JPS62148449A - Production of oleic acid - Google Patents

Abstract

PURPOSE:To obtain highly purified oleic acid in high purity, by adding urea to an organic solvent solution of a fatty acid mixture containing oleic acid, removing higher fatty acid from the mixture, separating the fatty acid mixture as a urea adduct and removing lower fatty acid from the adduct. CONSTITUTION:Highly purified oleic acid can be produced by (A) dissolving urea and a fatty acid mixture containing oleic acid in an organic solvent, cooling the solution to <=30 deg.C and separating and removing >=16C saturated fatty acids and mono-unsaturated fatty acids higher than oleic acid in the form of urea adduct, (B) dissolving urea in the above organic solvent solution, cooling the mixture and separating precipitated crystal (urea adduct of mixed fatty acids), (C) mixing >=50wt%, preferably >=70wt% of the crystal produced in the step B with water to separate and recover the fatty acid mixture, (D) dissolving the fatty acid mixture obtained by the step C and the remaining part of the crystal obtained by the step B in an organic solvent to effect partial saponification, cooling the reaction mixture and collecting the precipitated crystal (acidic salt of oleic acid) and (E) decomposing said crystal with an acid.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing highly purified oleic acid from a fatty acid mixture containing oleic acid.

[Conventional technology]

Oleic acid (cis-9-octadecene m>) is a typical monounsaturated fatty acid that constitutes natural oils and fats and biological lipids, and is an extremely important substance industrially and biologically.

Highly purified oleic acid is not only colorless, odorless, highly stable, and safe, but also has many excellent properties such as physical, chemical, and physiological properties. This has become clear in recent years. Accordingly, medicines,
Life sciences such as cosmetics and food, biosciences such as biosensors and biosurfactants,
Applications are becoming more active in fine chemical fields such as electronics, which aim to imitate biological functions, and in various cutting-edge fields that are currently opening up.

However, conventional commercially available oleic acid contains fatty acid homologs with different carbon chain lengths and degrees of unsaturation, and its purity ranges from 60% to 60%.
It is as low as 90% and also contains various trace impurities. For this reason, conventional commercially available oleic acid not only has insufficient qualities such as color, odor, stability, and safety, but also is unable to fully exhibit the functions unique to oleic acid.

Generally, methods for increasing the purity of fatty acids include solvent fractionation,
Various methods such as emulsion fractionation and urea fractionation have been known for a long time, and in recent years, chromatographic methods using adsorbents, ion exchange resins, etc. have been applied. However, these methods are not suitable as means for industrial production of highly pure fatty acids in terms of separation and purification, processing capacity, manufacturing cost, etc.

There is still a method to partially hydrogenate polyunsaturated fatty acids such as linoleic acid and lylunic acid to increase the purity of oleic acid.
There is a problem in that positional isomers and stereoisomers are generated.

[Problem that the invention seeks to solve]

As the uses of oleic acid have diversified and the demand has increased, high purity and high quality oleic acid has come to be required.

The object of the present invention is to obtain highly purified oleic acid from a wide range of raw materials without producing positional or stereoisomers.

[Means for solving problems]

The present invention involves (a) dissolving a fatty acid mixture containing oleic acid and urea in an organic solvent, cooling the mixture, separating and removing the precipitated crystals, and (b) adding urea to the organic solvent solution, dissolving it, and then cooling the mixture. (3) Separate and recover the fatty acid mixture by mixing 50% by weight or more of the crystals with water; (2) Collect the recovered fatty acid mixture and the remainder of the crystals from step (3) in an organic solvent. This is a method for producing oleic acid, which is characterized by dissolving and partially saponifying the oleic acid, cooling and separating the precipitated crystals, and (e) decomposing the obtained crystals with an acid.

Step (a) is a step in which higher saturated fatty acids having 16 or more carbon atoms and higher monounsaturated fatty acids than oleic acid are separated and removed as crystals of urea adducts from a fatty acid mixture containing oleic acid.

The (b) step is a step in which the fatty acid mixture containing oleic acid is separated as urea adduct crystals from the organic solvent solution obtained in the (a) step, and some of the impurities are removed while remaining in the solution. It is something to do.

