CN110734400B - Process for producing isoquinoline and process for separating isoquinoline - Google Patents
Process for producing isoquinoline and process for separating isoquinoline Download PDFInfo
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- CN110734400B CN110734400B CN201811474150.0A CN201811474150A CN110734400B CN 110734400 B CN110734400 B CN 110734400B CN 201811474150 A CN201811474150 A CN 201811474150A CN 110734400 B CN110734400 B CN 110734400B
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- C07D217/02—Heterocyclic compounds containing isoquinoline or hydrogenated isoquinoline ring systems with only hydrogen atoms or radicals containing only carbon and hydrogen atoms, directly attached to carbon atoms of the nitrogen-containing ring; Alkylene-bis-isoquinolines
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Abstract
The present disclosure provides a method of preparing isoquinoline with significantly reduced phenols in high yield. The method is a method for preparing isoquinoline by distilling and separating isoquinoline from an isoquinoline mixture containing isoquinoline and impurities. The preparation method carries out distillation separation of isoquinoline by carrying out continuous reduced pressure distillation on the isoquinoline mixture. The isoquinoline mixture may be a mixture comprising isoquinoline derived from coal tar.
Description
Technical Field
The present disclosure relates to techniques for distillative separation of isoquinoline from mixtures containing isoquinoline and impurities.
Background
Isoquinoline is a compound used as an industrial raw material, and is used as a medical raw material, a curing agent in a polyimide production process, and the like. As isoquinoline used in industry, it is desired to have high yield, high purity, and low cost. Isoquinoline contains different impurities according to the raw materials or preparation procedures. For example, the impurities may contain a phenol as an acidic substance in addition to a basic substance such as quinoline, 2-methylquinoline, or 8-methylquinoline which is in the same family as isoquinoline.
As a method for obtaining isoquinoline, a cyclization synthesis method is known, and from the viewpoint of cost, a method is generally industrially employed in which crude quinoline obtained by extracting a distillation fraction of coal tar with a mineral acid such as sulfuric acid and then neutralizing the distillation fraction with a base, is used as a raw material, and is produced through a series of distillation steps (1) to (4) below. The steps (1) to (4) are a step of extracting quinoline first and then obtaining isoquinoline from the residual liquid after extraction of quinoline.
(1) And a step of dehydrating and distilling the crude quinoline by a batch method or a continuous method to remove water and pyridine bases having a boiling point lower than that of quinoline, thereby producing a dehydrated crude quinoline.
(2) And a step of distilling the dehydrated crude quinoline by a batch method or a continuous method to produce quinoline.
(3) And a step of distilling the residue after extraction of quinoline in a batch to produce an isoquinoline fraction.
(4) And a step of distilling the isoquinoline fraction in a batch to produce isoquinoline.
The production of quinoline or isoquinoline by distillation may be carried out under normal pressure, but when it is carried out under normal pressure, the temperature inside the column may become high, and thus, decomposition, polymerization, or the like may occur, leading to deterioration in quality. Therefore, the steps (2), (3) and (4) are usually performed under reduced pressure.
In terms of quality of the isoquinoline, not only purity is a concern, but also the absence of phenols is preferred. This is because phenols are foreign substances having completely different properties from the use of isoquinoline. However, the above-mentioned coal tar-derived isoquinoline contains phenols as impurities. Accordingly, it is desirable to provide a technique capable of highly separating phenols.
A method for producing an isoquinoline having reduced phenol by distillation is proposed in the following patent document 1. In this method, crude quinoline is first distilled under reduced pressure to distill off quinoline. The raffinate containing isoquinoline was then distilled batchwise at atmospheric pressure and the phenols removed as a front cut. Thereafter, batch distillation was performed again under reduced pressure to prepare isoquinoline. Patent document 1 below discloses that isoquinoline having a purity of 96.47% and containing no phenols (0.00%) was obtained at a recovery rate of 87.4% from a quinoline distillation residue containing 39.53% of isoquinoline and 1.49% of phenols.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open No. 2004-107254
Disclosure of Invention
However, the method of the above-mentioned patent document 1 has the following 2 disadvantages: first, the distillation under reduced pressure is required in the process of atmospheric distillation, which makes the process complicated; secondly, the yield is low because isoquinoline is distilled off together with phenols.
