JPH0249770A - Isoquinoline purification method - Google Patents

Abstract

PURPOSE:To obtain isoquinoline having high purity and low sulfur-content by adding a solvent to an isoquinoline-containing mixed raw material oil obtained from a tar-base oil such as coal tar or liquefied coal oil and washing the crystallized isoquinoline with a washing solvent. CONSTITUTION:A mixed raw material oil containing >=90wt.%, preferably 95wt.% of isoquinoline and separated from a tar-base oil such as coal tar and liquefied coal oil is crystallized by the addition of a crystallization solvent (especially preferably benzene, toluene, xylene or ethylbenzene). The crystal separated by solid-liquid separation process is washed with a washing solvent (especially preferably n-pentane, n-hexane, cyclohexane, etc.) to obtain purified isoquinoline. The process enable easy and economical industrial separation of isoquinoline having high purity and low sulfur-content. Isoquinoline is a compound useful for the synthesis of pharmaceuticals, agricultural chemicals, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for obtaining isoquinoline of high purity and low sulfur content from tar oil such as coal tar and coal liquefied oil.

[Prior Art] Highly purified isoquinoline is attracting attention and being used as a compound useful in the synthesis of new medicines, agricultural chemicals, and the like.

Such isoquinoline can be obtained as Ansen 1 by precision distillation of the tar base obtained from tar oil such as coltar and coal liquefied oil by acid extraction. In tar-based isoquinoline,
For example, it contains impurities such as quinoline, quinaldine, 8-methylgynoline, and sulfur compounds, and has a low purity.

As a purification method for increasing the purity of such tar-based isoquinoline, there is a distillation method in which isoquinoline is concentrated by batch or continuous distillation under reduced pressure.
Publication No. 96, published by Japan Aromatic Industry Association (1978)
): Aromatics and Tar Industry Handbook, p. 92), salt recrystallization by adding an acid such as sulfuric acid to a tar base to form a salt, recrystallizing it for purification, and then alkaline decomposition to obtain high-purity isoquinoline. Act (Japanese Unexamined Patent Publication No. 61-254.564
No. 2) has been proposed.

However, in the above distillation method, 100 to 200 m11
Since it is necessary to perform rectification and concentration at a high centrifugal flow ratio under a reduced pressure of 1.5 g, it requires a large amount of thermal energy, and even if the number of theoretical plates for distillation is set to about 100, the purity that can be achieved is only about 95% at most. There is a problem in that it is difficult to purify to high purity, and in the case of sulfur compounds, it is almost impossible to remove carbon.

In addition, in the above salt recrystallization method, for example, 1 mole of sulfuric acid is used as an acid for 1 mole of isoquinoline, a solvent is used for recrystallization of the obtained sulfate, and a solvent is used for alkaline decomposition after recrystallization. In addition to the wide variety of auxiliary raw materials used, such as the use of 2 moles of alkali and the use of a solvent to separate the liberated isoquinoline, a large amount of wastewater containing inorganic salts is produced, making it difficult to treat wastewater. There is a problem in that a large amount of cost is required, and as a result, the cost of purifying isoquinoline is high.

[Problems to be Solved by the Invention] The present invention was created in view of this point of view, and its purpose is to provide a raw material for tar-based isoquinoline.
An object of the present invention is to provide a method for efficiently obtaining isoquinoline with high purity and low sulfur content at a low cost of 1 or more from mixed oil.

[Means for Solving the Problems] That is, the present invention provides 90% by weight of isoquinoline obtained by separating from tar-based oil such as coal tar and coal liquefied oil.
A solvent is added to the raw material mixed oil containing the above and crystallized,
This is an isoquinoline purification method in which the crystals obtained by solid-liquid separation are washed with a washing solvent.

In the present invention, the mixed oil used as a raw material is obtained by acid extraction from tar-based oil such as coal cool and coal liquefied oil.
It is a fraction mainly having a boiling point in the range of 242 to 245°C, obtained by precision distillation of the tar base obtained in the above process. If the isoquinoline content of this fraction is less than 90% by weight, distillation is performed again or the cutting temperature range is narrowed to increase the isoquinoline content to 90% by weight or more, preferably 95% by weight.
Mixed oils containing % heavy weight are used. If the raw material mixed oil contains less than 90% by weight of isoquinone, the purity of the final product will decrease or the yield will decrease.

In the method of the present invention, a solvent for crystallization is added to the raw material mixed oil for crystallization.

The crystallization solvent used to crystallize such a raw material mixed oil must meet the following conditions: ■ The freezing point is lower than the freezing point of isoquinoline; ■ The viscosity at the crystallization temperature is low; It is desirable that the solid-liquid separation operation is easy; (1) it is non-hazardous, industrially inexpensive, easily available, and can be disposed of, recovered, and reused; As a crystallization solvent that satisfies these conditions by adding t4, it is preferable to use a solvent with a carbon number of 6.
~8 aromatic compounds, and typical examples include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene.

Regarding the crystallization process performed by adding such a solvent for crystallization, in terms of odor, it is necessary to add a predetermined amount of the solvent for crystallization to the raw material mixed oil, mix well, and once dissolve it. Then, the solution is gradually cooled to a predetermined temperature to precipitate isoquinoline crystals, and solid-liquid separation is preferably performed while maintaining the cooling temperature to separate the isoquinoline crystals.

