JPH0761975B2 - Method for producing unsaturated fatty acid or esterified product thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for obtaining an unsaturated fatty acid or an esterified product thereof in a high yield.

[Conventional technology]

In recent years, unsaturated fatty acids have been attracting attention as useful components of health foods. However, conventionally, unsaturated fatty acids are refined from oils containing a large amount of unsaturated fatty acids, such as certain plant oils such as evening primrose and safflower, oils produced by microorganisms such as filamentous fungi, and oils extracted from protozoa such as green worms. Supply is not enough because it is made by
It was also expensive.

On the other hand, a method of removing a sulfonate group or a sulfonic acid group from a sulfonic acid type surfactant is known. For example,
Treatment with 70% phosphoric acid at 150-200 ℃, concentrated phosphoric acid or concentrated sulfuric acid, about 400% with phosphoric anhydride
It is a method of decomposing at ℃. However, according to these methods, not only the cleavage of the C—S bond but also the cleavage of the C—O bond is likely to occur, and the polymerization reaction is likely to occur simultaneously under strong acidity.

On the other hand, a method for producing an alkanesulfonate by melting an α-sulfofatty acid with an alkali is also known (USP.
3228980).

According to this method, a saturated fatty acid is produced by elimination of the sulfone group. Also, US Pat. No. 3,228,980 describes that α-sulfopalmitic acid is heated in O-dichlorobenzene to eliminate a sulfone group, thereby producing palmitic acid.

[Problems to be solved by the invention]

An object of the present invention is to provide a method for producing a highly useful unsaturated fatty acid in a large amount by a simple means. A further object of the present invention is to provide a method in which decarboxylation reaction, polymerization and the like are less likely to occur in removing a sulfone group.

[Means for solving problems]

The present invention is made based on the finding that when a sulfo fatty acid or a salt thereof is heated in a specific ether solvent, the sulfonic group is very selectively released and an unsaturated fatty acid is easily obtained without decarboxylation. It was.

That is, the present invention provides a sulfo fatty acid having a carbon number of 8 to 24, a salt thereof, and / or an esterified product thereof with a general formula (I) having a boiling point of 120 to 300 ° C .: R ₁ O (AO) _n R ₂ (I) (In the formula, R ₁ and R ₂ are an alkyl group having 1 to 15 carbon atoms, an alkenyl group, an aryl group or an alkylaryl group,
These may be the same or different. A has 1 to 3 carbon atoms
Is an alkylene group, and n is an integer of 0 to 6. The present invention provides a method for producing an unsaturated fatty acid or an esterified product thereof, which comprises heating in the presence of an ether represented by the formula (3) to eliminate a sulfone group or a sulfonate group.

The sulfo fatty acid or the salt thereof used in the present invention is a known method,
That is, it is a so-called sulfofatty acid-based surfactant produced by hydrolyzing or transesterifying natural oils and fats such as palm oil, coconut oil, and tallow, and then sulfonation and, if desired, neutralizing the fatty acid having 8 carbon atoms. It is in the range of ~ 24. The manufacturing method is specifically described in Japanese Patent Publication No.
28635, Japanese Patent Publication No. 41-965, Japanese Patent Application No. 58-119776, Japanese Patent Application No. 58-249681, Japanese Patent Application No. 59-221480 and the like.

Here, as the sulfo fatty acid, α-sulfolauric acid,
α-sulfopalmitic acid, α-sulfoarachidic acid, α-
Α-Sulfo fatty acids such as sulfomyristic acid, 9-sulfo stearic acid, 10-sulfo △ ^11,12 octadecenoic acid,
1 of sulfo fatty acids such as 8-sulfo-9-hydroxystearic acid and 7-sulfo-10-hydroxystearic acid
Examples include species and mixtures of two or more species. Examples of the salts of sulfo fatty acids include alkali metal salts such as sodium, potassium and lithium, ammonium salts, alkanolamine salts and the like.

