JP2000044982A - Method for concentrating and separating unsaturated fatty acid alkyl ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the recovery and recycling of urea and obtain an unsatd. fatty acid alkyl ester which does not contain different kinds of esters by mixing urea with a fatty acid alkyl ester mixture under heating in a solvent mixture comprising water and an org. ketone solvent, cooling the solvent mixture contg. the resultant mixture, and separating thus formed urea adduct crystals by filtration. SOLUTION: 1.5-4.5 pts.wt. urea is added to 2-15 pts.vol. solvent mixture comprising 10-85 wt.% water and an org. ketone solvent, and the solvent mixture contg. urea is heated under stirring to the b.p. of the ketone solvent to dissolve the urea. After 1 pt.wt. fatty acid alkyl ester is added to the resultant urea soln., the soln. is stirred and cooled to 0-30 deg.C. Thus, urea adduct crystals are formed, which are separated by filtration and washed with an org. ketone solvent having a water content of 5% or lower. This washing liquid is mixed with the filtrate separated from the urea adduct crystals by filtration, and thus obtd. mixture is distilled. The upper layer of the resultant distillation residue is subjected to washing with water and then solvent removal to give an unsatd. fatty acid alkyl ester mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for separating an unsaturated fatty acid alkyl ester mixture from a fatty acid alkyl ester mixture.

[0002]

2. Description of the Related Art Unsaturated fatty acids and unsaturated fatty acid alkyl esters such as icosapentaenoic acid, docosahexaenoic acid, and γ-linolenic acid have attracted attention for their physiological activities, and research on purification methods has been actively conducted. . The purification method is a fractional crystallization method [Oil Chemistry 12, 561 (196
3)), countercurrent distribution extraction method ("Counter Current" published by Nankodo on May 1, 1958, pp. 157-159), fractional distillation (JP-A-59-118740), silver nitrate-silicic acid column chromatography Graphy [ANAL. CHEM. 40 , 2017 (1968)], etc., and it is common to purify the target component by combining these methods. In the purification method,
The urea addition method is a method that has been known for a long time, because a saturated fatty acid or an ester thereof and an unsaturated fatty acid having a degree of unsaturation of 1, such as oleic acid, or an ester thereof form an adduct with urea and can be separated as crystals. Used for crude fractionation of saturated and unsaturated components.

[0003] The solvent used in the urea addition treatment has a high solubility of urea and can easily dissolve the required amount of urea for the reaction, and also has a high solubility of the raw material fatty acid mixture or fatty acid alkyl ester mixture. From methanol to ethanol, a method using a lower alcohol such as ethanol as a solvent is a common method, and particularly when used as an industrial method, a method in which urea has high solubility, a low boiling point, and inexpensive methanol is generally used. . [Oil chemistry
13 , 249, (1964)), February 20, 1980, Maruzen Co., Ltd., `` Pfizer Organic Chemistry Experiment, '' pp. 318-324,
(JP-A-59-118740), (JP-A-2-25447), (JP-A-2-180996), (JP-A-7-27858)
No. 5] Since urea is slightly decomposed by heating in a solution to generate ammonia, methanol, methanol,
When urea addition treatment is performed using an alcohol solvent such as ethanol, the generated ammonia serves as a catalyst to cause transesterification of a part of the fatty acid ester. Therefore, when the urea addition treatment is performed using an alcohol different from the source of the fatty acid ester, a different ester derived from the reaction solvent is mixed into the product. For example, when the urea addition treatment of a fatty acid ethyl ester is performed with a methanol solvent, a slightly different ester of methyl ester is mixed into the obtained product.

Further, a large amount of urea precipitates from the residue obtained by distilling off methanol for the purpose of recovering fatty acid esters from the filtrate of the urea addition treatment solution using methanol as a solvent, and water or warm water is added to wash out the urea. If so, emulsification occurs, and the recovery of fatty acid esters and urea becomes very difficult. The same applies to the recovery of urea from crystals obtained as an adduct of a saturated fatty acid ester and urea. In order to eliminate the emulsification and separate the urea and the fatty acid ester, a third extraction solvent such as hexane is usually used. However, if the type of the solvent increases, the operation becomes complicated, and the management of the solvent becomes difficult. Furthermore, since the urea recovered by this method is an aqueous solution, it is necessary to remove water in order to recycle the urea, resulting in a very high cost.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to develop a method for concentrating and separating unsaturated fatty acid alkyl esters at low cost and without containing different kinds of esters by easily recovering and recycling urea.