The purpose of the present disclosure is to provide a method for producing isoquinoline in high yield with significantly reduced phenols.
One aspect of the present disclosure relates to a method for preparing isoquinoline by distillatively separating isoquinoline from an isoquinoline mixture containing isoquinoline and impurities, the method performing the distillative separation of isoquinoline by subjecting the isoquinoline mixture to a continuous reduced pressure distillation.
By the method for producing isoquinoline, isoquinoline in which phenols are significantly reduced can be produced in high yield. It is known that, when isoquinoline is produced by distillation under reduced pressure, isoquinoline is distilled off together with phenols by azeotropy. On the other hand, although phenols can be removed as a front end fraction in atmospheric distillation, isoquinoline is deeply colored due to a high temperature in the distillation column. Although the reason has not been clarified, the above-mentioned production method by continuous vacuum distillation is indeed capable of remarkably reducing phenols and at the same time suppressing coloring.
The isoquinoline of one aspect of the present disclosure may comprise a mixture of isoquinolines derived from coal tar. The coal tar derived isoquinoline mixture contains phenols as impurities. Isoquinoline with significantly reduced phenols can be prepared from the isoquinoline mixture using the preparation methods described above.
The isoquinoline mixture may include a distillation residue obtained by removing a quinoline fraction from a quinoline-containing fraction obtained by at least a distillation step using coal tar as a raw material by distillation under reduced pressure. The isoquinoline mixture may include an isoquinoline fraction obtained by distilling a quinoline-containing fraction obtained by at least a distillation step on coal tar as a raw material under reduced pressure. The isoquinoline mixture may be a residue obtained by purifying isoquinoline.
Further, in one aspect of the present disclosure, the distillation pressure in the continuous reduced pressure distillation may be 400mmHg or less. The method for producing isoquinoline enables to produce isoquinoline in a high yield, which is remarkably suppressed in phenols and suppressed in coloration.
Another aspect of the present disclosure relates to a method for separating isoquinoline, which is a method for separating isoquinoline by distillation from a mixture of isoquinoline containing coal tar-derived isoquinoline and impurities by subjecting the mixture of isoquinoline to continuous vacuum distillation. The method for separating isoquinoline enables isoquinoline, in which the amount of phenols as impurities is significantly reduced, to be separated from an isoquinoline mixture in a high yield.
Drawings
FIG. 1 is a diagram for explaining an example of a method for producing an isoquinoline mixture.
FIG. 2 is a diagram for explaining an example of a method for producing an isoquinoline mixture.
FIG. 3 is a diagram for explaining an example of a method for producing an isoquinoline mixture.
FIG. 4 is a diagram for explaining an example of a method for producing an isoquinoline mixture.
FIG. 5 is a diagram for explaining an example of a method for producing an isoquinoline mixture.
FIG. 6 is a diagram for explaining an example of a method for producing isoquinoline.
FIG. 7 is a diagram for explaining an example of a method for producing isoquinoline.
Description of reference numerals
10, 8230and a distillation tower; 10a 8230, column 1; 10b 8230a column 2; 11\8230anda condenser; 12 \ 8230and a heater;
20, 8230, a continuous vacuum distillation tower; 21 8230a distillation column
Detailed Description
The method for distillative separation of isoquinoline from an isoquinoline mixture is described below with reference to the accompanying drawings.
<1. Isoquinoline mixture >
The isoquinoline mixture is a mixture formed by mixing isoquinoline and impurities. The impurities mentioned herein mean substances other than isoquinoline. As the impurities, for example, quinoline or phenols may be contained.