In the present invention, an esterified product can be used in addition to the sulfo fatty acid or its salt. Examples of the esterified product include an alkyl ester having 1 to 4 carbon atoms,
Specifically, α-sulfostearic acid methyl ester N
a, alpha-sulfo myristate ethyl K, 9-Suruhoraurin methyl, 10-sulfo - △ ^{11, 12-octadecenoic} acid butyl, 8-sulfo-9-hydroxystearic acid methyl
Li, ethyl 7-sulfo-10-hydroxystearate,
α-Sulfoplaquinate methylammonium and the like are exemplified.

In the present invention, the sulfo fatty acid, its salt or esterified product itself, that is, the solvent-free form can be used, but it is also used in the form of a commercially available aqueous slurry, a lower alcohol aqueous slurry such as water-EtOH or water-MeOH. It is possible, and of course, an inorganic salt, which is usually contained in a trace amount, and an unreacted oil component in the sulfonation reaction may be contained.

The present invention is characterized in that a sulfo fatty acid or the like is heated in the presence of an ether compound represented by the above general formula [I] having a boiling point of 120 to 300 ° C. to eliminate a sulfonic acid or sulfonate group. That is, in the present invention, it is important to use an ether solvent represented by the general formula (I), which has at least one alkoxy group in the molecule and does not contain active hydrogen. Among the compounds represented by the above general formula [I], those in which R ₁ and R ₂ are a methyl group, an ethyl group, a phenyl group and a tolyl group, and A is ethylene, propylene and n is 0 to 2 Is preferred.

Specific examples of the ether solvent represented by the general formula [I] used in the present invention include anisole, m-dimethoxybezene, m-diethoxybenzene, 1,2-diethoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, One or a mixture of two or more of diethylene glycol diisopropyl ether, tetraethylene glycol dimethyl ether and the like are exemplified. The boiling point of 120 ° C to 300 ° C corresponds to the reflux temperature at the time of reaction, and a substance having a boiling point outside this range is
Even if it corresponds to the general formula [I], the yield of desulfonation is low and it cannot be used in the present invention.

The sulfo group or sulfonate group is eliminated by dissolving or dispersing the sulfo fatty acid or the like in the ether solvent and raising the temperature by an appropriate means to bring it to a reflux state. This method may be carried out under an atmosphere of an inert gas such as nitrogen, or forced stirring may be carried out during the reaction. Since higher yield can be obtained when water does not exist in the system during the progress of the reaction, a dehydration device such as a test tube is installed under the reflux tube to remove water accompanying the raw material charging and water produced during the reaction in some cases. It is preferable to remove them sequentially out of the system. The amount of the ether solvent used in the above reaction is not particularly limited as long as it is at least such that the sulfo fatty acid in the reactor can freely flow during the reflux. However, it is usually desirable to use the ether solvent in an amount of 0.5 to 10 times by weight, preferably 1 to 3 times by weight, the amount of the sulfo fatty acid and the like. When a solvent other than the solvent of the present invention is mixed, its amount is 30% by weight of the ether solvent of the present invention.
Hereafter, it is preferable to set it to 5% by weight or less.

The reaction time, that is, the reflux time, varies depending on the molecular structure, type and reflux temperature of the ether solvent used, but is usually 1 to
Time is enough.

〔The invention's effect〕

According to the present invention, a sulfo fatty acid-based surfactant having a carboxyl group or a carboxylic acid ester group together with a sulfonate group or a sulfonic acid group is used, with high selectivity and high yield, with almost no decarboxylation or polymerization reaction. The unsaturated fatty acid can be obtained by advancing only the desulfonation reaction.

Therefore, unsaturated fatty acids, which are attracting attention as a component of health foods, can be industrially produced in large quantities by a very simple method.

Next, the present invention will be described with reference to examples.

〔Example〕

Example 1 A 500 ml flask equipped with a reflux condenser equipped with a test tube and a stirrer was charged with 60 parts of α-sulfofatty acid methyl ester ammonium salt (molecular weight 380) having an alkyl group having 11 to 19 carbon atoms.
% Aqueous slurry 50 g, tetraethylene glycol dimethyl ether (boiling point 278 ° C.) 300 g were charged. This was placed on a mantle heater, stirred and heated to bring it to a reflux state, and refluxed for 5 hours.

