JP3362468B2 - Process for producing N-mixed saturated fatty acyl neutral amino acids - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing N-mixed saturated fatty acid acyl neutral amino acids (glycine, alanine and β-alanine), and more specifically, a high-purity N-useful useful as a surfactant or the like. The present invention relates to a method for producing a mixed saturated fatty acid acyl neutral amino acid in high yield and economically advantageous.

[0002]

PRIOR ART AND PROBLEMS TO BE SOLVED BY THE INVENTION N-
Acyl amino acids are known to have low surface irritation, in which their alkali salts have excellent surfactant activity and bacteriostatic activity, and are used in various fields. Further, N-acyl amino acids are known to exhibit an excellent synergistic effect when used in combination with other surfactants. Generally, in order to produce these N-acyl amino acids, an aqueous solution containing an amino acid and an alkaline substance is reacted with a fatty acid halide by the Schotten-Baumann reaction, and then the N-acyl amino acid which is neutralized and precipitated with a strong acid is added. The method of filtering and washing is adopted.

However, according to this method, the inorganic salt is likely to remain in the crystals separated by filtration, a large amount of washing water is required to remove the inorganic salt, and the washing requires a long time, which deteriorates the manufacturing economy. There was a problem. In addition, when the crystals are not washed at all or washed with a relatively small amount of washing water, a large amount of inorganic salt remains, and therefore N-acyl amino acid produced by the above method is blended in the detergent, resulting in turbidity. And the stability at low temperature becomes poor.

Among the acylamino acids, glycine,
It is difficult to pick up crystals of alanine and β-alanine with a particle size having good filterability, and the operation itself, such as once picking up as crystals, is disadvantageous for large-scale industrial scale production.

JP-A-5-70418 discloses that when glycine and β-alanine are reacted with a fatty acid halide having a single chain length, if sodium hydroxide is used as a reaction neutralizing agent, gelation of the reaction solution may occur. It is described that potassium hydroxide should be used because it occurs and stirring becomes difficult. Further, JP-A-4-321656 discloses a method of distilling off a low boiling point substance in a fatty acid chloride in order to suppress thickening of a reaction liquid. However, the above problems have not been solved even by these methods, and development of a manufacturing method having high purity, high yield, and manufacturing economical advantage has been desired.

[0006]

[Means for Solving the Problems] Under such circumstances, as a result of intensive investigations by the present inventors, the fatty acid halide used in the Schotten-Baumann reaction was changed to a mixed saturated fatty acid halide, so that even in the presence of sodium hydroxide. It can be easily reacted without gelation, and after being neutralized with a strong acid, the organic layer and the aqueous layer are separated by heating at 60 ° C. or higher, and the N-mixed saturated fatty acid acyl neutral amino acid is separated from the organic layer. The present invention has been completed by finding that a highly pure N-mixed saturated fatty acid acyl neutral amino acid can be easily produced by recovering.

That is, according to the present invention, a mixed saturated fatty acid halide having 6 to 18 carbon atoms is added to an aqueous solution of glycine, alanine or β-alanine, and the mixture is reacted in the presence of an alkali to give an N-mixed saturated fatty acid acyl neutral. An amino acid salt aqueous solution is obtained (step (1)), and then a strong acid is added to the obtained N-mixed saturated fatty acid acyl neutral amino acid salt aqueous solution,
An N-mixed saturated fatty acid acyl neutral amino acid characterized by being separated into an organic layer and an aqueous layer at 0 ° C. or higher, and recovering the N-mixed saturated fatty acid acyl neutral amino acid from the organic layer (step (2)). Of the manufacturing method of.