The method for preparing the isoquinoline mixture is not particularly limited. As the isoquinoline mixture, for example, a coal tar-derived isoquinoline mixture, that is, an isoquinoline-containing mixture produced using coal tar as a raw material, can be used. Specifically, as the isoquinoline mixture, a residue after separation of quinoline from coal tar-derived sulfuric acid process crude quinoline (hereinafter referred to as crude quinoline) obtained by extraction of a distillation fraction of coal tar with a mineral acid such as sulfuric acid and neutralization with a base can be used. In other words, the crude quinoline contains a fraction obtained by at least a distillation step using coal tar as a raw material, and the fraction contains at least quinoline and isoquinoline. The isoquinoline mixture includes not only a mixture obtained by 1 distillation operation but also a mixture obtained by a plurality of distillation operations. The isoquinoline mixture may be a mixture of the fraction containing isoquinoline obtained by distillation and another substance. The method for separating quinoline from crude quinoline is not particularly limited. Further, although the separation of quinoline is not always necessary, the content of quinoline present as an impurity in the finally obtained isoquinoline can be reduced by separating quinoline in advance.
The isoquinoline-containing distillation fraction or raffinate, prepared from crude quinoline, may be used as a mixture of isoquinolines in various compositions, concentrations, and qualities. Further, a residual liquid obtained by separating quinoline from crude quinoline and purifying the isoquinoline by a conventional technique may be used as an isoquinoline mixture.
The following is a preparation example of an isoquinoline mixture used in the distillation separation of isoquinoline.
(i) Preparation example 1
As shown in FIG. 1, as the isoquinoline mixture, a distillation residue obtained by subjecting dehydrated crude quinoline to batch distillation under reduced pressure to remove a quinoline fraction may be used. The dehydrated crude quinoline is obtained by dehydrating and distilling crude quinoline obtained by a sulfuric acid method by a batch method or a continuous method to remove water and pyridine bases having a boiling point lower than that of quinoline. The dehydrated crude quinoline corresponds to a fraction containing isoquinoline obtained by distillation of coal tar. The distillation residue contains low concentrations of quinoline, isoquinoline, 2-methylquinoline, 8-methylquinoline, and high boiling methylquinolines. In fig. 1, reference numeral 10 denotes a distillation column, reference numeral 11 denotes a condenser, and reference numeral 12 denotes a heater. The same notation is used in other figures. The pressure reduction device is not shown in fig. 1. The other figures likewise do not show a pressure relief device.
(ii) Preparation example 2
As shown in FIG. 2, as the isoquinoline mixture, a distillation residue obtained by continuously distilling dehydrated crude quinoline under reduced pressure to remove a quinoline fraction may be used. The distillation residue contains low concentrations of quinoline, isoquinoline, 2-methylquinoline, 8-methylquinoline, and high boiling methylquinolines.
(iii) Preparation example 3
Fig. 3 shows an example of the preparation of an isoquinoline mixture by continuous vacuum distillation. Quinoline is separated by distillation using the 1 st column 10a of the 1 st stage, and quinoline in the raffinate is removed together with isoquinoline using the 2 nd column 10b of the 2 nd stage, whereby a distilled raffinate with an extremely small amount of quinoline can be obtained. This residual solution is an example of an isoquinoline mixture.
(iv) Preparation example 4
Fig. 4 shows an example of an isoquinoline mixture obtained by batch-wise vacuum distillation. After distilling the dehydrated crude quinoline to obtain quinoline, the distillation is further continued to obtain a crude isoquinoline fraction having a concentration of 60 to 85% and containing, as impurities, phenols in addition to quinoline, 2-methylquinoline and the like. This crude isoquinoline fraction is an example of an isoquinoline mixture.
