JPS6150967A - Method of extracting indole - Google Patents

Abstract

PURPOSE:To extract indoles from a mixture comprising indoles and hydrocarbons as main component, by using an extractant obtained by blending an amine, an alkylsulfoxide, and/or pyrrolidone with a specific amount of water. CONSTITUTION:In extracting indoles from a mixture comprising indoles and hydrocarbons, such as a coal tar fraction containing indoles having <=270 deg.C boiling point preferably obtained by distillation of coal tar, or a substance obtained by removing an acidic component and/or a basic component from the fraction, an extractant is obtained by blending 100pts.wt. one or more organic solvents (preferably monoethanolamine, etc.) selected from amines, alkyl sulfoxides, and pyrrolidones with 1-25pts.wt. water, and used. Especially the extractant is used as the first extractant, and a nonpolar solvent such as 5-10C alkanes, etc. is used as the second extractant, to raise the selectivity for the aimed compound without causing problems such as corrosion of device and requiring complicated purifying operations.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a method for extracting indoles, and more specifically, to selectively extract indoles from a mixture whose main components are indoles and hydrocarbons. Concerning how to.

(Prior art) A method for recovering indoles from a mixture whose main components are indoles and hydrocarbons is to separate indoles into their alkali salts using alkali hydroxide and then hydrolyze them. 5. Extract indoles with a polar solvent such as monoethanolamine, dimethyl sulfoxide, pyrrolidone, etc., wash this extract with an alkane or cycloalkane having a boiling point different from that of the hydrocarbons in the raw material, and then charcoal the accompanying charcoal. A method is known in which indoles are recovered by distillation after removing hydrogen (Japanese Unexamined Patent Publication No. 58-1989).
135862 and Japanese Patent Application Laid-open No. 59-62565)
.

[Problem that the invention seeks to solve]

However, in the former method, there are problems such as corrosion of the equipment due to the use of highly concentrated alkali hydroxide at high temperatures, and in the latter method, the selectivity for indoles is low; When the indoles recovered by extraction involve impurities that are difficult to remove by ordinary distillation and are converted to high purity 17! ! The problem is that it requires a crudely refined masterpiece.

(Means and effects for solving the problem) The present invention has been devised in view of the above, and in extracting indoles from a mixture whose main components are indoles and hydrocarbons, As an extractant for this type, 1 to 25 parts of water is mixed with 100 parts of EIQfn of one or more specific solvents selected from a group of organic solvents consisting of amines, alkyl sulfoxides, and pyrrolidones. This is a method for extracting indonyl compounds using an extractant made of

The raw material to which the extraction method of the present invention is applied is a mixture whose main components are indoles and hydrocarbons, and the content of indoles may be 1% by weight or more, and the boiling point range is Preferably the boiling point at normal pressure is 270°C
It is as follows.

An example of a raw material that satisfies these conditions is an indole-containing fraction with a boiling point of 270°C or less obtained by distillation of coal tar. or contains two or more kinds, and hydrocarbons such as naphthalene, phenyl,
Methylnaphthalenes such as 1-methylnaphthalene and 2-methylnaphthalene, 1.5-dimethylnaphthalene and 2゜6
-1 of dimethylnaphthalenes such as dimethylnaphthalene
Contains one species or two or more species.

This indole-containing fraction is preferably subjected to deacidification and/or abasic treatment with an acid aqueous solution or an alkaline aqueous solution to remove acidic and/or basic substances such as phenols, pyridines, and quinolines contained in the raw materials. It is better to remove the components.

In addition, an indole-containing fraction obtained by distillation of coal tar or a treated product obtained by deacidifying and/or debasing it is reacted with a caustic alkali such as potassium hydroxide under heating conditions. It is also possible to hydrolyze the generated indole alkali and use the crude indoles obtained as 4'l as a raw material.

In addition, when using this crude indole as a raw material, it is recommended to separate and remove water, pitch, sludge, etc. in advance. By deacidifying and/or 1B2 J2 crystallizing the raw materials, it is possible to prevent the acidic or basic components from being entrained with the indoles during extraction with polar solvents, thereby facilitating the subsequent purification process. can be carried out. In addition, by performing sludge removal treatment, etc., problems such as unclear interfaces and line blockages can be prevented from occurring.

The boiling point obtained by distillation of the above coal tar is 235~
The indole-containing fraction (A) below 268°C and the indole potash are hydrolyzed (removed crude indoles (
Regarding B), an example of its composition (weight %) is shown.

