JPH0321537B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing tetrakis[3-(3,5-dibutyl-4-hydroxyphenyl)propionyloxymethyl]methane, specifically, a method for producing tetrakis[3-(3,5-dibutyl-4-hydroxyphenyl)propionyloxymethyl]methane, specifically, a method for producing tetrakis[3-(3,5-dibutyl-4-hydroxyphenyl)propionyloxymethyl]methane,
An acrylic acid alkyl ester represented by _the following formula and 2,6-dibutylphenol represented by the formula () where R _{1 is} a methyl group or an ethyl group. Step (A) of producing a propionate ester represented by the reaction formula (); followed by pentaerythritol and the formula ()
Step (B) of transesterification with a propionic acid ester represented by The present invention relates to an improved method. The compound represented by the formula () is, for example, tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]
It is a well-known fact that methane is used as a stabilizer for polymers. The compound represented by the formula () can be produced by a combination of the above-mentioned step (A) and step (B), each of which is known as a unit operation. In industrial implementation, those skilled in the art usually employ the following two methods for combining step (A) and step (B). That is, (1) a method in which an intermediate represented by the general formula () is purified and separated from the reaction product in step A and the purified and separated intermediate is used as a raw material in step (B); ) without purifying and separating the intermediate from the reaction product in step (B).
This method uses it as a raw material. The present inventor has studied these two methods, and found that method (1) is based on known conditions for each unit operation related to step (A) and step (B), such as step (A).
If the conditions described in the specification of Japanese Patent Publication No. 42-18617 or the specification of Japanese Patent Publication No. 42-19083 are used as the conditions for step (B), the intermediate () or I was able to obtain the target object (). However, the product cost is high because it requires an operation to purify and separate the intermediate (), and it is necessary to add expensive catalysts in each step (A) and (B). Ta. The method (2) naturally does not have the drawbacks of the method (1) above, but is superior in obtaining the intermediate () in a good yield as a unit operation in step (A). It is specifically disclosed in the specification of the above publication. If the conditions are adopted as they are, the yield of the target compound of formula () contained in the reaction product of step (B) will be low, and furthermore, if the reaction product is purified by recrystallization, the yield will be low. It was found that this method has the drawback that the yield is extremely low, and the overall yield is much lower than that of method (1). The present inventor conducted studies to solve the drawbacks of the method (2), and as a result, developed a conventionally disclosed method that increases the yield of the intermediate compound of formula () as a unit operation in step (A). The conditions are that approximately 1.1 mole part or more of the acrylic ester of formula () is used per mole part of 2,6-dibutylphenol, and when step (A) is carried out under these conditions, the acrylic ester A considerable amount of diester in which two molecules of acrylic acid ester () are added to the polymer () and 2,6-dibutylphenol ()/molecule is produced as a by-product, and in the subsequent step (B), these by-products are combined with pentaerythritol. However, since these by-products, pentaerythritol, and the intermediate of formula () react, the yield of the final target compound of formula () is rather reduced, and furthermore, the reaction product of step (B) is When purifying by the recrystallization method, the reaction product contains many impurities derived from the side reactions in step (B).
It is important to know the series of causal relationships in which losses due to recrystallization increase additively, and to avoid such a situation, it is necessary to change step (A) even if the yield of intermediate () in step (A) is sacrificed slightly. I learned that suppressing the side reactions in A) actually increases the overall yield. The inventors of the present invention obtained the desired product () with a yield equivalent to or higher than that of the method (2) above by carrying out step (A) under the specific critical conditions described below. The present invention was achieved by knowing that this can be done. That is, the present invention reacts an acrylic acid ester represented by the above formula () with 2,6-dibutylphenol represented by the above formula () in the presence of a basic catalyst to produce a propionic acid ester represented by the above formula (). step (A) to generate the propionic acid ester represented by the formula () from the reaction product of step (A), which is transesterified by directly adding pentaerythritol to the reaction product of step (A) without isolating and purifying it; step (B) of carrying out the reaction; tetrakis [3-(3,5-dibutyl-
In a method for producing 4-hydroxyphenyl)propionyloxymethyl]methane, the reaction temperature in step (A) is 80 to 95°C, and acrylic ester of formula () and 2,6-dibutyl of formula () The molar ratio with phenol (()/()) is 1.02
-1.04 Tetrakis [3-
(3,5-dibutyl-4-hydroxyphenyl)
The present invention relates to a method for producing propionyloxymethyl]methane. According to the method of the present invention, the side reactions in step (A) are sufficiently suppressed, so that the side reactions in the subsequent step (B) are also slight, and furthermore, the side reactions in the reaction product of step (B) are Since there are few impurities, there is less loss in the purification process, and as a result, the reaction conditions for step (A) of the present invention do not use the unit operating conditions that increase the yield of the intermediate (), so the intermediate Although the yield of the product () is slightly lower, overall the desired product () is obtained.
