JPH09216861A - Production of pale-discolored alpha-sulfofatty acid alkyl ester salt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production process for an α-sulfofatty acid alkyl ester salt less colored and whiter. SOLUTION: A saturated fatty acid alkyl ester of the formula: R1 CH2 COOR2 (R1 represents an alkyl group of 6-24 carbon atoms, R2 represents an alkyl group of 1-6 carbon atoms) is sulfonated with a sulfonating agent such as a sulfonating gas in the presence of at least one of Lewis acid selected from the group consisting of N,N-dimethylformamide(DMF), N,N-dimethylacetamid (DMAc), tetramethyl-urea(TMU), N-methylpyrrolidone(NMP), N- methylmorpholine(NMM) to give a less colored and whiter α-sulfofatty acid alkyl ester salt in a high degree of conversion.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an α-sulfofatty acid alkyl ester salt, and more particularly to a method for producing a light-colored α-sulfofatty acid alkyl ester salt having a color close to white.

[0002]

2. Description of the Related Art α-Sulfo fatty acid alkyl ester salts are used as detergent materials because one of their uses is a surfactant, which has a particularly high detergency, good biodegradability and little impact on the environment. The performance of is highly evaluated. This α-sulfo fatty acid alkyl ester salt is obtained by sulfonating a fatty acid alkyl ester with SO ₃ , and then neutralizing it with an alkali.

[0003] The sulfonation mechanism of fatty acid alkyl esters is described in Smith and Stirton: JAO.
CS vol. 44, P. 405 (1967) and Schmid,
Baumann, Stein, Dolhaine: Proceeding of the Wor
ld Surfactants Congress Munchen, vol. 2, p.
105, Gel-nhausen, Kurle (1984) and H. Yosh.
imura: Oil Chemistry (JJOCS), Vol. 41, p. 10 (1992), it proceeds according to the following reaction scheme.

[0004] (In the formula, R and R'represent an alkyl group.)

In this sulfonation reaction, when the fatty acid alkyl ester is reacted with SO ₃ , it is efficient if the SO ₃ directly reacts with the α-position of the fatty acid ester to produce α-sulfo fatty acid alkyl ester. Actually, a reaction such as insertion into the alkoxy group occurs first, and SO ₃
A one-molecule adduct (hereinafter abbreviated as a one-molecule adduct) is produced. In the next step, it further reacts with SO ₃ to introduce a sulfone group at the α-position, thereby producing a SO ₃ biadduct (hereinafter abbreviated as a biadduct). Subsequently, SO ₃ inserted into the alkoxy group is eliminated to form an α-sulfofatty acid alkyl ester.

[0006] Here, the reaction proceeds rapidly until the above-mentioned step of forming the bimolecular adduct, but SO ₃ is eliminated from the bimolecular adduct to form an α-sulfofatty acid alkyl ester. Therefore, in the actual reaction, it is necessary to excessively use a sulfonating agent (sulfonation gas) such as SO ₃ containing gas. Further, it is necessary to promote the reaction from the saturated fatty acid alkyl ester to the bimolecular adduct formation step while introducing the sulfonated gas, and then provide an aging step to promote the elimination of SO ₃ .

In order to obtain the α-sulfofatty acid alkyl ester salt, the α-sulfofatty acid alkyl ester salt is obtained from the α-sulfofatty acid alkyl ester by neutralizing with an alkali after the aging step. However, the α-sulfofatty acid alkyl ester produced by the conventional method is markedly colored, and thus the α-sulfofatty acid alkyl ester salt obtained after alkali neutralization is also colored. When used as a detergent material, since the α-sulfofatty acid alkyl ester salt cannot be made into a product in a colored state, before or after this neutralization step, a bleaching step under severe conditions with hydrogen peroxide or the like is required. It is generally done.

That is, the conventional α-sulfo fatty acid alkyl ester salt undergoes a sulfonation reaction of a fatty acid alkyl ester by a sulfonation gas (sulfonating agent) introducing step and an aging step, and then a neutralization step by alkali neutralization, It is manufactured through a bleaching process. Then, during these steps, part of the ester bond is cleaved, so α
-By-product of sulfo fatty acid or α-sulfo fatty acid disoda is inevitable. Since the above-mentioned by-products have low detergency as a detergent active ingredient and poor water solubility, when these substances are produced in large amounts, it is possible to efficiently obtain α-sulfofatty acid alkyl ester salts suitable for detergents. Becomes difficult. Therefore, it is preferable that the bleaching step which is not directly related to the production of the α-sulfofatty acid alkyl ester salt can be simplified or omitted as much as possible because the production of these by-products can be prevented.

