comparative examples other than those of Akira Kokukai are shown below, but the present invention is not limited to these examples.

Example 1 A commercially available Y-type zeolite powder was granulated by spray drying to form spheres with a particle size of approximately 200 to 300 μm, which were then treated with an approximately 2N aqueous silver nitrate solution at 70° C. for 4 hours. Perform this operation 3
After repeating the process, it was washed with water and dried at 90°C for 6 hours. Next, the zeolite treated as described above was calcined at 400° C. for 4 hours and cooled in a desiccator. This was packed into a cylindrical stainless steel column with a diameter of 8 mm and a length of 1 OrrL. The weight of zeolite used for filling was 3602.

The temperature of the column was maintained at 86°C, and acetonitrile as a developing agent was supplied from one end of the column at a superficial flow rate of 5 m/hr. When the acetonitrile flowed out from the other end and became damp, the supply cock was switched, and the following composition was added. 721 was fed at the same flow rate.

The mixture weight (WB) per unit weight of zeolite is 0.2
Met.

Next, acetonitrile K as a developing agent is supplied again in a circular manner, and the above mixture leaves the column as a solution of P! iF L, I continued until I finished it.

The effluent was collected at regular intervals and subjected to analysis 3, I) fr
.

The relationship between the elution time and the concentration of each component is shown in Figure 1, and it can be seen that indole and methylindole are separated.

The recovery rate (199,5) of the indole fraction with an indole purity of 99.5% is 99.5%.
It was 8chi.

Example 2 Indole was separated in the same manner as in Example 1 except that the amount of the mixture fed was 1,442 kg, and the mixture composition and other chromatographic conditions were the same as in Example 1. WB=0.4.

FIG. 2 shows the relationship between the elution time and the concentration of each component. In this case as well, indole and methylindole are separated.

The recovery rate (R, 99.8) in this case was 94%.

Example 3 The length of the developing column was 51n, the weight of the zeolite used was 180f, and the amount of the fed mixture was 72f, but the indole fraction Pi16 was prepared in the same manner as in Example 1.
I did this. 4) with WB=0.4.

The relationship between the outflow (li', It) time and the concentration of each component is shown in No. 31y, 1. Separation of indole and methylindole is getting worse, but still quite a bit.
+ar is doing. Recovery rate in this case (R9a,s)
r,! , 67% 1, Example When using a mixture with a methyl indole content of 1, @M% or more, especially when the indole content is 10% by weight
An example in which a mixture of the above and high 01 is used will be described below.

Separation of indole was carried out in the same manner as in Example 1, except that the amount of the mixture fed was 22F and the composition of the mixture was as follows.

In this case, WB = 0.06, and when the concentration of methylindole and indole is high, the value of wn is low and 0.
A value of 0.05 to 0.15 is appropriate.

The relationship between the elution (elution) time and each component is shown in FIG. It can be seen that indole and methylindole are separated.

The recovery rate (R99J) in this case was 88 yen.

Example 5 Indole was separated in the same manner as in Example 1 except that propionitrile was used as a developing agent. In this case as well, indole and methylindole were separated, and the recovery rate (R119,1I) was 72.

Comparative Example 1 A commercially available Y-type zeolite powder was granulated by spray drying to form a sphere with a particle size of 200 to 300μ, which was then treated with an aqueous solution of lithium chloride at 70°C for 4 hours. . This operation was repeated three times, followed by washing with water and drying at 90° C. for 6 hours. Next, the zeolite treated as described above was calcined at 400° C. for 4 hours and cooled in a desiccator. This has a diameter of 8
1 packed in a cylindrical stainless steel column with a length of lOm.
The weight of the zeolite used for filling was 2861.

The temperature of the column was maintained at 86°C, and anisole as a developing agent was supplied from one end of the column at a superficial flow rate of 5 m/hr.
When anisole began to flow out from the other end, the feed cock was switched, and mixture 571 having the following composition was fed at the same flow rate. WB=0.2.

The developer anisole was then fed again at the same rate until the mixture had eluted from the column.

Effluent was collected at regular intervals and subjected to analysis. Outflow (solution)
I#) The relationship between time and the concentration of each component is shown in Figure 5, where indole and methyl indole are not separated. In this case, the recovery rate (Ro9.s) was 6.

Comparative Example 2 Indole was separated in the same manner as in Example 1 except that the amount of the mixture fed was 324f, and the mixture composition and other chromatographic conditions were the same as in Example 1. WB=0.9.

In this case, the separation of indole from methylindole and other components was poor, and the recovery rate was 21%.

[Brief explanation of the drawing]

FIG. 1 shows the INI relationship between time and the concentration of each component for the effluent from the column in Example IK. FIG. 2 illustrates the relationship between time and the concentration of each component in the effluent from the column in Example 2. Figure 3 illustrates the relationship between time and concentration II (°) of each component for the effluent from the column in Example 3. This diagram illustrates the relationship between each ingredient in concentrated fertilizer. FIG. 5 shows the relationship between time and the concentration of each component (13.1 -1 g<l) for the effluent from column 1 in Comparative Example IK. 1 Watch applicant Asahi Kasei Kogyo Co., Ltd. Hoshu (414II reference λ

Claims (1)

[Claims] 1. When indole is adsorbed and separated from a mixture of organic compounds consisting essentially of carbon, hydrogen, oxygen and/or nitrogen, including indole and methylindole, the aperture diameter is about 6A or more and substitution is performed. With zeolite, where most of the cations are silver. Claim 1: A method for separating indole characterized by chromatographic separation using acetonitrile and/or propionitrile as a developing agent, characterized in that the mixture of organic compounds is a coal tar fraction. Indole separation method 3 described in Section 3, zeolite with an open diameter of about 6A or more is X type and/or Y type.
The method for separating indole according to claim 1 or 2, characterized in that the method is a zeolite type zeolite.