The yield is extremely high. In addition, the present invention has the following advantages: the expensive catalyst used in step (A) can be used as is in step (B), and there is no need to newly add it, and there is no step of separating and purifying the intermediate (). The product cost of the object ( ) produced by the method is low. The structure and advantages of the present invention will be better understood by describing the present invention in detail below. In the present invention, in step (A), first, the acrylic ester of the formula (), that is, methyl acrylate or/and ethyl acrylate, and the 2,6-dibutylphenol of the formula () are mixed in a solvent and a basic catalyst. A propionic acid ester represented by the above formula () is produced by reacting in the presence of the above-mentioned compound. Preferred examples of 2,6-dibutylphenol () include 2,6-di-t-butylphenol, 2,6-di-s-butylphenol, and 2,6-di-isobutylphenol. A particularly preferred example is 2,6-di-t-butylphenol. Therefore, the compound () to be produced by the method of the present invention includes tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane, tetrakis[3-
Preferred examples include (3,5-di-s-butyl-4-hydroxyphenyl)propionyloxymethyl]methane, and tetrakis[3-(3,5-diisobutyl-4-hydroxyphenyl)propionyloxymethyl]methane. Tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane is particularly preferred for the production of the present invention. Basic catalysts that can be used in step (A) include sodium hydroxide, potassium hydroxide, lithium hydroxide,
Examples include lithium aluminum hydride, sodium boron hydride, lithium hydride, sodium t-butoxide, potassium t-butoxide, sodium methoxide, potassium methoxide, metallic sodium, and metallic potassium, among which sodium t-butoxide, potassium t-butoxide, - The use of butoxide, sodium methoxide and potassium methoxide is recommended. Such a basic catalyst is generally used in an amount of 0.5 to 8.0% by weight, preferably 1.0 to 5.0% by weight, based on 2,6-dibutylphenol (2,6-dibutylphenol). Although it is not necessary to use a solvent in step (A) of the present invention, it is preferable to use one. Solvents that can be used include dimethylformamide, dimethylacetamide,
Examples include dimethyl sulfoxide, hexamethylphosphoamide, acetonitrile, propionitrile, sulforane, diglyme, tetrahydrofuran and t-butyl alcohol, but the use of dimethylformamide, dimethylsulfoxide and sulforane is recommended. Such a solvent is used in a maximum of 5 parts by weight per 1 part by weight of 2,6-dibutylphenol (2,6-dibutylphenol);
Preferably, 0.1 to 1 part by weight is used. In the present invention, the most important structural requirements are the molar ratio of acrylic ester (2) and dibutylphenol (2) and the reaction temperature in step (A). In other words, the molar ratio of acrylic ester () and dibutylphenol () (()/
()) is 1.02-1.04, and the reaction temperature is 80 to 95°C. Under conditions that deviate from these conditions, the effects of the present invention cannot be achieved and they are excluded from the present invention. If the molar ratio exceeds 1.07 and there is a large amount of acrylic ester (), the yield of intermediate () will increase slightly in step (A), but the yield of acrylic ester () will increase slightly;
of polymer and acrylic acid ester () for one molecule of 2,6-dibutylphenol ().
A considerable amount of diester with two molecules added is produced as a by-product, and subsequently, in step (B) described later, these by-products and pentaerythritol react, and these by-products, pentaerythritol, and the intermediate of formula () react. Therefore, it has the drawback that the yield of the target compound of formula () decreases, and if the molar ratio is less than 1.00 and the amount of acrylic ester () is small, the amount of by-products such as the polymer of acrylic ester () and the diesters mentioned above increases. However, the yield of the intermediate is significantly lower, and the final target product () obtained in the subsequent step (B) is lower.
