JPH0119370B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to 1,3,5-trialkyl-2,
This invention relates to an improved method for producing 4,6-tris(3,5-dialkyl-4-hydroxybenzyl)benzene.

[Industrial application field]

1,3,5-trialkyl-2,4,6-tris(3,5-dialkyl-4-hydroxybenzyl)benzene is a compound useful as an antioxidant.

[Prior art]

Regarding the conventional manufacturing method of 1,3,5-trialkyl-2,4,6-tris(3,5-dialkyl-4-hydroxybenzyl)benzene, for example, the following method is described in Japanese Patent Publication No. 46-41536. has been done. That is, an ester of 3,5-dialkyl-4-hydroxybenzyl alcohol is produced by reacting 2,6-dialkylphenol with formaldehyde or its polymer, a secondary amine, and a carboxylic acid, and then the benzyl ester is reacted with sulfuric acid and 1 in the presence of an inert solvent,
1, by reacting with 3,5-trialkylbenzene
3,5-trialkyl-2,4,6-tris(3,5-dialkyl-4-hydroxybenzyl)
Methods for producing benzene are known. Furthermore, in this publication, the operations of isolating and purifying the benzyl ester are omitted, and 1,3,5-trialkyl-2,4,6-tris(3,5-dialkyl-
4-Hydroxybenzyl) benzyl ester, an intermediate in the production of benzene, in the presence of the entire reaction mixture containing the benzyl ester.
-Reacted with trimethylbenzene to produce 1,3,5-
A simple process for producing trimethyl-2,4,6-tris(3,5-dialkyl-4-hydroxybenzyl)benzene is described.

However, in this method, if the reaction mixture containing the benzyl ester is used as it is as a raw material for the second stage reaction, a large amount of acid catalyst is required, for example, 10 times the mole of 1,3,5-trialkylbenzene. It has the disadvantage of being. As a method to improve this, in the publication, page 3, right column, lines 12 to 16 and in the examples, the reaction mixture containing the benzyl ester is diluted with an inert organic solvent that is immiscible with water, such as methylene chloride, and then When this diluted mixture is extracted with water, the organic phase of the mixture is dried with a desiccant such as magnesium sulfate, and this is then used as a raw material for the second stage reaction. describes that the amount of acid catalyst (sulfuric acid) used can be reduced without changing the yield of the desired product. However, this method requires complicated processing operations and cannot be said to be a practical method when considering industrialization.

[Purpose of the invention]

The inventors have discovered that 1,3,5-trialkyl-2,
Recognizing that the prior art related to the production of 4,6-tris(3,5-dialkyl-4-hydroxybenzyl)benzene is in the above-mentioned situation, we have developed the objective product by a simple method with a small number of steps. A method for manufacturing with high yield was investigated.

[Structure of the invention]

As a result, they discovered that the objective could be achieved by using the following method, and completed the present invention. That is, according to the present invention, a mixture of 2,6-dialkylphenol, formaldehyde (or a polymer thereof), a secondary amine, and a carboxylic acid is reacted while heating and removing the generated water from the reaction system. A reaction mixture containing 1-acyloxymethyl-3,5-dialkyl-4-hydroxybenzene is obtained, and the resulting reaction mixture is then reacted with 1,3,5-trialkylbenzene in the presence of an acid catalyst to produce 1,3 ,5-trialkyl-2,4,6
- A method for producing tris(3,5-dialkyl-4-hydroxybenzyl)benzene is provided.

[Structure of the first stage reaction] In the first stage reaction carried out in the method of the present invention, 2,6-dialkylphenol,
A mixture of formaldehyde (or a polymer thereof), a secondary amine, and a carboxylic acid is reacted with heating while removing water from the reaction system to produce 1-acyloxymethyl 3,5-dialkyl-4-hydroxybenzene. A reaction mixture is obtained containing:

The 2,6-dialkylphenol used in the present invention is a compound having a lower alkyl having about 1 to 5 carbon atoms, and specifically includes 2,6-dimethylphenol, 2,6-diethylphenol,
2,6-propylphenol, 2,6-di-sec
-Butylphenol, 2,6-di-tert-butylphenol, 2,6-dipentylphenol, 2
Examples include -methyl-6-tert-butylphenol, among which 2,6-di-tert-butylphenol is preferred.

The formaldehyde used in the present invention is generally used in the form of an aqueous solution or a polymer such as paraformaldehyde.

The secondary amine used in the present invention is a dialkylamine having an alkyl group having about 1 to 8 carbon atoms, and specifically includes dimethylamine, diethylamine, methylethylamine, diisopropylamine, dibutylamine, propylpentylamine, Examples include dihexylamine and dioctylamine, among which diethylamine is preferably used.

The carboxylic acid used in the present invention is an aliphatic monocarboxylic acid having about 1 to 12 carbon atoms, and specific examples include formic acid, acetic acid, propionic acid, butyric acid, pentanoic acid, and dodecanoic acid. Among these, acetic acid is preferred from the viewpoint of economy and ease of carrying out the first stage reaction of the method of the present invention with high efficiency.

