JP2634233B2 - Concentration and separation of 2-methylquinoline - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for concentrating and separating 2-methylquinoline in a hydrocarbon oil containing 2-methylquinoline.
Specifically, a hydrocarbon oil containing 2-methylquinoline and α
A method of contacting cyclodextrins to form an inclusion compound of 2-methylquinoline and α-cyclodextrin in a 2-methylquinoline-containing hydrocarbon oil, recovering the inclusion compound and concentrating and separating 2-methylquinoline. .

[Background Art] 2-Methylquinoline is an important compound as a raw material of quinophthalone used as a yellow dye such as silk and wool.

However, in order to provide these uses, it is important that the purity is high, and in particular, the mixture of 8-methylquinoline as an isomer and an organic sulfur compound must be eliminated as much as possible.

2-Methylquinoline is present in a small amount in the coal tar-based crude quinoline (fraction at 235 to 240 ° C.) and is recovered from the bottom oil from which quinoline is separated. However, in the bottom oil from which quinoline was separated, 2-methylquinoline, 8-methylquinoline, quinoline, isoquinoline,
It contains a large amount of other impurities, and the purity of 2-methylquinoline obtained by distillation of the impurities is limited to about 85%. This is because it is impossible to separate from 8-methylquinoline, whose boiling point is very close.

[Problems to be Solved by the Invention] The present invention provides a novel 2-methylquinoline which is conventionally considered difficult to separate by concentrating and separating without using known concentrating and separating means such as distillation and crystallization. It is intended to provide a method for concentrating and separating methylquinoline.

[Means for Solving the Problems] In the present invention, α-cyclodextrins are used as a separating agent for 2-methylquinoline from a hydrocarbon oil containing 2-methylquinoline.

α-Cyclodextrins are cyclic oligosaccharides in which six glucopyranose groups are α-1,4 linked and have a crown-like structure, and include various organic compounds in their cavities to form inclusion compounds. Can be formed.

Attempts to apply the clathrate-forming ability to separation have hitherto centered on separation of benzene disubstituted isomers such as o-, m- and p- isomers and optical isomers.

On the other hand, coal tar fractions and petroleum fractions are complex mixtures composed of many types of components, and attempts to apply cyclodextrins to separate specific components in these fractions have been made for analysis purposes. Although there is an example, there is no example used for separation and concentration of a specific component.

The present inventors have conducted intensive studies on the concentration and separation of 2-methylquinoline in 2-methylquinoline-containing hydrocarbon oils and found that α-cyclodextrins and 2-methylquinoline in 2-methylquinoline-containing hydrocarbon oil were The formation constant of an inclusion complex with is very large, especially 8-methylquinoline hardly forms an inclusion complex, whereas 2-methylquinoline forms an inclusion complex extremely cheaply and is selectively included. Using this property, a novel method for concentrating and separating 2-methylquinoline was completed.

That is, the present invention relates to 2-methylquinoline-containing hydrocarbon oil and α-cyclodextrins,
A method for concentrating and separating 2-methylquinoline, comprising forming an inclusion compound of methylquinoline and α-cyclodextrins and recovering the inclusion compound.

As the α-cyclodextrin used in the present invention, α-cyclodextrin or α-cyclodextrin is chemically modified, for example, hydrogen of at least one hydroxyl group of α-cyclodextrin is converted to glucose, maltose, maltooligosaccharide, hydroxypropyl group. , A methyl group, a sulfone group, and a carboxyalkyl group. Since the solubility in water is improved by chemically modifying the α-cyclodextrin in this manner, the concentration of the aqueous solution at the time of inclusion and recovery can be increased, the apparatus for filtration and recovery can be made compact, and the purification operation can be performed. Not only can it be streamlined, but also the loss of product and clathrate can be reduced. In the present invention,
α-Cyclodextrins are dissolved or suspended in water, mixed with 2-methylquinoline-containing hydrocarbon oil, and vigorously stirred. In this case, the concentration of α-cyclodextrin is, for example, 5 to 20%, preferably 10 to 15% in the case of α-cyclodextrin. The mixing ratio of the α-cyclodextrin aqueous solution and the hydrocarbon oil containing 2-methylquinoline is 2%.
Α-cyclodextrin is used in an amount of 1 to 5 mol, preferably 1.5 to 2.5 mol, per 1 mol of -methylquinoline. The stirring is desirably performed as vigorously as possible, for several tens minutes to several hours. The temperature is desirably about 30 to 45 ° C.

