JP3159457B2 - Method for recovering isoquinoline and quinaldine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating isoquinoline and quinaldine, which are useful as raw materials for synthesizing medicines, agricultural chemicals, pigments and the like.

[0002]

BACKGROUND ART Isoquinoline can be synthesized by a method of condensing benzaldehyde and aminoacetal, a method of distilling homophthalimide with zinc powder, and a method of reacting quinine with aniline hydrochloride and paraaldehyde. Industrially, it is advantageous and generally practiced to recover a distillate from coal tar or coal liquefied oil from a tar base obtained by acid extraction. However, the thus recovered isoquinoline or quinaldine contains thienopyridine, other alkylisoquinolines and alkylquinolines present in the tar base as impurities. Since these impurities have a boiling point close to that of isoquinoline or quinaldine, separation by distillation is extremely difficult.

[0003] Therefore, a method for purifying isoquinoline recovered from coal base oil containing isoquinoline, quinaldine and other tar bases as main components obtained by separating from coal tar or coal liquefied oil. A method in which isoquinoline is reacted with an acid to form a crystalline salt, which is recrystallized and / or washed, and then subjected to alkali decomposition (Japanese Patent Application Laid-Open No.
1-225464) and a method of cooling and crystallizing isoquinoline (JP-A-2-49770).
Further, quinaldine and an acid are reacted to form a crystalline salt, which is recrystallized and / or washed and then alkali-decomposed (JP-A-62-198665), or quinaldine is reacted with urea and added. A method of forming an adduct, purifying it, and decomposing the adduct (JP-A-57-3877)
No. 1) is also known. Furthermore, one of the present inventors discloses that quinaldine is used as an azeotropic solvent in the form of an alkyl phenol having 8 carbon atoms.
For purification by azeotropic distillation with the addition of
No. 68678) was previously proposed.

[0004] However, these methods have problems in terms of economy, waste disposal, and the like when they are carried out industrially. For example, a method of forming a crystalline salt and purifying the same not only consumes an acid and an alkali, but also generates a large amount of waste liquid containing the same. In the method of cooling and crystallizing isoquinoline, not only is it necessary to increase the purity of isoquinoline by distillation in advance, but also a large amount of energy is required for cooling. The method of purifying by forming a urea adduct,
The operation is complicated, and not only is the separation of quinaldine and the aqueous urea solution poor, but also a large amount of urea aqueous solution waste is generated. In addition, a method of purifying quinaldine by adding an phenol having 8 carbon atoms as an azeotropic solvent and azeotropically distilling the quinaldine also needs to increase the quinaldine purity in advance.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to efficiently produce isoquinoline and quinaldine having high purity and low sulfur content.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to a coal base oil containing isoquinoline, quinaldine and other tar bases obtained by separating coal coal or coal liquefied oil as an azeotropic solvent. Alkylphenols having 8 carbon atoms (excluding 2,6-xylenol) are added, and azeotropic distillation is performed under reduced pressure to distill an azeotropic mixture mainly composed of isoquinoline and quinaldine. After separation of the alkylphenols from isoquino, characterized in that distillation separating the isoquinoline and quinaldine
This is a method for recovering phosphorus.

[0007] The coal base oil used as a raw material in the present invention is
It is mainly composed of isoquinoline, quinaldine and other tar bases obtained by separating from tartar or coal liquefied oil, which is obtained by distilling coal tar or coal liquefied oil. It is obtained by extracting tar oils with an aqueous acid solution. Preferably, it is a fraction mainly comprising a fraction having a boiling point in the range of 235 to 270 ° C, and quinoline, isoquinoline,
A base containing tar bases such as quinaldine, 8-methylquinoline and dimethylquinoline as main components, containing indole and thienopyridine, and having an isoquinoline concentration of 25 to 50% by weight and a quinaldine concentration of 15 to 40% by weight. Minutes.
Such a fraction is extracted from tar oil with an aqueous acid solution, and a fraction obtained by decomposing it with an alkali is distilled to obtain a fraction mainly composed of quinoline as a remaining fraction. Can be. This is also referred to as quinoline resid. 8-Methylquinoline and thienopyridine contained in this coal base oil have boiling points close to those of isoquinoline and quinaldine, and are difficult to separate by distillation. Isoquinoline obtained by precision distillation of this oil contains, for example, quinaldine. To 0.
It contains 5 to 3% by weight, mainly 3000 to 5000 ppm of sulfur derived from thienopyridines, and the quinaldine similarly obtained contains, for example, about 10 to 15% by weight of 8-methylquinoline and thienopyridines.

The azeotropic solvent to be added to the above-mentioned coal base oil is an alkylphenol having 8 carbon atoms (excluding 2,6-xylenol), and specifically, 2,3-xylenol,
2,4-xylenol, 2,5-xylenol, 3,4
-Xylenol, 3,5-xylenol, 2-ethylphenol, 3-ethylphenol and 4-ethylphenol, and one or a mixture of two or more thereof can be mentioned. When 2,6-xylenol is added alone, it cannot be used because it does not act as an azeotropic solvent. However, even if it is mixed with other alkylphenols having 8 carbon atoms, there is a particular disadvantage. Since it does not occur, for example, when a mixture of xylenols is used as an azeotropic solvent, there is no need to remove it. Further, impurities which are usually mixed in the alkylphenols or other solvents whose boiling points are not close to each other may be present. These alkylphenols
Of the compounds, preferred is 3,4-xylenol or 3,4-xylenol.
Although it is 5-xylenol, industrially, it has a boiling point of 210 to 210 separated from tar oils by means such as alkali extraction and distillation.
A mixture of alkylphenols mainly comprising a fraction at 230 ° C. is sufficient. The amount of the alkylphenols used is
The alkylphenols are used in an amount of 0.3 to 1 part by weight, preferably 0.4 to 0.6 part by weight, based on 1 part by weight of a coal base oil containing tar bases as a main component. Excessive addition only reduces distillation efficiency, while too little reduces recovery.

