JPH08301827A - Production of alkanolamide - Google Patents

Abstract

PURPOSE: To produce a high-purity alkanolamide which is a foam stabilizer, a dye dispersing agent, etc., by reacting a fatty acid with an alkanolamine so as not to locally provide an excessive amount of the fatty acid in the system during the reaction. CONSTITUTION: The reaction is carried out under stirring while dividedly or continuously charging a fatty acid (e.g. lauric acid) into an alkanolamine (e.g. ethanolamine) preferably at 0.05-0.5mol/hr charging rate based on 1mol alkanolamine at 90-200 deg.C to afford an alkanolamide (e.g. lauric acid monoethanolamide).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a highly pure alkanolamide by reacting a fatty acid with an alkanolamine.

[0002]

Alkanolamides are used as foam stabilizers, foam improvers, thickeners, dye dispersants and cosmetic emulsifiers. As a method for producing such an alkanolamide, a method for producing an alkanolamide by reacting a fatty acid ester with an alkanolamine in the presence of an alkali catalyst (US Pat. No. 2,844,609), and 2 for fatty acid ester and fatty acid ester are used. A method of reacting with a molar amount of alkanolamine (Japanese Patent Publication No. 36-1362).
No. 2), a method of reacting a fatty acid with an alkanolamine to form an amide ester, and then adding an alkanolamine having an alkali catalyst uniformly or dispersed therein to produce an alkanolamide (JP-A-53-44513).
Issue gazette) etc.

[0003]

However, in US Pat. No. 2,844,609, a relatively expensive fatty acid ester is used as a raw material, which is disadvantageous in terms of price.
In Japanese Patent Publication No. 36-13622, since the alkanolamine is used in an amount of 2 moles with respect to the fatty acid ester, the amount of residual alkanolamine increases, and as a result, the purity of the alkanolamide decreases. Further, in JP-A-53-44513,
When adding an alkali catalyst after completion of amide esterification,
Since the residual fatty acid reacts with the alkali catalyst to form soap, there is a drawback that it is necessary to use an excess amount of the alkali catalyst with respect to the residual fatty acid. The present invention has been made to solve such a problem, and an object of the present invention is to provide a method for easily producing a highly pure alkanolamide in a short time.

[0004]

The inventors of the present invention have made extensive studies to solve the above-mentioned problems. As a result, when monoethanolamine is used in excess with respect to a fatty acid to cause a reaction, monoethanolamine causes an autocatalytic action. Since it is possible to obtain an alkanolamide having a low content of amine ester or amide ester, which is a side reaction product that is considered to be a reaction product, a reaction system in which the number of moles of alkanolamine is always in excess of that of fatty acid, that is, in an alkanolamine The present invention has been completed based on the finding that a highly pure alkanolamide can be easily obtained in a shorter time than conventional ones by carrying out the reaction while dividing or continuously adding the fatty acid to.

That is, the gist of the present invention is: (1) In a method for producing an alkanolamide by reacting a fatty acid with an alkanolamine, the reaction is carried out while dividing the fatty acid into the alkanolamine or continuously charging the fatty acid. (2) The molar ratio of the fatty acid to the alkanolamine at the end of charging ((moles of fatty acid) / (moles of alkanolamine)) is 0.5 to 1.0. (3) The production method according to (1) above, wherein (3) the charging speed of the fatty acid is alkanolamine 1
The production method according to (1) or (2) above, which is 0.05 to 0.5 mol / Hr relative to the mole, (4) Any of (1) to (3) above, wherein the reaction temperature is 90 to 200 ° C. (5) The production method according to any one of (1) to (4), wherein the fatty acid is added dropwise, and (6) the (1) to (1) wherein the alkanolamine is monoethanolamine or diethanolamine. (5) The manufacturing method according to any one of the above.

The alkanolamide produced in the present invention is, for example, a compound having a structure represented by the following general formula.

[0007]

Embedded image

(In the formula, R represents an alkyl group or an alkenyl group having 7 to 21 carbon atoms.)

In the present invention, the above-mentioned alkanolamide is produced from fatty acids and alkanolamines as raw materials. The fatty acid used in the present invention is not particularly limited, and a known one generally used in the production of alkanolamide, that is, a fatty acid having 8 to 22 carbon atoms, preferably 8 to 18 carbon atoms is used. In particular,
Octanoic acid, lauric acid, capric acid, myristic acid,
Examples thereof include palmitic acid, stearic acid, arachidic acid, docosanoic acid and the like.