Step (c) is a step of recovering a fatty acid mixture containing oleic acid from the crystals of the urea adduct obtained in step (b).

B) step is to remove polyunsaturated fatty acids such as linoleic acid, monounsaturated fatty acids lower than oleic acid, lower saturated fatty acids, and impurities other than fatty acids from the fatty acid mixture containing oleic acid obtained in step (c). It is a process.

Step (e) is a step of obtaining free oleic acid from the crystals of the acid salt of oleic acid obtained in step (e).

Since impurities other than oleic acid can be efficiently separated and removed by the steps (a) to (e) above, highly purified oleic acid can be produced. Note that the isomers of oleic acid are separated and removed in steps (a), (b), and (b).

Furthermore, the degree of layer separation and purification can be improved by repeating step (e), and by performing adsorbent treatment or distillation after step (e), steps from (a) to (e) Since it is possible to remove trace impurities that could not be separated and removed in the process or those that have been contaminated, oleic acid with a higher degree of separation and purification can be produced.

Any fatty acid mixture containing oleic acid used as a raw material can be used as long as it contains oleic acid, such as olive oil, sesame oil, rice bran oil, soybean oil, tea seed oil, camellia oil, corn oil, rapeseed oil, Fatty acids obtained by hydrolyzing animal and vegetable oils such as palm oil, peanut oil, safflower oil, beef tallow, pork fat, chicken oil, mutton fat, and fish oil, as well as mixtures thereof, can be used, and commercially available oleic acid containing impurities can be used. It can also be used as a raw material. Naturally, a raw material with a high content of oleic acid can efficiently obtain oleic acid of high purity.

(a) Organic solvents used in the process include methanol,
Lower alcohols such as ethanol, n-glopanol, and isopronoquinol, and mixed solvents containing these as main components are used. The amount of organic solvent used depends on the composition of the raw fatty acids,
Although it cannot be determined in part depending on the target purity and yield, and the setting of the number of crystallizations, 0.5~
10 times by weight is preferred. If it is less than 0.5 times by weight, the separation effect will be reduced, and if it is more than 10 times by weight, the fatty acid concentration will be low and production efficiency will be reduced, which is disadvantageous.

The amount of urea used is determined by the composition of the raw fatty acid, the target purity and yield, the crystallization temperature, the amount of solvent, etc. It is preferably 3 to 50 times the total amount by weight of higher monounsaturated fatty acids. If it is less than 3 times by weight, removal of saturated fatty acids having 16 or more carbon atoms and monounsaturated fatty acids higher than oleic acid will be insufficient, and if it is more than 50 times by weight, the yield of oleic acid will decrease.

(a) Step is to add a fatty acid mixture containing urea and oleic acid to an organic solvent, dissolve it by heating, and then gradually cool it.
The temperature is usually 30°C or lower, preferably in the range of 20 to 0°C.

Saturated fatty acids having 16 or more carbon atoms, monounsaturated fatty acids higher than oleic acid, etc. form adducts with urea and crystallize, so these crystals are removed by conventional means such as filtration or centrifugation.

Usually, it is sufficient to carry out step (a) once, but it may be repeated if separation of saturated fatty acids having 16 or more carbon atoms or monounsaturated fatty acids higher than oleic acid is insufficient.

In the step (b), urea is added to the organic solvent solution obtained in the step (a), dissolved by heating, and then gradually cooled to 20 to 0°C.

The fatty acid mixture containing oleic acid crystallizes as a urea adduct, which is separated by conventional means. The amount of urea used is suitably 2 to 5 times the weight of oleic acid present in the organic solvent solution obtained in step (a). 2
If it is less than 5 times the weight, the recovery rate of oleic acid will decrease, and if it is more than 5 times the weight, the amount of crystals of the impurity urea adduct will increase, and furthermore, crystals of urea alone will be formed, resulting in a poor crystal state. It is.

In step (c), 50% by weight or more, preferably 70% by weight or more of the crystals of the urea adduct of the fatty acid mixture containing oleic acid obtained in step (b) are mixed with water and hydrolyzed, and the oleic acid A fatty acid mixture containing the following is obtained by static separation or centrifugation. The amount of water used may be at least an amount that can hydrolyze the urea adduct crystals, but from the viewpoint of work efficiency, it is preferably 2 to 5 times the weight of the urea adduct crystals. In this case, it is advantageous to use a dilute acid aqueous solution because the separation state is improved. The acids used here include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, carbonic acid, and boric acid, as well as acetic acid, oxalic acid, malonic acid, cono-phosphoric acid, and Organic acids such as golic acid, tartaric acid, and citric acid can be used.

