JPH0335305B2 - - Google Patents

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. [Prior Art] Oleic acid (cis-9-octadecenoic acid) 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 and odorless, highly stable and safe, but also has many excellent properties such as physical, chemical, and physiological properties. has become clear in recent years. Accordingly, the fields of life science such as pharmaceuticals, cosmetics, and food, bioscience such as biosensors and biosurfactants, fine chemical fields such as electronics that aim to imitate biological functions, and various cutting-edge fields that are opening up today. Applications are becoming more active in the field. However, conventional commercially available oleic acid contains fatty acid homologues with different carbon chain lengths and degrees of unsaturation, has a low purity of 60 to 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. In general, various methods such as solvent fractionation, emulsion fractionation, and urea fractionation have been known as methods for increasing the purity of fatty acids, and in recent years, chromatographic methods using adsorbents, ion exchange resins, etc. have been applied. are doing. 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 also a method of partially hydrogenating polyunsaturated fatty acids such as linoleic acid and linolenic acid to increase the purity of oleic acid, but this method has the problem of generating positional and stereoisomers. [Problems to be Solved by the Invention] As the uses of oleic acid have diversified and the demand has increased, high purity and high quality oleic acid has also been 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 the Problems] The present invention provides (a) dissolving a fatty acid mixture containing oleic acid and urea in an organic solvent and then cooling it to separate and remove precipitated crystals; Add urea to the solution and dissolve it, then cool and separate the precipitated crystals, (c) mix 50% by weight or more of the crystals with water to separate and recover the fatty acid mixture, and (d) collect the recovered fatty acid mixture and (c) Production of oleic acid characterized by dissolving the remainder of the crystals in the step in an organic solvent, partially saponifying the solution, cooling and separating the precipitated crystals, and (e) decomposing the obtained crystals with an acid. It is the law. Step (a) is a step of separating and removing higher saturated fatty acids having 16 or more carbon atoms and monounsaturated fatty acids higher than oleic acid as crystals of urea adducts from a fatty acid mixture containing oleic acid. Step (b) is a step in which the fatty acid mixture containing oleic acid is separated as crystals of urea adducts from the organic solvent solution obtained in step (a), and some of the impurities are left in the solution and removed. 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). Step (d) involves converting the fatty acid mixture containing oleic acid obtained in step (c) into polyunsaturated fatty acids such as linoleic acid, monounsaturated fatty acids lower than oleic acid,
This is a process for removing lower saturated fatty acids and impurities other than fatty acids. Step (e) is a step of obtaining free oleic acid from the crystals of the acid salt of oleic acid obtained in step (d). 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 (d). Furthermore, the degree of separation and purification can be improved by repeating step (d), and by performing adsorbent treatment or distillation after step (e).
Since trace impurities that could not be separated and removed in steps (a) to (e) and trace impurities that have been contaminated can be removed, 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, palm oil, peanut oil, safflower oil,
Fatty acids obtained by hydrolyzing animal and vegetable oils such as beef tallow, lard, chicken fat, mutton fat, and fish oil, and mixtures thereof can be used, and commercially available oleic acid containing impurities can also be used as a raw material. As a matter of course,
The higher the oleic acid content of the raw material, the more highly purified oleic acid can be obtained. As the organic solvent used in step (a), lower alcohols such as methanol, ethanol, n-propanol, and isopropanol, and mixed solvents containing these as main components are used. The amount of organic solvent to be used cannot be determined unconditionally depending on the composition of the raw fatty acid, the target purity and yield, the number of crystallizations, etc., but it is preferably 0.5 to 10 times the weight of the raw fatty acid. If it is less than 0.5 times the weight, the separation effect will decrease,
If the amount is more than 10 times the 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 the monounsaturated fatty acid higher than oleic acid. If it is less than 3 times the 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 the weight, the yield of oleic acid will decrease. In the step (a), a fatty acid mixture containing urea and oleic acid is added to an organic solvent, dissolved by heating, and then gradually cooled to a temperature usually below 30°C, preferably in the range of 20 to 0°C. Saturated fatty acids with 16 or more carbon atoms and monounsaturated fatty acids higher than oleic acid 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 step (b), urea is added to the organic solvent solution obtained in step (a) and dissolved by heating, and then slowly 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 2 to 2 of the amount of oleic acid present in the organic solvent solution obtained in step (a).