The alkanolamine used in the present invention is not particularly limited, and known monoalkanolamines, dialkanolamines and the like usually used in the production of alkanolamides can be used. Specific examples thereof include monoethanolamine and diethanolamine, with preference given to monoethanolamine.

In the present invention, the alkanolamide is produced by mixing and reacting the above fatty acid and alkanolamine under heating conditions. Here, it is a feature of the present invention that the reaction is carried out while the fatty acid is divided or continuously added to the alkanolamine. As described above, by gradually adding the fatty acid without adding it all at once, it is possible to prevent the fatty acid from locally becoming excessive in the system and suppress the production of by-products.

[0012] Here, the term "divided in divided amounts" means that a part of the fatty acid is introduced in plural times, and the term "introduced continuously" means that the fatty acids are gradually added over a certain period of time. Here, the mode of continuously charging is not particularly limited, but the mode of dropping the fatty acid dropwise is preferable from the viewpoint of reducing the fatty acid concentration in the reaction system as much as possible to suppress by-products. In order for the number of moles of alkanolamine to be always more than the number of moles of fatty acid during the reaction period, it can be realized by carrying out the reaction, for example, by adding fatty acid to alkanolamine. More specifically, for example, a mode in which a fatty acid is dividedly or continuously added to an alkanolamine can be mentioned.

In the present invention, the molar ratio of fatty acid to alkanolamine at the end of charging ((number of fatty acid moles))
/ (Mol of alkanolamine)) is 0.5 to 1.0
Is preferable, 0.8 to 1.0 is more preferable,
0.9 to 0.95 is particularly preferable. Here, the molar ratio is 0.5 from the viewpoint of reducing the amount of residual alkanolamine.
The above is preferable, and 1.0 or less is preferable from the viewpoint of reducing the amount of residual fatty acid and suppressing the formation of amide ester.

In the present invention, the feeding speed when feeding the fatty acid to the alkanolamine is not particularly limited, but it is 0.
The range of 05-0.5 mol / Hr is preferable, and 0.1-0.5 mol / Hr is preferable.
0.25 mol / Hr is more preferable, and 0.13 to 0.
2 mol / Hr is particularly preferred. Here, from the viewpoint of shortening the reaction time, 0.05 mol / Hr or more is preferable, and from the viewpoint of suppressing the production of amine ester due to the decrease of the excess ratio of alkanolamine to the residual fatty acid in the reaction system, 0.5 mol / Hr or less is preferable. preferable. In addition, in the case of divided charging, charging may be carried out on the same basis. For example, if the charging speed is Nmol / Hr, Nm per hour is obtained.
It suffices to divide and input so that it becomes ol.

Although the reaction temperature in the present invention is not particularly limited, it is preferably in the range of 90 to 200 ° C, more preferably 120 to 180 ° C, and 150 to 1 ° C.
70 ° C. is particularly preferred. Here, the reaction temperature is preferably 90 ° C. or higher from the viewpoint of obtaining a practical reaction rate, and is preferably 200 ° C. or lower from the viewpoint of preventing coloring of the product.

Further, during the reaction, in order to prevent coloration due to oxidation and to accelerate the dehydration of water produced by the reaction, it is possible to introduce an inert gas such as nitrogen or to reduce the pressure.

[0017]

EXAMPLES The present invention will be described in more detail with reference to Examples, Comparative Examples and Reference Examples, but the present invention is not limited to these Examples.

Example 1 Monoethanolamine 8 was added to a 500 mL four-necked flask.
3.6 g (1.37 mol) was charged and heated to 160 ° C. Next, 250 g of lauric acid dissolved by heating at 50 ° C
(1.25 mol) was added dropwise to the monoethanolamine over 5 hours while maintaining the reaction temperature at 160 ° C under stirring conditions using a dropping funnel. After the completion of the dropping, the obtained content was stirred at 160 ° C. for 2 hours for aging. In all of the above steps, the pressure was normal pressure with nitrogen gas flowing in.

After aging, 291.8 g (1.20 mol)
Lauric acid monoethanolamide was obtained. The purity of lauric acid monoethanolamide (monoethanolamide) was expressed by the weight ratio in the reaction product. In addition, analysis was performed using gas chromatography, and purity, by-products, and the like were examined. For by-products, 1.7 as amine ester
% And 0.6% as an amide ester were measured and expressed as a reaction rate based on a fatty acid. Table 1 shows the results.

Comparative Example 1 The procedure of Example 1 was repeated, except that lauric acid was added to monoethanolamine over 1 minute and aged for 8 hours. The results are shown in Table 1.