2) Step (3) The fatty acid mixture containing oleic acid obtained in step (3) and the remainder of the crystals of the urea adduct are dissolved in an organic solvent and partially saponified with an alkaline substance, and then 1
The mixture is slowly cooled to 0 to -20°C to precipitate oleic acid as acid salt crystals, which are separated.

By adding a portion of the urea adduct crystals without decomposition, urea forms an adduct with an acidic salt of oleic acid, resulting in hard and free crystals that improve filterability. This is preferable because separation efficiency is improved. Examples of organic solvents include methanol, ethanol, impropatol, n-butanol, imbutanol, acetyl,
Methyl ethyl ketone, diethyl ether, ethyl acetate,
Polar solvents such as acetonitrile and hydrated products of these solvents can be used. The crystallization rate and crystalline state of the oil/acid acid salt can be controlled by controlling the water content of the solvent.

The amount of solvent used is preferably 1 to 10 times the combined amount of the fatty acid mixture containing oleic acid and the crystals of the urea adduct;
If it is less than 1 times the weight, the separation and purification effect will be poor;
If the amount of 0Tff is too large, the concentration will become too thin and workability will decrease. As the alkaline substance, hydroxides and carbonates of lithium, sodium, potassium, ammonia, etc. can be used, and the saponification rate is preferably from 40% of the oleic acid content to 60% of the total fatty acid content.

If the saponification rate is less than 40 parts of the oleic acid content, the crystallization rate of the oleic acid acid salt will decrease, and if it is more than 60 parts of the total fatty acid content, the separation effect will decrease and the crystal state will deteriorate, resulting in poor filterability. . In addition, the cooling temperature for crystallizing the oleic acid acid salt is preferably 10 to -20'C; if it is higher than 10C, the crystallization rate will be low and the oleic acid yield will be reduced, and if it is lower than -20C, the oleic acid yield will be lowered. Impurities also crystallize, reducing the degree of separation and purification.

Furthermore, the crystals of oleic acid acid salt obtained in step (2) are as follows:
By repeating crystallization, the degree of separation and purification can be further improved.

In step (e), the oleic acid acid salt obtained in step (v) is mixed with an acidic aqueous solution and heated to undergo acid decomposition to obtain free oleic acid.

Acids used for acid decomposition include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, carbonic acid, and boric acid, as well as acetic acid, oxalic acid, malonic acid, succinic acid, malic acid, Organic acids such as tartaric acid and citric acid can be used. The amount of acid used is at least the equivalent of the base forming the acidic salt of oleic acid, preferably at least 1.2 equivalents.

After acid decomposition, the acid used for acid decomposition remaining in oleic acid is removed by washing with water. Adding a small amount of polybasic acid such as oxalic acid or citric acid during this water washing can prevent emulsification during water washing, and complete acid decomposition of the oleic acid salt.

Highly pure oleic acid can be obtained in this way, but in order to further remove trace amounts of impurities, it is also possible to perform adsorbent treatment and distillation, which are commonly used in the purification of fatty acids.

Adsorbents used for adsorbent treatment include white clay, activated clay,
There are activated carbon, silica gel, alumina gel, silica alumina gel, ion exchange resin, synthetic adsorbent, etc., which can be used alone or as a mixture. The amount of adsorbent used varies depending on the degree of purification of oleic acid and the target quality, but is 0.1 to 5% by weight based on oleic acid. The temperature of the adsorbent treatment is higher than the melting point of oleic acid, preferably 20 to 70°C.
It is. Processing time is 20 minutes to 2 hours.

Distillation is carried out under reduced pressure in an atmosphere of inert scum according to the method normally used for distillation of oleic acid, but it is desirable to carry out low-temperature distillation under as high a vacuum as possible.