The mixture becomes cloudy due to the formation of the inclusion compound of α-cyclodextrins. After completion of the stirring, the reaction product is separated. For example, after centrifugation at 2,500 rpm for 5-10 minutes,
This is filtered through a membrane filter having a pore size of 0.4 μm, washed with water, washed with an organic solvent such as acetone, and then dried to obtain a white solid inclusion compound.

Since the inclusion compound of this white solid also contains organic compounds other than 2-methylquinoline, once these are dissociated in hot water at 60 to 70 ° C. or higher, the clathration is repeated again. Thereby, the purity of 2-methylquinoline can be increased.

In the above all steps, the α-cyclodextrin molecule itself does not decompose, so that it can be recovered and recycled.

There are various methods for separating 2-methylquinoline and the like from inclusion compounds such as α-cyclodextrins and 2-methylquinoline. For example, a method of dissolving the clathrate compound in hot water to dissociate the clathrate complex, and then extracting the dissociated 2-methylquinoline or the like using a suitable organic solvent such as hexane or heptane, or Is suspended in water, a suitable organic solvent such as diethyl ether is added thereto, and the mixture is shaken to extract 2-methylquinoline and the like into the organic layer.

[Examples] Hereinafter, the present invention will be described more specifically with reference to Examples.

The main components in this example were analyzed by gas chromatography. The numbers in the table are the area percentages of each component.

Example 1 A glass flask having a capacity of 50 ml was charged with 25 ml of a 10% aqueous solution of α-cyclodextrin and 0.5 g of a raw material mixture of 2-methylquinoline and 8-methylquinoline having the composition shown in Table 1.
Stirred vigorously at 30 ° C. for 1 hour.

After completion of the stirring, the reaction product was filtered using a membrane filter having a pore diameter of 0.4 μm, and the collected clathrate was washed with water, washed with acetone, and dried. The clathrate was suspended in hot water to dissociate the clathrate, followed by extraction with diethyl ether. 2-methylquinoline and the like were separated and recovered, and separated from α-cyclodextrin.

 Table 1 shows the compositions of the raw materials and clathrates.

As shown in Table 1, 8-methylquinoline hardly forms an inclusion compound, whereas 2-methylquinoline has α
-An inclusion compound is formed very specifically with cyclodextrin, and an inclusion compound with a high concentration of 2-methylquinoline having a purity of 99% or more is obtained.

Example 2 A crude oil obtained by distilling a coal tar crude quinoline fraction to recover quinoline was distilled, and crude 2-methylquinoline having a composition shown in Table 2 was recovered. Then, 25 ml of a 10% aqueous solution of α-cyclodextrin and a second
0.5 g of crude 2-methylquinoline having the composition shown in the table was charged, and 30
Stirred vigorously for 1 hour at ° C.

After completion of the stirring, the reaction product was filtered using a membrane filter having a pore diameter of 0.4 μm, and the collected clathrate was washed with water, washed with acetone, and dried. The clathrate was suspended in hot water to dissociate the clathrate, then extracted with diethyl ether, and 2-methylquinoline was separated and recovered, and separated from α-cyclodextrin.

Table 2 shows the compositions of the crude 2-methylquinoline and the clathrate.

As shown in Table 2, 8-methylquinoline hardly forms an inclusion compound, whereas 2-methylquinoline has α
-A very specific inclusion compound is formed with cyclodextrin, and an inclusion compound in which 2-methylquinoline is concentrated at a high concentration is obtained.

[Effects of the Invention] As described above, according to the method of the present invention, impurities such as 8-methylquinoline and organic sulfur compounds are easily separated and removed from 2-methylquinoline-containing hydrocarbon oil, and 2-methylquinoline is concentrated and separated. can do.

Claims (1)

(57) [Claims] 1. A hydrocarbon oil containing 2-methylquinoline and an aqueous solution of α-cyclodextrin are brought into contact to form an inclusion compound of 2-methylquinoline and α-cyclodextrin, and the inclusion compound is recovered. A method for concentrating and separating 2-methylquinoline.