The charging ratio of each of the above components when carrying out the first stage reaction in the present invention can be varied, but usually formaldehyde or its polymer is added to 1 mole part of 2,6-dialkylphenol. is 1 to 3 mole parts, the secondary amine is 0.1 to 0.2 mole parts, and the carboxylic acid is 4 to 8 mole parts, calculated as formaldehyde. If necessary, each of these components may be added in an appropriate amount to satisfy the above range as the reaction progresses, instead of adding the entire amount at once at the start of the reaction.

The temperature of the first stage reaction is usually preferably 80 to 110°C, and the reaction time is usually 6 to 10 hours.

The first stage reaction of the present invention is carried out while removing water from the reaction system. In this case, water can be removed by, for example, incorporating a distillation column into the reactor to remove water by distillation. can be exemplified. The reaction is usually
Although the reaction is carried out under atmospheric pressure, the pressure may be appropriately reduced to facilitate distillation if necessary. In the present invention, when a carboxylic acid that is easily miscible with water, such as acetic acid, is used, an amount of carboxylic acid corresponding to the amount of carboxylic acid that is released accompanied by water is added to the charged amount of carboxylic acid. It is desirable to add them separately one after another.

[Effects of the invention due to the structure of the first stage reaction] One of the features of the present invention is that the reaction is carried out while removing water from the reaction system in the first stage reaction, and such a method is adopted. In particular, 1-acyloxymethyl-
The yield of 3,5-dialkyl-4-hydroxybenzene can be improved from about 70% when using the conventional method to about 80%.

[Configuration of the second stage reaction] The second stage reaction carried out in the method of the present invention is performed using the 1-acyloxymethyl-3,5-dialkyl-4 obtained in the first stage reaction. -reacting a reaction mixture containing hydroxybenzene with 1,3,5-trialkylbenzene in the presence of an acid catalyst, thereby producing the desired product 1,
3,5-trialkyl-2,4,6-tris(3,5-dialkyl-4-hydroxybenzyl)
Benzene is obtained.

Examples of acid catalysts used in the present invention include mineral acids such as sulfuric acid and phosphoric acid, organic sulfonic acids such as methanesulfonic acid and para-toluenesulfonic acid, Lewis acids such as aluminum chloride, molybdic acid, and tungstic acid. However, among these, it is preferable to use sulfuric acid.

Used in the present invention. 1,3,5-trialkylbenzene is a benzene having an alkyl group having about 1 to 5 carbon atoms, specifically 1,3,5-trialkylbenzene.
-trimethylbenzene, 1,3,5-triethylbenzene, 1,3,5-triisopropylbenzene, 1,5-dimethyl-5-ethylbenzene,
An example is 1,3-dimethyl-5-tert-butylbenzene, and among these, 1,3,5-trimethylbenzene is preferably used.

The second stage reaction in the present invention consists of the reaction mixture obtained in the first stage reaction, an acid catalyst and 1,
Although the reaction can be carried out using only 3,5-trialkylbenzene, the reaction is usually carried out with the addition of an inert organic solvent.

Examples of the inert organic solvent include paraffin hydrocarbons such as pentane, cyclohexane and decane, ethers such as methyl ethyl ether and methyl isobutyl ether, and chloroform, methylene chloride, methyl chloride, methyl bromide,
Examples include halogenated hydrocarbons such as ethylene dichloride, among which it is preferable to use halogenated hydrocarbons, with methylene chloride being most suitable.

In the second stage reaction of the present invention, the charging ratio of each component is 1% in the first stage reaction mixture.
-Acyloxymethyl-3,5-dialkyl-4
-The amount is usually within the following range per 1 mole part of hydroxybenzene.

1,3,5-trialkylbenzene
About 0.25 to about 0.32 mole parts Acid catalyst About 0.1 to about 3 moles Inert organic solvent 0 to about 40 moles The temperature of the second stage reaction in the present invention is about 0 to about 3 moles.
The temperature is about 100°C, preferably about 5 to about 50°C. The reaction time varies depending on the reaction temperature, amount of catalyst, etc., but is usually about 5 to about 10 hours.

[Separation of target product]

After completion of the second stage reaction in the present invention, the target product 1,3,5-trialkyl-2,4,6-tris(3,5-dialkyl-4
-Hydroxybenzyl)benzene is separated by methods such as crystallization. In particular, in the present invention, after the second stage reaction is completed, for example, when an inert organic solvent with a low boiling point such as a halogenated hydrocarbon is used, only the inert organic solvent is distilled off, and the remaining carbon atoms are mainly removed. This is preferred because crystals of the target product with excellent purity and color can be obtained directly from acid.

〔Effect of the invention〕

This is the method of the present invention. 1,3,5-trialkyl-2,4, When a method for producing 6-tris(3,5-dialkyl-4-hydroxybenzyl)benzene is adopted, the yield of the target product is higher than that of conventional methods,
Furthermore, since the amount of acid catalyst used is reduced and the manufacturing process is simplified, the desired product can be manufactured economically and at low cost.