〔Effect of the invention〕

By the method of the present invention, using a wide range of raw materials and a simple process, we can improve all quality aspects such as stability against chemicals, acids and bases, and safety for living organisms.
It is possible to obtain highly purified oleic acid whose quality has been improved to a level that was difficult to reach using conventional techniques.

The highly purified oleic acid thus obtained has the following properties.

■High purity, colorless and odorless.

■Contains no trace impurities such as oxidation products that cause deterioration.

■Excellent resistance to heat, oxidation, and drugs.

■Highly safe for living organisms.

■Exhibits physical properties unique to oleic acid, such as a sharp crystalline winter phenomenon.

Utilizing these properties, oleic acid obtained by the method of the present invention can be used in a wide range of fields, including fine chemical fields such as pharmaceuticals, cosmetics, biochemicals, and electronics, as well as various cutting-edge technology fields that are currently being developed. It can be used in

〔Example〕

The present invention will be explained by examples. In the examples, ``chi'' indicates weight unless otherwise specified.

Example 1 Add urea 16505' to methanol 5000F and make 60
After melting at 60°C, 1000 g of oleic safflower oil distilled fatty acid heated to 60°C was added and dissolved. Next, it was cooled to 15°C over 5 hours with stirring, and the crystals formed were separated and removed by centrifugal filtration to obtain filtrate 58571 (containing fatty acids 552
9) was obtained. Add urea 13509 to this filtrate and heat at 60°C.
After dissolution, the mixture was cooled to 15° C. over 5 hours with stirring and filtered to obtain 1812 crystals of the urea adduct. The crystals of this urea adduct were mixed with 0.5% citric acid solution tL54362 and 50%
The mixture was mixed at a temperature of 0.degree. C., hydrolyzed, and allowed to separate into layers to obtain a fatty acid mixture 457F (Acid Fiffi 1985) containing oleic acid. This fatty acid mixture was mixed with 29% sodium hydroxide. xr(
It was dissolved in 10% aqueous methanol 1585y containing 45% equivalent of the fatty acid mixture at 40°C, cooled to -5°C for 5 hours with stirring, and filtered to obtain crystals of oleic acid salt 4289 (acid salt content 4001). After adding 1666 F of water containing hydrochloric acid 502 (2 molar equivalents of the acid salt) to the crystals, they were mixed at 90°C for 2 hours for acid decomposition to obtain free oleic acid. % citric acid aqueous solution and dehydrated to obtain high purity oleic acid (A) 385F manufactured by Sui.

Example 2 Crystals of oleic acid acid salt obtained in the same manner as in Example 1 were dissolved in 10% aqueous methanol 1400F at 40°C, cooled to -5°C over 5 hours with stirring, and filtered to obtain crystals. 383f (acidic salt content 3722) was obtained. To the crystals, 3-hydrochloric acid solution 15452 was added and mixed at 90°C for 2 hours for acid decomposition. The resulting free oleic acid was thoroughly washed with 0.5% citric acid solution and then dehydrated to achieve high purity purification. Oleic acid (B) 358f' was obtained.

Example 3 Crystals of oleic acid acid salt obtained in the same manner as in Example 2 were dissolved in 13% aqueous methanol 13025' at 40°C, then cooled to -5°C with stirring for 5 hours, filtered, and dissolved. Crystal 365F (acidic salt content 3572) was obtained. 3% hydrochloric acid water 14802 was added to the crystals and mixed at 90°C for 2 hours for acid decomposition. The resulting free oleic acid was thoroughly washed with 0.5% citric acid water and then dehydrated to achieve high purity purification. Oleic acid (C) 3439 was obtained.

Example 4 0.0% activated carbon was added to the highly purified oleic acid obtained in Examples 1 to 3.
After adding 5% and stirring at 50° C. for 1 hour under a nitrogen gas atmosphere, the mixture was filtered to obtain highly purified oleic acids (A1), (B1), and (CI) treated with an adsorbent.

Example 5 Highly purified oleic acid obtained in Examples 1 to 3 was distilled at 1 m H9, 220°C or less under nitrogen gas blowing to obtain highly purified oleic acid (A2), (B2), (C2). ) was obtained.

Table 1 summarizes the composition and quality characteristics of the highly purified oleic acid of the present invention obtained in Examples 1 to 5 above and the commercially available oleic acid for comparison.

