KR900001312B1 - Process for the preparation of oleic acid - Google Patents

Abstract

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Description

Oleic acid manufacturing method

The present invention relates to a process for producing highly pure oleic acid from oleic acid containing a fatty acid mixture.

Oleic acid (cis-9-octadecanoic acid) is a representative unsaturated fatty acid constituting natural fats or biological lipids and is of great importance for industry and biology.

Recently confirmed, highly pure oleic acid is colorless, odorless, good in stability, high in safety, and has many physical, chemical and physiological properties. Based on this conclusion, oleic acid reveals a range of advanced technologies under development, as well as chemical fields such as the life sciences of drugs, cosmetics and foods, the biosciences of biosensors and biosurfactants, and the electronics that stimulate biofunction. Active and widely used.

However, commercially available oleic acid contains fatty acid homologues which differ in carbon number and double bond number, has a low purity of 60 to 90%, and contains a small amount of various impurities. Therefore, this commonly available oleic acid is insufficient in terms of quality such as color, smell, stability, safety, and the like, and it is not possible to sufficiently develop the inherent performance of oleic acid.

As a method of increasing the purity of fatty acids, various methods such as conventional solvent separation, emulsion separation, urea separation, and the like are known. Recently, a chromatographic method using an adsorbent, an ion exchange resin, or the like has been used. However, these methods produce fatty acids of high purity.

Furthermore, there is a method of partially hydrogenating highly unsaturated fatty acids such as linoleic acid, linolenic acid, and the like to increase the purity of oleic acid, but this method has the problem of generating positional and geometric isomers.

As the demand for oleic acid increases as the scope of application increases, there is a need to provide high purity and high quality oleic acid.

Accordingly, it is an object of the present invention to prepare high purity oleic acid from a wider range of starting materials in a simple process that does not produce positional and geometric isomers.

According to the present invention, a process for preparing oleic acid comprises the steps of: (a) dissolving oleic acid containing a fatty acid mixture and urea in an organic solvent, cooling and separating them to remove the resulting precipitated crystals; (b) partially saponifying the fatty acid mixture contained in this organic solvent solution to separate it by crystallization method, and (c) acid decomposing the resultant crystals.

According to the present invention, step (a) is a step of removing fatty acids having a higher saturation degree of 16 or more carbon atoms and fatty acids having a higher degree of unsaturation than oleic acid from oleic acid containing a fatty acid mixture. In step (a), inevitably a small amount of urea remains in the resulting organic solvent solution. When this solvent is applied in step (b), the remaining urea slowly produces an adduct with the acid salt of oleic acid, thereby improving the crystallized state of the partially saponified fatty acid mixture, thereby filtering the crystals obtained by crystallization. By making it easy, a high saturated fatty acid such as linoleic acid, a fatty acid having a lower unsaturation of 1 than oleic acid, and a saturation degree

Oleic acid containing a fatty acid mixture may be used as a mixture containing oleic acid, for example, olive oil, sesame oil, rice bran oil, soybean oil, tea fruit oil, camellia oil, corn oil, rapeseed oil, palm oil, peanut oil, Fatty acids and fatty acid mixtures obtained by hydrolyzing fats and oils such as safflower oil, sunflower oil, resins, lard, chicken oil, sheep fat, fish oil and the like. Moreover, as starting material, oleic acid containing commercially available impurities can be used. The importance of the starting material depends on the impurity separation effect according to the present invention, while starting materials with a high oleic acid content are generally beneficial, but the choice of starting material is dependent on the desired purity and quality of the oleic acid and the type of impurities in the starting material and It depends on the quantity.

Organic solvents used in step (a) include lower alcohols such as methanol, ethanol, n-propanol, isopropanol and the like, and mixed solvents consisting mainly of such lower alcohols. The amount of the organic solvent used cannot be reliably determined depending on the composition of the starting fatty acid, the desired purity and yield, the number of planned crystallization operations, and the like, but 0.5 to 10 times the weight of the starting fatty acid is preferable.

When the amount of the organic solvent is less than 0.5 times, the separation effect is lower, whereas when it exceeds 10 times, the concentration of fatty acids is lowered, which adversely reduces the production effect.

The amount of urea used is determined by the composition of the starting fatty acid, the desired purity and yield, the crystallization operating temperature, the amount of solvent and the like. Preferably, the amount of urea used is 3 to 50 times the total weight of saturated fatty acids having 16 or more carbon atoms and higher fatty acids having one degree of unsaturation higher than oleic acid contained in the starting fatty acid. If the amount of urea is less than three times, saturated fatty acids and

In step (a), the oleic acid containing the urea and fatty acid mixture is dissolved in an organic solvent with warming and then cooled slowly to adjust not to exceed 30 ° C (preferably within 20 ° -20 ° C). Therefore, saturated fatty acids having 16 or more carbon atoms and fatty acids having a higher degree of unsaturation than oleic acid form crystalline adducts with urea, so that the resulting crystals are removed by conventional methods such as filtration and centrifugation. .

