JPH05238989A - Production of alkyl-beta-(3,5-dialkyl-4-hydroxyphenyul) propionate - Google Patents

Abstract

PURPOSE:To obtain the subject high-purity compound useful as an antioxidant in high yield in a short time by using a dialkyl acrylate, a specific amount of a basic catalyst and a specific amount of an alkyl acrylate. CONSTITUTION:(A) A 2,6-dialkyl phenol (preferably 2,6 di-t-butylphenol) is reacted in the presence of (B) a basic catalyst in the molar ratio of the component A/B of 1/0.015 to 0.05 and formed water is removed. Then, (C) an alkyl acrylate in an amount to give the molar ratio of the component A/C of >1 is added and the reaction is carried out to give the objective compound. The formed water is preferably removed by a method of distilling away in a vacuum state of the system. The reaction time is generally 2-4 hours including dripping time of the component C. The reaction temperature is preferably at 100 to 150 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an alkyl group useful as an antioxidant and as an intermediate raw material for other antioxidants.
It relates to a method for producing β- (3,5-dialkyl-4-hydroxyphenyl) propionate.

[0002]

2. Description of the Related Art Conventionally, as a method for producing alkyl-β- (3,5-dialkyl-4-hydroxyphenyl) propionate, for example, Japanese Patent Publication No. 62-12786 discloses a 2,6-dialkylphenone. Is reacted with a large amount of potassium hydroxide catalyst in the presence of an organic solvent, and then the produced water is azeotropically removed with the organic solvent.
A technique for reacting a gut is disclosed, and JP
-180851 discloses 2,6-dialkylpheno-
Using less than 1.0 mol of alkyl acrylate and 0.005 to 0.05 mol of potassium hydroxide per mol of 1 mol, the by-product dialkyl-2- (3,5-dialkyl) is used. A technique for obtaining a target product having a low content of -4-hydroxybenzyl) glutarate is disclosed.

[0003]

However, Japanese Patent Publication No. 62-
In the production method described in JP12786, since a large amount of potassium hydroxide catalyst is used, the viscosity during production of 2,6-dialkylphenolate becomes high and stirring becomes difficult, and therefore an organic solvent must be used in combination. As a result, there was a problem that the kettle yield was lowered and that an organic solvent removing step was required.

Further, according to the production method described in JP-A-2-180851, an excess amount of 2,6-dialkylphen-
Must be separated, or else tetrakis [3- (3,5
There was a problem that it would adversely affect the purity and crystal form of -di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane. Further, although the amount of the catalyst used is set low, the value is extremely low, so that there is a problem that the reaction time becomes long.

The problem to be solved by the present invention is that an organic solvent is not required in the reaction system, and raw materials and by-products hardly remain, that is, high yield, high purity, and in a short time. Alkyl-β- (3,5-
It is to provide a method for producing dialkyl-4-hydroxyphenyl) propionate.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a specific amount of a basic catalyst and an alkyl acrylate are added to 2,6-dialkylphenol. It has been found that by using it, the desired product can be obtained in high yield and high purity in a short time.

That is, the present invention relates to 2,6-dialkylpheno-
(A) and the basic catalyst (B) alkyl acrylate, the molar ratio [(A) / (B)] is 1 / 0.015 to 0.
After reacting in the range of 05 to remove the produced water, the acrylic acrylate (C) was added in a molar ratio [(C) / (A)].
Relates to a process for producing alkyl-β- (3,5-dialkyl-4-hydroxyphenyl) propionate, which is characterized in that the reaction is carried out in the range of 1.0.

More specifically, 2,6-dialkylpheno-
(A) and the basic catalyst (B) in a molar ratio [(A) /
(B)] is in the range of 1 / 0.015 to 0.05, preferably 1 / 0.015 to 0.03, and the generated water is excluded from the system while carrying out the charging reaction. Examples of the method for removing the generated water include a method of removing the generated water by azeotropic distillation in the presence of an organic solvent in the reaction system, and a method of distilling the generated water under reduced pressure in the system. Then, the method is preferable because it is troublesome to add water to the system sequentially. The method is specifically 90-100
Stir under a reduced pressure of 20 to 30 mmHg at 0 ° C. to remove the produced water out of the system.

When the amount of the basic catalyst (B) used is set within the above range, not only the use of the organic solvent becomes unnecessary but also the production of by-products other than the intended product can be suppressed. , Especially the molar ratio [(A) / (B)] is 1 / 0.01
When the reaction is carried out in the range of 5 to 0.03, virtually no by-products are seen.

Then, after being brought to a substantially anhydrous state, the acrylic acrylate (C) was treated with a 2,6-dialkylpheno-
1.0 mol or more, preferably 1.0 to 1.50 mol, is continuously fed and reacted with respect to 1 mol of the ruthenium (A).

Acrylic acrylate (C) was added to 2,6-
When it is used in an amount of 1.0 mol or more, preferably 1.0 to 1.50 mol, based on 1 mol of dialkylphenol (A), excess alkyl acrylate (C) is distilled during the reaction. Alkyl acrylate (C) hardly remains in the system after being removed. Especially acrylic acrylate (C)
Is used in the range of 1.0 to 1.3 mol with respect to 1 mol of 2,6-dialkylphenol (A), the residual amount of the alkyl acrylate (C) is further reduced, and it is substantially observed. I will not be able to.

In the present invention, the effect of the present invention is exhibited only when both the amount of the basic catalyst (B) used and the amount of the acrylic acrylate (C) used are satisfied. The effect of the present invention is not exhibited only by the requirement of.