Test item (■) is based on gas chromatography using a capillary column. Oleic acid is C18: 1 ci3
It is shown as ω9.

■ is a value indicating the content of carbonyl compounds, which are typical trace impurities (milliequivalents/su).

(2) is an index evaluated by a sensory test, with O indicating no odor and 10 indicating the strength of the odor of commercially available oleic acid (A).

In (2) to (2), the larger the numerical value of the hue, the greater the degree of coloring and the worse the quality.

(2) is the hue after heating oleic acid at 205° C. for 1 hour in a nitrogen stream, indicating hue stability against heat.

(2) is the hue after heating oleic acid at 150° C. for 3 hours in the atmosphere, indicating hue stability against thermal oxidation.

■ Adds equimolar jetanolamine to oleic acid,
The hue after heating at 150° C. for 2 hours while stirring with nitrogen gas indicates hue stability against basic agents.

■ is oleic acid and para-toluenesulfonic acid.

05% and heated to 150°C while stirring with nitrogen gas.
The hue after heating for 1 hour indicates hue stability against acidic agents.

■ While stirring the oleic acid with aeration (300 g/min),
Peroxide value (milliequivalent/K) after heating at 60°C for 5 hours
f), the larger the value, the worse the oxidation stability.

0 is Tsutsugane method (The Journal of Dermatology,
Vol. 2, p. 19 (1975)) The results of a skin irritation test by K., where negative means no irritation and positive means strong irritation, indicate safety for living organisms.

Example 6 Add urea 1730F to methanol 5000F and heat to 60℃
Tea seed oil decomposition undistilled fatty acids 10 heated to 60℃ after dissolving in
009 was added and dissolved. Next, it was cooled to 10°C over 5 hours while stirring, and the crystals formed were separated by filtration to obtain a filtrate of 6270.
f (fatty acid content 508f) was obtained. This filtrate contains urea 13
After adding 30f and dissolving at 60°C, it was cooled to 10°C for 5 hours with stirring and filtered to obtain urea adduct crystal 1765f.
I got it. 0.5% of crystal 1588 of this urea adduct
Mix with IJ malic acid aqueous solution 47659 at 50 ° C., hydrolyze it, stand still and separate the layers to obtain fatty acid mixture 39 containing oleic acid.
85' (acid 1iffi 196.5) was obtained. This fatty acid mixture and crystals of the urea adduct 1772 were mixed with sodium hydroxide 31. Of (50 ti equivalents of fatty acid mixture) containing 1
It was dissolved in 0% aqueous methanol 17689 at 40°C, cooled to -7°C over 6 hours with stirring, and then separated to obtain crystals of oleic acid acid salt 4259C (acid salt content: 3979). After adding 5% aqueous phosphoric acid solution 1990F (1.5 molar equivalent of acid salt) to the crystals, the mixture was mixed at 90° C. for 2 hours and subjected to acid decomposition to obtain free oleic acid. This oleic acid is 0
．． After thorough washing with 5% IJ malic acid aqueous solution, it was dehydrated to obtain highly purified oleic acid (D) 382F.

Example 7 Crystals of oleic acid acid salt obtained in the same manner as in Example 6 were
After dissolving in 2% aqueous methanol 1191F at 40°C,
The mixture was cooled to -5° C. over 5 hours with stirring, and filtered to obtain crystal 380f (acidic salt content: 3692). 5 to this crystal
1852% phosphoric acid in ice water was added and mixed at 90°C for 2 hours for acid decomposition. The resulting free oleic acid was thoroughly washed with a 0.5% malic acid aqueous solution, and then dehydrated to obtain highly purified oleic acid ( E) 3559 was obtained.

Example 8 High-purity purified oleic acid obtained by adding 3% silica gel to the high-purity purified oleic acid obtained in Examples 6 and 7, stirring at 40 degrees for 1 hour under a nitrogen gas atmosphere, filtering and treating with an adsorbent. (Dl) and (El) were obtained.

Example 9 The highly purified oleic acids obtained in Examples 6 and 7 were distilled in the same manner as in Example 5 to obtain highly purified oleic acids (D2) and (E2).