In addition, to further refer to the effect when the first stage reaction of the present invention is carried out while removing water,
If this method is adopted, the conventional method
The inventors have discovered that the second stage reaction can be carried out in high yield without removing water-soluble impurities from the first stage reaction mixture by water extraction treatment, as in Publication No. 41536). This discovery led to the completion of the simple manufacturing process of the present invention.

[Embodiments of the invention]

Hereinafter, the content of the present invention will be explained in more detail with reference to Examples.

Example 1 Into the 200ml three-necked flask shown in Figure 1,
6-di-tert-butylphenol 20.6g, diethylamine 0.87g, paraformaldehyde (purity 95
%) and 30 ml of acetic acid were sequentially added and stirred at room temperature to prepare 10 ml of acetic acid for addition in dropping funnel A.
The flask was immersed in an oil bath, heated to 100°C, and reacted for 8 hours. During this time, nitrogen was introduced little by little from nitrogen inlet B, and a mixture of water and acetic acid was added from distillation port C at a rate of 1 ml per hour. Upon extraction, acetic acid was added from A at a rate of 1 ml per hour. Analysis of the reaction mixture by high performance liquid chromatography revealed that the yield of the ester, 2,6-di-tert-butyl-4-acetoxymethylphenol, was 86.5%.

The above reaction mixture was cooled to 15°C while adding 30 ml of methylene chloride, 2.75 g of 1,3,5-trimethylbenzene was added, and while stirring, 4 g of concentrated sulfuric acid (1,3,5-trimethylbenzene
1.7 times the mole) was added dropwise over 30 minutes. then 15℃
After stirring for 2 hours at 40℃ and 5 hours at 40℃, the reaction solution was analyzed by gas chromatography.
3,5-trimethyl-2,4,6-tris (3,
The amount of 5-di-tert-butyl-4-hydroxybenzyl)benzene produced was 16.0 g (yield based on 1,3,5-trimethylbenzene: 90.4%).

The reaction mixture was kept at 40°C and methylene chloride was distilled out while nitrogen was introduced.
Crystallization of tert-butyl-4-hydroxybenzyl)benzene began. After cooling to 10°C to complete crystallization and washing the collected crystals with a small amount of acetic acid, white and highly pure 1,3,5-trimethyl-2,4,
13.9 g of 6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene was obtained.

Example 2 78% paraformaldehyde in Example 1
The same procedure was carried out except that 7.69 g was used.
The yield of 2,6-di-tert-butyl-4-acetoxymethylphenol was 82.2%, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert
The amount of (butyl-4-hydroxybenzyl)benzene produced was 15.8 g (yield based on 1,3,5-trimethylbenzene: 89.0°C), and the crystallization yield was 13.6 g.

Example 3 The steps up to the ester synthesis stage were carried out in the same manner as in Example 1, except that 4 g of p-toluenesulfonic acid (0.9 times the mole relative to 1,3,5-trimethylbenzene) was used instead of sulfuric acid in the subsequent reaction. It was carried out in exactly the same way. As a result of analysis of the reaction mixture, 1, 3, 5
-The amount of trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene produced was 15.8g (yield based on 1,3,5-trimethylbenzene was 89.0%). It was hot.

Comparative Example 2,6-di-tert-butyl-4-acetoxymethylphenol was synthesized by performing the first stage in Example 1 without removing water. The same procedure as in Example 1 was carried out except that 4.23 g of 78% parformaldehyde was used at this time. Analysis of the reaction mixture during the synthesis of 2,6-di-tert-butyl-4-acetoxymethylphenol revealed that the yield of the compound was 69%. Add to this 30 ml of methylene chloride and 2.10 g of 1,3,5-trimethylbenzene.
and 8 g of concentrated sulfuric acid (3.5 times the mole relative to 1,3,5-trimethylbenzene) were added according to Example 1, and the mixture was stirred at 15°C for 3 hours and at 40°C for 5 hours. As a result of analyzing the reaction mixture, the amount of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene produced was 12.6 g, and methylene chloride was distilled out. The subsequent crystallization yield was 10.1 g.

[Brief explanation of drawings]

FIG. 1 shows an example of an apparatus for producing 1,3,5-trialkyl-2,4,6-tris(3,5-dialkyl-4-hydroxybenzyl)benzene according to the method of the present invention. A: Dripping device for adding solvent, B: Nitrogen inlet,
C: Water outlet, D: Stirrer.

Claims (1)

[Claims] 1 A mixture of 2,6-dialkylphenol, formaldehyde (or its polymer), secondary amine, and carboxylic acid is reacted with heating while removing the water produced from the reaction system to form 1-acyloxymethyl-3, 1,3,5- characterized by obtaining a reaction mixture containing 5-dialkyl-4-hydroxybenzene and then reacting the obtained reaction mixture with 1,3,5-trialkylbenzene in the presence of an acid catalyst. Trialkyl-2,4,6-tris(3,5-dialkyl-4-hydroxybenzyl)
Benzene production method.