[0006]

Means for Solving the Problems As a result of earnest studies to solve the problems, the present inventors have developed a urea addition treatment method using a mixture of water and a ketone organic solvent as a solvent. That is, the present invention is characterized in that (1) a mixture of urea and a fatty acid alkyl ester is heated and mixed in a mixed solution of water and a ketone-based organic solvent, and the urea adduct crystals formed by cooling are filtered and separated. (2) In the method for concentrating and separating unsaturated fatty acid alkyl esters, in the method described in (1), after filtering and separating the urea adduct crystals, the urea adduct is washed with a ketone organic solvent having a water content of 5% or less. (3) a method for concentrating and separating unsaturated fatty acid alkyl esters, characterized in that:
In the method described in (1), the filtrate obtained by filtration and separation of the urea adduct crystals and the washing solution obtained by washing the urea adduct crystals with a ketone-based organic solvent having a water content of 5% or less are distilled together to form a residue upper layer, Washing and desolvation to obtain a mixture of unsaturated fatty acid alkyl esters by subjecting the filtrate to a method of concentrating and separating unsaturated fatty acid alkyl esters, wherein the filtrate obtained by filtering and separating urea adduct crystals is used. The washing solution obtained by washing the urea adduct crystals with a ketone-based organic solvent having a water content of 5% or less is combined and distilled. The residue lower layer is heated and dissolved together with the urea adduct crystals, and left standing to separate into two layers. The urea solution as the lower layer is recycled and used for the urea addition treatment. The method for concentrating and separating unsaturated fatty acid alkyl esters, and (5) the ketone organic solvent is acetone That (1) to about concentration and separation process of unsaturated fatty acid alkyl ester according to any one of (4).

[0007] Ketone-based organic solvents have very low urea solubility and are not suitable for use alone as a urea addition treatment solvent. Therefore, by adding water having high urea solubility, it can be used as a urea addition treatment solvent. Therefore, the ketone-based organic solvent used as the processing solvent needs to dissolve water, and acetone, methyl ethyl ketone and the like can be used. However, since the solubility of water is high, urea can be dissolved at a high concentration, Acetone is preferred because of its low cost and low distillation recovery cost.

Although the amount of water in the processing solvent can be set arbitrarily,
The amount of urea needed to add urea must be dissolved,
Also, in recovering urea from the urea adduct crystals, it is necessary to have a sufficient amount of water to dissolve the urea adduct crystals,
Furthermore, considering that the solubility of the fatty acid ester mixture in the processing solvent decreases when the water content is high, the water content is
10-85% is preferred. The ratio of the fatty acid ester mixture, urea, and solvent to be charged in the urea addition treatment can be changed depending on the ratio of the saturated / unsaturated fatty acid ester in the fatty acid ester mixture.
In the case of 75% by weight, the weight of the fatty acid ester mixture is 1
The appropriate range is 1.5 to 4.5 weight of urea and 2 to 15 volumes of solvent.

In the present invention, the fatty acid alkyl ester includes, but is not limited to, methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester and the like. The fatty acid alkyl ester can be obtained by subjecting a vegetable oil such as evening primrose oil or the like to a transesterification reaction in addition to a marine oil such as sardine oil, tuna oil, shark liver oil, scallop liver oil and the like. Urea is added to a mixture of water and a ketone-based organic solvent, and the mixture is heated and stirred at a temperature up to the boiling point of the ketone-based organic solvent to dissolve the urea, and the fatty acid ester mixture is added to the urea solution and stirred. Is cooled to precipitate urea adduct crystals. Cool the reaction solution at 0-30 ° C
Is economical and preferred. The cooled treatment liquid is filtered under pressure or under reduced pressure so as to leave as little filtrate as possible on the crystals.