In general, step (a) is sufficient to operate only once. However, if the removal of saturated fatty acids having 16 or more carbon atoms and fatty acids having a higher degree of unsaturation than oleic acid is 1, this step (a) may be repeated.

In step (b), the organic solvent solution of fatty acid obtained in step (a) is first partially saponified by the addition of alkaline compounds such as hydroxides, carbonates and the like such as lithium, sodium, potassium, ammonia and the like. At this time, the salt of oleic acid is produced by partial saponification. As it cools, it produces a crystal that can be gradually filtered through the addition of a small amount of urea remaining in step (a). It is easy to separate from the same components. The degree of saponification is from 20% of oleic acid to 60% of the total amount of fatty acid mixture, preferably from 30% of oleic acid to 55% of the total amount of fatty acid mixture. If the degree of saponification is less than 20% of oleic acid, the resulting yield of oleic acid is low, while if it exceeds 60% of the total amount of fatty acid mixture, not only the separation effect is lowered, but also the crystallization state and the possibility of filtration are poor. The resulting purity of oleic acid is lowered.

The cooling temperature for crystallizing the acid salt of oleic acid is 10 ° to -30 ° C, preferably 5 ° to-

The resulting acid crystals of oleic acid are separated in a conventional manner from a solution containing a fatty acid having a high degree of unsaturation.

Furthermore, purity can be increased by repeatedly recrystallizing the acid crystals of oleic acid.

Solvents used in the repeated recrystallization operation for the salt of oleic acid include polar solvents such as methanol, ethanol, isopropanol, n-butanol, isobutanol, acetone, methyl ethyl ketone, diethyl ether, ethyl acetate, acetonitrile, and the like. There are mixed solvents containing polar solvents. In this case, the amount of the solvent used is preferably 1 to 10 times the weight of the acid salt of oleic acid.

Step (c) is an acid decomposition of the oleic acid by the addition of acid to the acid salt of the oleic acid. Examples of the acid used for this acid decomposition include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, phosphorous acid, superphosphoric acid, carbonic acid and boronic acid: and acetic acid, oxalic acid, malonic acid, succinic acid, malic acid, tartaric acid and citric acid. There is an organic acid. The amount of acid used is at least 1 equivalent, preferably at least 1.2 equivalents relative to the base to produce the acid salt of oleic acid.

After acid decomposition, the remaining acid for acid degradation in oleic acid is washed off with water. In this washing operation, a dilute aqueous solution of polyacid such as oxalic acid, citric acid or the like is added to prevent emulsification, thereby completely performing acid decomposition of the remaining small amount of acid salt of oxalic acid.

In this way, high purity oxalic acid is obtained. Moreover, in order to remove a small amount of impurities, the resulting oxalic acid is subjected to the adsorption treatment generally used for fatty acid purification.

As the adsorbent used in the adsorption treatment, clay, activated clay, activated carbon, silica gel, alumina gel, silica-alumina gel, ion exchange resin, synthetic adsorbent and the like can be used as such or in combination. The amount of adsorbent used is from 0.1 to 5% by weight of oxalic acid, depending on the purity of the oxalic acid and the desired quality. In this adsorption treatment, the temperature is at least the melting point of oleic acid, preferably 30 ° to 80 ° C., and the treatment time is about 20 minutes to 2 hours.

On the other hand, distillation is carried out under reduced pressure in an inert gas atmosphere in a conventional manner. In this case, distillation under high pressure and low temperature is preferable.

According to the method of the present invention, high-quality, high-purity oleic acid, such as stability against oxidation, heat and acid and basic chemicals, stability to skin health, etc., can be obtained from a wide range of starting materials in a simple process. It could not be obtained conventionally.

The high purity oleic acid thus obtained has the following characteristics:

(i) a high purity colorless, odorless substance; (ii) does not contain minor amounts of impurities such as oxidation products resulting from acid decomposition of oleic acid; (iii) good stability to heat, oxidation and chemicals; (iv) high stability against skin health; (v) It has such characteristics as clear polymorphism.

By using the above properties, the oleic acid obtained according to the present invention can be widely used in sophisticated chemical fields such as pharmacology, cosmetics, biochemistry, electromagnetism, etc. as well as the high technology under development.

The present invention will be described in detail with reference to the following examples, without restricting the present invention thereto.