The apparatus for performing the azeotropic distillation of the present invention may be any apparatus having a theoretical plate number of about 80 or more, and the distillation conditions are 300 Torr or less, preferably 100 T or less.
The pressure is preferably reduced to orr or less, and the reflux ratio is preferably 20 or more, and more preferably 40 or more. In this azeotropic distillation, first, an excess azeotropic solvent is distilled off, and then thienopyridines such as quinoline, 8-methylquinoline, and thieno [3,2-b] pyridine are distilled out, and then isoquinoline, quinaldine, and alkylphenol are removed. The distillate mixture distills off as an azeotrope. The general composition of the azeotrope is, for example, isoquinoline 3
5 to 45% by weight, quinaldine 20 to 30% by weight, and alkylphenols 25 to 45% by weight.

The azeotrope thus obtained can be freed of alkylphenols by washing it with, for example, a 5 to 20% by weight aqueous alkali solution, or the azeotrope can be washed at about 760 to 600 Torr. 80-95% by weight of alkylphenols by distillation at around normal pressure
Can be removed. After the alkylphenols are removed, if isoquinoline and quinaldine are separated by distillation, for example, by distillation at a reduced pressure of 300 Torr or less, preferably 100 Torr or less, isoquinoline having a purity of 98% by weight or more and a sulfur content of 300% by weight or less and / or Quinaldine having a purity of 95% by weight or more can be obtained.

[0011]

When a coal-based base oil containing isoquinoline and quinaldine and other tar bases as a main component is added with an alkylphenol as an azeotropic solvent and distilled under reduced pressure, quinoline, 8-methylquinoline, Mainly a quaternary azeotrope of thienopyridines and alkylphenols and 3 quinolones of isoquinoline, quinaldine and alkylphenols
A component azeotrope is formed, and the former has a lower boiling point, so that the former distills out first, and a ternary azeotrope containing no difficult-to-separate impurities is distilled out later to efficiently produce isoquinoline and quinaldine. It is thought that it can be separated. It is considered that 4-methylquinoline, dimethylquinoline, indole and the like having a high boiling point form an azeotropic mixture having a higher boiling point than the ternary azeotropic mixture.

[0012]

Embodiments of the present invention will be described below. In Examples, "parts" indicates "parts by weight" and "%" indicates "% by weight". Example 1 As a coal base oil, a tar oil obtained by distilling a coal tar is extracted with an aqueous acid solution, and is mainly composed of a tar base obtained by decomposing with an alkali. Residual oil after distilling a fraction mainly composed of quinoline from the fraction (composition: quinoline 7.8%, thienopyridine 0.3%, isoquinoline 2
7.8%, indol 6.8%, quinaldine 21.5
%, 3.2% 8-methylquinoline, 1.2% 1-methylisoquinoline, 8.6% 6- and 7-methylquinoline,
(5.3% of 4-methylquinoline, 8.3% of other methylquinoline and methylisoquinoline, 7.5% of dimethylquinoline and dimethylisoquinoline and 1.3% of others)
Using 100 parts of this coal-based oil as an azeotropic solvent,
50 parts of alkylphenols mainly composed of 3,5-xylenol were added, and the mixture was distilled with a packed column type distillation apparatus having 80 theoretical plates. The distillation conditions were a distillation pressure of 50 Torr and a reflux ratio of 50. At this time, the distillation temperature of the azeotropic mixture of isoquinoline, quinaldine and alkylphenols is 156.
To 159 ° C., and the distillation amount was 60 parts. This composition was 37.1% isoquinoline, 24.6% quinaldine and 38.3% alkylphenols, and contained 59% sulfur.
It was 0 ppm.

Next, 100 parts of the azeotrope was distilled using the same distillation apparatus as above to separate and collect isoquinoline and quinaldine. The distillation conditions were normal pressure and a reflux ratio of 50. First, 20 parts of alkylphenols (fraction 1) are distilled, and then 14.6 parts of a mixture of isoquinoline, quinaldine and alkylphenols is subjected to an intermediate fraction (fraction 2).
After the distillation, the distillation pressure was changed to 50 Torr and the reflux ratio was changed to 50, and the distillation was continued. First, isoquinoline (fraction 3) and then quinaldine (fraction 4) were 18.
3 and 6 parts were distilled off. Table 1 shows the amount and composition of each fraction.

[0014]

[Table 1]

[0015]

According to the method of the present invention, 8-methylquinoline and thienopyridine which are present as impurities in a tar base oil containing tar bases as a main component and are difficult to separate by ordinary distillation. By removing such impurities, isoquinoline and / or quinaldine with high purity and low sulfur content can be efficiently produced.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C07D 217/02 C07D 215/04 CAPLUS (STN)

Claims (1)

(57) [Claims] 1. A coal base oil containing isoquinoline, quinaldine and other tar bases as main components obtained by separating coal tar or coal liquefied oil, and an alkylphenol having 8 carbon atoms (2) as an azeotropic solvent. , Except 6-xylenol) and azeotropic distillation under reduced pressure to distill an azeotrope containing isoquinoline and quinaldine as main components. Then, after separating alkylphenols from the obtained azeotrope, A method for recovering isoquinoline, which comprises separating isoquinoline and quinaldine by distillation.