The separated crystals are washed with the same ketone-based organic solvent used as the processing solvent and having the lowest possible water content. It is possible to use a different solvent from the one used for the processing solvent.
It is necessary to perform an operation of separating different solvents, and the operation becomes complicated. Therefore, it is preferable to use a solvent of the same kind as the treatment liquid for washing. The solvent used for washing preferably has as low a water content as possible, and when the crystals are washed with a solvent having a high moisture content, a part of the adduct crystals holding the saturated fatty acid ester dissolves and the saturated fatty acid ester is mixed. As a result, the unsaturated fatty acid ester content of the washing solution is reduced.
It is preferable to use an anhydrous solvent, but practically 5%
It can be used even if it contains water within the range.

Since the ketone organic solvent has a low solubility of urea, washing with a solvent having a low water content elutes only the unsaturated fatty acid ester from the adduct crystals without dissolving the urea. As compared with the case of using a solvent having a high solubility of urea as described above, the content of the unsaturated fatty acid ester contained in the cleaning solution is high, and the recovery rate is high. The amount of the solvent used for washing can be used in a large amount because the crystals are hardly dissolved, but the amount can be sufficiently washed so that the crystals are immersed.

The filtrate and the washing solution are distilled together, and the distillation is terminated when the temperature of the distillation residue is 5 to 10 ° C. higher than the boiling point of the solvent when water is not contained. When the distillate becomes difficult to distill, the distillation is stopped to leave water in the residue. By removing most of the ketone-based solvent by distillation and increasing the water content of the residue, the solubility of the fatty acid ester dissolved by the dissolving action of the ketone-based organic solvent is reduced and separation can be performed. The water content of the fraction obtained by distillation is less than 5%, and most of the remaining water in the reaction solvent remains in the distillation residue.

The distillation residue is composed of an ester mixture containing a large amount of unsaturated fatty acid which did not form a urea adduct, water, urea,
It is composed of a non-evaporated ketone organic solvent. When the organic solvent contained in this residue is an alcohol-based organic solvent such as methanol, the emulsion is emulsified as described above. However, since the ketone-based organic solvent has a demulsifying effect, the residue is separated into two layers. I do. The separated upper layer is composed of an ester mixture containing a large amount of unsaturated fatty acid and a small amount of a ketone-based organic solvent, and the lower layer is composed of an aqueous solution of a ketone-based organic solvent containing urea. The remaining solvent is distilled off to obtain a non-urea-added oil.

The lower layer is heated together with the filtered urea adduct crystals to dissolve the adduct crystals. After the crystals are dissolved, 2
Allow to stand until separated into layers and separate into upper and lower layers. The upper layer is an ester mixture containing a large amount of saturated fatty acid formed as an adduct with urea, and contains a small amount of a ketone-based organic solvent. To obtain a urea-added oil. The separated lower layer contains urea, water, and a ketone-based organic solvent, and can be used again for the urea addition treatment after adjusting the components by adding each component. The process of the present invention is schematically shown in FIG.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Comparative Examples] Examples of the conventional methanol method are described below. The analysis conditions of the gas chromatograph (hereinafter referred to as GLC) in the control examples and examples are as follows. The amounts of each component were indicated by area percentage. (1) Column (2) Carrier gas Helium 12 ml / min (3) Detector Flame ionization detector (4) Temperature Each temperature condition of the column oven, the detector, and the injection port is shown in each example.

[Comparative Example 1] The GLC temperature conditions in this example are as follows. Column oven 225 ° C. Detector 240 ° C. Inlet 240 ° C. 300 g of urea was added to 800 ml of methanol and dissolved by heating under reflux. 100 g of sardine oil fatty acid ethyl ester mixture (ethyl icosapentaenoate (GLC analysis)
21.5% of EPA-Et) and 6.6% of ethyl docosahexaenoate (hereinafter referred to as DHA-Et) were added, and the mixture was cooled to 15 ° C with stirring. The precipitated crystals are filtered under reduced pressure,
When the outflow of the filtrate was stopped, the crystals were washed with 100 ml of methanol cooled to 10 ° C. The filtrate and the washing were combined and distilled under normal pressure. When the distillation of methanol stopped, distillation was stopped, and 500 ml of water was added to the residue, followed by stirring at 60 ° C. for 20 minutes to dissolve urea crystals.

