Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11C—FATTY ACIDS FROM FATS, OILS OR WAXES; CANDLES; FATS, OILS OR FATTY ACIDS BY CHEMICAL MODIFICATION OF FATS, OILS, OR FATTY ACIDS OBTAINED THEREFROM
  • C11C1/00—Preparation of fatty acids from fats, fatty oils, or waxes; Refining the fatty acids
  • C11C1/08—Refining

Definitions

• This invention relates to a method of producing a highly purified oleic acid from an oleic acid containing fatty acid mixture.
• Oleic acid (cis-9-octadecenoic acid) is a typical unsaturated fatty acid constituting natural fats and oils or biological lipids, which is a very important substance in industry and biology.
• oleic acid is colorless and odorless, excellent in the stability, high in the safety and has many excellent physical, chemical and physiological properties.
• oleic acid is actively and widely applied to fine chemical fields such as life sicene of pharmaceuticals, cosmetics and foods, bioscience of biosensors and biosurfactants, electronics aiming at simulation of biological function and so on as well as presently developing high technologies.
• commerically available oleic acid includes fatty acid homologues having different carbon number and double bond number, and has a purity as low as 60-90%, and contains various minor impurities. Therefore, the commercially available oleic acid is insufficient in the qualities such as color, odor, stability, safety and the like and can not sufficiently develop performances inherent to oleic acid.
• the step (a) is a step for removing higher saturated fatty acids having a carbon number of not less than 16 and monounsaturated fatty acids higher than oleic acid from the oleic acid containing fatty acid mixture.
• a small amount of urea inevitably remains in the resulting organic solvent solution.
• the remaining urea moderately forms an adduct with an acid salt of oleic acid to produce a hard and light powdery crystal, so that the crystallized state of the partially saponified fatty acid mixture is improved to facilitate the filtration of crystal obtained by crystallization, whereby the removal of polyunsaturated fatty acids such as linoleic acid and so on, monounsaturated fatty acids lower than oleic acid, lower saturated fatty acids and other impurities can be performed efficiently.
• polyunsaturated fatty acids such as linoleic acid and so on, monounsaturated fatty acids lower than oleic acid, lower saturated fatty acids and other impurities
• oleic acid containing fatty acid mixture use may be made of any mixtures containing oleic acid, an example of which includes fatty acids and mixtures thereof obtained by hydrolysis of fats and oils such as olive oil, sesame oil, rice bran oil, soybean oil, teaseed oil, camellia oil, corn oil, rapeseed oil, palm oil, peanut oil, safflower oil, sunflower oil, tallow, lard, chicken oil, mutton tallow, fish oil and the like. Further, the commercially available oleic acid containing impurities may be used as the starting material.
• fats and oils such as olive oil, sesame oil, rice bran oil, soybean oil, teaseed oil, camellia oil, corn oil, rapeseed oil, palm oil, peanut oil, safflower oil, sunflower oil, tallow, lard, chicken oil, mutton tallow, fish oil and the like.
• the commercially available oleic acid containing impurities may be used as
• the starting material having a higher oleic acid content is generally advantageous, but the selection of the starting material is determined by the objective purity and quality of oleic acid and the kind and amount of impurities in the starting material.
• the organic solvent used in the step (a) use may be made of lower alcohols such as methanol, ethanol, n-propanol, isopropanol and the like and a mixed solvent consisting mainly of such a lower alcohol.
• the amount of the organic solvent used can not absolutely be determined in accordance with the composition of the starting fatty acids, objective purity and yield, set of crystallization number and the like, but it is preferably 0.5-10 times the weight of the starting fatty acids. When the amount of the organic solvent is less than 0.5 times by weight, the separation effect lowers, while when it exceeds 10 times by weight, the concentration of fatty acid lowers and the production efficiency reduces unfavorably.
• the amount of urea used is determined by the composition of the starting fatty acids, objective purity and yield, crystallization temperature, amount of solvent and the like.
• the amount of urea used is 3-50 times the total weight of saturated fatty acids having a carbon number of not less than 16 and monounsaturated fatty acids higher than oleic acid, which are contained in the starting fatty acids.