On the other hand, one of the causes of the coloring of the α-sulfofatty acid alkyl ester described above is due to the presence of an excessive sulfonated gas. It has also been confirmed that this coloring proceeds particularly during the aging step. However, it is essential that this ripening step be performed sufficiently to suppress by-products. That is, the α-sulfofatty acid alkyl ester is converted into an α-sulfofatty acid alkyl ester salt by neutralization with an alkali after the aging step, and at this time, when the above-mentioned bimolecular adduct remains,
For example, the reaction shown in the following (II) occurs by alkali neutralization of sodium hydroxide or the like, and α-sulfofatty acid disoda having poor detergency and water solubility is produced. That is, when the SO ₃ elimination reaction in the aging step is insufficient and the neutralization is performed in a state where the bimolecular adduct is present in a large amount in the sulfonation reaction product, α-sulfofatty acid disoda is generated, It becomes difficult to obtain physical properties as a surfactant, for example, preferable detergency and penetrating power. Therefore, the most desired α
-The method for producing a sulfo fatty acid alkyl ester salt is a method capable of sufficiently performing the aging step, increasing the reaction rate, and simplifying or omitting the bleaching step. This is a method capable of producing an α-sulfofatty acid alkyl ester salt from an α-sulfofatty acid alkyl ester not containing.

[0010]

Regarding the method for obtaining this light-colored α-sulfofatty acid alkyl ester salt, an inorganic sulfate (Japanese Patent Application Laid-Open No.
-43716), fatty acid amides (WO 90039)
67, pyridine (DE 4030852), thiodiglycol diester (DE Publication 422).
(4735 gazette), etc., the method of performing a sulfonation reaction in the coexistence is proposed. However, when a fatty acid amide is used, a sufficient effect cannot be obtained unless the addition amount is large, and when pyridine is used, there is a problem in terms of odor,
Further, other methods have not always been satisfactory in terms of reaction rate and color tone improving effect.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a pale-colored α-sulfofatty acid alkyl ester salt that is close to white.

[0013]

Means for Solving the Problems The present inventors have found that the coexistence of a specific Lewis base in the sulfonation reaction of a saturated fatty acid alkyl ester increases the production rate of α-sulfofatty acid alkyl ester, The inventors have found that the color tone is also improved and have completed the present invention.

That is, a) a saturated fatty acid alkyl ester represented by the following general formula (I), b) N, N-dimethylformamide (DMF), N, N
-Dimethylacetamide (DMAc), tetramethylurea (TMU), N-methylpyrrolidone (NMP), N
The sulfonation with a sulfonating agent (sulfonation gas) in the presence of at least one Lewis base selected from the group consisting of methylmorpholine (NMM) and urea was taken as a means for solving the above problems. R ₁ CH ₂ COOR ₂ ... (I) (R ₁ represents an alkyl group having 6 to 24 carbon atoms, R ₂ represents 1 carbon atom
~ Represents an alkyl group of 6)

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The method for producing an α-sulfofatty acid alkyl ester salt of the present invention comprises a sulfonation gas (sulfonating agent) introducing step, an aging step and a neutralizing step, and particularly, the color tone of the α-sulfofatty acid alkyl ester obtained after the aging step is It is an improved method, and as a result, a method of obtaining a pale-colored α-sulfofatty acid alkyl ester salt close to white. The method for producing this α-sulfo fatty acid alkyl ester salt is as follows: a) a saturated fatty acid alkyl ester represented by the following general formula (I); b) N, N-dimethylformamide (DMF), N, N
-Dimethylacetamide (DMAc), tetramethylurea (TMU), N-methylpyrrolidone (NMP), N
-Sulfonating with a sulfonation gas in the presence of at least one Lewis base selected from the group of methylmorpholine (NMM) and urea. R ₁ CH ₂ COOR ₂ ... (I) (R ₁ represents an alkyl group having 6 to 24 carbon atoms, R ₂ represents 1 carbon atom
~ Represents an alkyl group of 6)

