JP2999305B2 - Method for producing imidazoline compound with low diamide content - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing imidazoline by reacting a diamine with a fatty acid or an ester thereof to obtain a high-quality imidazoline compound having a small amount of diamide as a by-product by adding phosphoric acid. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Compounds having an imidazoline ring structure and substituted at one position by an alkylol group (hereinafter referred to as imidazoline compounds) are known as useful intermediates of imidazoline surfactants. In fact, some of the shampoos on the market use this surfactant. Particularly in recent years, surfactants used in detergents and the like are required to be excellent in various properties such as biodegradability, safety, and low irritation to the skin, in addition to the surfactant activity,
One of the surfactants satisfying these requirements is an imidazoline-type surfactant. The imidazoline-type surfactant is characterized by extremely low irritation to the eyes and skin in addition to excellent foaming and detergency, and its use as a major component of hypoallergenic shampoos and the like has recently been increasing.

[0003] As described above, imidazoline compounds are not only useful as intermediates of various imidazoline-type surfactants, but also themselves are frequently used as surfactants. In this case, the point required for the quality of the imidazoline compound is that the content of the by-product diamide is low,
Good hue and the like.

[0004] Imidazoline compounds are produced by dehydrating and condensing higher fatty acids and diamines. Generally, in the condensation reaction, when an appropriate amount of a fatty acid or an ester thereof is used, the amidoamine is first formed (reaction formula), and then this is cyclized to form a predetermined imidazoline ring (reaction formula). When a fatty acid is used as a raw material, this reaction can be exemplified as follows.

[0005]

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[0006] Such a diamide has poor solubility in water, and when an imidazoline compound having a large diamide content is used as a raw material in a final product such as a shampoo, not only causes turbidity in the product system but also various additions. In many cases, the solubility of the agent is impaired, and the appearance of the product or the performance inherent in the product is significantly impaired.

As a method for producing an imidazoline compound having a low diamide content, for example, Japanese Patent Publication No. 61-39939 discloses a method in which a reaction is carried out under a specific pressure higher than the vapor pressure of a diamine.
Japanese Patent Application Laid-Open No. 54-63078 discloses a method of decreasing the pressure logarithmically with respect to time. The former method is
1 mol of coconut oil fatty acid and 1.05 mol of diamine were charged into a predetermined reaction vessel, and then heated to 180 ° C.
While maintaining the reaction temperature near 0 ° C, increase the reaction pressure to 100 mmHg
After that, the pressure and the temperature around 180 ° C are reduced to 5
It is intended to maintain the time and obtain the desired product. That is, in this method, the reaction is carried out under a specific pressure higher than the vapor pressure of the diamine to obtain an imidazoline compound having a low diamide content. However, in such a method, although it is described in the examples that about 3.2 to 4.0% of diamide is contained in the product, when the method is performed (Comparative Example 4 of the present application), it is actually 10%. It was found that a certain amount of diamide was contained in the product, and the product quality was not satisfactory. In the latter method, the reaction time is long, there is a high possibility that other qualities such as hue are impaired, and the reaction operation is complicated, such as performing the reaction by decreasing the reaction pressure logarithmically with respect to time. Yes,
It is not a reasonable manufacturing method.

[0008]

DISCLOSURE OF THE INVENTION The present inventors have enthusiastically developed a method for improving the above-mentioned disadvantages of the conventional method and efficiently producing a high-quality imidazoline compound having a low diamide content by a simple operation. As a result of repeated studies, they have found that imidazoline having a low diamide content can be produced by adding phosphoric acid when reacting a higher fatty acid or its ester with a diamine. Without any literature suggesting such a fact, the present inventors were able to efficiently produce a high-quality imidazoline compound with a simple operation only by reaching this fact.

[0009] The present invention has the general formula _{(1) R 1 COOR 2 (} 1) ( wherein, R ₁ represents an alkyl group, an alkenyl group or hydroxyalkyl group having 7 to 21 carbon atoms, R ₂ is H or A lower fatty acid group or a higher fatty acid thereof or an ester thereof, and a general formula (2) H ₂ NC ₂ H ₄ NHX (2) (wherein X represents an alkylol group having 2 to 4 carbon atoms) .)
With a diamine represented by the general formula (3)

[0010]

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(Wherein, R ₁ and X represent the above-mentioned general formulas (1) and (2)
The present invention provides a method for producing an imidazoline compound having a low diamide content, wherein the reaction is carried out in the presence of phosphoric acid in producing the imidazoline compound represented by the formula (1). The phosphoric acid in the present invention is a concept including not only orthophosphoric acid but also cyclic or linear polyphosphoric acid such as pyrophosphoric acid and metaphosphoric acid.

The higher fatty acid represented by the general formula (1) or an ester thereof used in the present invention includes, for example, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behenic acid , Erucic acid, 12-hydroxystearic acid, coconut oil fatty acids or methyl esters and ethyl esters of these higher fatty acids.