The compositions and quality characteristics of the highly purified oleic acids of the present invention obtained in Examples 6 to 9 are summarized in Table 2 (2).

Example 10 Add methanol 3000PK urea 10602 and heat at 60°C
After dissolution, 1000F of olive oil-decomposed undistilled fatty acids heated to 60°C were added and dissolved. Then, while stirring, 15
℃ for 4 hours, the resulting crystals were filtered off, urea 7502 was added to the resulting filtrate, and dissolved again at 50°C, then cooled to 10°C with stirring, the resulting crystals were filtered off, and the filtrate 34882 (fatty acid content 4429) was obtained. Urea 1127F was added to this filtrate, dissolved at 60°C, cooled to 15°C over 5 hours with stirring, and filtered to obtain crystals of urea adduct 1502F. Add these crystals to a 0.5-tartaric acid aqueous solution 6
008f at 40°C, hydrolyzed and left to stand to separate the fatty acid mixture 375F (acid 11[11
96,7) was obtained. This fatty acid mixture was dissolved in 100% water-containing methanol 1500 PK containing potassium hydroxide 33.2 F (equivalent to 45% of the fatty acid mixture) at 35°C, cooled to -10°C in 6 hours with stirring, and then filtered to dissolve the oleic acid salt. Crystal 360? (acid fund z334 y)
I got it. Add 10% citric acid aqueous solution 2190f (
After adding 2 molar equivalents of the acid salt, the mixture was mixed at 90° C. for 2 hours and subjected to acid decomposition to obtain free oleic acid.

After thoroughly washing this oleic acid with a 0.5-tartaric acid aqueous solution, it was dehydrated to obtain highly purified oleic acid (F) 3222.

Example 11 Crystals of oleic acid acid salt obtained in the same manner as in Example 10 were dissolved in 80% aqueous acetone 1336F at 40°C, cooled to -2°C over 5 hours with stirring, and filtered to obtain crystals 3.
21 (acidic salt content 3127) was obtained. 10 in this crystal
Add 2,040 g of an aqueous solution of chicitric acid, mix at 90°C for 2 hours, and perform acid decomposition to reduce the resulting free and free oleic acid to 0.5%.
After thorough washing with an aqueous tartaric acid solution, the mixture was dehydrated to obtain highly purified oleic acid (G) 3005'.

Example 12 2% activated clay was added to the highly purified oleic acid obtained in Examples 10 and 11, and the mixture was heated at 40°C for 30 minutes in a nitrogen gas atmosphere.
After stirring for a minute, the mixture was filtered to obtain adsorbent-treated highly purified oleic acid (Fl) and (Gl).

Example 13 The high-purity 'liI oleic acid obtained in Examples 10 and 1 was distilled in the same manner as in Example 5 to obtain high-purity purified oleic acid (
F2) and (G2) were obtained.

Table 3 summarizes the composition and quality characteristics of the highly purified oleic acids of the present invention obtained in Examples 10 to 13.

The above results demonstrate that the present invention can almost completely remove saturated fatty acids, monounsaturated fatty acids other than oleic acid, polyunsaturated fatty acids such as linoleic acid, and other impurities contained in raw fatty acids. it is obvious.

In addition, the highly purified oleic acid obtained by the present invention is colorless and odorless because it has been purified to a level of 100 microns, and is also stable against heat, oxidation, and chemicals, and safe for living organisms. It turns out that it is excellent.

Claims (1)

[Claims] 1. (a) A fatty acid mixture containing oleic acid and urea are dissolved in an organic solvent and then cooled to separate and remove precipitated crystals; (b) urea is added and dissolved in the organic solvent solution. After cooling, the precipitated crystals are collected, (c) 50% by weight or more of the crystals are mixed with water to separate and recover the fatty acid mixture, (d) the recovered fatty acid mixture and the crystals from step (c) are separated and recovered. A method for producing oleic acid characterized by dissolving the remainder in an organic solvent, partially saponifying it, cooling it, separating the precipitated crystals, and (e) decomposing the obtained crystals with an acid. 2.(d) Claim 1 of repeating the crystallization process
A method for producing oleic acid as described in Section 1. 3. The method for producing oleic acid according to claim 1 or 2, wherein after step (e), an adsorbent treatment or distillation is performed.