In the above-mentioned saturated fatty acid alkyl ester, the fatty acid residue has 6 to 24 carbon atoms, the alcohol residue has 1 to 6 carbon atoms, and the total carbon number of both is 9 to 26. The alkyl esters of saturated fatty acids include animal fats and oils derived from beef tallow, fish oil, etc., vegetable fats and oils derived from coconut oil, palm oil, soybean oil, etc., and synthetic fatty acids derived from the oxo process of α-olefins. Any of alkyl esters and the like may be used, and there is no particular limitation. These include, for example, methyl or ethyl laurate, methyl or ethyl palmitate, methyl or ethyl stearate, methyl or ethyl hardened tallow fatty acid, methyl or ethyl hardened fish oil fatty acid, methyl or ethyl coconut fatty acid, -Methyl or ethyl fatty acid fatty acid; methyl or ethyl fatty acid palm kernel oil; These saturated fatty acid alkyl esters may be used alone or in a mixture, but a lower iodine value is less likely to cause coloration during the production process, and therefore,
It is 0.5 or less, more preferably 0.1 or less.

N, N-dimethylformamide (DM
F), N, N-dimethylacetamide (DMAc), tetramethylurea (TMU), N-methylpyrrolidone (NMP), N-methylmorpholine (NMM), and the amount of the Lewis base selected from the group of urea are It is 0.1 to 10% by weight, preferably 2 to 8% by weight, based on the saturated fatty acid alkyl ester. If the amount of Lewis base added exceeds this range, the amount of these contained in the product increases,
The activator performance deteriorates. Also, the Lewis base must be recovered. If it is less than 0.1, the effect of improving the color tone is hardly recognized. Since the mixing time of this Lewis base is preferable from the viewpoint of operability, it is usually before the introduction of the sulfonation gas, but it is also possible to add and mix it after the introduction step of the sulfonation gas, that is, before the aging step. Is.

The sulfonation method of the present invention can be applied to any of the sulfonation methods such as the thin film sulfonation method and the batch sulfonation method, but the batch sulfonation method is preferable in consideration of the color tone of the α-sulfofatty acid ester. In consideration of cost and the like at the production level, the thin film sulfonation method is preferable. As the sulfonating agent (sulfonation gas),
SO ₃ gas, fuming sulfuric acid, etc. are used, but preferably,
SO ₃ gas, which is diluted with an inert gas such as nitrogen, is used. Usually, SO ₃ gas diluted to a concentration of 3 to 30% by volume with an inert gas such as air or nitrogen is used, and SO ₃ is 1.0 to 1.5 of the raw material saturated fatty acid ester.
It is used in an amount of double mole, preferably 1.1 to 1.3 mole.
If the molar ratio is less than 1.0 times, the sulfonation reaction does not proceed sufficiently. If the molar ratio exceeds 1.5 times, the sulfonation reaction becomes more intense, so that coloring due to local heat becomes remarkable, and the light-colored target product is It is not preferable in terms of obtaining.

The reaction temperature in the sulfonation gas introduction step may be a temperature at which the saturated fatty acid alkyl ester has fluidity. Generally, a temperature from the freezing point to a temperature 100 ° C. higher than the freezing point is applied. It is preferably from the freezing point to a temperature 70 ° C. higher than the freezing point. The reaction time at this time varies depending on the sulfonation method.
It is about 30 seconds and about 10 to 120 minutes in the batch sulfonation method.

In the aging step for advancing the SO ₃ elimination reaction from the bimolecular adduct, the reaction temperature is 70 to 90.
C is appropriate. If it is lower than this, the reaction does not proceed rapidly, and if it is higher, the product is markedly colored. The reaction time at this time is preferably 10 to 120 minutes.

In order to use the α-sulfofatty acid alkyl ester produced after the aging step as a surfactant, a neutralization step with an alkali is required. This neutralization step is
The reaction mixture of the sulfo fatty acid alkyl ester and the alkali is preferably carried out in an acidic or weakly alkaline range, and when it is carried out under strong alkaline, the ester bond may be easily broken. As the alkali used, for example, an alkali metal hydroxide, ammonia, ethanolamine or the like is used. Before or after this neutralization step, a bleaching step can be performed, if necessary.

The aspects of the present invention can be summarized as follows. (1) In the present invention, the Lewis base may be present at least in the aging step, and preferably the saturated fatty acid alkyl ester and 0.1 to 10% by weight of the saturated fatty acid alkyl ester are Lewis bases. After contacting the mixture with SO ₃ gas at a reaction temperature above the freezing point of the saturated fatty acid alkyl ester, S
A method of performing an aging step of desorbing O ₃ is used.