The present invention will be described in detail below. The mixed saturated fatty acid halide used in the step (1) of the present invention is a fatty acid obtained by mixing a single saturated fatty acid having 6 to 18 carbon atoms, or a natural mixed saturated fatty acid such as coconut oil fatty acid. Alternatively, it is a halide of a mixed unsaturated fatty acid hydrogenated product, and the fatty acid composition ratio thereof is (weighted saturated fatty acid halide having 12 or less carbon atoms) / (saturated fatty acid halide having 13 or more carbon atoms) = 100/0 by weight ratio.
10/90, preferably 95/5 to 20/80, and particularly preferably 80/20 to 50/50. The composition ratio of the fatty acid can be changed within the range in which the organic layer and the aqueous layer can be separated in the step (2). When only a saturated fatty acid halide having 12 or less carbon atoms is used, it is essential that the content of lauroyl halide is 95% or less. Further, the mixed fatty acid halide may contain an unsaturated fatty acid halide within a range that does not impair the objects and effects of the present invention.

The neutral amino acid used in the reaction is selected from glycine, alanine and β-alanine. In the case of alanine, either an optically active substance or a DL form may be used. The reaction ratio of acylation is based on the mixed saturated fatty acid halide,
It is sufficient if the neutral amino acid is 1 to 1.2 equivalents. The reaction is carried out by adding an alkali such as sodium hydroxide or potassium hydroxide to the neutral amino acid to prepare an aqueous solution having a pH of 9.5 to 12.5, and adding a fatty acid halide and an alkali such as sodium hydroxide while keeping the pH alkaline. Do it. At this time, it is preferable that the reaction temperature is 45 ° C. or lower because decomposition of the fatty acid halide is suppressed. After the fatty acid halide is added dropwise, the mixture is stirred for 0.1 to 5 hours to complete the reaction.

Next, a strong acid such as hydrochloric acid or sulfuric acid is added to neutralize the solution to pH 4 or lower, and then the reaction solution is heated to 60 ° C. or higher, preferably 7
By heating to 0 to 90 ° C., the organic layer and the aqueous layer composed of the N-mixed saturated fatty acid acyl neutral amino acid are separated. At this time, if the temperature is lower than 60 ° C, the layer is not separated. In addition, once the layers are separated, impurities such as salts are not sufficiently selected, and when the organic layer is repeatedly washed, the washing can be efficiently performed by setting the pH of the washing liquid to 5 or less. When washing is performed with water having a pH of 5 or more, the N-mixed saturated fatty acid acyl neutral amino acid may be dissolved or emulsified in water depending on its fatty acid composition, and the layer separation cannot be performed efficiently. As the pH adjuster for the washing liquid, inorganic acids such as sulfuric acid, hydrochloric acid and phosphoric acid, and organic acids such as citric acid can be used.

The N-mixed saturated fatty acid acyl neutral amino acid obtained by the production method of the present invention is cooled and solidified,
Although it can be taken up as a free form by crushing, it can be used as a surfactant by converting it into an inorganic salt or an organic salt by a conventional method, if necessary.

[0012]

The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 Process for producing N-mixed saturated fatty acid acyl-DL-alanine triethanolamine salt (1): DL-alanine 94 g was dissolved in water 451 ml, and 27% sodium hydroxide was added thereto to adjust pH to 1.
1.3 aqueous solution with fatty acid composition; C ₁₀ : 10
%, C ₁₂ : 40%, C ₁₄ : 40%, C ₁₆ : 10% fatty acid chloride 234 g was added while adjusting the pH to 11.3 using a 27% aqueous sodium hydroxide solution. The reaction temperature was maintained at 30 to 35 ° C. and the addition was performed over 1 hour. After the addition was completed, the temperature was raised to 45 ° C. and the mixture was stirred for 1 hour. Heating the reaction solution obtained in step (2) (1) to 60 ° C.,
69 g of sulfuric acid was gradually added dropwise to bring the temperature to 80 ° C. N-
After the mixed saturated fatty acid acyl-DL-alanine was dissolved, the aqueous layer separated from the bottom was extracted, and an aqueous triethanolamine solution was added so that the concentration of the active agent was 30%, and the solution was taken as an aqueous solution. The purity of the product was 92%, and the salt concentration (wt%) was Cl: 0.1% or less and SO ₄ : 0.1% or less.