After the solution was cooled to 40 ° C. or lower, 500 ml of hexane was added thereto, and the mixture was stirred for 10 minutes to extract the oil component with hexane, and the lower layer of the residue was separated. Further residue is hexane 500
Extraction was performed twice with each ml to obtain a total of three hexane extracts. The combined hexane extracts were washed twice with 100 ml of water and then distilled to remove hexane. Hexane extracted oil is 5
4.1 g was obtained and contained 34.2% of EPA-Et and 10.4% of DHA-Et by GLC. The hexane extraction residue was dissolved by heating together with the filtered crystals, and the oil was extracted three times with 500 ml each of hexane. The hexane extract was washed twice with 100 ml of water and distilled, and the solvent was distilled off to obtain 43.3 g of an oil. This is GL
C contained EPA-Et 5.5% and DHA-Et 1.8%. About 1 L of extraction residue was obtained, containing a large amount of urea.
Since it also contained 00 ml of water, it was not reused.

[Comparative Example 2] The GLC temperature condition of this example is the same as that of Comparative Example 1. Add 300 g of urea to 1 L of methanol,
The mixture was dissolved by heating under reflux. 100 g of sardine oil fatty acid ethyl ester mixture (23.2% EPA-Et by GLC analysis, D
HA-Et 9.1%) and cooled to 10 ° C. with stirring. The precipitated crystals were filtered under reduced pressure, and when the outflow of the filtrate was stopped, the crystals were washed with 75 ml of methanol cooled to 5 ° C. The filtrate and the washing were combined and distilled under normal pressure. When the distillation of methanol stopped, distillation was stopped, and 500 ml of water was added to the residue, followed by stirring at 60 ° C. for 20 minutes to dissolve urea crystals.

After the solution was cooled to 40 ° C. or lower, 500 ml of hexane was added, and the mixture was stirred for 10 minutes to extract an oil component with hexane, and the lower layer of the residue was separated. Further residue is hexane 500
Extraction was performed twice with each ml to obtain a total of three hexane extracts. The combined hexane extracts were washed twice with 100 ml of water and then distilled to remove hexane. Hexane extracted oil is 5
7.1 g was obtained and contained 33.6% of EPA-Et and 12.9% of DHA-Et by GLC. The hexane extraction residue was dissolved by heating together with the filtered crystals, and the oil was extracted three times with 500 ml each of hexane. The hexane extract was washed twice with 100 ml of water and distilled, and the solvent was distilled off to obtain 41.0 g of an oil. This is GL
C contained 8.5% EPA-Et and 3.4% DHA-Et. About 1 L of extraction residue was obtained and contained a large amount of urea.
Since it also contained 00 ml of water, it was not reused.

[Comparative Example 3] The GLC temperature conditions in this example are as follows. Column oven 190 ° C Detector 220 ° C Inlet 220 ° C 300 g of urea was added to 700 ml of methanol and dissolved by heating under reflux. To this solution was added 100 g of a fatty acid ethyl ester mixture containing 38.4% of ethyl oleate, 10.3% of ethyl linoleate, and 17.2% of ethyl γ-linolenate, and the mixture was cooled to 15 ° C with stirring. The precipitated crystals were filtered under reduced pressure. When the filtrate no longer flowed out, the crystals were washed with 100 ml of methanol cooled to 10 ° C. The filtrate and the washing were combined and distilled under normal pressure to remove methanol, and then 500 ml of water was added to the residue, followed by stirring at 60 ° C. for 20 minutes to dissolve urea crystals.

After the solution was cooled to 40 ° C. or lower, 500 ml of hexane was added thereto, and the mixture was stirred for 10 minutes to extract the oil content with hexane, and the lower layer of the residue was separated. Further residue is hexane 500
Extraction was performed twice with each ml to obtain a total of three hexane extracts. The combined hexane extracts were washed twice with 100 ml of water and then distilled to remove hexane. Hexane extracted oil is 1
GLC contained 17.1% of ethyl oleate, 13.2% of ethyl linoleate, and 67.5% of ethyl γ-linolenate by GLC. The hexane extraction residue was dissolved by heating together with the filtered crystals, and the oil was extracted three times with 500 ml each of hexane.
The hexane extract is washed twice with 100 ml of water and distilled.
The solvent was distilled off to obtain 81.9 g of an oil. This is GLC, 42.5% ethyl oleate, 9.7% ethyl linoleate, γ
-Contains 7.6% of ethyl linolenate. About 800 ml of extraction residue is obtained and contains a large amount of urea, but about 500 ml
No water was reused.