Ingredients (A) (B
)2-Methylnaphthalene 43.4 2.11-Methylnaphthalene 14.8 1.2Dimethylnaphthalenes 18.6 1.4Indole 3.
8 81.0 Methylindoles 0.7 11.
3 Others 18.7 3.0 In addition to the above-mentioned indole-containing fraction obtained by distillation of coal tar, raw materials to which the method of the present invention is applied include, for example, synthetic indoles and waste indoles. etc,
Any product containing indoles and hydrocarbons may be used, but in this case, except for those that are separated and removed by distillation, they are extracted with a polar solvent. It is desirable to separate and remove as much as possible in advance.

In addition, in the method of the present invention, the extractant is one or more organic solvents selected from a group of organic solvents consisting of amines, alkyl sulfoxides, and pyrrolidones.
An extractant prepared by mixing 1 to 25 parts by weight of water with respect to 0.00 parts by weight is used. Suitable organic solvents include boiling points,
In terms of solvency and selectivity, amines include monoethanolamine, alkyl sulfoxides include dimethyl sulfoxide, and pyrrolidones include 2-pyrrolidone.

These organic solvents contain 1 to 25 parts, preferably 5 parts, within the range of their solubility, per 100 parts of organic solvent.
Add ~20 tons of water to make an extractant. By adding water to an organic solvent, the solubility for indole decreases slightly, but the solubility for hydrocarbons decreases significantly.
The selectivity of indole extraction is significantly improved. For this reason,
By slightly increasing the amount of extractant used to compensate for the decrease in solubility, it is possible to obtain high-purity indoles at a high recovery rate even with a small number of extraction stages. Even if it is difficult to form a separation layer between hydrogen and hydrogen, the use of a water-containing extractant makes it possible to separate into two phases and extract indoles. If the amount of water added is less than 1 layer, the effect of improving selectivity will be small;
If the amount is more than 0, the solubility of the indoles becomes too low to be practical.

In addition, as an extraction agent, 1 to 25 parts by weight of water is used per 100 parts by weight of one or more organic solvents selected from the group consisting of the above-mentioned amines, alkyl sulfoxides, and pyrrolidones. and one or two non-polar solvents selected from the group consisting of alkanes and cycloalkanes having 15 to 10 carbon atoms.
It is more efficient to extract indoles by using the above-mentioned non-essential solvent as a second extractant for extracting hydrocarbons and using these two types of extractants in combination.

The above-mentioned non-polar solvent exhibits high dissolving power for hydrocarbons, especially aromatic hydrocarbons, which are extracted into the water-mixed solvent phase when indoles are extracted from the water-mixed solvent. In addition to removing the hydrocarbons from the water-mixed solvent phase, it also facilitates phase separation from the water-mixed solvent phase during extraction. In general, its boiling point is quite different from the boiling point of the hydrocarbons in the raw material, so it is easy to recover and reuse.

Examples of such alkanes and cycloalkanes having 5 to 10 carbon atoms include n-pentane, 1so-
Mention may be made of pentane, n-hexane, n-hebutane, n-octane, 1so-octane, cyclopentane, cyclohexane, methylcyclohexane, petroleum ether, petroleum benzine or mixtures thereof.

Various types of extraction equipment can be used as the extraction means used in carrying out the extraction method of the present invention, but in order to extract indoles with low hydrocarbon content rd at a high recovery rate Preferably, it is a multi-stage extraction device that performs extraction in multiple stages, and specifically, a base type extraction device such as a packed column, a perforated plate column, a baffle column, a stirring type extraction column, a pulsating type extraction column, or a mixer/settler type. Batch-type extraction devices such as extraction devices can be mentioned.

The method of operation of these extractors is preferably such that fresh extractant of opposite polarity to the liquid being withdrawn from the withdrawal line is charged and contacted at a location close to the withdrawal line;
By doing this, the transfer of hydrocarbons and non-polar solvents in the raw material 1 to the extractant made of a water-mixed solvent is suppressed to a minimum, and the indoles in the raw material are effectively extracted. Indoles in the raw materials can be extracted with good recovery and selectivity.

In addition, in the extraction method of the present invention, for example, coal tar containing 35% by weight of 2-methylnaphthalene, 20% by weight of 1-methylnaphthalene, 25% by weight of dimedylnaphthalenes, and 5% by weight of indole is used as a raw material. When using distillate, various polar solvents, water and n-hexane,
The indole distribution coefficient (K) is expressed as the ratio of the concentration of indoles transferred to the hydrocarbons and non-polar solvent side in the raw material and the concentration of indoles transferred to the water-mixed solvent side.
Table 1 shows the selectivity (S) represented by the ratio of the distribution coefficient of ND and 2-methylnaphthalene (K), which is a typical impurity, to the distribution coefficient of indoles (-8N).