(v) Preparation example 5
Fig. 5 shows an example of an isoquinoline mixture obtained by continuous vacuum distillation. In this example, quinoline was obtained as the product and crude isoquinoline was obtained as a fraction. The crude isoquinoline fraction is an example of an isoquinoline mixture. Although the crude isoquinoline fraction varies depending on the distillation conditions, the crude isoquinoline fraction obtained herein has a concentration of 60 to 85% and contains phenols as impurities in addition to quinoline, 2-methylquinoline and the like.
(vi) Others
The continuous vacuum distillation of the crude isoquinoline may be carried out in a semi-continuous manner. For example, crude isoquinoline may be intermittently fed to the distillation column, or a raffinate may also be intermittently withdrawn from the distillation column.
In addition, the residual liquid after purifying isoquinoline from the crude isoquinoline fraction may be used as the isoquinoline mixture.
In addition, compared with the distillation residue of fig. 1 to 3, isoquinoline in the isoquinoline mixture (crude isoquinoline fraction) obtained from fig. 4 and 5 is further concentrated, and therefore, a high-purity isoquinoline product can be obtained even if purification of isoquinoline is performed by batch distillation on the isoquinoline mixture obtained from fig. 4 and 5. For example, even when the crude isoquinoline fraction of fig. 4 and 5 is further distilled under reduced pressure in a batch manner by a conventional method, an isoquinoline product having a purity of about 95% can be obtained.
However, in the method for producing isoquinoline of the present disclosure, not only the isoquinoline mixture of fig. 4 and 5, but also crude isoquinoline having a low concentration of fig. 1 to 3 as a raw material can be obtained as a high-purity isoquinoline product containing almost no phenols by continuous vacuum distillation.
<2 > production of isoquinoline by continuous vacuum distillation of isoquinoline mixture >
Fig. 6 is a diagram showing a preferable preparation example in the case where the quinoline concentration in the isoquinoline mixture as the raw material is low. As this isoquinoline mixture, for example, the distillation residue obtained in fig. 3 may be used. Of course, the separation operation can also be carried out using an isoquinoline mixture having a high quinoline concentration. In the case shown in FIG. 6, isoquinoline of high purity can be obtained from the top of the continuous vacuum distillation column 20.
The conditions of the continuous vacuum distillation can be arbitrarily set according to the performance of the distillation column or the quality of the crude quinoline. Among them, for example, a distillation column having a theoretical plate number of 30 or more can be used, and the distillation pressure can be 400mmHg (53.33 kPa) or less; the reflux ratio may be in the range of 5 to 60.
Fig. 7 is a diagram showing a preferable preparation example in the case where the concentration of quinoline in the isoquinoline mixture as the raw material is high. As the isoquinoline mixture, for example, the isoquinoline mixtures obtained in fig. 1, fig. 2, fig. 4, and fig. 5 can be used. In the case shown in fig. 7, it is possible to distill off quinoline and isoquinoline from the top of the continuous vacuum distillation column 21 and obtain isoquinoline from the vicinity of the middle stage of the distillation column.
The conditions of the continuous vacuum distillation can be arbitrarily set according to the performance of the distillation column or the quality of the crude quinoline. Among them, for example, a distillation column having a theoretical plate number of 60 stages or more can be used, the distillation pressure may be 400mmHg (53.33 kPa) or less, and the reflux ratio may be in the range of 5 to 200. In this case, the influence of the quinoline content on the reflux ratio is large.
[ example 1]
Isoquinoline having reduced phenols was produced by continuous vacuum distillation using the vacuum distillation apparatus of fig. 6 under the following distillation conditions. The results are shown in Table 1.
The distillation conditions were as follows:
a distillation column: the theoretical plate number is 80 sections; the charging layer section: paragraph 40 from the top; pressure at the top of the column: 100mmHg (13.33 kPa); reflux ratio: 35
[ TABLE 1]
[ example 2]
Continuous vacuum distillation was performed under the same conditions as in example 1 except that the overhead pressure was set to 400mmHg, thereby producing isoquinoline reduced in phenols.