Example 2 Process for producing N-mixed saturated fatty acid acylglycine / triethanolamine salt (1): 79 g of glycine was dissolved in 466 ml of water, and 155 g of 27% sodium hydroxide was added thereto to give a glycine sodium salt aqueous solution. , Fatty acid composition of this; C
_{8: 5%, C 10:} 10%, C 12: 60%, C 14: 20
%, C ₁₆ : 5% acid chloride (221 g) was added while adjusting the pH to 11.2 using a 27% aqueous sodium hydroxide solution. The reaction temperature was kept at 25 ° C., and the reaction was added over 0.5 hours. After the addition was completed, the temperature was raised to 30 ° C. and the mixture was stirred for 1 hour. Step (2): The reaction solution was heated to 50 ° C., 69 g of sulfuric acid was gradually added dropwise, and the temperature was raised to 85 ° C. After the N-mixed saturated fatty acid acylglycine was dissolved, the aqueous layer separated from the bottom was removed. Further, the same amount of sulfuric acid aqueous solution adjusted to pH 2.5 as that of the removed water layer was added, the temperature was again adjusted to 85 ° C., and the water similarly separated was removed. Then, triethanolamine and water were added so that the concentration of the activator was 30%, and the solution was taken up as an aqueous solution. The purity of the product is 94%, the salt concentration (wt%) is Cl: 0.1%, SO _4: was 0.2%.

Comparative Example 1 When the mixed saturated fatty acid chloride used in Example 2 was replaced with lauroyl chloride, which is a fatty acid having a single composition, and potassium hydroxide was used instead of sodium hydroxide, the step (2) Therefore, the organic layer and the aqueous layer could not be separated.

Example 3 After performing steps (1) and (2) in the same manner as in Example 2, 2
The same procedure was performed except that the washing solution for the second washing was adjusted to pH 2.3 with citric acid. Product purity is 94%, salt concentration (w
t) was Cl: 0.1% and SO ₄ : 0.1% or less.

Example 4 Reaction was carried out in the same manner as in Example 2, and after carrying out steps (1) and (2), the same procedure was carried out except that the washing liquid for the second washing was water (pH 6.0). However, the separation between the organic layer and the water layer is poor,
It was inseparable.

Comparative Example 3 When the step (1) was carried out in the same manner as in Example 2 and the temperature was 55 ° C. after neutralization with sulfuric acid in the step (2), the layer was not separated at all and became a cream.

Example 5 Process for producing N-mixed saturated fatty acid acyl β-alanine-potassium salt (1): 94 g of β-alanine was dissolved in 451 ml of water, and 27% sodium hydroxide was added thereto to adjust pH to 11.
221 g of the same mixed saturated fatty acid chloride as in Example 2 was added thereto while adjusting the pH to 11.3. The reaction temperature was maintained at 30 to 35 ° C. and the addition was performed over 1 hour. After the addition was completed, the temperature was raised to 45 ° C. and the mixture was stirred for 1 hour. Step (2): The reaction liquid obtained in the step (1) was heated to 60 ° C., 69 g of sulfuric acid was gradually added dropwise to bring the temperature to 75 ° C. After dissolution of the N-mixed saturated fatty acid acyl β-alanine,
Remove the separated water layer from the bottom and adjust the pH to the same level as the removed water layer.
A sulfuric acid aqueous solution adjusted to 2.0 was added, the temperature was again raised to 75 ° C., and the aqueous layer similarly separated was extracted. After that, the activator concentration is 3
An aqueous solution of potassium hydroxide was added to 0%, and the solution was taken as an aqueous solution. Product purity is 93%, salt concentration (w
t%) was Cl: 0.1% or less and SO ₄ : 0.1% or less.

