JPS6150966A - Method of extracting indole - Google Patents

Abstract

PURPOSE:To extract selectively indoles from a mixture comprising indoles and hydrocarbons as main components without causing problems such as corrosion of device, etc., by using a polar solvent having a boiling point of >= a specific temperature at normal pressure as an extractant. CONSTITUTION:In extracting indoles from a mixture comprising indoles and hydrocarbons, such as a fraction 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, a polar solvent having >=270 deg.C boiling point at normal pressure, preferably sulfolane, etc., such as the polar solvent containing especially <=20wt% water, is used as an extractant, and, more preferably both the extractant as the first extractant and a nonpolar solvent selected from 5-10C alkanes and cycloalkanes as the second extractant are used to raise recovery ratio of the aimed compound and selectivity for it without requiring immense energy.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for extracting indoles, and more specifically to a method for selectively extracting indoles from a mixture whose main components are indoles and hydrocarbons. Regarding the extraction method for

[Conventional technology]

Methods for recovering indoles from a mixture whose main components are indoles and hydrocarbons include a method in which indoles are separated into their alkali 4H form using alkali hydroxide, and then hydrolyzed. ethanolamine,
Indoles are extracted with a polar solvent such as dimethyl sulfoxide or pyrrolidone, and this extract is washed with an alkane or cycloalkane that has a boiling point different from that of the hydrocarbons in the raw material to remove the accompanying hydrocarbons, and then distilled. There is a known method for recovering indoles by
135862 and Japanese Unexamined Patent Publication No. 59-62.565).

[Problems that Brahma attempts to solve]

However, the former method, J5, has problems such as corrosion of the equipment due to the use of alkali hydroxide with a high temperature of 11 degrees Celsius, and the latter method has problems such as corrosion of the indoles. Although it is necessary to recycle polar solvents to increase the amount of water used, there is a problem in that a large amount of energy is required to recover the polar solvents.

Means and operation for solving problem C] The present invention was devised in view of this point of view, and when extracting indoles from a mixture whose main components are indoles and hydrocarbons, This method extracts indoles using a polar solvent with a boiling point higher than 270"C as an extractant.

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 at least 1m2%, and within a range of >71 points. The boiling point at normal pressure is preferably 27
The temperature is below 0°C.

Examples of raw materials that satisfy these conditions include indoles-containing fractions with a boiling point of 270°C or less obtained by distillation of coal tar, and indoles such as alkylindoles such as indole, methylindole, and dimethylindole. It also contains one or more kinds of hydrocarbons, such as naphthalene, phenyl,
-Methylnaphthalenes such as methylnaphthalene and 2-methylnaphthalene, 1.5-dimethylnaphthalene and 2゜6-
Contains one or more dimethylnaphthalenes such as dimethylnaphthalene.

This indole-containing fraction is preferably deoxidized and/or deoxidized using an acid aqueous solution or an alkaline aqueous solution. It is best to use beef that removes stone-like ingredients.

In addition, an indole-containing fraction obtained by distillation of coal tar, or a treated product obtained by deacidifying and/or debasing the same, is reacted with a caustic alkali such as potassium hydroxide under heating conditions. It is obtained by hydrolyzing the indole alkali produced.

Crude indoles can also be used as raw materials.

In addition, when using this crude indole as a raw material, it is preferable to separate and remove water, pitch, sludge, etc. in advance. By deacidifying and/or debasing the raw material, the acidic or stone-like components mentioned above are prevented from being accompanied by the indoles during extraction with a polar solvent, thereby facilitating the subsequent information processing. can be carried out. In addition, by performing sludge removal treatment, etc., it is possible to prevent problems such as unclear interfaces and line blockages from occurring.

The above coal tar distillation cost J2 and 19? 111
Indoles-containing fraction (A,
) and crude indoles (B) obtained by hydrolyzing an indole alkali, no examples of the composition (wt%) are given.

, component (A) (B
)2-Methylnaphthalene 43.4. 2.11-Methylnaphthalene 14.8 1.2 Dimethylnaphthalenes 18.6. 1.4 indole 3
．． 8 81.0 Methylindoles 0.7 11
．． 3 Others 18.7. 3.0 Furthermore,
Raw materials to which the method of the present invention is applied include, in addition to the Bundol-containing fraction obtained by distilling coal tar as described above, for example, synthetic indoles, waste indoles, etc.
Any indole may be used as long as it contains hydrocarbons, but even in this case, except for those that can be removed by distillation, those that can be extracted with a polar solvent can be prepared in advance. It is desirable to separate and remove it.

Furthermore, the extraction agent used in the method of the present invention has a boiling point of 2 at normal pressure.
A polar solvent with a temperature higher than 70°C, preferably 280°C. Indoles in hydrocarbons are selectively extracted with polar solvents. If a polar solvent with a temperature of 270° C. or lower is used, separation by distillation becomes difficult, or it becomes necessary to distill off the remaining extractant during distillation.