• the amount of urea is less than 3 times by weight, the removal of saturated fatty acids and higher mono­unsaturated fatty acids is insufficient, while when it exceeds 50 times by weight, the yield of oleic acid lowers.
• urea and oleic acid containing fatty acid mixture are dissolved in the organic solvent by warming and then gradually cooled down to a temper­ature of not more than 30°C, preferably within a temperature range of 20°C ⁇ -20°C.
• the saturated fatty acids having a carbon number of not less than 16 and the monounsaturated fatty acids higher than oleic acid form crystalline adduct with urea, so that the resulting crystals are removed by the usual manner such as filtration, centrifugal separation or the like.
• step (a) it is sufficient to operate the step (a) a time. However, the operation of the step (a) may be repeated when the removal of the saturated fatty acids having a carbon number of not less than 16 and the monounsaturated fatty acids higher than oleic acid is insufficient.
• the organic solvent solution of the fatty acid mixture obtaining at the step (a) is first subjected to a partial saponification by adding alkaline chemicals such as hydroxides, carbonates and so on of lithium, sodium, potassium, ammonia and the like.
• alkaline chemicals such as hydroxides, carbonates and so on of lithium, sodium, potassium, ammonia and the like.
• an acid salt of oleic acid is formed by the partial saponification, which moderately forms an adduct with a small amount of urea remaining in the step (a) after the cooling to make a filterable crystal as a whole, so that the separation from components such as polyunsaturated fatty acids and so on is easy.
• the degree of saponification is within a range of from 20% of oleic acid contained to 60% of the total of the fatty acid mixture, preferably from 30% of oleic acid to 55% of the total of the fatty acid mixture.
• the degree of saponification is less than 20% of oleic acid, the yield of the resulting oleic acid is low, while when it exceeds 60% of the total of the fatty acid mixture, not only the separation effect lowers, but also the crystallized state and filtrability are poor to decrease the purity of the resulting oleic acid.
• the cooling temperature for crystallizing the acid salt of oleic acid is 10°C ⁇ -30°C, preferably 5°C ⁇ -20°C.
• the cooling temperature is higher than 10°C, the yield of oleic acid lowers, while when it is lower than -30°C, the purity of oleic acid reduces.
• the resulting acid salt crystal of oleic acid is separated from the solution containing polyunsaturated fatty acid and so on in the usual manner.
• the purity can be further increased by repeatedly subjecting the acid salt crystal of oleic acid to recrystallization.
• polar solvents such as methanol, ethanol, isopropanol, n-butanol, isobutanol, acetone, methyl ethyl ketone, diethyl ether, ethyl acetate, acetonitrile and so on, and a mixed solvent containing such polar solvents.
• the amount of the solvent used is preferably 1-10 times the weight of the acid salt of oleic acid.
• the step (c) is a step wherein the acid salt of oleic acid is subjected to an acid decomposition by adding an acid to produce free oleic acid.
• the acid used in the acid decomposition mention may be made of inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, carbonic acid, boric acid and so on; and organic acids such as acetic acid, oxalic acid, malonic acid, succinic acid, malic acid, tartaric acid, citric acid and so on.
• the amount of the acid used is not less than an equivalent, preferably not less than 1.2 equivalents to the base forming the acid salt of oleic acid.
• the acid for the acid decomposition remaining in oleic acid is removed by washing with water.
• the emulsification can be prevented by adding a diluted aqueous solution of a polybasic acid such as oxalic acid, citric acid or the like, whereby the acid decompo­sition for the slight amount of the remaining acid salt of oleic acid is performed completely.
• the high purity oleic acid is obtained.
• the resulting oleic acid may be subjected to an adsorbent treatment or distillation usually used in the refining of fatty acids.
• adsorbent used in the adsorbent treatment mention may be made of clay, activated clay, activated carbon, silica gel, alumina gel, silica-alumina gel, ion exchange resin, synthetic adsorbent and so on, which may be used alone or in admixture.
• the amount of the adsorbent used is dependent upon the refining degree of oleic acid and the objective quality, but it is 0.1-5% by weight to oleic acid.