[0023] (2) sulfonating agent SO ₃ gas is preferably an (sulfonating gas), in particular, SO ₃ diluted to a concentration 3-30% by volume with an inert gas such as air or nitrogen
Gas is preferably used. (3) The reaction temperature in the sulfonation gas introduction step is carried out at a temperature equal to or higher than the freezing point of the saturated fatty acid alkyl ester, more preferably from the freezing point to the freezing point + 70 ° C. (4) The reaction temperature in the aging step is preferably 70 to 90 ° C. (5) The iodine value of the saturated fatty acid alkyl ester as a raw material is preferably 0.5 or less, more preferably 0.1 or less.

(6) After the aging step, neutralization with an alkali under acidic or weakly alkaline conditions gives an α-sulfofatty acid alkyl ester salt suitable as a surfactant. (7) The α-sulfofatty acid alkyl ester salt obtained by the production method of the present invention is subjected to at least an aging step in the presence of a Lewis base, and preferably the saturated fatty acid alkyl ester and the saturated fatty acid alkyl ester are 0. 1 to 10% by weight of a Lewis base is mixed with SO at a reaction temperature above the freezing point of the saturated fatty acid alkyl ester.
After being brought into contact with ₃ gas, it is produced through an aging step of desorbing SO ₃ from the bimolecular adduct.

[0025]

The present invention will be described in more detail with reference to the following examples, but the technical scope of the present invention is not limited thereto. (Examples 1 to 8 and Comparative Example) Methyl myristate (saturated fatty acid alkyl ester) having an iodine value of 0.09 was used in Table 1.
As shown in (1), a Lewis base was mixed (for Comparative Example 1, nothing was added), jacket cooling, and a stirrer 300
1.2 ml of anhydrous sulfuric acid gas diluted with N ₂ gas to 20% by volume while maintaining the temperature at 80 ° C. using a ml glass reactor.
Double mole (relative to the methyl myristate) for 60 minutes,
The mixture was introduced at a constant rate, and after the introduction of the entire amount, stirring was continued for 30 minutes while maintaining the temperature at 85 ° C. to produce methyl α-sulfomyristate (α-sulfo fatty acid alkyl ester). The addition amount of the above-mentioned Lewis base is shown in Table 1 in% by weight with respect to the raw material methyl myristate.

The reaction rate of the raw material methyl myristate was determined, and the color tone of methyl α-sulfomyristate was measured as follows. The color tone was measured with a Klett photometer using a 5% by weight ethanol solution of methyl α-sulfomyristate after the aging step under the above conditions, using a 40 mm optical path length, No. 42 blue filter. The results are shown together in Table 1. In Examples 1 to 8 according to the present invention, the color tone of methyl α-sulfomyristate was lighter than that of Comparative Example, and its improving effect was observed. Further, it is understood from the results of Examples 1 to 3 that the effect of improving the color tone is increased by increasing the addition amount of DMF which is a Lewis base. Further, the reaction rates of Examples 1 to 7 are higher than the reaction rates of Comparative Examples, and the presence of the Lewis base not only provides the effect of improving the color tone, but also the effect of increasing the production rate of methyl α-sulfomyristate. You can see that The thus-obtained methyl α-sulfomyristates of Examples 1 to 8 and Comparative Example were each neutralized by a conventional method, but the color tone did not change.

[0027]

[Table 1]

[0028]

The method for producing an α-sulfofatty acid alkyl ester salt of the present invention is a method of sulfonation of a saturated fatty acid alkyl ester with a sulfonation gas in the presence of a Lewis base as described above. It is possible to obtain a light-colored α-sulfofatty acid alkyl ester salt that has a high rate and is closer to white than conventional ones. Therefore, the bleaching step can be simplified or omitted as necessary, the production of by-products can be suppressed, and the quality and cost can be improved.

Continuation of front page (72) Inventor Sakuishi Sakuishi 2-636-11, Nakaseido, Kiyose-shi, Tokyo

Claims (1)

[Claims] 1. A) a saturated fatty acid alkyl ester represented by the following general formula (I): b) N, N-dimethylformamide (DMF), N, N
-Dimethylacetamide (DMAc), tetramethylurea (TMU), N-methylpyrrolidone (NMP), N
A method for producing a light-colored α-sulfofatty acid alkyl ester salt, which comprises sulfonation with a sulfonating agent in the presence of at least one Lewis base selected from the group of methylmorpholine (NMM) and urea. R ₁ CH ₂ COOR ₂ ... (I) (R ₁ represents an alkyl group having 6 to 24 carbon atoms, R ₂ represents 1 carbon atom
~ Represents an alkyl group of 6)