The above-mentioned general formula (2) used in the present invention
As the diamine represented by, for example, H ₂ NC ₂ H ₄ NHC ₂ H ₄ O
Compounds such as H and H ₂ NC ₂ H ₄ NHC ₃ H ₆ OH can be mentioned.

In the production method of the present invention, the reaction temperature for obtaining a high-quality imidazoline compound is 180-180.
220 ° C is preferred. When the reaction temperature is 180 ° C. or lower, the reaction rate of imidazoline formation (reaction to the right in the reaction formula) is low, and the decomposition rate of diamide (reaction to the left in the reaction formula) is low. As a result, the rate at which the diamide is decomposed and converted into the imidazoline compound is low, so that it is difficult to reduce the diamide content to a desired level. On the other hand, when the reaction temperature is higher than 220 ° C., the color tone is deteriorated.

The reaction pressure in the production method of the present invention is not problematic as long as generated water can be efficiently removed.
Usually, it is necessary to set the starting material so that the diamine does not go out of the system together with water. In the case of amidation, it is usually about 400 mmHg, in the case of a ring closure reaction to imidazoline, it is preferably 200 mmHg or less, and in the step of removing remaining diamine, it is 50 mmHg.
Hg or less, preferably 10 mmHg or less. During the ring closure of the imidazoline and the step of removing the diamine, the diamide is decomposed and converted into a monoamide and further into an imidazoline.

In the method of the present invention, the molar ratio of the diamine to the higher fatty acid or its ester is usually 1: 1.
To 1.5: 1, preferably 1: 1 to 1.3: 1.

The amount of phosphoric acid used is from 0.01 to 5 mol%, preferably from 0.1 to 5 mol%, based on the fatty acid or its ester.
~ 3 mol%. If the amount of phosphoric acid used is less than this range, it is difficult to obtain the desired low diamide content imidazoline, while if the amount of phosphoric acid used is more than this range, effects beyond this range cannot be expected, so from an economic viewpoint. Not preferred.

The phosphoric acid may be added from the beginning, that is, when the fatty acid or its ester is charged, or when the amidation is completed and the process proceeds to the step of closing the ring to imidazoline.

The present inventors have surprisingly found that the production of imidazoline by the addition of phosphoric acid of the present invention surprisingly lowers the diamide content in the system as compared with the non-added system. Although the details of this reason are largely unknown, the acidic phosphoric acid acts on the amide portion of the monoamide, promoting the imidazoline ring closure reaction by helping the amide polarization,
That is, the equilibrium of the above reaction formula is shifted from the amidoamine side to the imidazoline side, and at the same time, regeneration of amidoamine by decomposition of diamide by-produced in the reaction formula is promoted.
That is, it is presumed that the diamide content is reduced by the action of promoting the regeneration of the amidoamine by the decomposition of the diamide and the conversion of the regenerated amidoamine to the imidazoline compound.

Thus, the present invention is useful as a method for producing high-purity imidazoline.

[0021]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 200 g of lauric acid (molecular weight) was placed in a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a pressure gauge.
200, 1 mol) and aminoethylethanolamine 109.2
g (molecular weight: 104, hereinafter abbreviated as AEAA). The mixture was stirred while warm water at 80 ° C was passed through the reflux condenser.
Heated to 140 ° C. Thereafter, the reaction pressure was increased to 400 over 1 hour.
The reaction was set at mmHg and reacted for 2 hours to effect amidation. After that, the pressure was returned to normal pressure with N ₂ , and orthophosphoric acid 0.98 g (molecular weight
98, 0.01 mol). Next, the reaction temperature was lowered to 200 mmHg over a period of 1.5 hours at a reaction temperature of 200 ° C., and aging was performed under these conditions for 1 hour. Further increase the pressure for about 1.5 hours to 10mmHg
The reaction was carried out for 1 hour under these conditions to remove excess AEAA. During this time, the generated water and the vapor of AEEA were collected in a dry ice / methanol cooling trap. The finished product is
Composition analysis was performed using high performance liquid chromatography (hereinafter abbreviated as HPLC). Table 1 shows the composition of the reaction product.

Example 2 220.5 g of coconut oil fatty acid methyl ester (molecular weight: 220.5,
1 mol) and 109.2 g of AEEA were charged into the same reactor as in Example 1, and the temperature was raised to 160 ° C. over about 1 hour. Then about 1
The pressure was reduced to 200 mmHg over time, and aging was performed for 1 hour in that state to perform amidation. Then, the pressure was returned to normal pressure with N ₂ , and 2.94 g (0.03 mol) of orthophosphoric acid was added. After that, the reaction temperature was set to 200 ° C and the pressure was set to 200 mmHg over 1.5 hours.
Aging was performed under these conditions for one hour. The pressure was further reduced to 10 mmHg over about 1.5 hours, and the reaction was carried out for 1 hour under these conditions to remove excess AAEA. During this time, generated water, methanol, and vapors of AEEA were collected in a dry ice / methanol cooling trap. The finished product was subjected to composition analysis using HPLC. Table 1 shows the composition of the reaction product.

