JPH01242563A - Production of organic plate crystal - Google Patents

Abstract

PURPOSE:To obtain an organic plate crystal useful as a cosmetic powder, solid lubricant, etc., by dissolving an amino acid derivative such as N-long-chain monoacyl basic amino acid in a strongly acidic or strongly alkaline aqueous solution, neutralizing the solution and crystallizing the compound. CONSTITUTION:A amino acid derivative of formula I-III (R1 and R2 are 7-21 alkyl; R3 is 8-20 alkyl; m and n are 1-4) is dissolved in an aqueous solvent having a pH of <=2 or >=11, the solution is neutralized and the compound is crystallized to obtain an organic plate crystal. The aqueous solvent is preferably contains 5-95vol.% (preferably 30-70vol.%) of a hydrophilic organic solvent such as alcohols, polyhydric alcohols or lower ketones and the pH is adjusted with hydrochloric acid, sulfuric acid, phosphoric acid, NaOH, etc. Crystals having uniform size can be produced by the above method to improve the decoloration and purification efficiency and suppress the foaming. Accordingly the yield of crystal per unit volume of crystallizer can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an industrial method for producing organic platelet crystals using hydrophobic α-amino acid derivatives represented by the following soft formulas (1) to (3). The purpose is to obtain organic plate crystals with excellent lubricity suitable as cosmetic powders or solid lubricants.

RICONH(CH2)mcHcOOH(1)H2 R2NHCO(CH2)ncHcOOH(2>H2 R3CHCOOH(3) H2 (However, R1 and R2 are long chain alkyl groups with 7 to 21 carbon atoms, and R3 is a long chain alkyl group with 8 to 20 carbon atoms. Represents a long chain alkyl group, and m and n represent integers from 1 to 4.) Prior art and problems N - long chain monoacyl basic amino acid, acidic amino acid - ω
- Amino acid derivatives such as long-chain amides and α-amino long-chain fatty acids are extremely insoluble in water and ordinary organic solvents, and
Because it has characteristics such as water repellency, antioxidation, and smoothness, it is being considered for use in cosmetics, lubricants, and other fields as a new organic powder material (Japanese Patent Application Laid-Open No. 10503-1983).
), Since the particle shape of powder materials used in such fields has a large effect on their physical properties, it is necessary to manufacture them on an industrial scale with crystal shapes and particle sizes suitable for the application. However, as mentioned above, these amino acid derivatives all contain water and the usual 1f! ! It is extremely difficult to dissolve in solvents, which causes many problems in purification by recrystallization and grain shape adjustment. For example, by dissolving a small amount of N-acyl basic amino acid in a large amount of alkaline or acidic aqueous solution and then neutralizing it. The method for obtaining crystals is known (Japanese Patent Publication No. 51-28610, Yukagaku, 26.2.26 (1)
977)), but due to its low solubility, rapid crystallization occurs during neutralization, making it difficult to control the crystal shape and making it impossible to obtain crystals with uniform particle size.Furthermore, crystallization from an aqueous solution alone does not cause coloration. However, organic substances such as aminocaprolactam and alkylamines cannot be removed sufficiently, resulting in problems such as crystals turning brown. Furthermore, since significant foaming occurs during dissolution, the amount of liquid is small relative to the capacity of the crystallization tank, making it unsuitable for industrial production in terms of cost.

On the other hand, there is a method of dissolving in hot acetic acid and then cooling and recrystallizing.
These amino acid derivatives are only a few percent soluble at most in hot acetic acid at 90'C, and acetic acid requires high temperatures for recovery, making it unsuitable for industrial recrystallization. Also,
A method has also been devised in which N-long chain monoacyl basic amino acids are washed and purified using hydrogen peroxide, etc. (Japanese Patent Publication No. 57-47984), but such a method simply removes impurities and is not effective in decolorizing and purifying. The crystal shape and grain size cannot be adjusted.

Problems to be Solved by the Invention As mentioned above, N-long chain monoacyl basic amino acids,
Amino acid derivatives such as acidic amino acid-ω-long-chain amides and α-amino long-chain fatty acids are compounds that are difficult to purify by recrystallization, and therefore are suitable for use in cosmetics, solid lubricants, etc. The reality is that no industrially viable method for obtaining highly pure plate crystals with a certain particle size has been found so far.

Means for Solving the Problems The present inventors have conducted various studies on methods for crystallizing amino acid derivatives such as N-long-chain monoacyl basic amino acids, acidic amino acid-ω-long-chain amides, and α-amino long-chain fatty acids. , containing a hydrophilic organic solvent, pH below 2 or p
) Ii The inventors have completed the present invention by discovering that plate crystals with uniform particle size can be obtained industrially advantageously by dissolving these amino acid derivatives in one or more aqueous solvents and then neutralizing them.

Hydrophilic V1 solvents used in the present invention include lower alcohols such as methanol, ethanol, propatool, butanol, ethylene glycol, glycerin, etc.
Polyhydric alcohols such as butylene glycol, acetone,
Examples include lower ketones such as methyl ethyl ketone, and lower alcohols such as methanol and impropatol are particularly effective.