As is clear from the results in Table 1, the selectivity of indoles tends to improve with the addition of water, the use of non-polar solvents, and an increase in the amount of crystals used. Although it varies depending on the composition of the raw materials and the type of water-mixed solvent used as the extractant, when only a water-mixed solvent is used, the ratio of raw material: extractant is about 1:0.1 to 0.5. When using a crystal mixture solvent and a non-polar solvent together, the ratio of raw materials: water mixture solvent: non-polar solvent is often 1:0.1 to 0.5.
: About 0.3 to 1.5 is sufficient.

Further, in the extraction method of the present invention, the operating conditions of the extraction device may be such that the extraction temperature is from room temperature to about 70°C;
The number of theoretical plates may be about 5 to 10.

In this extraction process, the indoles are extracted from the raw materials and recovered from the aqueous mixed solvent phase containing 1q of indoles. First, the water is expelled from the water mixed solvent by distillation, and then the organic solvent is removed. to recover.

At this time, the illuminating surface operation can be performed smoothly by performing dehydration heat surface using an azeotropic dehydrating agent such as benzene or xylene.

The indole fraction recovered by surface removal of the organic solvent is subjected to precision thermal processing to obtain high purity indoles such as indole and methyl indole. In addition, the recovered organic solvent is recycled and used, and if impurities from the raw materials accumulate in the solvent, part or all of it can be removed by distillation, extraction, etc.
After that, use the circulation.

On the other hand, the hydrocarbons in the raw material extracted in this extraction step are subjected to precision thermal processing, if necessary, and recovered as hydrocarbons that do not contain indoles. Boiling point 230 as a raw material
When a coal tar fraction of ~270°C is used, methylnaphthalenes such as methylnaphthalene and dimethylnaphthalene can be recovered.

In addition, when a non-polar solvent consisting of alkanes and cycloalkanes is used as the second extractant, the non-polar solvent phase is separated by distillation, and the recovered non-polar solvent is recycled and used as a raw material. The hydrocarbons contained therein can be recovered as indole-free hydrocarbons in the same manner as in the above case.

〔Example〕

Hereinafter, the method of the present invention will be specifically explained according to Examples and Comparative Examples.

Example Six extractors are used as an extraction device, and a coal tar reduction with a boiling point of 240 to 265 ° C. treated with sulfuric acid and caustic soda and having the composition shown in Table 2 is used as a raw material from the charging port of the third extractor. In addition, a mixed solvent of monoethanolamine and water with a ratio of 25:2.5 as the first extractant is charged from the charging port of the first extractor located at one end, and the first extractor → It flows in the order of second extractor → third extractor → fourth extractor → fifth extractor → sixth extractor, and further, n-hexane is extracted as the second extractant of the non-polar solvent in the sixth extraction at the other end. It is charged from the charging port of the container and flows in the order of 6th extractor → 5th extractor → 4th extractor → 3rd extractor → 2nd extractor → 1st extractor. The extractants are each extracted from one outlet of the extractor on the opposite side from the charging side extractor while being in contact with each other in each extractor, and at this time, each is charged to the third extractor. The indoles in the raw material are dissolved in the first extractant and extracted from the extraction port together with the first extractant, and the hydrocarbons in the raw material are dissolved in the second extractant. Then, it was extracted from the extraction port together with this second extractant.

For 100 parts of coal tar fraction charged, 27.5 parts of the first extractant was charged, and 50 parts of the second extractant were charged, and indoles were extracted from each outlet. 27.3 iu of the first extractant extracted from the coal tar and 147.7 fflυ of the second extractant that dissolved the hydrocarbons in the coal tar surface were extracted.

The compositions of the first extractant and second extractant extracted from each outlet are as shown in Table 2, and the recovery rate of indole is 82.
The indole concentration (selectivity) in the first extractant was 82.8 ffi%.

Comparative Example The same extraction equipment as in the above example was used, but unlike in the above example, 25 m2 parts of monoethanolamine was used as the first extractant, and 50 m2 parts of the second extractant was charged. Ta. From each outlet, 29.4 weight parts of the first extractant which extracted indoles and 138.8 weight parts of the 12 extractant which dissolved the hydrocarbons in the coal tar surface were extracted. The compositions of the first extractant and second extractant extracted from each outlet are as shown in Table 2, and the recovery rate of indole was 943%, and the indole in the first extractant was The concentration (selectivity) was 74.7% by weight.

〔Effect of the invention〕

According to the method of the present invention, the selectivity of indoles is increased and high purity indoles can be easily produced by a simple distillation operation.