[0022]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited by these examples. [Example 1] The GLC temperature conditions in this example are as follows. Column oven 225 ° C Detector 240 ° C Inlet 240 ° C 80% 80% acetone water was added to 300 ml of urea and dissolved by heating under reflux. 100 g of sardine oil fatty acid ethyl ester mixture (EPA-Et 21.5% by GLC analysis, DHA-Et 6.6
%) And cooled to 15 ° C. with stirring.
The precipitated crystals were filtered under reduced pressure. When the filtrate no longer flowed out, the crystals were washed with 100 ml of acetone having a water content of 0.5%. The filtrate and washings were distilled together under normal pressure. When the temperature of the distillation residue reached 65 ° C, the distillation was stopped. After leaving still for 10 minutes, the lower layer was separated and the upper layer was washed twice with 30 ml of water. Thus, 42.0 g of urea-free oil was obtained. This is GLC and EPA-Et 47.2
% DHA-Et 14.2%.

The lower layer was combined with the crystals, heated and stirred, dissolved and allowed to stand to separate into two layers, and the upper layer was washed twice with 30 ml of water to obtain 56.4 g of a urea-added oil. This is GLC and EPA-Et 2.3
%, DHA-Et 0.9%. 734.6 g of the lower layer was obtained, and 10 ml was collected for the purpose of component analysis.
The distillation residue was measured. The amount of evaporation residue of this measurement value is regarded as the amount of urea, the remaining water amount and acetone amount are calculated, and based on this value, the amount of urea, water and acetone of 734.6 g of the lower layer obtained is calculated and prepared for recycling. Was.

Embodiment 2 The GLC temperature conditions in this embodiment are the same as those in Embodiment 1. 734.6 g of the lower layer obtained in Example 1 had a composition of 294.0 g of urea, 149.5 g of water, and 291.1 g of acetone. 6 g of urea, 0.5 g of water and 379.5 g of acetone were added thereto and dissolved by heating and stirring. Add 100g of fatty acid ethyl ester mixture (EPA-Et 23.2% by GLC analysis, DHA-Et
9.1%) and cooled to 10 ° C. with stirring. The precipitated crystals were filtered under reduced pressure. When the filtrate no longer flowed out, the crystals were washed with 100 ml of acetone having a water content of 1.2%. The filtrate and washings were distilled together under normal pressure. When the temperature of the distillation residue reached 65 ° C, the distillation was stopped. After leaving still for 10 minutes, the lower layer was separated and the upper layer was washed twice with 30 ml of water. Thus, 40.9 g of urea-free oil was obtained. This is GLC and EPA-Et 5
It contained 1.1% and 20.0% DHA-Et.

The lower layer was combined with the crystals, heated and stirred, dissolved and allowed to stand to separate into two layers, and the upper layer was washed twice with 30 ml of water to obtain 57.4 g of a urea-added oil. This is GLC and EPA-Et 3.7
%, DHA-Et 1.4%. 819.2 g of the lower layer was obtained, and 10 ml was collected for the purpose of component analysis.
The distillation residue was measured. The residual amount of evaporation of this measurement value is regarded as the amount of urea, the remaining water amount and acetone amount are calculated, and the urea, water and acetone amounts of the lower layer 819.2 g obtained based on these values are calculated and prepared for recycling. Was.

