JPH06721B2 - Method for producing oleic acid ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to cosmetics, pharmaceuticals, foods, synthetic resins, lubricating oils,
The present invention relates to a method for producing an oleic acid ester which has a good hue suitable for use in hydraulic oils and other industrial products, has a small odor, is excellent in stability, and has low skin irritation.

[Conventional technology]

Fatty acid esters obtained from fatty acids and alcohols are extremely useful materials that are widely used in cosmetics, pharmaceuticals, foods, synthetic resins, lubricating oils, hydraulic oils and other industrial products.

As the fatty acid used as the raw material, various kinds of fatty acids having a short chain length to a long chain length such as saturated, unsaturated, straight chain and branched chain are used according to the purpose.

Of the fatty acids, oleic acid has a wide range of uses because it is liquid at room temperature, but commercially available oleic acid contains a considerable amount of saturated palmitic acid and stearic acid, and linoleic acid and linolenic acid with different degrees of unsaturation. However, the purity of oleic acid is as low as 50 to 90%, and it contains trace amounts of impurities such as aldehydes, ketones, and metals in addition to fatty acids, which cause strong coloring and odor and poor oxidative stability. It also has a stimulating effect.

Oleic acid ester produced from such oleic acid as a raw material also has the same drawback.

[Problems to be solved by the invention]

An object of the present invention is to produce an oleic acid ester having improved hue and odor, improved stability, and no skin irritation.

[Means for solving problems]

The applicant previously applied for a method for producing oleic acid, which is colorless and odorless and has excellent stability such as stability against heat and oxidation and skin irritation (Japanese Patent Application No. 59-119170).

By reacting oleic acid, its lower alkyl ester or its acid halide obtained by this method with alcohol, the present inventors have an excellent hue, almost no odor, high stability, and skin irritation. It has been found that an oleic acid ester free of odor can be obtained, and the present invention has been completed.

Oleic acid used in the present invention, (a) the fatty acid mixture containing oleic acid and urea are dissolved in an organic solvent and then cooled to remove the precipitated crystals, and (b) the fatty acid contained in the organic solvent solution. This is oleic acid obtained by partially saponifying the mixture, then recrystallizing the crystals, and (c) acid-decomposing the obtained crystals.

The step (a) is a step of removing higher saturated fatty acids having 16 or more carbon atoms and monounsaturated fatty acids higher than oleic acid from a fatty acid mixture containing oleic acid, and the resulting organic solvent solution inevitably contains a small amount. Urea remains. When the following step (b) is carried out using this organic solvent solution, residual urea forms an acid salt of oleic acid and an adduct in an appropriate amount to form a hard and free-flowing crystal, and therefore a partially saponified fatty acid mixture The crystalline state is improved and the crystals obtained by recrystallization become easier, and polyunsaturated fatty acids such as linoleic acid, monounsaturated fatty acids lower than oleic acid, lower saturated fatty acids and other impurities can be removed efficiently. As it can be carried out, highly pure and highly purified oleic acid is produced.

As the fatty acid mixture containing oleic acid used as this raw material, anything containing oleic acid can be used, and olive oil, sesame oil, rice bran oil, soybean oil,
Fatty acids obtained by hydrolyzing fats and oils such as tea seed oil, camellia oil, corn oil, rapeseed oil, palm oil, peanut oil, safflower oil, beef tallow, lard, chicken oil, sheep 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 content of oleic acid, the more efficiently the highly pure oleic acid can be obtained.

As the organic solvent used in the step (a), lower alcohols such as methanol, ethanol, n-propanol, and isopropanol, and mixed solvents containing these as the main components are used. The amount of the organic solvent used cannot be determined unconditionally depending on the composition of the raw material fatty acid, the target purity and yield, the setting of the number of crystallizations, etc., but is preferably 0.5 to 10 times the weight of the raw material fatty acid. If the amount is less than 0.5 times by weight, the separation effect is lowered, and if the amount is more than 10 times by weight, the fatty acid concentration is low and the production efficiency is lowered, which is disadvantageous.

The amount of urea used depends on the composition of the raw material fatty acid, the target purity and yield, the crystallization temperature, the amount of solvent, etc., but the saturated fatty acid having 16 or more carbon atoms and oleic acid contained in the raw material fatty acid. It is preferably 3 to 50 times by weight of the total amount of the higher monounsaturated fatty acids. If it is less than 3 times by weight, the 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 oleic acid yield 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, usually at 30 ° C or lower, preferably in the range of 20 to -20 ° C. Saturated fatty acids having 16 or more carbon atoms, monounsaturated fatty acids higher than oleic acid, and the like form adducts with urea and are crystallized. Therefore, the crystals are separately removed by a usual means such as centrifugation.