Patent applicant Nippon Steel Chemical Co., Ltd. Agent
Patent attorney: Masao Naruse, agent Patent attorney: Satoshi Nakamura Proceedings R1i Masayama (self-motivated) December 14, 1980 Commissioner of the Patent Office Manabu Shiga 1, Indication of the case 1982 Patent Application No. 172466 2 , Invention name Extraction method 3 of indoles, Relationship with the case of the person making the amendment Patent applicant address 5-13-16 Ginza, Chuo-ku, Tokyo Name (6
64) Nippon Steel Chemical Co., Ltd. 4, Agent 105 Telephone 03 (433) 442
05, Date of amendment order Voluntary amendment 6, Number of inventions not increased by amendment 7, Contents of amendment in "Detailed explanation of the invention" column of the specification subject to amendment (11) Page 4, line 14 of the specification and ``r270'c or less'' written in lines 16-17 respectively'' to ``200-3
00℃”.

(2) "Polar solvent" described in the last line of page 5 of the specification is corrected to "water-containing extractant."

(3) Delete "hereinafter" written on page 6, line 7 of the specification.

(4) The statement on page 7, line 4 of the specification is amended as follows.

“Items that cannot be separated and removed, and can be used as a water-containing extractant.”
(5) The statement "For extraction...a multi-stage extraction device" written in lines 2 and 3 of page 10 of the specification is amended as follows.

"In order to extract, it is preferable to use a multistage extraction device that performs extraction in multiple stages." (6) "Batch type" stated in line 6 of page 10 of the specification is corrected to "seed type" .

(7) The statement "to touch the extraction line" written in lines 8 to 10 on page 10 of the specification is corrected as follows.

``Charge the M2 extractant from a position close to the extraction port of the first extract phase.

Charge the first extractant from a position close to the outlet of the second extractant phase so that both phases come into contact with each other. Delete "Solvent".

(9) The description in the 1st to 4th lines of page 11 of the book is amended as follows.

When one-stage extraction was performed using a coal tar fraction with various organic solvents, water, and n-hexane, 12
"Concentration of indole dissolved in the extractant side and amount of indole dissolved in the first extractant side.""coefficient" is supplemented with "indole partition coefficient".

(11) "Selectivity (S)" written on page 11, line 8 of the Meiji 1ffl book is corrected to "selectivity (β)".

(12) Correct "selectivity J" described in page 11, line 11 of Ming #1 as "selectivity".

(13) ``5~
Correct 711i as "about 10j to about r3~10".

(14) "Aqueous mixed solvent" described in page 12, line 6 of the specification is corrected to "water-containing extractant."

(15) "An extractor is used" written in page 13, line 14 of the specification is corrected as follows.

``A mixer/settler continuous extraction device for pears consisting of an extractor is used.'' amended as follows.

``The first extractant phase and the second extractant phase come into contact with each other in each extractor, and then are separated into two phases, each of which is sent to the extractor on the opposite side of the charging side extractor, and the final extractant phase is It is extracted from the extractor.

(17) [In the first extractant] described on page 15, lines 5 to 7 of the specification. ' shall be corrected as follows.

"The indole concentration in the extract obtained by removing water and organic solvent from the first extractant phase was 82.8%." (18) " in the first extract.'' is corrected as follows.

"The indole concentration in the extract obtained by removing water and organic solvent from the first extractant phase was 74.7% by weight." (19) *i: rSJ written in Jun is corrected to "β".

that's all

Claims (1)

[Claims] (1) In extracting indoles from a mixture containing indoles and hydrocarbons as main components, a group consisting of amines, alkyl sulfoxides, and pyrrolidones is used as an extractant for indoles. 1 selected from organic solvents
1 to 25 parts per 100 parts by weight of a species or two or more organic solvents
A method for extracting indoles, characterized by using an extraction agent mixed with parts by weight of water. (2) A mixture whose main components are indoles and hydrocarbons is obtained by distilling coal tar and has a boiling point of 270°C.
The method for extracting indoles according to claim 1, which is obtained by removing the following coal tar fraction containing indoles or acidic and/or basic components from this fraction. <3) Claim 1 in which the organic solvent is monoethanolamine, dimethyl sulfoxide, or 2-pyrrolidone
2. The method for extracting indoles according to paragraph 2 or paragraph 2. (4) One or two selected from a group of organic solvents consisting of amines, alkyl sulfoxides, and pyrrolidones.
A first extractant prepared by mixing 1 to 25 parts by weight of water to 100 parts by weight of an organic solvent of at least 1 species, and a nonpolar solvent selected from a group of alkanes and cycloalkanes having 5 to 10 carbon atoms. 4. The method for extracting indoles according to any one of claims 1 to 3, which uses a second extractant comprising one or more nonpolar solvents.