JPH0780808B2 - Method for separating fatty acids - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to separation of fatty acids in lipids, and more particularly to a method for separating unsaturated fatty acids, their respective components and saturated fatty acids with high purity.

[0002]

2. Description of the Related Art Lipids are in demand for foods, fuels and pharmaceuticals, and are also widely used in soaps and cosmetics. Lipids are classified into neutral lipids, phospholipids and glycolipids, and are extracted and produced from natural substances such as oils and fats of plants and animals. Among them, neutral fatty acids having 14 to 22 carbon atoms are widely used in nutritional studies,
It is also medically excellent. For example, an unsaturated fatty acid having 20 carbon atoms, eicosapentaenoic acid (EPA), is present in fish oil and the like, has a thrombolytic action and a blood lowering action, and has a high added value as a pharmaceutical.

As one of the methods for separating eicosapentaenoic acid from many fatty acids contained in fish oil such as sardines, an extraction separation method using a supercritical fluid of CO ₂ is applied. In this method, first, fatty acids are extracted from fish oil, and then EPA is separated by chromatography using a similar CO ₂ supercritical fluid as a mobile phase. However, according to this method, unsaturated fatty acids having 18 to 22 carbon atoms are not completely separated, and the purity of 1
It's hard to get a 100%. In addition, this method needs to be maintained at 72.9 atm or more in order to bring it into a supercritical state, and the system must be made to withstand pressure.

[0004]

The above-mentioned prior art is suitable for separating fatty acids having different carbon numbers and having obviously different molecular weights. However, among saturated fatty acids and unsaturated fatty acids, and further unsaturated fatty acids, There was a problem with separation between compounds having different numbers of unsaturated bonds. The present invention has been made in view of the above circumstances, and an object thereof is to separate saturated fatty acids and unsaturated fatty acids and to separate unsaturated fatty acids.

[0005]

The present inventors have found that a lead salt of a fatty acid can be selectively dissolved in a specific solvent, and have arrived at the present invention as a result of earnest research.
That is, the invention claimed in the present application is as follows. (1) In the separation of a saturated compound of a fatty acid and an unsaturated compound, and further between unsaturated fatty acids having different numbers of unsaturated bonds, these compounds are reacted with a solution containing lead ions to form a lead salt, A method for separating fatty acids, characterized in that fatty acids are separated by utilizing the difference in solubility of each lead salt in a polar solvent and a non-polar solvent.

(2) As a non-polar solvent for dissolving unsaturated lead salt, benzene, dichloromethane, diethyl ether,
The method for separating fatty acids according to claim 1, wherein one or a mixture of two or more of chloroform and dimethylformamide is used. Lead ions undergo a saponification reaction with both saturated fatty acids and unsaturated fatty acids to produce fatty acid lead. Especially carbon number C16, C
Fatty acids of both 18, C20, C22 and C24, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid as saturated fatty acids, palmitoleic acid, oleic acid, gadoleic acid etc. of monoene fatty acids as unsaturated fatty acids are completely It saponifies with lead ions to form a lead salt, which forms an insoluble precipitate in water and polar solvents. Only one of the precipitates formed here is dissolved in a specific solvent due to the difference between the saturated and unsaturated fatty acid salts.

On the other hand, linoleic acid as a diene fatty acid, linolenic acid as a triene fatty acid, stearidonic acid, arachidonic acid as a tetraene fatty acid, eicosapentaenoic acid (EPA) as a pentaene fatty acid, and docosahexaenoic acid (DHA) as a hexaenoic acid are mixed with lead ions. The reaction does not form a lead salt precipitate. Table 1 shows the solubility of the fatty acid salt in each organic solvent. An appropriate solvent can be selected according to the difference in solubility thereof and used for the separation operation.

[0008]

[Table 1]

[0009]

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. Example 1 A mixture of stearic acid and oleic acid as a C18 fatty acid is mixed with lead (II) oxide and heated and melted at 150 to 180 ° C. By the above reaction, stearic acid as a saturated fatty acid and oleic acid as an unsaturated monoene fatty acid form lead stearate and lead oleate to form a lead salt insoluble in water or a polar solvent. The produced lead oleate is selectively dissolved in diethyl ether, but not lead stearate. Therefore, lead oleate is subjected to solvent extraction with diethyl ether and solid-liquid separated by filtration or the like. On the other hand, lead stearate dissolves in hot benzene (65 ° C). The above procedure allowed the separation of the stearic acid and oleic acid mixture.

Example 2 A mixture of stearic acid and oleic acid and linoleic acid as C18 fatty acid was dissolved in ethanol to give 0.1N.
An aqueous solution of lead acetate containing lead ions (II) is added to a sodium C18 acid solution neutralized with a sodium hydroxide solution. By the above reaction, stearic acid as a saturated fatty acid and oleic acid as an unsaturated monoene fatty acid form lead salts insoluble in water and polar solvents as lead stearate and lead oleate, and precipitate. Here, since linoleic acid, which is a diene fatty acid, does not form a lead salt, solid-liquid separation is performed by filtration or the like. The precipitated lead stearate and lead oleate are selectively soluble only in certain unique non-polar solvents. That is, lead oleate dissolves in nonpolar solvents such as benzene, dichloromethane, diethyl ether, chloroform, etc., but lead stearate does not dissolve in these solvents. Therefore, chloroform is added to the mixture of the lead salts to dissolve only lead oleate, and solid-liquid separation is performed by filtration or the like. Lead stearate is soluble in hot benzene (65 ° C). The above procedure allowed the separation of a mixture of three C18 fatty acids, stearic acid, oleic acid and linoleic acid.

[0011]

EFFECTS OF THE INVENTION Conventionally, it was difficult to separate compounds having different unsaturated bond numbers among saturated fatty acids, unsaturated fatty acids, and further unsaturated fatty acids. Separation operations based on the interaction of saturated or unsaturated fatty acids with double bonds have enabled their separation with high separation performance without the need for special equipment.

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Claims (2)

[Claims] 1. A method for separating a saturated compound and an unsaturated compound of a fatty acid, and further a compound having a different unsaturated bond number among unsaturated fatty acids, wherein a solution containing the fatty acid is reacted with a solution containing lead ions. A method for separating fatty acids, wherein each of the fatty acids is separated into a lead salt, and the fatty acids are separated by utilizing the difference in solubility of the lead salt of each fatty acid in a polar solvent and a non-polar solvent. 2. The non-polar solvent for dissolving the unsaturated lead salt is one or a mixture of two or more selected from benzene, dichloromethane, diethyl ether, chloroform and dimethylformamide.
The method for separating fatty acids described.