Example 6 Process for producing N-mixed saturated fatty acid acylglycine / potassium salt (1): 79 g of glycine was dissolved in 466 ml of water, and 27% sodium hydroxide was added thereto to adjust pH to 11.0.
Of the fatty acid composition; C ₁₀ : 20%, C
216 g of acid chloride with ₁₂ : 70% and C ₁₄ : 10%
Was added while adjusting the pH to 11.0 with 27% sodium hydroxide. The reaction temperature was kept at 30 ° C. and the addition was continued for 0.5 hours. After the addition was completed, the temperature was raised to 50 ° C. and the mixture was stirred for 1 hour. Step (2): The reaction liquid obtained in the step (1) was heated to 60 ° C., 69 g of sulfuric acid was gradually added to bring the temperature to 85 ° C. After the N-mixed saturated fatty acid acylglycine was dissolved, the aqueous layer separated from the bottom was removed. After that, the activator concentration is 30
Aqueous potassium hydroxide solution was added so that the amount became 100%, and the solution was taken up as an aqueous solution. Product purity is 94%, salt concentration (wt
%) Was Cl: 0.2% and SO ₄ : 0.2%.

Example 7 Process for producing N-mixed saturated fatty acid acyl β-alanine triethanolamine salt (1) 94 g of β-alanine was dissolved in 451 ml of water, and 27% sodium hydroxide was added thereto to adjust pH to 11.3.
And mixed fatty acid (NAA-415, manufactured by NOF CORPORATION), fatty acid composition C ₈ : 4%, C ₁₀ : 8%, C
_{12: 60%, C 14:} 25%, C 16: were added while adjusting to using 27% aqueous sodium hydroxide solution acid chloride 222g of 3%) pH 11.3. The reaction temperature was kept at 25 to 30 ° C, and the mixture was added in 1.5 hours. After the addition was completed, the temperature was raised to 40 ° C. and the mixture was stirred for 2 hours. Step (2): The reaction liquid obtained in the step (1) was heated to 60 ° C., 69 g of sulfuric acid was gradually added to bring the temperature to 80 ° C. After dissolution of the N-mixed saturated fatty acid acyl β-alanine,
The aqueous layer separated from the bottom is extracted, and the same amount of pH is 2.6.
The hydrochloric acid aqueous solution adjusted to was added, the temperature was again adjusted to 80 ° C., and the aqueous layer similarly separated was extracted. Then, an aqueous solution of triethanolamine was added so that the concentration of the activator was 30%, and the aqueous solution was taken up. Product purity is 92%, salt concentration (wt
%) Was Cl: 0.1% and SO ₄ : 0.1% or less.

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Claims (3)

(57) [Claims] 1. A method for producing an N-mixed saturated fatty acid acyl neutral amino acid, which comprises performing the following steps (1) and (2). Step (1): A mixed saturated fatty acid halide having 6 to 18 carbon atoms is added to an aqueous solution of glycine, alanine or β-alanine, and the mixture is reacted in the presence of an alkali to give an aqueous solution of an N-mixed saturated fatty acid acyl neutral amino acid salt. Obtaining step Step (2): A strong acid is added to the obtained N-mixed saturated fatty acid acyl neutral amino acid salt aqueous solution, and the mixture is separated into an organic layer and an aqueous layer at 60 ° C. or higher, and the N-mixed saturated fatty acid is extracted from the organic layer. Step to recover acyl neutral amino acid 2. The composition of the mixed saturated fatty acid halide used in the step (1) is (saturated fatty acid halide having 12 or less carbon atoms) / (saturated fatty acid halide having 13 or more carbon atoms) = 100/0 to 10/90. The method according to claim 1, wherein 3. A method for producing an N-mixed saturated fatty acid acyl neutral amino acid, wherein the organic layer obtained by the production method according to claim 1 is further washed with water having a pH of 5 or less.