Example 2 The same procedure as in Example 1 was carried out except that 250 g of lauric acid was divided into 10 times every 36 minutes and charged into monoethanolamine. The results are shown in Table 1.

Comparative Example 2 Lauric acid 25 dissolved in a 500 mL four-necked flask
0 g was taken and heated to 160 ° C., 41.8 g (0.68 mol) of monoethanolamine was added under stirring conditions and the reaction was carried out for 11 hours while maintaining the reaction temperature.
Monoethanolamine 41.8g after lowering to 0 ℃
(0.68 mol) was added and the reaction was carried out for 5 hours. The results are shown in Table 1. In all of the above steps, the pressure was normal pressure with nitrogen gas flowing in.

Comparative Example 3 Lauric acid 25 dissolved in a 500 mL four-necked flask
0 g was taken and heated to 160 ° C., and 41.8 g of monoethanolamine was added under stirring conditions to maintain the reaction temperature at 1
The reaction was carried out for 1 hour, the reaction temperature was further lowered to 90 ° C., and then 41.8 g of monoethanolamine in which 2.8 g of caustic soda was dissolved was added and the reaction was carried out for 4 hours. The results are shown in Table 1. In the above steps, all under nitrogen gas inflow,
The pressure was normal pressure.

Example 3 79.8 g (1.31 mol) of monoethanolamine was added to 5
The mixture was placed in a 00 mL flask and heated to 95 ° C. Next, 250 g of lauric acid that had been heated and melted while maintaining the reaction temperature was added dropwise to the monoethanolamine from the dropping funnel over 20 hours and aged for 2 hours. The results are shown in Table 1. In all of the above steps, the pressure was normal pressure with nitrogen gas flowing in.

Reference Example 1 The molar ratio of lauric acid to monoethanolamine ((mol of lauric acid) / (mol of monoethanolamine)) was 0.5 (lauric acid: 1 mol, monoethanolamine: 2 mol). ), 0.67 (lauric acid: 1 mol, monoethanolamine: 1.5 mol), 0.83
(Lauric acid: 1 mol, monoethanolamine: 1.2
Mol), 1.0 (lauric acid: 1 mol, monoethanolamine: 1 mol), 1.25 (lauric acid: 1 mol, monoethanolamine: 0.8 mol), 2.0 (lauric acid: 1 mol) , Monoethanolamine: 0.5 mol), and monoethanolamine is added to the fatty acid all at once.
The reaction was carried out under the conditions of 160 ° C. and 8 hours. The obtained reaction product was analyzed in the same manner as in Example 1. Lauric acid monoethanolamide (monoethanolamide), amine ester, amide ester, and residual fatty acid corresponding to the respective molar ratios were expressed by the reaction rate based on the fatty acid. Table 2 shows the results.

[0026]

[Table 1]

[0027]

[Table 2]

From the above, the following has been found. According to the production method of the present invention, highly pure monoethanolamide can be easily obtained in a short time (Examples 1 to 3).
On the other hand, the production method in which fatty acids are added to monoethanolamine all at once (Comparative Example 1) and the production method in which monoethanolamine is added to fatty acids (Comparative Example 2) are not preferable because many by-products are produced. . Although high-purity monoethanolamide can be obtained by the conventional method, the process is more complicated and the required reaction time is longer as compared with the examples (Comparative Example 3). Further, when the molar ratio ((moles of fatty acid) / (moles of alkanolamine)) exceeded the predetermined range, a large amount of by-products were generated (Reference Example 1).

[0029]

Industrial Applicability According to the present invention, a highly pure alkanolamide can be easily obtained in a short time by dividing a fatty acid into an alkanolamine or continuously charging the fatty acid.

Claims (6)

[Claims] 1. A method for producing an alkanolamide by reacting a fatty acid with an alkanolamine, wherein the reaction is carried out while dividing the fatty acid into the alkanolamine or continuously introducing the fatty acid into the alkanolamine. Method. 2. The molar ratio of fatty acid to alkanolamine ((mol of fatty acid) / (mol of alkanolamine)) at the end of charging is 0.5 to 1.0.
The manufacturing method described. 3. The production method according to claim 1, wherein the rate of introducing the fatty acid is 0.05 to 0.5 mol / Hr with respect to 1 mol of the alkanolamine. 4. The production method according to claim 1, wherein the reaction temperature is 90 to 200 ° C. 5. The production method according to claim 1, wherein the fatty acid is added dropwise. 6. The method according to claim 1, wherein the alkanolamine is monoethanolamine or diethanolamine.