Examples of polar solvents used as extractants in the method of the present invention include sulfolane, which is well known as an extractant such as benzene, toluene, and xylene, glycerin esters such as glycericin acetate, triethylene glycol, and tetraethylene. Examples include ethylene glycols such as glycol.

Many of these polar solvents dissolve water, but the solubility jl! It is preferable to add water within a certain range to obtain an extraction agent. By adding water to a polar solvent, the solubility for indoles is slightly lowered, but the solubility for hydrocarbons is significantly lowered, and the selectivity for extraction of indoles is improved. Therefore, if a water-containing extractant is used by 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. In addition, even in cases where it is difficult to form a layer with hydrocarbons using only polar solvents, it is possible to separate into two phases and extract indoles by using a water-containing extractant that contains water. become.

Further, as an extractant, the above-mentioned polar solvent with a boiling point higher than 270° C. at normal pressure is used as a first extractant for extracting indoles,
In addition, one or two selected from a group of nonpolar solvents consisting of alkanes and cycloalkanes having 5 to 10 carbon atoms.
It is more effective if one or more non-polar solvents are used as the second extractant for extracting hydrocarbons, and these two extractants are used in combination to extract indoles.

The non-polar solvent exhibits high dissolving power for hydrocarbons, especially aromatic hydrocarbons, which are extracted in small amounts into the polar solvent phase when indoles are extracted with a polar solvent,
In addition to removing these hydrocarbons from the polar solvent phase, it facilitates phase separation from the polar solvent phase during extraction. Roughly,
Since its boiling point is significantly different from the boiling point of the hydrocarbons in the raw material, it is easy to recover and reuse.

Examples of such alkanes and cycloalkanes having 5 to 1 o 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 a high recovery rate with a low amount of hydrocarbons. It is preferable to use a multi-stage extraction apparatus that performs extraction in a multi-stage manner, and specifically, a base type extraction apparatus such as a packed column, perforated plate column, baffle column, stirring type extraction column, pulsation type extraction column, or a mixer cell. Batch-type extraction devices such as 1-R type extraction devices can be mentioned.

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

Further, in the extraction method of the present invention, for example, a coal tar fraction containing 35% by weight of 2-methylnaphthalene, 2011% by weight of 1-methylnaphthalene, 25% by weight of dimethylnaphthalenes, and 5% by weight of indole is used as a raw material. And each M! When polar solvents, water and n-hexane are used, the distribution of indoles is expressed as the ratio of the concentration of indoles transferred to the hydrocarbons and non-polar solvent side of the raw material and the concentration of indoles transferred to the polar solvent side. Coefficient (K)
INO.

and the typical impurity 2-methylnaphthalene distribution coefficient yjl(K) and the above indole distribution coefficient 2-)
The selectivity (S) indicated by the ratio of IN is as shown in Table 1.

As is clear from the results in Table 1, the selectivity of indoles improves by increasing the use of various solvents as extractants, by increasing the use of non-polar solvents, by increasing the use of non-polar solvents, and by adding water. The grade of the extractant charged into the extractor varies depending on the composition of the raw materials and the type of polar solvent used as the extractant, but when only polar solvents are used, 31: The ratio of extraction agent may be about 1 = 0.1 to 0.5, and when a polar solvent and a non-polar solvent are used together, the ratio of raw material bipolar solvent: non-polar solvent is i:o, i ~ 0 .5: About 0°3 to 1.5 is sufficient.In addition, in these cases,
The amount of water to be added is within the range of water solubility in polar solvents, usually 25% by weight or less in polar solvents,
Preferably it is 5 to 20%.

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 polar solvent phase containing the indoles and water added as necessary. First, the indoles are extracted from the polar solvent by distillation. This polar solvent is recovered by expelling water and water, and indoles such as indole and methyl indole are recovered by performing precision thermal processing on the recovered indole fraction.
The recovered polar solvent is recycled and used, and if impurities in the raw materials accumulate in the polar solvent due to this recycling, some or all of the impurities are purified by means such as distillation or extraction and then recycled.

On the other hand, the hydrocarbons in the raw material obtained in this extraction step are subjected to precision thermal heating, if necessary, and recovered as hydrocarbons that do not contain indoles. As a raw material, the boiling point is 230~
When a coal tar fraction at 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. The hydrocarbons in No. 14 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 explained in detail according to examples.

Six extractors are used as extractor 2, and a coal tar region 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 charged from the charging port of the third extractor. In addition, as the first extractant of the polar solvent, a mixture of triethylene glycol (boiling point 288°C) and water with a weight ratio of 50:10 was used as the first extractant, which was located at one end.
It is charged from the charging port of the extractor and flows in the order of the first extractor → second extractor → third extractor → fourth extractor → fifth extractor → sixth extractor. n- as the second extractant
Hexane is charged from the charging port of the sixth extractor on the other end side, and the sixth extractor → fifth extractor → fourth extractor → third extractor → second
The triethylene glycol and n-hexane are flowed in the order of the extractor → the first extractor, and the triethylene glycol and n-hexane are in contact with each other in each extractor, while flowing from the outlet of the extractor on the opposite side to the charging side extractor. At this time, the indoles in the raw materials are dissolved in triethylene glycol and are discharged together with the triethylene glycol from the outlet of the sixth extractor. In addition, the hydrocarbons in the raw material were dissolved in n-hexane and discharged together with this n-hexane from the outlet of the first extractor.