The water flowing out during this period was temporarily removed from the system. At the start of reflux, an alkaline gas was generated from the upper part of the reflux condenser opened to the atmosphere, but when absorbed in water, a gas exhibiting acidity was generated, and the generation of the acidic gas continued until the end of the reaction.

After the reflux was completed, the temperature was cooled to 50 ° C. or lower, the reflux condenser was replaced with a distillation tube head and the mixture was reheated under reduced pressure, and the solvent tetraethylene glycol dimethyl ether was distilled off. afterwards,
The pressure was returned to normal pressure, the whole amount in the flask was transferred to a separating funnel, water was added, and oil was completely extracted with n-hexane. N was collected from the collected n-hexane layer by vacuum topping.
-Hexane was distilled off and the ester was recovered. This is 200m
l The mixture was transferred to a round bottom flask, methanol and water were added, and sodium hydroxide was added in a slight excess over the equivalent amount of the ester. A reflux condenser was attached to this, a small amount of zeolite was added, and the mixture was heated in a water bath and refluxed for 1 hour. After cooling, the mixture was acidified with dilute sulfuric acid, the whole amount was transferred to a round-bottomed flask, and oil was extracted with n-hexane. The n-hexane layer was washed with water, dried over anhydrous sodium sulfate, and n-hexane was distilled off under reduced pressure to obtain 20,1 g of oil (unsaturated fatty acid). (Desulfonation rate 95%). The composition of the obtained oil was analyzed by NMR, IR,
As a result, it was found that the unsaturated fatty acid having a C _11-19 alkyl group was about 100%. The yield of unsaturated fatty acid was 95% based on the raw material α-sulfo fatty acid methyl ester salt.
%Met.

Comparative Example 1 An attempt was made to remove the sulfonate group in the same manner as in Example 1 except that 250 g of ethylene glycol (boiling point 197 ° C.) as a solvent and 10 g of concentrated sulfuric acid as a catalyst were used, and reflux was carried out for 2 hours. Was completely carbonized and the recovered oil content was almost zero.

Comparative Example 2 Xylene (boiling point 140 ° C.) as a solvent and 85 as a catalyst
Reaction and purification were carried out in the same manner as in Comparative Example 1 except that% phosphoric acid was used. As a result, 4.7 g of oil was recovered (desulfurization rate 22%). When this oil was analyzed by gas chromatography and high performance liquid chromatography, 30% of the recovered oil was a polymer (mostly olefin dimer), and the yield of the unsaturated fatty acid of interest was extremely low at 15.4%.

Comparative Example 3 The reaction and purification were carried out in the same manner as in Comparative Example 1 except that 1,2-dimethoxyethane (boiling point: 83 ° C.) was used as the solvent, no catalyst was used, and the reflux was carried out for 10 hours. As a result, the amount of oil recovered was as small as 1.5 g (desulfonation ratio of 7.2
%).

Example 2 50 g of a 50% aqueous slurry of an α-sulfofatty acid diammonium salt (molecular weight: 375) having an alkyl group having 11 to 19 carbon atoms and diethylene glycol-di-n-butyl ether (boiling point: 230 ° C.) as a solvent were used. Reacted in the same manner as in Comparative Example 3. As a result, 13.4 g of oil was recovered (desulfonation rate: 75%). When analyzed in the same manner as in Example 1, no polymer was found in this oil, and C _11-19
The unsaturated fatty acid having an alkyl group was almost 100%. The yield of unsaturated fatty acid was 75% based on the raw material α-sulfofatty acid di salt.

Example 3 A 60% aqueous slurry of α-sulfofatty acid methyl ester sodium salt (MW385) having an alkyl group having 11 to 19 carbon atoms was used, and anisole (boiling point 155 ° C.) was used as a solvent.
The reaction was performed in the same manner as in Comparative Example 3 except that the reaction mixture was refluxed for 7 hours, and 19.2 g of oil was recovered (desulfonation rate 92%). Almost no polymer was observed in this, and the unsaturated fatty acid having a C _11-19 alkyl group was almost 100%. The yield of unsaturated fatty acid based on the raw material α-sulfofatty acid methyl ester salt was 92%.