Example 1

1,242 g of urea was added to and dissolved in 4000 g of methanol during heating at 50 ° C., and 1000 g of oleic safflower oil, a distilled fatty acid, warmed to 50 ° C. was added and dissolved. The resulting solution was then cooled from 50 ° C. to 10 ° C. with stirring over 4 hours. The precipitated crystals were filtered off by centrifugation to obtain 5,212 g of filtrate (fatty acid content: 625 g, acid value: 198.5, urea content: 325 g). The filtrate was added to 576 g of an aqueous solution containing 41.5 g of sodium hydroxide at 40 ° C. (corresponding to 45% of the equivalent of fatty acid contained), cooled to −70 ° C. with stirring over 6 hours, and filtration of oleic acid. 427 g of acid crystals (acid content: 370 g) were obtained. The crystal thus obtained was added to 1,856 g of an aqueous solution containing 93 g of phosphoric acid (corresponding to 1.5 times the acid equivalent), followed by acid decomposition with stirring at 90 ° C. over 2 hours. The oleic acid layer thus obtained was washed thoroughly with 0.5% citric acid aqueous solution and dehydrated to obtain 356 g of high purity oleic acid (A).

Example 2

427 g of acid crystals of oleic acid obtained in the same manner as in Example 1 were dissolved at 1,280 g of methanol containing 10% of water while warming at 40 ° C., then cooled to −5 ° C. with stirring over 5 hours, and filtered. 357 g of crystals were obtained. 1,690 g of an aqueous 5% phosphoric acid solution was added thereto, followed by acid decomposition with stirring at 90 ° C. for 2 hours. The resulting oleic acid layer was washed thoroughly with 0.5% citric acid aqueous solution, and dehydrated to obtain 324 g of high purity oleic acid (B).

Example 3

The acid crystals of the oleic acid obtained by recrystallization in the same manner as in Example 2 were dissolved in 1,071 g of methanol containing 13% of water, heated at 40 ° C., and then cooled to −5 ° C. with stirring over 5 hours to obtain filtration. Obtained 317 g of crystals. This crystal was added to 1574 g of 5% aqueous phosphoric acid solution and acid-decomposed with stirring at 90 ° C for 2 hours. The resulting oleic acid layer was washed thoroughly with 0.5% citric acid aqueous solution and dehydrated to obtain 302 g of high purity oleic acid (C).

Example 4

High purity oleic acid of Examples 1-3 was added to 5% activated carbon, respectively, and stirred for 1 hour at 50 ° C under a nitrogen gas atmosphere, followed by filtration to obtain higher purity oleic acid (A1), (B1) and (C1). Were obtained respectively.

Example 5

Oleic acid having high purity of Examples 1 to 3 was streamed at 1 mmHg and lower than 220 DEG C while blowing nitrogen gas to obtain higher oleic acid (A2), (B2) and (C2), respectively.

The composition and qualitative characteristics of high purity oleic acid obtained in Examples 1 to 5 according to the present invention are shown in Table 1 below in comparison with oleic acid (a) and (b) which can be commonly obtained as a comparative example.

TABLE 1a

TABLE 1b

Test item 1 shows the composition of the fatty acid mixture measured by gas chromatography using a capillary column.

Test item 2 shows the content of carbonyl compound (meg / kg) as a representative small amount of impurities.

Test item 3 is a direction index evaluated by the sensory test, in which there is no direction, 0, and the direction strength of oleic acid that is generally available is 10.

In Test Items 4 to 8, the larger the value of the color, the larger the coloration and the lower the quality.

Test item 5 shows the thermal color stability of oleic acid after heating at 205 ° C. for 1 hour under a stream of nitrogen.

Test item 6 shows the thermal oxidation color stability of oleic acid after heating at 150 ° C. for 3 hours in air.

Test item 7 shows the color stability of oleic acid to basic chemicals after adding oleic acid to an equivalent mole of diethanol amine and heating with nitrogen gas for 2 hours with stirring.

Test item 8 shows the color stability of oleic acid to acidic chemicals after oleic acid was added to 0.05% para toluene sulfonic acid and heated at 150 ° C. for 1 hour with stirring with nitrogen gas.

Test item 9 shows the peroxide value (meg / kg) after heating oleic acid at 60 ° C. for 5 hours with stirring under ventilation (300 ml / min).

Test item 10 shows the result of a skin irritation test according to the Kawai method (Skin Disease Journal, Vol. 2, p. 19 (1975)), where voice is non-irritating, almost negative is weak, almost Positive is a moderate stimulus, positive is a strong stimulus. As a result, it can be seen that there is safety for skin health.

