KR100292812B1 - Method for producing formamidine useful for blocking ultraviolet rays - Google Patents

Abstract

PURPOSE: A method for producing formamidine useful for blocking ultraviolet rays is provided to produce high purity formamidine having improved ultraviolet ray blocking effect in higher yield. CONSTITUTION: The method for producing formamidine useful for blocking ultraviolet rays comprises the steps of: mixing ethyl 4-aminobenzoate, methylformanilide, catalyst and organic solvent; adding sodium hydroxide into the mixture at 50 deg.C or less to separate the organic layer and water soluble layer; washing the organic layer with deionizing water until the organic layer has neutral pH; adding deionizing water into the organic layer and adding phosphoric acid into thereto to produce powder; dissolving the powder in organic solvent and adding sodium hydroxide thereinto to adjust the hydrogen concentration to pH 9 to 10; reacting the mixture and holding it to separate the organic layer and water soluble layer; and removing the water soluble layer followed by filtrating and evaporating the organic layer.

Description

Manufacturing method of formamidine for sunscreen

[Industrial use]

The present invention relates to a method for producing formamidine for sunscreen, and more particularly, to a method for producing formamidine for sunscreen capable of producing formamidine of high purity.

[Prior art]

Ultraviolet rays are light rays in a shorter wavelength range than purple of visible light, and are classified into UVC (200-280 nm), UVB (280-320 nm), and UVA (320-400 nm). Ultraviolet rays emitted from the sun to the earth are absorbed and scattered from the ozone layer in the upper atmosphere and reach the ground. However, recently, as the ozone layer is destroyed by freon, the filter effect decreases and the amount of ultraviolet rays reaching the earth is increasing, and when the skin is exposed to such ultraviolet rays, the skin color becomes black or the aging is promoted. It is a cause of promoting yellowing of the substance and aging.

Accordingly, there is an increasing demand for an industrial UV absorber that can absorb ultraviolet rays and block ultraviolet rays. Various types of ultraviolet absorbers are used depending on the wavelength range of the ultraviolet absorber. As the compound mainly used as the ultraviolet absorber, a compound having benzophenone, benzotriazole, HLS (Hindered Amine Light Stabilzer), and formamidine group is mainly used in chemical structure. As the double bond in the compound used as the ultraviolet absorber absorbs ultraviolet rays and converts them into infrared energy form, the skin and ultraviolet rays can be blocked from direct contact.

Such a UV absorber should be effective even when a small amount is used, and it is preferable that a wavelength range capable of absorbing UV rays can absorb the entire UV region of 290 to 400 nm, and also have excellent thermal stability and compatibility. . Formamidine compounds are prepared and used as compounds that satisfy these physical properties. However, the purity of the compound produced is low, and the UV blocking effect has not reached a satisfactory level.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a high-purity formamidine for sunscreens, to provide a method for producing formamidine for sunscreens excellent in the sunscreen effect.

1 is a process diagram schematically showing the sequence of a process for producing the formamidine for sunscreen of the present invention.

Figure 2a is a graph showing the ultraviolet absorption rate of formamidine for sunscreen of the present invention.

Figure 2b is a graph showing the ultraviolet absorption of the conventional benzotriazole derivatives for sunscreen.

Figure 2c is a graph showing the ultraviolet absorption of the conventional benzophenone derivatives for sunscreen.

[Means for solving the problem]

In order to achieve the above object, the present invention is prepared by mixing ethyl 4-aminobenzoate, methylformanilide, catalyst and organic solvent; Injecting an aqueous sodium hydroxide solution into the mixture at a temperature not exceeding 50 ° C. to separate the organic layer and the aqueous layer; The organic layer obtained is washed sufficiently with deionized water until the pH becomes neutral; Injecting deionized water into the washed organic layer, and then adding phosphoric acid with a recrystallized solvent to produce a powder; Dissolving the powder in an organic solvent, and then injecting an aqueous sodium hydroxide solution to adjust the pH to 9-10 to be alkaline; After reacting the mixture, the mixture is left to separate an organic layer and an aqueous layer; It provides a method for producing N '-(4-ethoxycarbonylphenyl) -N-methyl-N-phenylformamidine of the formula (1) including removing the aqueous solution layer and filtering and distilling the obtained organic layer. do.