• the temperature is not less than the melting point of oleic acid, preferably 30-80°C, and the treating time is about 20 minutes to 2 hours.
• the distillation is performed under a reduced pressure in an inert gas atmosphere in the usual manner. In this case, it is desirable to perform a low temperature distillation under a higher vacuum.
• a highly purified oleic acid having a high level of qualities such as stability to oxidation, heat and acidic and basic chemicals, safety to cutaneous health and so on, which have never been attained in the prior art, can be obtained from wide starting materials by a simple process.
• oleic acid obtained according to the method of the invention can widely be employed in the fine chemical fields such as pharmaceuticals, cosmetics, biochemicals, electronics and so on as well as presently developing high technologies.
• This filtrate was added with 576 g of an aqueous solution containing 41.5 g of sodium hydroxide (corresponding to 45% of the equivalent of the contained fatty acid) at 40°C and cooled to -7°C with stirring over 6 hours to obtain 427 g of a crystal of acid salt of oleic acid (content of acid salt: 370 g) through filtration.
• the thus obtained crystal was added with 1,856 g of an aqueous solution containing 93 g of phosphoric acid (correspond­ing to 1.5 times the equivalent of the acid salt) which was subjected to an acid decomposition with stirring at 90°C for 2 hours.
• the thus obtained oleic acid layer was fully washed with an aqueous solution of 0.5% citric acid and dehydrated to obtain 356 g of a highly purified oleic acid (A).
• the acid salt crystal of oleic acid obtained through recrystallization in the same manner as in Example 2 was dissolved into 1,071 g of methanol contain­ing 13% of water under warming at 40°C and then cooled to -5°C with stirring over 5 hours to obtain 317 g of a crystal through filtration.
• This crystal was added with 1,574 g of an aqueous solution of 5% phosphoric acid, which was subjected to an acid decomposition with stirring at 90°C for 2 hours.
• the resulting oleic acid layer was fully washed with an aqueous solution of 0.5% citric acid and dehydrated to obtain 302 g of a highly purified oleic acid (c).
• Each of the highly purified oleic acids of Examples 1-3 was added with 0.5% of activated carbon, stirred at 50°C under nitrogen gas atmosphere for 1 hour and filtered to obtain each of more highly purified oleic acids (A1), (B1), and (C1).
• Each of the highly purified oleic acids of Examples 1-3 was distilled below 220°C at 1 mmHg while blowing a nitrogen gas to obtain each of more highly purified oleic acids (A2), (B2) and (C2).
• compositions and quality characteristics of the highly purified oleic acids obtained in Examples 1-5 according to the invention are shown in the following Table 1 together with those of commercially available oleic acids (a) and (b) as Comparative Examples.
• the test item 1 shows the composition of fatty acid mixture measured by a gas chromatography using a capillary column. Oleic acid is represented by C 18:1 cis- ⁇ 9 .
• the test item 2 shows a content (milli equivalent/kg) of carbonyl compounds as typical minor impurities.
• the test item 3 gives an odor index evaluated by an organoleptic test, wherein odorless is 0 and the odor intensity of the commercially available oleic acid (a) is 10, respectively.
• the test item 5 shows a heat color stability of oleic acid after heated at 205°C in a nitrogen stream for 1 hour.
• the test item 6 shows a thermal oxidation color stability of oleic acid after heated at 150°C in air for 3 hours.
• the test item 7 shows a color stability of oleic acid against basic chemicals after oleic acid is added with an equimolar amount of diethanolamine and heated at 150°C for 2 hours while being stirred with nitrogen gas.
• the test item 8 shows a color stability of oleic acid against acidic chemicals after oleic acid is added with 0.05% of paratoluenesulfonic acid and heated at 150°C for 1 hour while being stirred with nitrogen gas.
• the test item 9 shows a peroxide value (milli equivalent/kg) after oleic acid is heated at 60°C for 5 hours while being stirred through aeration (300 ml/min). The larger the value, the poorer the oxidation stability.
• the test item 10 shows a result of skin irritation test according to Kawai's method [The journal of Dermatology, vol 2, p 19 (1975)], wherein negative is no irritation, almost negative is weak irritation, almost positive is middle irritation and positive is strong irritation. This indicates the safety to cutaneous health.