Example 6

1,640 g of urea was added and dissolved in 5000 g of methanol while warmed at 60 ° C., and 1000 g of polysilic acid fatty acid warmed at 60 ° C. was added to dissolve. The resulting solution was then cooled from 60 ° C. to 8 ° C. with stirring over 4 hours, and the precipitated crystals were filtered off to obtain 6,196 g of filtrate (content of fatty acids: 512 g, acid value: 192.2, of urea). content :

Example 7

The acid crystals of oleic acid obtained in the same manner as in Example 6 were dissolved in 1,254 g of methanol containing 12% of water, heated at 40 ° C., then cooled to −5 ° C. with stirring over 5 hours, and filtered through 350 g of crystals. Got. This crystal was added to 1,230 g of an aqueous 3% hydrochloric acid solution and acid-decomposed with stirring at 90 ° C for 2 hours. The resulting oleic acid layer was washed thoroughly with an aqueous 0.5% malic acid solution and dehydrated to obtain 318 g of high purity oleic acid (E).

Example 8

High purity oleic acid in each of Examples 6 and 7 was added to 3% silica gel with stirring over 1 hour at 40 ° C. under a nitrogen gas atmosphere, followed by filtration to obtain higher purity oleic acid (D1) and (E1). Respectively obtained.

Example 9

High purity oleic acids of each of Examples 6 and 7 were distilled in the same manner as in Example 5 to obtain higher oleic acids (D2) and (E2), respectively.

According to the present invention, the composition and qualitative characteristics of high purity oleic acid in Examples 6-9

TABLE 2a

TABLE 2b

Example 10

After heating at 60 ° C., 1,060 g of urea was added to 3,000 g of methanol to dissolve,

Example 11

The acid crystals of oleic acid obtained in the same manner as in Example 10 were dissolved in 1,026 g of acetone containing 8% of water, heated at 50 ° C, and then cooled to -2 ° C with stirring over 5 hours, and crystals were filtered through 276 g. Got. This crystal was added to 1716 g of an aqueous 10% citric acid solution and acid-decomposed with stirring at 90 ° C. for 2 hours. The resulting oleic acid layer was thoroughly washed with 0.5% tartaric acid aqueous solution and dehydrated to obtain 252 g of oleic acid (G) having high purity.

Example 12

High purity oleic acid obtained in each of Examples 10 and 11 was added to 2% activated clay, stirred for 30 minutes under a nitrogen gas atmosphere of 40 ° C, and filtered to obtain a higher purity ol.

Example 13

High purity oleic acid and the like obtained in each of Examples 10 and 11 were distilled in the same manner as in Example 5 to obtain higher oleic acids (F2) and (G2), respectively.

The composition and qualitative characteristics of the high purity oleic acids obtained in Examples 10 to 13 are shown in Table 3 below.

TABLE 3a

TABLE 3b

According to the results, small amounts of impurities contained in the starting fatty acid mixtures and other fatty acids except oleic acid can be almost completely removed according to the present invention. Moreover, the high purity oleic acid according to the present invention is colorless and odorless since it reaches almost 100% purity, and is extremely excellent in stability to heat, oxidation and chemicals and safety for skin health.

Claims (14)

(a) dissolving the oleic acid containing the fatty acid mixture and urea in an organic solvent followed by cooling to remove the resulting precipitated crystals; (b) partially saponifying the fatty acid mixture contained in this organic solvent solution to separate the crystals by crystallization; And (c) acid decomposing the resultant crystals. A process according to claim 1, wherein the fatty acid of step (a) is selected from among the hydrolyzates of oleic acid which are available and commonly available. The method of claim 1, wherein the component of step (a) is used in an amount of 3 to 50 times the total weight of saturated fatty acids having 16 or more carbon atoms and fatty acids having a higher degree of unsaturation than oleic acid contained in the fatty acid mixture. The method of claim 1 wherein the organic solvent in step (a) is used in an amount of 0.5 to 10 times the weight of the fatty acid mixture. 2. The process of claim 1 wherein in step (a) the cooling operation is cooled by cooling to less than 30 ° C. The method of claim 1 wherein the partial saponification reaction in step (b) is carried out by adding an alkaline chemical. The method according to claim 1, wherein the degree of saponification in step (b) is within a range of 20% of oleic acid to 60% of the total amount of fatty acid mixture contained in the organic solvent solution. The method of claim 6, wherein the alkaline chemical is selected from hydroxides and carbonates of lithium, sodium, potassium and ammonia. The method of claim 1, wherein the crystallization operation of step (b) is repeated. The method according to claim 9, wherein said crystallization operation is carried out in the presence of a polar solvent or a mixed solvent thereof. The process of claim 1 wherein step (c) is carried out with an inorganic or organic acid. The method of claim 11, wherein the inorganic acid is selected from sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, phosphorous acid, superphosphoric acid, carboxylic acid, and boronic acid. The method of claim 11, wherein the organic acid is selected from acetic acid, oxalic acid, malonic acid, succinic acid, malic acid, tartaric acid, and citric acid. The method of claim 1, wherein the oleic acid produced as a result of step (c) is adsorbed or distilled.