(Wherein R ₁ is ethyl, A, B and C are H, R ₂ is a methyl group)

Hereinafter, the manufacturing method of the present invention will be described in more detail with reference to FIG.

In a first reaction vessel such as a reaction tank jacket or the like, ethyl 4-aminobenzoate, methylformanilide and solvent are mixed in a molar ratio of 1: 1: 1-2: 1-4, and the catalyst is added to the mixture. Inject Toluene or chloroform may be used as a solvent, and phosphorus pentachloride (PCl ₅ ) or POCl ₃ may be used as a catalyst. When the mixture is reacted at about 50 ° C. for about 1 hour while circulating cooling water around the first reaction vessel, formamidine of Formula 1 is produced according to a reaction as in Scheme 1 below. At this time, in Formula 1 R ₁ is ethyl, A, B and C is H, R ₂ is a methyl group. By circulating the cooling water, it is possible to prevent the sudden rise in temperature due to the rapid reaction.

When the reaction is completed, the initial product (crude) is sampled (sampling), and then carried out an analytical experiment to confirm the reaction state. The initial product is then cooled to about 30 ° C. in order to prevent the temperature from increasing excessively as the base is added in the next extraction process. If the temperature is too low in the cooling process, the initial product may harden, which is undesirable.

2) primary extraction

While slowly injecting the initial product into a 23% aqueous sodium hydroxide solution, the temperature is controlled so that the cooling water is circulated around the second reaction vessel to not exceed about 50 ° C. If the temperature exceeds 50 ° C., it is not preferable because the initial product decomposes before reacting with sodium hydroxide.

When the initial product injection is completed, the cooling water circulation is stopped and the cooling water is discharged, and then steam is imported around the second reaction vessel to raise the temperature inside the reaction vessel to 50 ° C and react for 1 hour. When the reaction is completed, it is left for 1 hour to separate the organic layer and the aqueous layer. When the separation is completed, the aqueous layer of the lower layer is discharged, and check whether the pH of the discharge solution is 12 or more. The bottom layer solution is drained completely to completely remove the alkaline component. When the alkaline component remains in the organic layer, since a reverse reaction occurs in the next powder treatment step, it is sufficiently washed with deionized water until the pH of the organic layer becomes neutral.

3) powder production

About 2.5 moles of deionized water was injected into the obtained organic layer, and about 1 mole of phosphoric acid was added to the recrystallized solvent while stirring to react for 1 hour to form a powder. Subsequently, the organic layer containing the produced powder is separated from the solid powder and liquid produced by the centrifuge.

4) secondary extraction

About 2 mol of deionized water and about 2 mol of organic solvents, such as toluene, are put into a 3rd reaction container, a powder is inject | poured into a reaction tank, and it melt | dissolves completely. Subsequently, 5% aqueous sodium hydroxide solution is injected into the obtained product to adjust the pH to about 9 to 10 to be alkaline.

The temperature inside the third reaction tank is raised to 40 ° C, reacted for 30 minutes, left for 30 minutes, the organic layer and the aqueous solution layer are separated, and the separated aqueous solution layer is removed. If a small amount of water remains in the tank, the product may decompose over time, so the water must be completely separated. In order to remove the water more effectively, it is also possible to remove the water using a chemical agent such as a moisture absorbent.

5) Filtration

The obtained organic layer is filtered and transferred to a fourth reaction tank.

6) distillation

When the filtration step is completed, the organic solvent is removed by a distillation step of connecting a vacuum pump to the fourth reaction tank and raising the temperature of the reaction tank to 100 ° C., thereby obtaining a yellow compound, an ultraviolet absorber.

EXAMPLE

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention, and the present invention is not limited to the following examples.

Example 1

In a first reaction tank jacket, ethyl 4-iminobenzoate, methylformanilide and toluene solvent were mixed in a molar ratio of 1: 1: 1 and POCl ₃ was injected into the mixture as a catalyst. The mixture was reacted at about 50 ° C. for about 1 hour while circulating cooling water around the first reaction tank jacket. When the reaction was completed, the initial product (crude) was sampled (sample), and the analysis experiment was carried out to confirm the reaction state. The initial product was then cooled to about 30 ° C.

While slowly injecting the initial product into a 23% aqueous sodium hydroxide solution, the temperature was adjusted to not exceed about 50 ° C. by circulating cooling water around the second reaction tank jacket.