5 times the weight is suitable. If it is less than 2 times by weight, the recovery rate of oleic acid will decrease, and if it is more than 5 times by weight, the amount of crystals of the impurity urea adduct will increase, and furthermore, crystals of urea alone will be formed, which will deteriorate the crystal state, which is disadvantageous. 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 above is obtained by static separation or centrifugation. The amount of water used should be at least the amount that can hydrolyze the urea adduct crystals, but from the viewpoint of work efficiency,
~5 times by weight is preferred. In this case, it is advantageous to use a dilute acid aqueous solution because the separation state is improved. The acids used here include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid,
Inorganic acids such as phosphorous acid, hypophosphorous acid, carbonic acid, and boric acid, and organic acids such as acetic acid, oxalic acid, malonic acid, succinic acid, malic acid, tartaric acid, and citric acid can be used. Step (d) involves dissolving the fatty acid mixture containing oleic acid obtained in step (c) and the remainder of the crystals of the urea adduct in an organic solvent, and partially saponifying the mixture with an alkaline substance at a temperature of 10 to -20°C. The solution is slowly cooled until oleic acid is precipitated as acid salt crystals and 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. As the organic solvent, polar solvents such as methanol, ethanol, isopropanol, n-butanol, isobutanol, acetone, methyl ethyl ketone, diethyl ether, ethyl acetate, and acetonitrile, and hydrated products of these solvents can be used. The crystallization rate and crystal state of the oleic acid salt can be controlled by controlling the water content of the solvent. The amount of solvent used is the combined amount of the fatty acid mixture containing oleic acid and the crystals of the urea adduct.
The amount is preferably 10 times by weight; if it is less than 1 times by weight, the separation and purification effect will be poor, and if it is more than 10 times by weight, the concentration will be too diluted and workability will be reduced. 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% of the oleic acid content, the crystallization rate of the oleic acid acid salt will decrease, and if it exceeds 60% 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, and if it is higher than 10°C, the crystallization rate will decrease and the oleic acid yield will decrease.
If the temperature is lower than -20°C, impurities will also crystallize, reducing the degree of separation and purification. Note that the degree of separation and purification of the crystals of the oleic acid acid salt obtained in step (d) can be further improved by repeating crystallization. In step (e), the oleic acid acid salt obtained in step (d) 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,
Organic acids such as succinic acid, malic acid, 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 water washing can prevent emulsification during water washing, and complete acid decomposition of the oleic acid salt. In this way, highly pure oleic acid is obtained, but in order to further remove trace impurities, the adsorbent treatment commonly used in the purification of fatty acids can also be carried out by distillation. Adsorbents used in the adsorbent treatment include clay, activated clay, activated carbon, silica gel, alumina gel, silica-alumina gel, ion exchange resins, synthetic adsorbents, and the like, which may 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. Processing time is 20 minutes to 2 hours. Distillation is carried out under reduced pressure in an inert gas atmosphere 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. [Effects of the Invention] The method of the present invention uses a wide range of raw materials through a simple process, and is superior to the conventional technology in all quality aspects such as stability against heat, oxidation, chemicals such as acids and bases, and safety for living organisms. It is possible to obtain highly purified purified oleic acid whose quality has been improved to a level that was difficult to reach. 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 thermal, oxidative and drug stability. Highly safe for living organisms. It exhibits physical properties unique to oleic acid, such as sharp crystal polymorphism. Taking advantage of these properties, oleic acid obtained by the method of the present invention is widely used in fine chemical fields such as pharmaceuticals, cosmetics, biochemicals, and electronics, as well as in various cutting-edge technology fields that are currently being developed. It can be used in a wide range of fields. [Example] The present invention will be explained with reference to an example. Note that in the examples, % indicates weight % unless otherwise specified. Example 1 1,650 g of urea was added to 5,000 g of methanol and dissolved at 60°C, and then 1,000 g of distilled fatty acid from oleracea flower oil 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 a filtrate of 5857 g (fatty acid content
552g) was obtained. Add 1350g of urea to this filtrate.
After dissolving at 60°C, the mixture was cooled to 15°C over 5 hours with stirring and filtered to obtain 1812 g of urea adduct crystals. Crystals of this urea adduct were dissolved in 0.5% citric acid aqueous solution 5436.
457g of fatty acid mixture containing oleic acid (acid value 198.5) by mixing with g at 50℃, hydrolyzing, and separating into layers by standing.
I got it. Add this fatty acid mixture to sodium hydroxide
29.1 g (45% equivalent of the fatty acid mixture) was dissolved in 1585 g of 10% aqueous methanol at 40°C, cooled to -5°C for 5 hours with stirring, filtered, and 428 g of crystals of oleic acid salt (acid salt content 400g) was obtained. Add 50 g of hydrochloric acid (2 molar equivalents of the acid salt) to this crystal.