Acrylic acrylate (C) is continuously supplied for 1 to 10 hours, preferably 2 to 4 hours from the viewpoint of suppressing by-products and safety in production. Good.

The reaction time varies depending on the molar ratio of the raw materials, the type of catalyst, the reaction temperature, etc., but in general, the reaction is completed within 2 to 4 hours including the dropping time of the acrylic acrylate. The reaction temperature is selected from the range of room temperature to about 200 ° C., but in order to accelerate the reaction, 100 to 1
A range of 50 ° C is preferred.

After completion of the reaction, the catalyst may be neutralized and removed, and then purified by a conventionally known method such as distillation under reduced pressure or recrystallization. However, in the present invention, a high purity can be obtained without purification operation. The target product is obtained.

The alkyl group of 2,6-dialkylphenol (A) used in the present invention is a linear or branched alkyl group having 1 to 4 carbon atoms (methyl, ethyl, n-propyl, i-). Propyl, n-butyl, t-butyl etc.), which may be the same or different, but especially 2,6-di-
t-Butylphenol is preferred.

The alkyl group of the alkyl acrylate is a linear or branched alkyl group having 1 to 22 carbon atoms (methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, nonyl group). , Dodecyl group, tetradecyl group, octadecyl group, eicosyl group, etc.).

The basic catalyst (B) used in the present invention includes basic compounds such as inorganic hydroxides such as potassium hydroxide and sodium hydroxide, sodium methoxide and potassium t-butoxide. Alcohol may be used, but potassium hydroxide is preferred because of its ease of handling.

[0019]

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

Example 1 103 g (0.5 mol) of 2,6-di-t-butylphenol and 0.56 g of potassium hydroxide were placed in a 500 ml flask and heated to 90 ° C. with stirring to bring the system to 30 to 50 m.
The produced water was distilled off from the system by holding it for 30 minutes under a reduced pressure of mHg. Then, the pressure was adjusted to normal pressure, 47.4 g (0.55 mol) of methyl acrylate was added dropwise at 130 ° C. over 2 hours, and the mixture was further stirred at the same temperature for 2 hours. After cooling to 80 ° C., it was neutralized with acetic acid and filtered to obtain the desired product. As a result of analysis by gas chromatography, the yield of the target methyl β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate was 97%, and the by-product dimethyl-2- (3 The yield of 5,5-di-t-butyl-4-hydroxybenzyl) glutarate was 0.27%.

Example 2 103 g (0.5 mol) of 2,6-di-t-butylphenol and 0.8 g of potassium t-butoxide were placed in a 500 ml flask and heated to 90 ° C. with stirring to bring the system to 30 to 30 ° C.
Under a reduced pressure of 50 mmHg, the generated water was retained for 30 minutes to distill out of the system. Next, the pressure was adjusted to normal pressure, 47.4 g (0.55 mol) of methyl acrylate was added dropwise at 130 ° C. over 2 hours, and the mixture was further stirred at the same temperature for 2 hours. 80
After cooling to ℃, it was neutralized with acetic acid and filtered to obtain the desired product. As a result of analysis by gas chromatography, the yield of the target product methyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate was 95%, and the by-product dimethyl-2- (3,3 The yield of 5-di-t-butyl-4-hydroxybenzyl) glutarate was 0.47%.

Comparative Example 1 103 g (0.5 mol) of 2,6-di-t-butylphenol and 0.35 g of potassium hydroxide were placed in a 500 ml flask and heated to 90 ° C. with stirring to bring the system to 30 to 50 m.
The produced water was distilled off from the system by holding it for 30 minutes under a reduced pressure of mHg. Next, the pressure was adjusted to normal pressure, 42.2 g (0.49 mol) of methyl acrylate was added dropwise at 130 ° C. over 3 hours, and the mixture was further stirred at the same temperature for 3 hours. After cooling to 80 ° C., it was neutralized with acetic acid and filtered to obtain the desired product. As a result of analysis by gas chromatography, the yield of the target product methyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate was 89.5%, and the by-product dimethyl-2- ( The yield of 3,5-di-t-butyl-4-hydroxybenzyl) glutarate was 1.29%, and the raw material 2,6-di-t-butylphenol was 9.8.
% Remained.

[0023]

EFFECTS OF THE INVENTION According to the present invention, an organic solvent is not required in the reaction system, and raw materials and by-products hardly remain, that is, high yield, high purity, and short-term alkyl- β- (3,5-Dialkyl-4-hydroxyphenyl) propionate is obtained.

Claims (6)

[Claims] 1. A molar ratio [(A) / (B)] of 2,6-dialkylphenol (A) and basic catalyst (B) is 1 /.
After reacting in the range of 0.015 to 0.05 to remove the produced water, the alkyl acrylate (C) is reacted in the range of molar ratio [(C) / (A)] being larger than 1.0. A process for producing alkyl-β- (3,5-dialkyl-4-hydroxyphenyl) propionate, which is characterized in that 2. The process according to claim 1, wherein the produced water is removed while the 2,6-dialkylphenol (A) and the basic catalyst (B) are reacted under reduced pressure. 3. The 2,6-dialkylphenol (A) is 2,6-di-t-butylphenol and the alkyl acrylate (C) is methyl acrylate.
Or the production method described in 2. 4. The method according to claim 3, wherein the basic catalyst (B) is potassium hydroxide. 5. The molar ratio [(B) / (A)] is 0.015.
The method according to claim 4, wherein the molar ratio [(C) / (A)] is more than 1.01 and not more than 1.50. 6. The production method according to claim 1, wherein the reaction is carried out at 100 to 150 ° C. after removing the produced water.