When the initial product injection was completed, the cooling water circulation was stopped, the cooling water was discharged, and steam was injected to react the reaction by raising the temperature of the second reaction tank to 50 ° C.

After reacting for 1 hour, the mixture was left for 1 hour to separate the organic layer and the aqueous layer. When separation was completed, the aqueous layer of the lower layer was completely discharged, and the pH of the discharge solution was checked to be 12 or more. The organic solvent layer was sufficiently washed with deionized water until the pH of the organic layer became neutral.

2.5 mol of deionized water was injected into the obtained organic layer, 1 ball of phosphoric acid was injected while rotating a tank stirrer, and the reaction was carried out for 1 hour to produce a powder. Subsequently, the organic layer including the produced powder was separated from the solid powder and liquid by using a centrifuge.

2 mol of deionized water and 2 mol of organic solvents, such as toluene, were put into the 3rd reaction tank, and the powder was inject | poured into the said 3rd reaction tank, and it melt | dissolved completely. Subsequently, 5% aqueous sodium hydroxide solution was injected into the obtained product to adjust the pH to about 9, thereby making alkaline.

The temperature inside the third reaction tank was raised to 40 ° C, reacted for 30 minutes, left for 30 minutes, and the organic layer and the aqueous solution layer were separated. The separated aqueous layer was separated from the third reaction tank and discharged into the wastewater tank.

The organic layer was filtered by connecting a filter to the third reaction tank, and then transferred to the fourth reaction tank.

When the filtration process is complete, a vacuum pump is connected to the fourth reaction tank, and toluene is removed by a distillation process of raising the temperature of the fourth reaction tank to 100 ° C., which is a yellow compound N ′-(4). -Ethoxycarbonylphenyl) -N-methyl-N-phenylformamidine was obtained.

Comparative Example 1

In a stirred solution of N, N-bis (4-ethoxycarbonylphenyl) formamidine (6.8 g, 0.02 mol) dissolved in 50 ml of dimethylformamide, 2.0 g of potassium hydroxide and 2 ml (0.02 mol) of dimethyl sulfate ) Was added. The solution was stirred overnight and heated to 100 ° C. for 3 hours. The reaction mixture was added to 100 ml of water, and the precipitate was filtered and dried to obtain a solid. This solid was dissolved in 150 ml of benzene, the undissolved material was filtered off and the filtrate was concentrated to a solid residue. This solid residue was dissolved in 50 ml of chloroform. The remaining solid was removed by filtration and the filtrate was concentrated to produce N, N'-bis (4-ethoxycarbonylphenyl) -N-methylformamidine.

The purity of formamide prepared according to the method of Example 1 and formamidine prepared by the conventional method was measured, and the results are shown in Table 1 below.

As shown in Table 1, it can be seen that the purity of formamidine prepared by the method of the present invention is much higher than that of formamidine prepared by the method of Comparative Example 1.

In addition, the ultraviolet absorption ability of the formamidine, the conventional benzotriazole derivatives and the benzophenone derivatives of Example 1 was measured and shown in FIGS. 2A to 2C, respectively. As shown in Figures 2a to 2c, since the formamidine of the present invention is excellent in the ultraviolet absorption rate, it can be seen that the UV blocking effect is excellent.

As described above, formamidine produced by the method of the present invention is very high in purity and excellent in UV blocking ability, and thus is useful as a sunscreen.

Claims (1)

Mixing ethyl 4-aminobenzoate, methylformanilide, catalyst and organic solvent; Injecting an aqueous sodium hydroxide solution into the mixture at a temperature not exceeding 50 ° C. to separate the organic layer and the aqueous layer; The organic layer obtained is washed sufficiently with deionized water until the pH becomes neutral; Injecting deionized water into the washed organic layer, and then adding phosphoric acid with a recrystallized solvent to produce a powder; Dissolving the powder in an organic solvent, and then injecting an aqueous sodium hydroxide solution to adjust the pH to 9-10 to be alkaline; After reacting the mixture, the mixture is left to separate an organic layer and an aqueous layer; A method for producing N '-(4-ethoxycarbonylphenyl) -N-methyl-N-phenylformamidine comprising the step of removing the aqueous solution layer and filtering and distilling the obtained organic layer.