These hydrophilic organic solvents have the effect of increasing the dispersibility of amino acid derivatives that are highly hydrophilic and difficult to wet with water in aqueous solvents, and suppressing foaming during dissolution. The content of these hydrophilic organic solvents in the aqueous solvent is 5 to 95 vol. %
, preferably 30 to 70 vol. %. If the content of the hydrophilic organic solvent is low, the dispersibility and solubility of the amino acid derivative will decrease, resulting in the disadvantage that rapid crystallization occurs during neutralization, making it difficult to obtain particles of uniform particle size. Furthermore, the solubility of raw materials such as fatty acids and alkyl amines and by-product impurities such as aminocaprolactam is also reduced, and the efficiency of purification of colored substances by recrystallization is also reduced. Furthermore, there are disadvantages such as a decrease in the foaming suppressing effect. On the other hand, if the content of the hydrophilic organic solvent increases, the inorganic salts produced as a by-product during neutralization will precipitate and mix with the crystals of the amino acid derivative, or the solubility of the raw amino acid will decrease, resulting in a decrease in purification efficiency.

The aqueous solvent in which the amino acid derivative is dissolved is adjusted to have a pH of 2 or less or 11 or more, preferably a strongly acidic or alkaline pH of 1 or less or 12 or more. This is an essential operation to increase the solubility of amino acid derivatives, and is generally performed at pH 3 to PHI.
pH range up to O, specifically pKa of amino acid derivatives
In the pH range of ~ pKb, such amino acid derivatives form inner salts, so their solubility in aqueous solvents is extremely low, and they cannot be industrially advantageously purified and recrystallized.

゛As for the acid used for pH adjustment, in addition to hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, balatoluenesulfonic acid, etc., any acid that can adjust the aqueous solvent to the above pH range may be used. - In addition to sodium hydroxide, potassium hydroxide, etc., any alkali can be used as long as the aqueous solvent can be adjusted to the above pH range.

In obtaining organic platelet crystals by the method of the present invention, the temperature during crystallization and the dropping rate of acid or alkali during neutralization are determined depending on the type of amino acid derivative, the length of its hydrocarbon chain, and the hydrophilic organic solvent. When obtaining α-aminobalmitic acid platelet crystals with a particle size of about 10 to 20 μm, which varies depending on the content of 0 or the particle size of the target crystal, for example, from a 50 vol 1% aqueous methanol solution with a pH of 12 or higher,
The temperature during crystallization is preferably 40 to 60°C, and the acidic solution must be added slowly over 1 to 2 hours. When crystallizing at a lower temperature or increasing the dropping rate, crystal ripening becomes insufficient and the particle size becomes smaller. On the other hand, if crystallization is carried out at high temperature while slowly neutralizing, crystal growth will proceed and large crystals will be obtained. As described above, the particle size changes depending on these conditions, but in any case, the shape is plate-like, and such conditions are not essential conditions for obtaining plate-like crystals of amino acid derivatives as defined in the present invention. That is, conditions such as crystallization temperature and dropping time may be appropriately set according to the type of amino acid derivative of interest, the intended particle size, and the like.

Incidentally, the amino acid derivatives referred to in the present invention are exemplified by the following. That is, as the basic amino acid constituting the N-long chain acyl basic amino acid represented by the general formula (1) described in claim 1, α
, β-diaminopropionic acid, α, γ-diaminobutyric acid,
Ornithine, lysine, etc. are mentioned, and fatty acids that are the other component include octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, icosanoic acid, tocosanoic acid, isostearic acid, etc. It will be done.

, and the acidic amino acid represented by maximum (2) above -ω
- Acidic amino acids constituting the long chain amide include aspartic acid, glutamic acid, α-aminoadipic acid, α-
Examples of the aliphatic amine include octylamine, decylamine, laurylamine, myristylamine, palmitylamine, stearylamine, icosylamine, and tocodylamine.

In addition, the α-amine long chain fatty acids represented by maximum (3) above include α-amine octanoic acid, α-aminodecanoic acid, α-aminolauric acid, α-aminomyristic acid,
α-aminopalmitic acid, α-amine stearic acid, α
-aminoicosanoic acid, α-aminotocosanoic acid, α-aminoisostearic acid, and the like.

In the method for producing organic platelets according to the present invention, each of these amino acid derivatives may be an optically active form or a racemic form.

EXAMPLES Examples of the present invention are shown below, but it goes without saying that the present invention is not limited thereto.

Example I 10 g of crude crystals of N-lauroyl lysine were mixed with methanol and 1
2:1 mixed solution of 0% sulfur hydroxide aqueous solution 60c
c (pH 12 or higher) and stir to dissolve while heating to 40°C. While keeping the temperature constant, slowly drop a 10% aqueous hydrochloric acid solution to neutralize to pH 6.5. The precipitated crystals were filtered and dried to obtain 9.6 g of white plate-like crystals.