The disadvantage is that the yield of Even if the molar ratio satisfies the above conditions, if the reaction temperature exceeds 95°C, a considerable amount of the acrylic acid ester () polymer and the above diester will be produced as by-products, and the yield of the intermediate () will decrease slightly, so this will be discussed later. In step (B), the yield of the final target product () is reduced, and if the temperature is below 80°C, a considerable amount of the diester is produced as a by-product, and the yield of the intermediate () is significantly reduced. Therefore, it has the disadvantage that the yield of the final target product () in the subsequent step (B) also decreases. The reaction in step (A) is usually carried out under stirring for 2 to 10 hours, preferably 6 to 8 hours. Although it can be carried out either under normal pressure or increased pressure, it is usually carried out at normal pressure to 5 kg/cm ² G. The reaction apparatus used may be of any type as long as it is a reaction vessel equipped with a conventional stirring device. In the reaction product from step (A), the intermediate of formula () is produced at a slightly lower theoretical yield of about 94 to slightly less than 96% based on the 2,6-dibutylphenol () used. However, the total amount of by-products such as polymers of acrylic ester () and the following formulas () and (), in which two molecules of acrylic ester are added to one molecule of 2,6-dibutylphenol (), is The amount is extremely small, about 0.4% by weight or less based on the intermediate (). The reaction product in step (A) is fed to the transesterification reaction in step (B) without purifying and separating the intermediate (), but before carrying out step (B), the final reacted acrylic ester ( ) is preferably removed from the reaction product by distillation. In step (B), a known method for producing (), which is the object of the present invention, by reacting intermediate () with pentaerythritol can be adopted. That is, pentaerythritol is added in an amount of 1/4 to 1/5 mole part, preferably 1/42 to the intermediate ()/mole part.
Use 1/46 to 1/46 mole part. The transesterification reaction in step (B) proceeds while the ester group of intermediate () and the hydroxyl group of pentaerythritol react to produce methanol or ethanol. At this time, any catalyst used for normal transesterification can be used as a catalyst, but
The catalyst used in (A) can also be used as a catalyst in step (B), and the amount used in step (A) is sufficient, so there is no need to add a catalyst especially for the transesterification reaction. Also, it is preferable to use a solvent in step (B), but in step (A)
The solvent that can be used in step (B) can also be used in step (B), and since the transesterification reaction proceeds sufficiently with the amount of solvent used in step (A), there is no need to particularly add a solvent. Step (B) is carried out until the transesterification reaction is almost completed, and is usually carried out at a temperature of 80 to 140°C.
It will be held for 10 hours. Methanol or ethanol produced at this time is removed from the reaction system. For the removal method, normal means are adopted, for example, 5 to 50 mm.
Examples include a method of distilling Hg under reduced pressure. There is no need for any special equipment to be used in step (B), and any reaction vessel equipped with a stirring device, a heating device, and an ethanol or methanol distillation device can be used. In such a step (B), there are few by-products in the reaction product of step (A) used as a raw material, so
Although the yield of intermediate () in step (A) is slightly low, the yield of target product () is high and there are few by-products. Next, the target product () is purified and separated from the reaction product of step (B). A recrystallization method is preferably employed as the purification and separation means. Examples of solvents used at this time include hexane, cyclohexane, heptane, ethanol, isopropanol, n-propanol, isobutanol, s-butanol, n-butanol, and isopropanol,
A preferred method is to use an intermediate alcohol such as n-propanol, isobutanol, s-butanol, or n-butanol as a solvent, and to precipitate the desired product () as an adduct with these alcohols. In the purification and separation operation using this recrystallization method, the target substance () is present in the reaction product of step (B) in high yield,
Moreover, since there are few by-products, there is little loss. Thus, the target compound (2) can be obtained in high yield through step (A), step (B), and purification and separation step according to the method of the present invention. The compound () produced by the method of the present invention has high purity and is excellent as, for example, an antioxidant. Examples will be specifically described below. Example 1 Step (A) includes a stirrer, a reflux condenser, a thermometer,
In a 500 ml 4-necked flask equipped with a nitrogen inlet tube, under a nitrogen atmosphere, add 26 ml of dimethylformamide, 2.83 g of potassium t-butoxide, 93.25 g of 2,6-di-t-butylphenol (), and 40.48 g of methyl acrylate (molar ratio). [()/()] is 1.04) was added and kept at 87° C. under stirring for 8 hours.