After adding 1,666 g of water containing 1,666 g of water, 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% citric acid aqueous solution,
After dehydration, 385 g of highly purified oleic acid (A) was obtained. Example 2 Crystals of oleic acid acid salt obtained in the same manner as in Example 1 were dissolved in 1400 g of 10% water-containing methanol at 40°C, then cooled to -5°C with stirring for 5 hours, filtered to obtain crystals. 383 g (acidic salt content 372 g) was obtained. Add 1,545 g of 3% hydrochloric acid to the crystals, mix at 90°C for 2 hours for acid decomposition, thoroughly wash the resulting free oleic acid with 0.5% citric acid, and then dehydrate to obtain highly purified oleic acid. (B) 358g was obtained. Example 3 Crystals of oleic acid acid salt obtained in the same manner as in Example 2 were dissolved in 1302 g of 13% water-containing methanol at 40°C, then cooled to -5°C over 5 hours with stirring, filtered, and the crystals were dissolved. 365 g (acidic salt content 357 g) was obtained. Add 1,480 g of 3% hydrochloric acid to the crystals, mix at 90°C for 2 hours for acid decomposition, wash the resulting free oleic acid thoroughly with 0.5% citric acid, and then dehydrate to obtain highly purified oleic acid. (C) 343g was obtained. Example 4 0.5% activated carbon was added to the high-purity purified oleic acid obtained in Examples 1 to 3, and the mixture was stirred at 50°C for 1 hour in a nitrogen gas atmosphere, followed by filtered adsorbent-treated high-purity purified oleic acid ( A1), (B1), and (C1) were obtained. Example 5 Highly purified oleic acid obtained in Examples 1 to 3 was distilled under nitrogen gas blowing at 1 mmHg and below 220°C to obtain highly purified oleic acid (A2), (B2), and (C2). Ta. 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.

[Table] Test items are based on gas chromatography using a capillary column. Oleic acid is C18:
It is shown as 1cisω9. is a value indicating the content of carbonyl compounds, which are typical trace impurities (milliequivalents/Kg). is an index evaluated by a sensory test, with 0 representing no odor and 10 representing the strength of the odor of commercially available oleic acid (a). In ~, the larger the numerical value of the hue, the greater the degree of coloring and the worse the quality. is oleic acid in a nitrogen stream at 205°C.
The hue after being heated for a period of time indicates hue stability against heat. is the hue after heating oleic acid at 150°C for 3 hours in the atmosphere, indicating hue stability against thermal oxidation. shows the hue after adding an equimolar amount of diethanolamine to oleic acid and heating at 150° C. for 2 hours while stirring with nitrogen gas, and shows the hue stability against basic drugs. is oleic acid and paratoluenesulfonic acid.
Add 0.05% and while stirring with nitrogen gas,
The hue after heating at 150°C for 1 hour indicates hue stability against acidic agents. is the peroxide value (milliequivalents/Kg) after heating at 60° C. for 5 hours while aerating oleic acid (300 ml/min) and stirring; the larger the value, the worse the oxidation stability. These are the results of a skin irritation test conducted by Kawaho (The Journal of Dermatology, Vol. 2, p. 19 (1975)), where negative means no irritation and positive means strong irritation, indicating safety for living organisms. Show your gender. Example 6 Tea seed oil-decomposed undistilled fatty acids prepared by adding 1730 g of urea to 5000 g of methanol, dissolving it at 60°C, and then heating it to 60°C.
1000g was added and dissolved. Then while stirring 10
The mixture was cooled to 0.degree. C. for 5 hours, and the resulting crystals were filtered off to obtain 6270 g of a filtrate (fatty acid content: 508 g). Add 1330g of urea to this filtrate and dissolve at 60℃, then stir while stirring.
The mixture was cooled to 10° C. for 5 hours and filtered to obtain 1765 g of urea adduct crystals. 1588g of crystals of this urea adduct
was mixed with 4,765 g of a 0.5% malic acid aqueous solution at 50° C. and hydrolyzed to obtain 398 g of a fatty acid mixture containing oleic acid (acid value: 196.5) which was left to stand and separate into layers. 177 g of crystals of this fatty acid mixture and urea adduct were dissolved in 1768 g of 10% aqueous methanol containing 31.0 g of sodium hydroxide (50% equivalent of the fatty acid mixture) at 40°C, and cooled to -7°C over 6 hours with stirring. After filtering, 425 g of crystals of oleic acid acid salt (acid salt content: 397
g) was obtained. Add 1990g of 5% phosphoric acid aqueous solution to this crystal.