When the raw mixed oil is cooled, isoquinoline crystals begin to precipitate around 19°C, and at this point the viscosity increases rapidly, and the mother liquor becomes a viscous slurry.
Solid-liquid separation cannot be performed as it is, but by adding a crystallization solvent, the viscosity of the mother liquor is lowered, making solid-liquid separation possible and easy, and the addition of this crystallization solvent is essential. It is.

The amount of this crystallization solvent to be used may be an amount sufficient to enable the above-mentioned solid-liquid separation, but it is usually 15 to 30 parts by weight, preferably 20 to 30 parts by weight, per 100 car parts of the raw material mixture oil. Go to the weight department. If the amount of this crystallization solvent used is small, the effect of lowering the viscosity of the raw material mixed oil will be unstable, making solid-liquid separation difficult, and if it is more than 30 parts by weight, the amount to be processed will increase and the size of the equipment will increase. This is economically disadvantageous due to problems such as increased cooling costs and increased cooling costs.

The isoquinoline crystals obtained by crystallization and solid-liquid separation are then washed with a washing solvent. This washing removes the mother liquor adhering to the crystals and improves the purity of the isoquinoline. The crystalline form of isoquinoline is not one in which impurities are incorporated into the crystal, but impurities attached around the crystal, so if the cleaning solvent temperature is above the crystallization temperature, the crystals will sweat, which will cause purification. Both effects can be obtained.

The cleaning solvent used for this purpose is required to have low solubility for isoquinoline in addition to the same conditions as the crystallization solvent. Solvents that satisfy these conditions include paraffins having 5 to 8 carbon atoms, typically n-pentane, n-hexane, cyclohexane, n-hebutane, low octane, or a mixture thereof. Examples include oil.

The process of cleaning isoquinoline crystals using such a cleaning solvent involves first immersing the crystals in the cleaning solvent and separating the solid-liquid, and then using the solid-liquid separation equipment as is when performing solid-liquid separation after the crystallization operation. This can be carried out in any suitable manner, such as by passing II through a washing solution. Although not particularly limited, the temperature at which the cleaning solvent is used is preferably higher than the temperature during the solid-liquid separation, and is preferably in the range of -20 to 20°C. The greater the amount of washing solvent used and the number of washings, the higher the purity of the obtained crystals, but the lower the yield. The amount of cleaning solvent used and the number of times of cleaning required to achieve the target purity depend on the purity of the raw material mixture oil used or the N! For example, in order to obtain isoquinoline with a purity of 98% or higher, the amount of cleaning solvent used should be about 1 to 1.2 times the weight of the wet cage after solid-liquid separation, and the number of cleanings should be once. is sufficient.

Furthermore, in the present invention, the crystallization solvent used in the crystallization step and the cleaning solvent used in the washing step are preferably recovered after the crystallization operation or the washing operation is completed, and are combined together. It is preferable to send it separately or separately to a distillation purification process for purification, and then circulate it again to the crystallization process or washing process for reuse. Purifying and reusing crystallization solvents and cleaning solvents in this way not only minimizes solvent loss, but also minimizes the amount of waste liquid treated, especially when used in large quantities. This is advantageous when there is a need for purification.

[Example] Hereinafter, the method of the present invention will be specifically explained based on Examples.

Example 1 A raw material mixed oil 2501i suspension containing 95% isoquinoline obtained by precision distillation of a tar base obtained by acid extraction of coal tar, and 70% benzene as a solvent for crystallization were used.
1 part by weight was placed in a container equipped with a stirrer and stirred to form a homogeneous solution. Next, the temperature of this solution was gradually lowered to −20° C. while stirring to precipitate isoquinoline crystals.

Roughly maintaining this cooling temperature, solid-liquid separation was carried out, and the obtained solid phase was washed with a 242-mass part at 21°C,
The mother liquor attached to the surface of the crystal is removed and dried to a purity of 9.
9, ″>6% by weight, total sulfur content 4801) I)m 108.2 [i parts] of crystals of isoquinoline were obtained.

The isoquinoline recovery rate at this time was 45.6% by weight.

Example 2 Using exactly the same container and raw material mixed oil as in Example 1, and using 55 parts by weight of the solvent benzene for crystallization, Example 1
Crystals were precipitated in the same manner as above, and solid-liquid separation was performed. The obtained solid phase was washed with 135 parts of hexane at 15°C,
It is then dried to obtain a purity of 98.7 fi% and a total sulfur content of 85.
143 parts by weight of crystals of 0 ppm isoquinoline were obtained.

The isoquinoline recovery rate at this time was 60.3ff1%.

[Effects of the Invention] According to the present invention, isoquinoline with high purity and low sulfur content can be produced easily, industrially and economically by using a raw material mixed oil obtained by separating from coal tar, liquefied petroleum oil, etc. can be separated into right and left.

Claims (3)

[Claims] (1) A raw material mixture oil containing 90% by weight or more of isoquinoline obtained by separating it from tar-based oil such as coal tar and coal liquefied oil is crystallized by adding a solvent, and is obtained by solid-liquid separation. A method for purifying isoquinoline, the method comprising washing the obtained crystals with a washing solvent. (2) The method for purifying isoquinoline according to claim 1, wherein an aromatic hydrocarbon having 6 to 8 carbon atoms is used as a solvent for crystallization. (3) The method for purifying isoquinoline according to claim 1, wherein paraffins having 5 to 8 carbon atoms are used as the cleaning solvent.