Next, the pressure was reduced to 30 mmHg to distill off unreacted methyl acrylate, and then nitrogen was introduced to return the pressure to atmospheric pressure. Gas chromatography analysis was performed on the reaction solution, and 3-(3,5-di-t-butyl-4-
Methyl hydroxyphenyl)propionate ()
When the amount of produced was investigated, the theoretical yield was 95.6% based on 2,6-di-t-butylphenol. Continue to process (B), and reduce the amount to 1/4.4 for ().
Add 13.37 g of pentaerythritol equivalent to mol, stir at 87°C for 10 minutes, and then heat at 90°C/30mmHg for 1 hour to distill off the generated methanol.
Then, the temperature was maintained at 100-140°C/20 mmHg for 6 hours to distill off dimethylformamide and complete the reaction. Next, nitrogen was introduced again to break the vacuum and glacial acetic acid was added to neutralize. Next, benzene was added and the solution was washed with water until it became neutral. After washing with water, it was dehydrated and dried, and then benzene was distilled off to obtain 129 g of a pale yellow candy-like substance. It was confirmed by liquid chromatography analysis that this candy-like substance contained 75.4% of tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane (). Therefore, step (B)
It was found that the target product () was produced in a theoretical yield of 84.1% based on pentaerythritol.
This candy-like substance was recrystallized from 90% isopropanol to precipitate the desired product as an adduct, which was dried to obtain 93.38 g of white crystals with a purity of 99% or more.
In other words, the recovery rate of the target product () from the candy-like substance is
The overall yield was 77.2%. However, the overall yield is the product of three factors: (A) the theoretical yield of the step, (B) the theoretical yield of the step, and the recovery rate of the target product (). Examples 2 to 4, Comparative Examples 1 to 4 In Example 1, the molar ratio of methyl acrylate ()/2,6-di-t-butylphenol () and reaction temperature in step (A) were 80 to 95. All operations were the same as in Example 1 except that the temperature range was changed as shown in Table 1. The amount of 2,6-di-t-butylphenol charged in step (A) was the same as in Example 1. The results are shown in Table 1. Reference example In step (A) of Example 1, the molar ratio of methyl acrylate/2,6-di-t-butylphenol
1.14, Methyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate () was synthesized according to the procedure of step (A) of the example except that the temperature was maintained at 87°C. . The theoretical yield of () was 96.5%. Next, the reaction product was kept at 100℃/20mmHg to distill off unreacted methyl acrylate and dimethylformamide, and then neutralized by adding hydrochloric acid.Benzene was added, washed with water, dehydrated and dried, and then benzene was distilled off. Distilled under reduced pressure, boiling point 130-135℃/0.1
117.33 g of mmHg fraction () was obtained. The theoretical yield of () up to this stage corresponds to 88.8%. 12.42 g of pentaerythritol, 2.83 g of potassium t-butoxide, and 26 ml of dimethylformamide, which are equivalent to 1/4.4 mole of this fraction (), were charged into the reactor used in step (A), and Example When step (B) was carried out under the operating conditions described in 1, a pale yellow candy-like substance was obtained, and the theoretical yield of the target compound () contained in the substance was 88.7% based on pentaerythritol. From this candy-like substance, 90.92 g of white crystals () with a purity of 99% were obtained with a recovery rate of 96% by the same operation as described in Example 1. The overall yield was 75.6%. 【table】

Claims (1)

[Claims] 1. An acrylic ester represented by the formula () and CH ₂ =CH-COOR ₁ () (in the formula, R ₁ is a methyl group or an ethyl group) in the presence of a basic catalyst.
2,6-dibutylphenol shown by the formula () By reacting, the propionic acid ester represented by the formula () is produced. Step (A) to generate the propionic acid ester of formula () from the reaction product of step (A) without isolation and purification, add pentaerythritol to the reaction product of step (A), and perform the transesterification reaction. Tetrakis [3-(3,5-dibutyl-4
In the method for producing -hydroxyphenyl)propionyloxymethyl]methane, in step (A), the reaction temperature is 80 to 95°C, and the acrylic ester of formula () and 2,6-dibutylphenol of formula () are mixed. The molar ratio [()/()] of 1.02 to
Tetrakis [3-
(3,5-dibutyl-4-hydroxyphenyl)
A method for producing methane.