Example 3 0.1 g (0.001 mol) of orthophosphoric acid was added to lauric acid and AE
The reaction was carried out in the same manner as in Example 1 except that EA was charged at the same time and no phosphoric acid was added. Table 1 shows the composition of the reaction product.

Example 4 A reaction was carried out in the same manner as in Example 2 except that 0.49 g (0.005 mol) of orthophosphoric acid was charged at the same time as the coconut oil fatty acid methyl ester and AEEA, and no phosphoric acid was added. Was. Table 1 shows the composition of the reaction product.

Example 5 Instead of orthophosphoric acid, 0.89 g of pyrophosphoric acid (molecular weight: 17
8, 0.005 mol) of Example 1
The reaction was carried out in the same manner as described above. Table 1 shows the composition of the reaction product.

Comparative Example 1 The reaction of Example 1 was carried out without adding orthophosphoric acid.
Table 1 shows the composition of the reaction product.

Comparative Example 2 The reaction of Example 2 was carried out without adding orthophosphoric acid.
Table 1 shows the composition of the reaction product.

Comparative Example 3 In Example 3, 3.13 g (0.3%) of 35% hydrochloric acid was used instead of orthophosphoric acid.
03 mol), and the reaction was carried out under the same conditions as in Example 3. Table 1 shows the composition of the reaction product.

Comparative Example 4 In Example 3, 3 g of 98% sulfuric acid (0.03%) was used instead of orthophosphoric acid.
Mol), and the reaction was carried out under the same conditions as in Example 3. Table 1 shows the composition of the reaction product.

Comparative Example 5 In Example 3, boric acid (molecular weight: 61.20) was used instead of orthophosphoric acid.
8) 1.85 g (0.03 mol) was added, and the reaction was carried out under the same conditions as in Example 3. Table 1 shows the composition of the reaction product.

Comparative Example 6 An imidazoline compound was synthesized according to the method of Japanese Patent Publication No. 61-39939, which was published as a method for producing imidazoline having a low diamide content. Using the same reactor as in Example 1, 200 g of lauric acid (molecular weight: 200
) And AEEA 109.2g, and reduce the pressure to 100mmH
After reaching g, heating was started. The temperature in the flask is 130
C., and when the flow of the reaction water began to flow, the temperature was raised slowly to reach a reaction temperature of 180.degree. C., and the reaction was carried out for 3 hours. Thereafter, the reaction pressure was reduced to 10 mmHg, and excess AEEA
After cooling, the mixture was cooled. The finished product was subjected to composition analysis using HPLC. Table 1 shows the composition of the reaction product.

[0033]

[Table 1]

[0034] As is apparent from the results in Table 1, in the case of Examples 1 to 5 diamide ingredient content is low by-product, and high content of imidazoline compounds. On the other hand, when no phosphoric acid is added as in Comparative Examples 1 to 6, when hydrochloric acid, sulfuric acid, or boric acid is added instead of phosphoric acid, or in a conventional reduction method under reaction conditions, the diamide component is It is clear that the content is high and the content of the imidazoline compound is low.

[0035]

According to the present invention, the production of a high-quality imidazoline compound, which has conventionally been considered extremely difficult, can be easily achieved from a diamine, a higher fatty acid or its ester and phosphoric acid. Moreover, industrial operation is extremely simple. Further, the imidazoline compound obtained by the production method of the present invention can be used as a high-quality imidazoline compound without any post-treatment for various uses as a high-quality imidazoline compound because of its good hue, high purity, and low diamide content. .

Claims (2)

(57) [Claims] A compound represented by the general formula (1): R ₁ COOR ₂ (1) wherein R ₁ represents an alkyl group, an alkenyl group or a hydroxyalkyl group having 7 to 21 carbon atoms, and R ₂ represents H or a lower alkyl group. And a higher fatty acid or an ester thereof represented by the general formula (2) H ₂ NC ₂ H ₄ NHX (2) (wherein, X represents an alkylol group having 2 to 4 carbon atoms).
Is reacted with a diamine represented by the general formula (3). (Wherein, R ₁ and X are the same as those of the above general formulas (1) and (2)). In producing an imidazoline compound, the reaction is carried out in the presence of phosphoric acid. A method for producing an imidazoline compound. 2. The method for producing an imidazoline compound having a low diamide content according to claim 1, wherein the amount of phosphoric acid is 0.01 to 5 mol% based on the higher fatty acid or ester thereof used.