Example 3 The GLC temperature conditions in this example are as follows. Column oven 190 ° C. Detector 220 ° C. Inlet 220 ° C. 300 g of urea was added to 1 L of 85% acetone water and dissolved by heating under reflux. To this solution was added 100 g of a mixture of fatty acid ethyl esters containing ethyl γ-linolenate (containing 38.4% of ethyl oleate, 10.3% of ethyl linoleate, and 17.2% of ethyl γ-linolenate by GLC analysis), and stirred. ° C
Cooled down. The precipitated crystals were filtered under reduced pressure, and when there was no more outflow of the filtrate, acetone 100% with a water content of 2.3% was used.
The crystals were washed with ml. The filtrate and washings were distilled together under normal pressure. When the temperature of the distillation residue reached 65 ° C, the distillation was stopped. After leaving still for 10 minutes, the lower layer was separated and the upper layer was washed twice with 30 ml of water. Thus, 19.6 g of urea-free oil was obtained. This is GL
C is ethyl oleate 6.1%, ethyl linoleate 12.2
%, 72.4% ethyl γ-linolenate.

The lower layer was combined with the crystals, heated and stirred, dissolved and allowed to stand to separate into two layers, and the upper layer was washed twice with 30 ml of water to obtain 78.6 g of a urea-added oil. It contained 46.3% ethyl oleate, 9.8% ethyl linoleate, and 3.3% ethyl γ-linolenate by GLC. The lower layer was obtained in an amount of 823.3 g, and 10 ml was collected for the purpose of component analysis, and the weight, moisture, and distillation residue were measured. The residual amount of evaporation of this measurement value is regarded as the amount of urea, the remaining water amount and acetone amount are calculated, and based on this value, the amount of urea, water and acetone in the lower layer of 823.3 g is calculated and prepared for recycling. Was.

Embodiment 4 The GLC temperature conditions in this embodiment are the same as those in Embodiment 1. 330 g of urea was added to 330 ml of 23% methyl ethyl ketone water and dissolved by heating. Add 100g of fatty acid ethyl ester mixture (EPA-Et 21.5 by GLC analysis)
%, DHA-Et6.6%) and cooled to 15 ° C. with stirring. The precipitated crystals were filtrated under reduced pressure, and when the outflow of the filtrate was stopped, the crystals were washed with 300 ml of methyl ethyl ketone having a water content of 0.2%. The combined filtrate and washings are 70
Distillation under reduced pressure was carried out at ℃, distillation was stopped when the distillate distills almost disappeared. After standing for 10 minutes, the lower layer was separated. The upper layer was washed three times with 50 ml of water and distilled under reduced pressure to remove urea. 50.1 g of oil was obtained. This is GLC with EPA-Et 38.1%, DH
It contained 11.6% A-Et.

The lower layer was combined with the crystals, heated and stirred, dissolved and allowed to stand to separate into two layers. The upper layer was washed three times with 50 ml of water and distilled under reduced pressure to obtain 48.3 g of a urea-added oil. This is GLC
Contained 4.1% of EPA-Et and 1.4% of DHA-Et. 532.2 g of the lower layer was obtained, and 10 ml was collected for the purpose of component analysis, and the weight, moisture, and distillation residue were measured. The amount of residual evaporation of this measurement value is regarded as the amount of urea, the amount of remaining water and the amount of methyl ethyl ketone are calculated, and the amount of urea, water and methyl ethyl ketone in the lower layer 532.2 g obtained based on these values is calculated and prepared for recycling. Was.

Embodiment 5 The GLC temperature conditions in this embodiment are as follows. Column oven 190 ° C Detector 220 ° C Inlet 220 ° C 75% acetone water 650ml was added to 650ml, heated and refluxed to dissolve. To this solution was added 100 g of a fatty acid ethyl ester mixture containing ethyl γ-linolenate (containing 38.4% of ethyl oleate, 10.3% of ethyl linoleate, and 17.2% of ethyl γ-linolenate by GLC analysis), and stirred.
Cooled to ° C. The precipitated crystals were filtered under reduced pressure, and when there was no more outflow of the filtrate, acetone 10% with a water content of 0.3% was removed.
The crystals were washed with 0 ml. The filtrate and washings were distilled together under normal pressure. When the temperature of the distillation residue reached 65 ° C, the distillation was stopped. After leaving still for 10 minutes, the lower layer was separated and the upper layer was washed twice with 30 ml of water. Thus, 20.3 g of urea-free oil was obtained. This is GL
C is ethyl oleate 4.1%, ethyl linoleate 15.3
%, 77.1% of ethyl γ-linolenate.