(1.5 molar equivalents of acid salt) was added, followed by mixing at 90° C. for 2 hours and acid decomposition to obtain free oleic acid. After thoroughly washing this oleic acid with a 0.5% malic acid aqueous solution, it is dehydrated to produce highly purified oleic acid (D) 382.
I got g. Example 7 Crystals of oleic acid acid salt obtained in the same manner as in Example 6 were dissolved in 1191 g of 12% aqueous methanol at 40°C, and then cooled to -5°C over 5 hours with stirring.
After separation by filtration, 380 g of crystals (acidic salt content: 369 g) were obtained.
Add 1850g of 5% phosphoric acid water to this crystal and heat it at 90℃ for 2 hours.
After time-mixing and acid decomposition, the resulting free oleic acid was thoroughly washed with a 0.5% malic acid aqueous solution, and 355 g of dehydrated highly purified oleic acid (E) was obtained. Example 8 3% silica gel was added to the highly purified oleic acid obtained in Examples 6 and 7, and the mixture was heated under a nitrogen gas atmosphere.
After stirring at 40 degrees for 1 hour, the mixture was filtered to obtain adsorbent-treated highly purified oleic acids (D1) and (E1). 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). Table 2 summarizes the composition and quality characteristics of the highly purified oleic acid of the present invention obtained in Examples 6 to 9.
Shown below.

[Table] Example 10 1060 g of urea was added to 3000 g of methanol and dissolved at 60°C, and then 1000 g of olive oil-decomposed undistilled fatty acid heated to 60°C was added and dissolved. Then while stirring
Cool to 15℃ for 4 hours, filter out the formed crystals, add 750g of urea to the obtained filtrate, dissolve again at 50℃, cool to 10℃ with stirring, separate the formed crystals by filtration, and obtain 3488g of filtrate ( Fatty acid content 442g) was obtained. To this filtrate, 1127 g of urea was added and dissolved at 60°C, then cooled to 15°C over 5 hours with stirring and filtered to obtain 1502 g of crystals of urea adduct. this crystal
It was mixed with 6008 g of a 0.5% tartaric acid aqueous solution at 40°C, hydrolyzed, and allowed to stand still for layer separation to obtain 375 g of a fatty acid mixture containing oleic acid (acid value: 196.7). This fatty acid mixture was added to 33.2 g of potassium hydroxide (45% of the fatty acid mixture).
The mixture was dissolved in 1500 g of 10% water-containing methanol (equivalent) at 35°C, cooled to -10°C over 6 hours with stirring, and then filtered to obtain 360 g of crystals of oleic acid salt (acid salt content: 334 g). After adding 2190 g of a 10% aqueous citric acid solution (2 molar equivalents of the 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 was thoroughly washed with a 0.5% tartaric acid aqueous solution and then dehydrated to obtain 322 g of highly purified oleic acid (F). Example 11 Crystals of oleic acid acid salt obtained in the same manner as in Example 10 were dissolved in 1336 g of 8% aqueous acetone at 40°C, cooled to -2°C over 5 hours with stirring, filtered, and 321 g of crystals ( Acid salt content: 312 g) was obtained. Add 2,040 g of 10% citric acid aqueous solution to the crystals, mix at 90°C for 2 hours for acid decomposition, wash the obtained free oleic acid thoroughly with 0.5% tartaric acid aqueous solution, and then dehydrate highly purified purified oleic acid ( G) 300g was obtained. Example 12 2% activated clay was added to the highly purified oleic acid obtained in Examples 10 and 11, and the mixture was heated in a nitrogen gas atmosphere for 40 minutes.
After stirring at °C for 30 minutes, the mixture was filtered to obtain adsorbent-treated highly purified oleic acids (F1) and (G1). Example 13 The highly purified oleic acids obtained in Examples 10 and 11 were distilled in the same manner as in Example 5 to obtain highly purified oleic acids (F2) and (G2). Table 3 summarizes the composition and quality characteristics of the highly purified oleic acid of the present invention obtained in Examples 10 to 13.
Shown below.

[Table] From the above results, 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 clear that it can be removed. Furthermore, the highly purified oleic acid obtained by the present invention is approximately 100%
It is clear that it is colorless and odorless due to its high purity, and that it also has excellent stability against heat, oxidation and chemicals, and safety for living organisms.

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, which comprises 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. The method for producing oleic acid according to claim 1, wherein the crystallization in step (d) is repeated. 3. The method for producing oleic acid according to claim 1 or 2, wherein after step (e), an adsorbent treatment or distillation is performed.