Further, the distillation conditions were the same as in example 1 including the isoquinoline mixture used, except that the overhead pressure was set to 400mmHg. The results of the continuous vacuum distillation are shown in Table 2.
[ TABLE 2]
[ reference example 1]
Continuous atmospheric distillation was performed in the same manner as in example 1, except that the column top pressure was set to normal pressure. The results are shown in Table 3.
[ TABLE 3 ]
[ reference example 2]
The same raw materials as in example 1 were used for batch distillation under reduced pressure. The results of batch-wise vacuum distillation under the following distillation conditions are shown in table 4.
The distillation conditions were as follows:
a distillation column: the diameter is 1000mm, and the theoretical plate number is 80 sections; adding raw materials: 20000kg;
pressure at the top of the column: 100mmHg (13.33 kPa); reflux ratio: 35
[ TABLE 4 ]
< evaluation >
As shown in tables 1 and 2, the isoquinolines prepared in examples 1 and 2 did not contain phenols, and were almost completely separated. Further, example 1 in which distillation was performed under a more highly reduced pressure condition enabled to obtain colorless transparent isoquinoline. Further, example 2 in which distillation was performed under reduced pressure at a level lower than that of example 1 was able to obtain isoquinoline that was transparent in pale yellow.
As described above, by treating the isoquinoline mixture containing impurities such as phenols by continuous vacuum distillation, isoquinoline in which the content of phenols is significantly reduced and coloration is suppressed can be produced at a high recovery rate exceeding 96%.
As shown in tables 3 and 4, phenols remained in the isoquinolines prepared in reference examples 1 and 2. In reference example 1 in which the column top pressure was set to normal pressure, isoquinoline was brown. In reference example 2 in which batch distillation was carried out, colorless transparent isoquinoline was obtained because the temperature in the column was low under reduced pressure, but phenols remained and the recovery rate of isoquinoline was low.
<3. Effect >
(3a) By using the method for producing isoquinoline of the present embodiment, that is, the method for separating isoquinoline from an isoquinoline mixture by continuous vacuum distillation, isoquinoline in which coloration is suppressed while phenol is significantly reduced can be produced in a high yield.
Conventionally, when isoquinoline is produced by distillation under reduced pressure, phenols remain, whereas when isoquinoline is produced by distillation under atmospheric pressure, coloration (which is generally considered to be the case) occurs. The reason why isoquinoline contains phenols is considered to be that phenols are azeotroped with isoquinoline under the condition of reduced pressure distillation. Therefore, it is considered that the incorporation of phenols into isoquinoline cannot be avoided in the case of vacuum distillation. On the other hand, when crude quinoline is subjected to batch-type atmospheric distillation, phenols can be separated as a front cut fraction, so that isoquinoline containing no phenols can be obtained, but since the inside of the column needs to be set at a high temperature, degradation in quality due to decomposition, polymerization, or the like occurs, and there is a problem that, for example, coloration is likely to occur.
However, in the production method of the present disclosure, although the reason has not been clarified, the high separation of phenols and the suppression of coloring can be simultaneously achieved.
(3b) The preparation of isoquinoline using coal tar as a raw material is more advantageous in cost than other preparation methods such as cyclized synthesis, but has a problem of easy residual phenol. In the production method of the present embodiment, phenol can be significantly reduced, and therefore the quality of coal tar-derived isoquinoline can be improved.
Further, when the total amount of isoquinoline and phenols is 100wt%, the residual amount of phenols is preferably 0.1wt% or less, particularly preferably 0.05wt% or less, and in the present embodiment, the residual amount of phenols can be made 0.01wt% or less.
<4 > other embodiments
The embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above embodiments, and various production methods can be adopted within the technical scope of the present disclosure.
For example, as long as it is a method of separating isoquinoline from an isoquinoline mixture by continuous vacuum distillation, specific components of the isoquinoline mixture and distillation conditions are not particularly limited.
