KR100273778B1 - Method of producing tetrakis(3(3,5-di-tertiary-buthyl-4-hydroxyphenyl)propionyloximethyl)methan under the solvent of aromatic compounds - Google Patents

Abstract

PURPOSE: A method for preparing tetrakis(3(3,5-di-tertiary-butyl-4-hydroxyphenyl) propionyl oxymethyl)methane is provided for using the composition as the antioxidant to the polyolefin by synthesizing it from 2,6-di-tertiary-butylphenol and methylacrylate. CONSTITUTION: The method for preparing tetrakis(3(3,5-di-tertiary-butyl-4-hydroxyphenyl) propionyl oxymethyl)methane comprises the first step of performing ester exchange process for penta-erythritol and 3(3,5-di-tertiary-butyl-4-hydroxyphenyl)propionic oxy-methyl)methane in the presence of the catalyst such as organic tin compound, for example, dibutyltin oxide. The preparation method involves the use of the reactive solvent as ethylbenzene, cumene, indane or isobutyl benzene. After the ester exchange process, the tetrakis(3-(3,5-di-tertiary-butyl-4-hydroxyphenyl)propionyl oxymethyl)methane composition is obtained by using the reactive solvent as part of the crystallization solvent to crystallize the resultant product.

Description

Method for preparing tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl) methane in the presence of an aromatic solvent

The present invention relates to a method for producing tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl) methane used as an antioxidant such as polyolefin.

Generally, (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid methyl ester or ester of (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid ethyl ester with pentaerythritol Tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl) methane was prepared by exchange. As the solvent for these reactions, N, N-dimethylsulfoxide, aliphatic hydrocarbons, etc. are mainly used, and as a catalyst, NaOMe, t-BuOK, LiH, Bu ₂ SnO, etc., are used at a temperature of 120 to 200 ° C and reduced pressure. It is known to carry out the reaction under.

Existing reaction methods tend to oxidize the product by depressurizing under high temperature to introduce a certain amount of oxygen into the reactor, so that high-quality tetrakis 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy Methyl) methane is difficult to obtain, and under these conditions, the complete recovery of the produced methanol and solvents is impossible, resulting in an increase in product cost and environmental problems.

The present invention is to solve the above problems due to the reaction under reduced pressure, the object of the present invention is to exhibit an excellent conversion rate by removing the methanol produced by the addition of an alkylbenzene solvent in the reaction system, and also prevents the inflow of oxygen into the reactor This is to prepare tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl) methane, an excellent product of pure white color, by preventing oxidation of the product.

In order to achieve the above object, the present invention provides a four-necked flask equipped with a mantle, a stirrer and a thermometer, a nitrogen inlet tube, and a cooler, which is a reaction apparatus, methyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate. A benzene-based hydrocarbon solvent substituted with a benzene alkyl group having an ester and a boiling point of 80 to 280 ° C. was introduced into a nitrogen-substituted flask, completely dissolved, and then pentaerythritol and a catalyst were additionally introduced into the reactor to flow the nitrogen gas to 100 to 240 ° C. It is characterized by producing tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl) methane while gradually raising to ℃.

Hereinafter, the present invention will be described in detail.

By-product methanol in the solvent is distilled out of the reactor in the form of a mixture. In the case of solvents that do not mix with methanol (such as indane), they are separated in an improved Dean-Stark separator, where methanol is removed and the solvent is fed back into the reactor. In the case of using a solvent mixed with methanol (such as ethylbenzene), the amount of pure solvent that is removed is continuously replenished during the reaction, and the mixture is recovered by distillation. When the amount of separated and removed ethanol reaches 95% of the calculated amount, it is aged for about 2 hours and the reaction is completed. At the end of the reaction, the reaction mixture is analyzed to yield conversion.

The amount of n-heptane solvent required for crystallization is further added, and the corresponding acid in the equivalent amount of the previously added catalyst is added to neutralize, and the resulting salt is filtered off. The filtrate is heated to 100 ~ 150 ℃ and then stirred at 30 ~ 80 ℃ for 2 hours and aged for 4 hours to crystallize. The crystals are filtered at 20 ° C., washed with heptane and dried to afford the final product.

The (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid methyl ester used in the present invention was synthesized from 2,6-di-tert-butylphenol and methyl acrylate. As the catalyst, Bu ₂ SnO, NaOMe, t-BuOK, LiH, and the like, which are basic catalysts, were used. Preferably, Bu ₂ SnO is used.

Solvents used in the present invention include benzene, toluene, ethylbenzene, xylene, ethyltoluene, indane, propylbenzene, cumene, trimethylbenzene, tetralin, diethylbenzene, butylbenzene, cymene, isobutylbenzene, amylbenzene, Alkylbenzenes, such as isoamylbenzene, diisopropylbenzene, and phenyloctane, Preferably ethylbenzene, cumene, indane, isobutylbenzene are used. In particular, when ethylbenzene, cumene, indane and isobutylbenzene are used, the reaction byproduct methanol can be easily separated and removed, and the reaction can be advanced at high temperature.

In the present invention, the equivalent of (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid methyl ester to the reactor is 1.0 to 1.2 equivalents, preferably 1.1 equivalents to pentaerythritol. The amount of catalyst used in the present invention is 0.1 to 10% by weight, preferably 1.0% by weight based on the weight of (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid methyl ester.