Comparative Example 4 Reaction and purification were carried out in the same manner as in Example 3 except that o-dichlorobenzene (boiling point 180 ° C.) was used as the solvent.
As a result, 14.4 g of oil was recovered (desulfonation ratio 69
%). However, 5% of the polymer was contained in this oil, and 28% of hydrocarbons (olefins etc.), which are thought to be the result of the decarboxylation reaction, were contained, and the carbon number of the alkyl group was 11%.
The yield of unsaturated fatty acids of ~ 19 was as low as 46%.

Example 4 Sulfo produced by sulfonation and neutralization (PH6) of a fatty acid methyl ester (iodine number 51) prepared from palm oil as a starting material in a usual manner, and then extracting and separating an unsulfonated ester. Fatty acid methyl ester sodium salt aqueous slurry (molecular weight 410, pure content 50%) 50g, and diethylene glycol diethyl ether (boiling point 190 ° C) 300
g was charged in the same apparatus as in Example 1 and reacted under reflux for 8 hours. When refined in the same manner as in Example 1, oil 1
6.3 g was recovered (95% desulphonation). When the structure was confirmed by NMR, IR, and gas chromatography, no polymerized oil was found and unsaturated fatty acids having an alkyl group with 15 carbon atoms 3.
It contained 4%, 93.5% unsaturated fatty acids (17%) and 3.1% other unsaturated fatty acids. C17 alkyl 1
The unsaturated fatty acids having 7 alkyl groups were mainly oleic acid, elaidic acid and linoleic acid. The yield of unsaturated fatty acid based on the sulfofatty acid methyl ester salt from the raw material palm oil was 95%.

Comparative Example 5 The same sulfo fatty acid methyl ester sodium salt aqueous slurry as in Example 4 and anisole were charged in the same apparatus as in Example 1 and reacted at 125 ° C. below the boiling point of anisole for 8 hours, and refined to give 4.7 g of an oil content. Recovered. The desulfonation rate was 27%.

Example 5 In an apparatus similar to that of Example 1, 50 g of an aqueous slurry of α-sulfofatty acid ethyl ester sodium salt having an alkyl group having 11 to 19 carbon atoms (pH 6, molecular weight 399: purity 50%), diethylene glycol diethyl ether (boiling point 190 C.) 300 g was charged and the reaction was carried out in the same manner as in Example 1. After the reaction was completed, the whole amount was transferred to a 1-eggplant flask, and the solvent was distilled off and recovered under reduced pressure. On the other hand, the whole amount of the residue was transferred to a separating funnel, water was added, and oil was completely extracted with n-hexane. The n-hexane layer was washed with water and dried over anhydrous sodium sulfate, and n-hexane was distilled off under reduced pressure to recover 21 g of an oil component (desulfonation rate 95%). When the composition of oil was examined by NMR, IR, and gas chromatography, it consisted of almost 100% unsaturated fatty acid ester.
%, Ethyl mono- or dioxyethylene ether ester 5%. The yield of unsaturated fatty acid ester based on the raw material α-sulfo fatty acid ethyl ester sodium salt is
It was 95%.

Claims (1)

[Claims] 1. A sulfo fatty acid having a carbon number in the range of 8 to 24, its salt and / or its esterified product,
General formula (I) having a boiling point of 00 ° C .: R ₁ O (AO) _n R ₂ (I) (In the formula, R ₁ and R ₂ are an alkyl group, an alkenyl group, or an aryl group having 1 to 15 carbon atoms. A group or an alkylaryl group,
These may be the same or different. A has 1 to 3 carbon atoms
Is an alkylene group, and n is an integer of 0 to 6. ) A method for producing an unsaturated fatty acid or an esterified product thereof, which comprises heating in the presence of an ether represented by to eliminate a sulfonic group or a sulfonate group.