To 1 part of 1100ff of coal tar fraction, 60 parts by weight of the triethylene glycol/water mixture as the first extractant was charged, and 100 parts by weight of n-hexane as the second extractant were charged. The 66% triethylene glycol/aqueous phase from which indoles have been extracted is extracted from the actual outlet of the 6th extractor, and the hydrocarbons in the coal tar fraction are dissolved from the outlet of the 1st extractor. One portion of 194 double ω parts of the n-hexane phase was extracted.

The compositions of the triethylene glycol/aqueous phase and n-hexane phase extracted from each outlet are as shown in Table 2.
Moreover, the recovery rate of indole was 91%.

Furthermore, xylene was added to the above triethylene glycol/water phase to perform hot surface dehydration, followed by precise thermal heating to achieve a purity of 99%.
．． For duplication, 4.4% of indole was obtained. In this case, the recovery rate from the raw coal tar fraction was 83%.

〔Effect of the invention〕

According to the method of the present invention, not only can the recovery rate and selectivity of indoles be increased, but also the energy required for heating can be significantly reduced.

Patent applicant Nippon Steel Chemical Co., Ltd. Agent
Patent attorney Katsuhiro Naruse, agent Patent attorney Satoshi Nakamura (author of the procedure) December 14, 1980 Manabu Shiga, Commissioner of the Japan Patent Office 1, Display of $ 1980 Patent Application No. 172465 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, No number of inventions increased by amendment 7, [Detailed explanation of the invention] column 8 of the specification subject to amendment, Contents of amendment Contents of amendment (1) Specification No. 5 "Heating with an alkali" written on the 11th line of the page is corrected to "heating with an alkali."

(2) Delete "hereinafter" written on page 6, line 4 of the specification.

(3) "Indoles" written on page 6, line 18 of the specification is amended from 1 to "indoles."

(4) In the first line of page 7 of the specification, [other than what is possible] is replaced with "what is not possible, and
Correct to.

(5) The statement "For extraction...a multi-stage extraction device" stated on page 9, lines 17-18 of the specification shall be corrected as follows.

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

(7) The statement "to contact the extraction line" written in lines 3 to 5 on page 10 of the specification is corrected as follows.

"The non-polar solvent is charged from a position close to the outlet for the polar solvent phase, and the polar solvent is charged from a position close to the outlet for the non-polar solvent phase so that both phases come into contact with each other. 1 (8) Specification Delete "Non-polar solvent" written on page 10, line 8.

(9) The ``concentration of indoles using...'' stated on page 10, lines 17 to 19 of the specification is corrected as follows.

"When one-stage extraction is carried out using The ``indole partition coefficient'' described in the second and third rows is the ``indole partition coefficient.''
and correct it.

(11) "Selectivity (S)" written on page 11, line 4 of the Meiji 1fl book is corrected to "selectivity (β)".

(12) The "selectivity" described in Book 10 of Meiji Meiji, page 11, line 9 is corrected by 1 to "selectivity".

(13) “5-1” written in Mei 11, page 12, line 3
"about 3 o" is corrected to "about 3 to 10".

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

``A continuous extraction device of the Michili-settler type consisting of an extractor was used.'' , &issued,'' is corrected as follows.

After these triethylene glycol phase and n-hexane phase come into contact with each other in each extractor, they are separated into two phases, each of which is sent to the extractor on the opposite side from the charging side extractor and the final phase is extracted. Extracted from extractor. (16) "S" written in the rightmost column of Table 1 on page 16 of the specification is amended to "β".

that's all -Y21-

Claims (4)

[Claims] (1) In extracting indoles from a mixture whose main components are indoles and hydrocarbons, the indoles are extracted using a polar solvent with a boiling point higher than 270°C at normal pressure as an extractant. Extraction method of indoles. (2) The method for extracting indoles according to claim 1, wherein the polar solvent contains 20% by weight or less of water. (3) Claim 1 or 2, wherein the extractant is one or more polar solvents selected from the group of polar solvents consisting of sulfolane, glycericin acetate, triethylene glycol, and tetraethylene glycol. Extraction method of indoles described in section. (4) A mixture whose main components are indoles and hydrocarbons is obtained by distilling coal tar and has a boiling point of 270°C.
Claims 1 to 3 are obtained by removing acidic and/or basic components from the following fraction or this fraction:
A method for extracting indoles as described in any of paragraphs. (4) When extracting indoles from a mixture whose main components are indoles and hydrocarbons, a polar solvent with a boiling point higher than 270°C at normal pressure is used as the first extractant, and a carbon number of 5 to 10 Any one of claims 1 to 3, wherein one or more non-polar solvents selected from a group of non-polar solvents consisting of alkanes and cycloalkanes are used as the second extractant. The method for extracting indoles described in .