The amount of the alkylbenzene solvent for reaction in the present invention is 10 to 400% by weight, preferably 50 to 80% by weight, based on the weight of the (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid methyl ester. to be. When the amount of the alkyl benzene solvent is less than 10% by weight, the conversion rate is low because it is difficult to remove by-product methanol, and when the amount of the alkyl benzene solvent is 400% by weight or more, the reaction time is long, resulting in a decrease in production.

In this invention, 100-240 degreeC of reaction temperature is preferable, More preferably, it is 180-200 degreeC. The reaction temperature can be changed depending on the boiling point of the solvent used. If the temperature is 100 ° C. or lower, the reaction rate is slow and the productivity is low. If the temperature is 240 ° C. or higher, the product is decomposed to lower the quality of the product.

The catalyst used in the present invention is neutralized by adding an equivalent amount of acid after the reaction is completed and removed by filtration. The acid used may be most acids such as oxalic acid, hydrochloric acid, sulfuric acid, but oxalic acid is preferred.

The crystallization solvent in the present invention uses a mixture of n-heptane and a reaction solvent. By using the solvent used in the reaction as part of the crystallization solvent, solvent loss and production time due to solvent exchange can be shortened. The amount of the crystallization solvent added may be up to 50 to 600% by weight based on the weight of the (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid methyl ester, but preferably 300% by weight. After adding the solvent, raise the temperature to 100 ~ 200 ℃ to make a homogeneous system and crystallize while cooling. After the crystallization is completed, it is filtered to obtain the final product.

In synthesizing tetrakis 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl) methane by the preparation method according to the present invention, the conversion rate is 94-97% based on pentaerythritol The yield of the final product reached and separated after crystallization is 91-94%. The melting point of the final product is 120-124 ° C. and the chromaticity of the product / toluene 10 wt / vol% solution is 15 APHA. The required specifications of commercialized products are melting point 110 ~ 125 ℃ and chromaticity up to 80 APHA.

The present invention will be described in more detail with reference to the following Examples.

EXAMPLE

Example 1

Methyl ester of 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate in a 1,000 ml four-necked flask equipped with a thermometer, a magnetic stirrer, a nitrogen introducer, an improved Dean-Stark aliquot, and a cooler 142.0 100 g of g (0.49 mol) and indane (boiling point of 176 ° C.) were added and dissolved completely by raising the temperature to 100-130 ° C., followed by 15.0 g (0.11 mol) of pentaerythritol and 0.5 g (0.002 mol) of dibutyl oxide. After flowing nitrogen for 10 minutes and adjusting the temperature to 180 ~ 190 ℃ and reacted for 4 hours while removing by-product methanol. When the amount of methanol removed reached 95% of the calculated amount, the reaction solution was analyzed after aging over about 2 hours, and the conversion rate according to the result is shown in Table 1.

The reaction solution was cooled to 100 ° C., 200 ml of heptane was added, and 0.25 g (0.002 mol) of oxalic acid was added and stirred for 30 minutes. Insolubles were removed by filtration at 95 ° C., and the clear filtrate was heated to 100-130 ° C. to form a homogeneous solution, which was then crystallized by stirring at 40-50 ° C. for 4 hours. The crystals were filtered at 20 DEG C, washed with heptane and dried under reduced pressure to prepare a target product of granular crystals having excellent color. The yield and physical properties of the target material after separation were shown in Table 1.

Example 2

It was prepared in the same manner as in Example 1 except that ethylbenzene was used as part of the reaction solvent and the crystallization solvent. The reaction temperature was adjusted to 150 ~ 160 ℃ to react for 4 hours. Conversion rate, yield and physical properties of the target are shown in Table 1.

Example 3

Except for using cumene as part of the reaction solvent and crystallization solvent, the target product was prepared in the same manner as in Example 1. The reaction temperature was adjusted to 170 ~ 180 ℃ to react for 2 hours. Conversion rate, yield and physical properties of the target are shown in Table 1.

Example 4

A target product was prepared in the same manner as in Example 1, except that diethylbenzene (o-, m-, p-mixture) was used as part of the reaction solvent and the crystallization solvent. The reaction temperature was adjusted to 190 ~ 210 ℃ to react for 1.5 hours. Conversion rate, yield and physical properties of the target are shown in Table 1.

Example 5

Except that butylbenzene was used as part of the reaction solvent and crystallization solvent, the target product was prepared in the same manner as in Example 1. The reaction temperature was adjusted to 200 ~ 210 ℃ to react for 2.0 hours. Conversion rate, yield and physical properties of the target are shown in Table 1.

Claims (2)

Pentaerythritol and (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid ester in the presence of a catalyst in ethylbenzene, cumene, indane or isobutylbenzene which are benzene hydrocarbons substituted with alkyl groups as reaction solvents After transesterification and terminating transesterification, tetrakis (3- (3,5-di-tert-butyl-4-hydride) is directly crystallized by using the reaction solvent as part of a crystallization solvent. Process for the preparation of oxyphenyl) propionyloxymethyl) methane. The tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl) methane as claimed in claim 1, wherein the catalyst is an organotin compound such as dibutyl tin oxide. Manufacturing method.