Normally, (a) step is sufficient for one operation, but carbon number 1
It may be repeated if the separation of saturated fatty acids of 6 or more and monounsaturated fatty acids higher than oleic acid is insufficient.

In the step (b), first, a basic compound such as a hydroxide or a carbon salt of lithium, sodium, potassium, ammonia or the like is added to the organic solvent solution of the fatty acid mixture obtained in the step (b) to partially remove it. Harmonize Oleic acid forms an acid salt by this partial saponification, and when cooled, becomes an acid salt of oleic acid.
The small amount of urea remaining in the step (a) forms an adduct in a suitable amount to form a crystal that easily passes as a whole, and separation of components such as polyunsaturated fatty acids to be removed is easy. The neutralization rate in this case is from 20% of the oleic acid contained to 60% of the total fatty acid mixture, preferably 30% of the oleic acid.
% To 55% of the total fatty acid mixture. When the neutralization rate is less than 20% of oleic acid, the yield of oleic acid obtained is low, and when it exceeds 60% of the total fatty acid mixture, the separation effect is lowered and the crystalline state of the crystallized acid salt of oleic acid is deteriorated. And the purity of the obtained oleic acid decreases.

The temperature for cooling to crystallize the acid salt of oleic acid is 10 to -30 ° C, preferably 5 to -20 ° C. 1
If the temperature is higher than 0 ° C, the yield of oleic acid will decrease, and if it is lower than -30 ° C, the purity of oleic acid will decrease.

The crystals of the acid salt of oleic acid thus formed are separated from the solution containing the polyunsaturated fatty acid by a conventional method.

The crystal of the acid salt of oleic acid can be further improved in purity by repeating recrystallization.

As the solvent used for repeating the recrystallization of the acid salt of oleic acid, methanol, ethanol, isopropanol,
A polar solvent such as n-butanol, isobutanol, acetone, methyl ethyl ketone, diethyl ether, ethyl acetate or acetonitrile, or a mixed solvent containing these is used. In this case, the concentration of the acid salt of oleic acid is 1
0 to 50% by weight, and the cooling temperature is preferably 5 to -20 ° C.

In the step (c), an acid of an acid salt of oleic acid is added for acid decomposition,
This is a step of obtaining oleic acid.

As the acid used for acid decomposition, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, carbonic acid, inorganic acids such as boric acid, 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 the acid used is equal to or more than the equivalent of the base forming the acid salt of oleic acid, and preferably 1.2 equivalent or more.

After acid decomposition, the acid used for acid decomposition remaining in oleic acid is removed by washing with water. When a small amount of polybasic acid such as oxalic acid or citric acid is added during the water washing, emulsification during the water washing can be prevented, and acid decomposition of the acid salt of oleic acid is also completely carried out.

In this way, high-purity oleic acid can be obtained, but in order to remove a trace amount of impurities, it is also possible to carry out an adsorbent treatment or distillation which is usually used for refining fatty acids.

As the adsorbent used for the adsorbent treatment, clay, activated clay,
Activated carbon, silica gel, alumina, silica-alumina, ion exchange resins, synthetic adsorbents and the like are available, and they are used alone or as a mixture. Although the amount of the adsorbent used varies depending on the degree of purification of oleic acid and the target quality, it is 0.1 to 5% by weight relative to oleic acid. The temperature of the adsorbent treatment is not less than the melting point of oleic acid, preferably 30 to 80 ° C. The processing time is about 20 minutes to 2 hours.

Distillation is performed under reduced pressure in an atmosphere of an inert gas under the conditions usually used for distillation of oleic acid. The vacuum should be as low as possible and the distillation temperature should be as low as possible.

That is, the present invention is a process for producing an oleic acid ester, which comprises esterifying an oleic acid, a lower alkyl ester thereof or an acid halide thereof obtained by this method with an alcohol.

Methyl oleate, ethyl oleate and the like can be used as the lower alkyl ester of oleic acid, and oleic acid chloride, oleic acid bromide and the like can be used as the oleic acid halide. These compounds can be produced by a known method.

As the alcohol used in the present invention, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tert-butanol, pentanol, hexanol, octanol, 2-ethylhexanol, decanol, dodecanol, isotridecanol, tetradecanol, tetradecanol, Linear or branched such as hexadecanol, hexyldecanol, octadecanol, isostearyl alcohol, octyldodecanol, docosanol, dodecyl tetradecanol, octacosanol, triacontanol, allyl alcohol, oleyl alcohol, linole alcohol, erucyl alcohol , Saturated or unsaturated monohydric alcohols, ethylene glycol, propylene glycol, tetramethylene glycol, octandio Le, dodecanediol, octadecanediol, neopentyl glycol, glycerine,
Trimethylolpropane, erythritol, pentaerythritol, dipentaerythritol, sorbitol,
There are polyhydric alcohols such as sorbitan, tripentaerythritol and sucrose, and sterins such as cholesterin, sitosterin and ergosterin.