• This filtrate was added with 703 g of an aqueous solution containing 35.1 g of sodium hydroxide (corresponding to 50% of the equivalent of the contained fatty acid) at 40°C and then cooled to -10°C with stirring over 6 hours to obtain 418 g of crystals of the acid salt of oleic acid (content of acid salt: 361 g) through filtration.
• This crystal was added with 1,535 g of an aqueous solu­tion of 3% hydrochloric acid, which was subjected to an acid decomposition with stirring at 90°C for 2 hours.
• the resulting oleic acid layer was fully washed with an aqueous solution of 0.5% malic acid and dehydrated to obtain 347 g of a highly purified oleic acid (D).
• the acid salt crystal of oleic acid obtained in the same manner as in Example 6 was dissolved into 1,254 g of methanol containing 12% of water under warming at 40°C and then cooled to -5°C with stirring over 5 hours to obtain 350 g of a crystal through filtration.
• This crystal was added with 1,230 of an aqueous solution of 3% hydrochloric acid, which was subjected to an acid decomposition with stirring at 90°C for 2 hours.
• the resulting oleic acid layer was fully washed with an aqueous solution of 0.5% malic acid and dehydrated to obtain 308 g of a highly purified oleic acid (E).
• Each of the highly purified oleic acids of Examples 6 and 7 was added with 3% of silica gel, stirred at 40°C under nitrogen gas atmosphere for 1 hour and filtered to obtain each of more highly purified oleic acids (D1) and (E1).
• Example 6 Each of the highly purified oleic acids of Examples 6 and 7 was distilled in the same manner as in Example 5 to obtain each of more highly purified oleic acids (D2) and (E2).
• compositions and quality characteristics of the highly purified oleic acids obtained in Examples 6-9 according to the present invention are shown in the following Table 2.
• This filtrate was added with 372 g of an aqueous solution containing 38.8 g of potassium hydroxide (corresponding to 45% of the equivalent of the contained fatty acid) at 40°C and then cooled to -10°C with stirring over 6 hours to obtain 342 g of a crystal of the acid salt of oleic acid (content of acid salt: 289 g) through fitration.
• This crystal was added with 1,894 g of an aqueous solution of 10% citric acid, which was subjected to an acid decomposition with stirring at 90°C for 2 hours.
• the resulting oleic acid layer was fully washed with an aqueous solution of 0.5% tartaric acid and dehydrated to obtain 278 g of a highly purified oleic acid (F).
• the acid salt crystal of oleic acid obtained in the same manner as in Example 10 was dissolved into 1,026 g of acetone containing 8% of water under warming at 50°C and then cooled to -2°C with stirring over 5 hours to obtain 276 g of a crystal through filtration.
• This crystal was added with 1,716 g of an aqueous solution of 10% citric acid, which was subjected to an acid decomposition with stirring at 90°C for 2 hours.
• the resulting oleic acid layer was well washed with an aqueous solution of 0.5% tartaric acid and dehydrated to obtain 252 g of a highly purified oleic acid (G).
• Each of the highly purified oleic acids obtained in Examples 10 and 11 was added with 2% of activated clay, stirred at 40°C under nitrogen gas atmosphere for 30 minutes, and filtered to obtain each of more highly purified oleic acids (F1) and (G1).
• Each of the highly purified oleic acids obtained in Examples 10 and 11 was distilled in the same manner as in Example 5 to obtain each of more highly purified oleic acids (F2) and (G2).
• compositions and quality characteristics of the highly purified oleic acids obtained in Examples 10-13 are shown in the following Table 3.
• the highly purified oleic acid according to the invention has a purity of approximately 100%, so that it is colorless and odorless and considerably excellent in the stability to heat, oxidation and chemicals and the safety to cutaneous health.

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Cited By (4)

• 1985
  • 1985-12-05 DE DE8585308858T patent/DE3582072D1/de not_active Expired - Lifetime
  • 1985-12-05 EP EP19850308858 patent/EP0225946B1/fr not_active Expired

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