For example, in the above embodiment, an example in which an isoquinoline-containing fraction obtained by distilling coal tar is used as the isoquinoline mixture is shown, but an isoquinoline mixture not derived from coal tar or an isoquinoline mixture not containing phenols may be used.
Further, the isoquinoline mixture may include an isoquinoline-containing fraction obtained by distilling coal tar, but the "distillation of coal tar" described herein is not limited to a fraction obtained by 1 distillation operation but also includes a fraction obtained by a plurality of distillation operations. Further, the isoquinoline mixture may be a mixture of an isoquinoline-containing fraction obtained by distillation and other substances.
Further, the distillation pressure can be greater than 400mmHg. However, coloring can be suppressed by setting the distillation pressure to 400mmHg or less. Although not exemplified in the examples, a transparent isoquinoline mixture with almost no coloration can be prepared by adjusting the distillation pressure to 250mmHg or less. As shown in the examples, by setting the distillation pressure to 100mmHg or less, a highly transparent isoquinoline mixture can be prepared.
Claims (5)
1. A process for producing isoquinoline by distillative separation of isoquinoline from an isoquinoline mixture containing isoquinoline and impurities, the process being characterized by,
the isoquinoline mixture contains a distillation residue obtained by removing a quinoline fraction by distilling a quinoline-containing fraction under reduced pressure, wherein the quinoline-containing fraction is a fraction obtained by at least a distillation step using coal tar as a raw material, and
in the method for producing isoquinoline, separation by distillation of isoquinoline is carried out by subjecting the isoquinoline mixture to continuous distillation under reduced pressure.
2. The method for producing an isoquinoline according to claim 1,
the isoquinoline mixture contains phenols.
3. The method for producing an isoquinoline according to claim 1 or 2,
the isoquinoline mixture comprises isoquinoline derived from coal tar.
4. The method for producing an isoquinoline according to claim 1 or 2,
the distillation pressure in the continuous vacuum distillation is 400mmHg or less.
5. A method for separating isoquinoline from an isoquinoline mixture containing isoquinoline derived from coal tar and impurities by distillation, the method being characterized in that,
the isoquinoline mixture comprises a distillation residue obtained by removing a quinoline fraction by distilling a quinoline-containing fraction under reduced pressure, wherein the quinoline-containing fraction is a fraction obtained by using coal tar as a raw material and passing through at least a distillation step, and
in the method for separating isoquinoline, the distillation separation of isoquinoline is carried out by subjecting the isoquinoline mixture to continuous vacuum distillation.
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| JP2018135241A JP6901440B2 (en) | 2018-07-18 | 2018-07-18 | Isoquinoline production method and isoquinoline separation method |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004107254A (en) * | 2002-09-18 | 2004-04-08 | Sumikin Air Water Chemical Inc | Method for removing tar acid from quinolines |
| CN103641778A (en) * | 2013-11-22 | 2014-03-19 | 徐广苓 | Method for extracting quinoline and isoquinoline from coal tar wash oil |
| CN103641780A (en) * | 2013-12-05 | 2014-03-19 | 南京理工大学 | Method for purifying isoquinoline from crude product of coal tar |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3159457B2 (en) * | 1991-03-04 | 2001-04-23 | 新日鐵化学株式会社 | Method for recovering isoquinoline and quinaldine |
| JP2003073359A (en) * | 2001-09-04 | 2003-03-12 | Kanegafuchi Chem Ind Co Ltd | Method for refining isoquinoline |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004107254A (en) * | 2002-09-18 | 2004-04-08 | Sumikin Air Water Chemical Inc | Method for removing tar acid from quinolines |
| CN103641778A (en) * | 2013-11-22 | 2014-03-19 | 徐广苓 | Method for extracting quinoline and isoquinoline from coal tar wash oil |
| CN103641780A (en) * | 2013-12-05 | 2014-03-19 | 南京理工大学 | Method for purifying isoquinoline from crude product of coal tar |
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