A known manufacturing method is adopted in the manufacturing method of the present invention.
Sulfuric acid for esterification reaction of oleic acid and alcohol,
Bronsted acids such as paratoluenesulfonic acid and methanesulfonic acid, boron trifluoride, aluminum chloride,
It is preferable to use a Lewis acid such as zinc chloride, tin chloride, titanium chloride or antimony chloride as a catalyst, and when reacting at a high temperature, a non-catalyst or a basic compound such as an alkali carbonate such as sodium carbonate is used as a catalyst. You can also do it. Further, the esterification reaction can also be carried out in the presence of benzene, toluene, xylene or the like which is an azeotropic solvent with water. The transesterification reaction between the lower alkyl oleic acid ester and the alcohol may use an acidic catalyst, but a basic catalyst such as sodium hydroxide, potassium hydroxide or sodium methoxide may also be used. In the reaction of oleic acid halide with alcohol,
It is also possible to use a scavenger for hydrogen halide produced as a by-product such as pyridine or quinoline.

In the production method of the present invention, similarly to a normal esterification reaction, depending on the quality of the target oleic acid ester, adjusting the esterification rate, or performing alkali purification,
It can be decolorized using an adsorbent such as activated carbon, activated clay, activated alumina, or purified by distillation.

〔The invention's effect〕

According to the method of the present invention, an oleic acid ester having high purity, almost no coloration and odor, excellent stability and less skin irritation can be obtained.

Therefore, the obtained oleic acid ester is
Suitable for use in medicines, foods, synthetic resins, plasticizers, lubricants, hydraulic oils and other industrial products.

〔Example〕

Next, the present invention will be specifically described with reference to Reference Examples, Examples, Comparative Examples and Test Examples. In addition,% shows weight%.

Reference example 33.5 kg of urea was added to 108 kg of methanol and dissolved by heating.
Oleic safflower oil distilled fatty acid 2 heated to 50 ℃
7 Kg was added and dissolved. Then, the mixture was cooled to 12 ° C. with stirring, and the resulting crystals were centrifuged to obtain a liquid 140.7 kg (fatty acid content 17.6 kg, acid value 198.8, urea content 6.3 kg). 1.1 kg of sodium hydroxide in this liquid (45% of fatty acid content
15.6 Kg of an aqueous solution containing 1 equivalent) was added and dissolved, and the mixture was cooled to −8 ° C. with stirring and separated, and then an acid salt crystal of oleic acid was obtained.
11.5 kg (acid salt content 13.3 kg) was obtained. Phosphoric acid in this crystal
50.1 Kg of an aqueous solution containing 2.5 Kg (1.5 times the equivalent of the acid salt) was added, and the mixture was heated to undergo acid decomposition. The resulting oil layer was thoroughly washed with a 0.5% aqueous citric acid solution and then dehydrated to remove oleic acid 1
0.4 kg was obtained. This oleic acid has an acid value (AV) of 199.2, an iodine value (IV) of 88.2, a peroxide value (POV) of 0.00, a hue (APHA) of 20,
It was odorless.

This oleic acid 10.3Kg under a nitrogen gas atmosphere, 2.5mmHg,
Distillation at 230 ° C. or lower gave 10.2 kg of oleic acid.

This distilled oleic acid is AV199.5, IV88.3, P
OV0.00, hue (APHA) 15, odorless, fatty acid composition 95.2% oleic acid, 1.3% palmitic acid, stearic acid
The amounts were 1.5%, linoleic acid 1.8%, and linolenic acid 0.2%.

Example 1 600 g of oleic acid obtained in Reference Example, 2700 of methanol
g and 50% trifluoride boron methanol complex 300
g was placed in a four-necked flask of 5 and reacted at 65 ° C. for 1 hour under reflux. The acid value at this point was 0.19.
Then, it was extracted with n-hexane 2, washed with purified water 1 three times, deoxidized with 0.5% aqueous sodium carbonate solution 4 four times, and the washing liquid was neutralized with purified water. It was washed until it became, and then allowed to stand. The separated n-hexane layer was desolvated and then distilled at 2 mmHg and a distillation temperature of 162 ° C. The methyl oleate obtained is 55
It was 3 g (yield 95%). AV0.08, P of this thing
It had an OV of 0.00, a saponification value (SV) of 189.2, and a hue (APHA) of 20, and had almost no odor, and the purity confirmed by gas chromatography was 95.1%.