Example 2 10 g of crude crystals of N-lauroyl lysine were mixed with methanol and 1
Add to 60 cc of a 2=1 mixed solution of 0% aqueous hydrochloric acid (pH 2 or less) and stir to dissolve while heating to 40°C. While keeping the temperature constant, slowly drop a 10% aqueous sodium hydroxide solution to neutralize to pH 6.5. The precipitated crystals were filtered and dried to obtain 9.5 g of white plate-like crystals.

Example 3 10 g of crude crystals of glutamic acid-ω-laurylamide were mixed with isopropanol and 15% aqueous sodium hydroxide solution.
:1 Add to 60cc of mixed solution (pH 12 or higher) and add 40cc of mixed solution
Stir and dissolve while heating to °C. While keeping the temperature constant, 10% hydrochloric acid aqueous solution was slowly added dropwise to pH 6,
Neutralize up to 5.

The precipitated crystals were filtered and dried to obtain 9.4 g of white plate-like crystals.

Example 4 10 g of crude crystals of α-aminopalmitic acid were dissolved in a 3:1 mixed solution of methanol and 10% aqueous sodium hydroxide solution (60 g).
cc (pH 12 or higher) and stir to dissolve while heating to 60°C. While keeping the temperature constant, slowly drop a 10% aqueous hydrochloric acid solution to neutralize to pH 6.5.

The precipitated crystals were filtered and dried to obtain 9.7 g of white plate-like crystals.

Example 5 10 g of crude crystals of N-valmitoyllysine was added to 60 c of a 3=1 mixed solution of methanol and 10% aqueous potassium hydroxide solution.
c (pH 12 or higher) and dissolve by heating to 60°C and stirring. While keeping the temperature constant, slowly drop a 10% aqueous hydrochloric acid solution to neutralize to pH 6.5. The precipitated crystals were filtered and dried to obtain 9.5 g of white plate-like crystals.

Comparative Example I 2 of an aqueous solution prepared by adjusting 10 g of crude crystals of N-lauroyl lysine to pH 10.5 with methanol and sodium hydroxide.
An attempt was made to add the mixture to 60 cc of the =1 mixed solution (pH approximately 10) and stir it to dissolve it without heating. However, 9
Even when heated to 0° C., the crystals hardly dissolved and white plate-like crystals could not be obtained.

Comparative Example 2 10 g of crude crystals of N-lauroyl lysine were added to 60 cc of a 2=1 mixed solution of methanol and water (pH about 6°5),
I tried to dissolve it by stirring without heating it. However, even when heated to 90° C., the crystals were hardly dissolved and white plate-like crystals could not be obtained.

Comparative Example 3 10 g of crude crystals of N-lauroyl lysine were added to 60 cc of a 2=1 mixed solution of methanol and aqueous hydrochloric acid (pH approximately 3.0)
In addition, an attempt was made to dissolve the substance by stirring without heating. However, even when heated to 90°C, the crystals hardly dissolved and white plate-like crystals could not be obtained.

Comparative Example 4 10 g of crystals of N-lauroyl lysine were added to 100 cc of acetic acid at 40°C, and an attempt was made to dissolve the mixture by stirring. However, at 40°C, the crystals hardly dissolve, and
Even when heated to 90°C, some undissolved crystals remained. The insoluble matter was passed through and the crystals obtained by cooling and crystallization were white needle-shaped crystals.

Effects of the Invention The method for producing organic platelet crystals of the present invention is effective in producing on an industrial scale amino acid derivatives, which have conventionally been difficult to purify and crystallize due to their sparse solubility.

Specifically, by performing crystallization under the conditions of the present invention, it is possible to achieve excellent lubricity, which is difficult to obtain with conventional methods and is suitable for use in fields such as cosmetics and lubricants. It becomes possible to obtain plate-like crystals having cleavage properties.

In addition, it becomes easier to control the crystal precipitation process, yielding crystals with uniform particle size, increasing decolorization purification efficiency, and suppressing foaming, which increases the number of crystals collected per unit crystallization tank capacity. Industrial advantages include:

Claims (1)

[Scope of Claims] 1. Amino acid derivatives such as N-long-chain monoacyl basic amino acids, acidic amino acids-ω-long-chain amides, and α-amino long-chain fatty acids represented by the following general formulas (1) to (3) pH2
1. A method for producing organic platelet crystals, which comprises dissolving them in an aqueous solvent having a pH of 11 or less, followed by neutralization and crystallization. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(2) (However, R1 and R2 are long-chain alkyl groups with 7 to 21 carbon atoms, and R3 is a long-chain alkyl group with 8 carbon atoms. ~20 represents a long chain alkyl group, and m and n represent integers of 1 to 4.) 2. The aqueous solvent is lower alcohols such as methanol, ethanol, propanol, isopropanol, isobutanol, butanol, ethylene glycol , glycerin,
95 to 5 vol. of at least one hydrophilic organic solvent such as polyhydric alcohols such as 1,3 butylene glycol, and lower ketones such as acetone and methyl ethyl ketone. The method for producing organic platelet crystals according to claim 1, which comprises an aqueous solution containing in the range of %.