The lower layer was combined with the crystals, heated, stirred, dissolved and allowed to stand to separate into two layers, and the upper layer was washed twice with 30 ml of water to obtain 78.3 g of a urea-added oil. It contained 47.1% ethyl oleate, 8.9% ethyl linoleate and 1.6% ethyl γ-linolenate by GLC. 579.2 g of the lower layer was obtained, and 10 ml was collected for the purpose of component analysis, and the weight, water content, and distillation residue were measured. The residual amount of evaporation of this measurement value is regarded as the amount of urea, the remaining water amount and acetone amount are calculated, and the urea, water and acetone amounts of the lower layer 579.2 g obtained based on these values are calculated and prepared for recycling. Was.

Embodiment 6 The GLC temperature conditions in this embodiment are as follows. Column oven 225 ° C Detector 240 ° C Injector 240 ° C 220 g of urea was added to 700 ml of 80% acetone water and dissolved by heating under reflux. 100 g of tuna oil fatty acid ethyl ester mixture (7.6% EPA-Et and 27.8% DHA-Et by GLC analysis)
And cooled to 15 ° C. with stirring. The precipitated crystals were filtered under reduced pressure. When the filtrate no longer flowed out, the crystals were washed with 100 ml of acetone having a water content of 0.4%. The filtrate and washings are distilled together under atmospheric pressure, and the distillation residue temperature is
When the temperature reached 65 ° C., the distillation was stopped, and the mixture was allowed to stand for 10 minutes, and then the lower layer was separated. The upper layer was washed twice with 30 ml of water to obtain 40.6 g of a urea-free oil. This is GLC, EPA-Et17.5%, DH
It contained 63.9% of A-Et.

The lower layer was combined with the crystals, heated, stirred, dissolved and allowed to stand to separate into two layers. The upper layer was washed twice with 30 ml of water to obtain 57.6 g of a urea-added oil. This is GLC and EPA-Et0.7
%, DHA-Et 2.4%. The lower layer was 614.2 g, and 10 ml was collected for the purpose of component analysis.
The distillation residue was measured. The residual amount of evaporation of this measured value is regarded as the amount of urea, the amount of remaining water and the amount of acetone are calculated, and the amount of urea, water and acetone in the lower layer 614.2 g obtained based on these values is calculated and prepared for recycling. Was.

[0034]

According to the present invention, there is no transesterification reaction with the solvent used during separation and purification, and the ester obtained by purification is more unsaturated fatty acid than the fraction obtained by the conventional methanol method. The alkyl ester becomes highly pure.
Furthermore, urea can be easily recycled and separation and purification can be performed efficiently even though only one kind of organic solvent is used.

[Brief description of the drawings]

FIG. 1 shows a flowchart.

Claims (5)

[Claims] 1. An unsaturated fatty acid alkyl comprising heating and mixing a mixture of urea and a fatty acid alkyl ester in a mixture of water and a ketone-based organic solvent, cooling the resulting mixture, and filtering and separating urea adduct crystals formed. A method for concentrating and separating esters. 2. The unsaturated fatty acid according to claim 1, wherein after filtering the urea adduct crystals, the urea adduct crystals are washed with a ketone-based organic solvent having a water content of 5% or less. A method for concentrating and separating alkyl esters. 3. The method according to claim 1, wherein the filtrate obtained by filtering and separating the urea adduct crystals and the washing liquid obtained by washing the urea adduct crystals with a ketone-based organic solvent having a water content of 5% or less are distilled together. A method for concentrating and separating unsaturated fatty acid alkyl esters, wherein the residue upper layer is washed with water and desolvated to obtain a mixture of unsaturated fatty acid alkyl esters. 4. The method according to claim 1, wherein the filtrate obtained by filtering and separating the urea adduct crystals and the washing liquid obtained by washing the urea adduct crystals with a ketone-based organic solvent having a water content of 5% or less are distilled together. The lower layer of the residue is heated and dissolved together with the urea adduct crystals, and left to separate into two layers. The lower layer urea solution is recycled and used for the urea addition treatment. A method for concentrating and separating esters. 5. The method for concentrating and separating unsaturated fatty acid alkyl esters according to claim 1, wherein the ketone organic solvent is acetone.