Example 2 705 g of oleic acid and isopropanol 7 obtained in Reference Example
50 g and 10 g of paratoluene sulfonic acid were placed in a three-necked four-necked flask and reacted under reflux for 4 hours.
The generated water and isopropanol were distilled off from the reaction element.
Then, 1500 g of new isopropanol was added, and the same reaction and distillation were carried out. Further, this operation was repeated twice. The reaction time was 16 hours, and the acid value of the product was 2.0. Subsequently, it was deoxidized with 2.5% aqueous sodium hydroxide solution 1, washed with water until the washing liquid became neutral, and allowed to stand, and the separated oil layer was distilled at 2 mmHg and 187 ° C. Nitrogen gas was blown into the distillate at 55 ° C and 1 mmHg or less for 2 hours to deodorize it.
78 g (yield 96%) was obtained. The analytical value of this product is 95.7% purity by gas chromatography, AV0.07, PO
It was V0.00, SV192.0, and hue (APHA) 20.

Comparative Example 1 Using commercially available distilled oleic acid (purity of oleic acid by gas chromatography: 71.0%), reaction, deoxidation, distillation and deodorization were performed in the same manner as in Example 2. The yield of the obtained isopropyl oleate was 751 g (yield 93%) and was odorous. Analysis value is the purity by gas chromatography
71.3%, AV0.28, POV0.51, SV191.5, hue (APH
A) It was 140.

Example 3 846 g of oleic acid obtained in the reference example, 674 g of tetradecyl alcohol (purity 99.0%) and stannous chloride (S _n Cl ₂ ·.
2H ₂ O) (1.5 g) was placed in a three-necked four-necked flask, and the reaction was carried out at 185 ° C. for 6 hours under a nitrogen gas atmosphere. When 1.5 g of stannous chloride was further added and the reaction was carried out at the same temperature for 6 hours, the acid value became 2.0.
The mixture was deoxidized three times with 2.5% aqueous sodium hydroxide solution 1, washed with purified water until the washing liquid became neutral, and then distilled at 1 mmHg and 217 ° C. The distillate was further deodorized by blowing nitrogen gas at 55 ° C and 1 mmHg or less for 2 hours to obtain almost odorless tetradecyl oleate 13
39 g (yield 93%) was obtained. The analysis value of this product is 95.8% purity by gas chromatography, AV0.1, PO
It was V0.02, SV115.0, and hue (APHA) 30.

Comparative Example 2 Using the commercially available distilled oleic acid used in Comparative Example 1, reaction, deoxidation, distillation and deodorization were performed in the same manner as in Example 3. The obtained tetradecyl oleate had an amount of 1324 g (yield 92%) and was odorous. The analytical values are gas chromatographic purity 70.9%, AV0.3, POV0.49, SV11.
4.1, hue (APHA) 200.

Test Examples The oleic acid esters obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were tested for oxidation stability, storage stability and skin irritation.

Oxidation stability: The peroxide value was measured after heating the sample at 60 ° C. for 5 hours while passing 300 ml of air per minute.

Storage stability: A sample was placed in a 50 ml sample bottle, sealed with a nitrogen gas and tightly closed, and stored in a thermostatic chamber at room temperature and 50 ° C. for 1 month, and then the peroxide value was measured.

Skin irritation: Five panelists conducted a closed patch test for 48 hours and judged visually. Negative shows no change on skin and no irritation, and positive indicates change on skin and irritation.

The test results are shown in Table 1 together with the main analysis results before the test. The oleic acid ester obtained by the method of the present invention has good hue and odor, is excellent in stability, and has no skin irritation. Recognize.

 ─────────────────────────────────────────────────── --Continued front page (56) References JP-A-59-71397 (JP, A) JP-A-56-71037 (JP, A) Chemical Abstracts, 85 [13] (1976), 92265w. Chemical Abstracts s, 81 [4] (1974), 14951v.

Claims (2)

[Claims] 1. A fatty acid contained in an organic solvent solution, wherein [A] (a) a fatty acid mixture containing oleic acid and urea are dissolved in an organic solvent and then cooled to separate and separate the precipitated crystals. After partially saponifying the mixture, the crystals are separated by recrystallization, and (c) oleic acid produced by acid-decomposing the obtained crystals, its lower alkyl ester or its acid halide, and [B] alcohol. A method for producing an oleic acid ester, which comprises esterification. 2. The method for producing an oleic acid ester according to claim 1, wherein after the step (c), adsorbent treatment or distillation is carried out.