RU2257375C1 - METHOD FOR PREPARING β-(4-HYDROXY-3.5-DI-TERTIARY-BUTYLPHENYL)-PROPIONIC ACID ESTERS - Google Patents

Abstract

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for preparing β-(4-hydroxy-3,5-di-tert.-butylphenyl)-propionic acid esters that are used in industry of polymers as stabilizing agents. Method involves carrying out the process of the ester interchange reaction of β-(4-hydroxy-3,5-di-tert.-butylphenyl)-propionic acid methyl ester with polyhydric alcohols in inert gas flow at enhanced temperatures (130-190°C in the presence of the following components, wt.-%: 2,6-di-tert.-butylphenolate sodium, 1.5-3.6; 4-(β-methylcaboxyethyl)-2,6-di-tert.-butylphenolate sodium, 4.0-8.6; sodium acrylate, 2.1-6.4; 2,6-di-tert.-butylphenol, the balance. Indicated compounds of alkaline metal are used in the amount 0.4-5.1 wt.-% of the amount of β-(4-hydroxy-3,5-di-tert.-butylphenyl)-propionic acid methyl ester as measure for the sum of 4-(β-methylcarboxyethyl)-2,6-di-tert.-butylphenolate sodium, alkaline metal 2,6-di-tert.-butylphenolate and sodium acrylate. Invention provides increasing yield of the end product and its enhanced quality.

EFFECT: improved preparing method.

2 cl, 1 tbl, 10 ex

Description

The invention relates to organic chemistry, specifically to the production of esters of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid, which are used in the polymer industry as stabilizers.

A known method of producing esters of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid by transesterification of methyl ester of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid (methylox) polyatomic alcohols at a temperature of 130-190 ° C for 6-12 hours in the presence of a catalyst dibutyltin dilaurate and dibutyltin oxide [US Patent No. 4618700 from 10.21.86 g].

The disadvantages of this method are the high cost and high toxicity of the catalyst used.

A known method of producing esters of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid using lithium amide and lithium hydride as a catalyst [US Patent No. 4618700 from 10/21/86].

The disadvantage of this method is the use of scarce and explosive fire hazard catalyst.

A known method of producing pentaerythryl-tetrakis- [3- (4-hydroxy-3,5-di-tert-butylphenyl) propionate], which consists in the transesterification of methylene pentaerythritol in the presence of dimethylformamide or dimethyl sulfoxide and a catalyst of zinc acetate as a solvent [Application No. 20022132169 / 04 to the patent of the Russian Federation of December 28, 2002].

The disadvantage of this method is its high cost, due to the use of significant amounts of solvent and the instability of the catalyst, which decomposes at elevated temperatures.

A known method of producing methyl ester of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid by alkylation of 2,6-ditretbutylphenol with methyl acrylate at an elevated temperature using a catalytic complex of the following composition,% wt .: 2,6-di sodium tert-butylphenolate 1.4-11.0; β- (4-hydroxy-3,5-di-tert-butylphenyl) sodium propionate 0.4-3.0; 2,6-di-tert-butylphenol the rest [RF Patent No. 2178408, IPC С 07 С 69/732, issued December 20, 2002].

The disadvantages of the above method include the formation of a by-product of β-4- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid due to the use of β- (4-hydroxy-3,5-di-tert-butylphenyl in the catalyst ) sodium propionate, giving a yellow-cream color to the target product.

The closest technical solution (prototype) is a method for producing esters of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid in the process of transesterification of methyl ester of β- (4-hydroxy-3,5-di-tert -butylphenyl) propionic acid with polyhydric alcohols at 135-180 ° C in an inert gas stream in the presence of a catalyst of the following composition,% wt .: 4- (β-methylcarboxyethyl) -2,6-di-tert-butylphenolate sodium 22.8-12 0; Potassium 2,6-di-tert-butylphenolate 5.1-1.8; 2,6-di-tert-butylphenol the rest [A.S. No. 1685920, IPC C 07 C 69/732, 67/02].

These alkali metal compounds are used in an amount of 1.5-10.0 mol% of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid methyl ester.

The disadvantage of this method is the relatively low yield of the target product, which does not exceed 94%.

The technical problem, the solution of which is proposed in the present invention, is to develop a method for producing esters of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid, characterized by a low number of by-products formed and an increase in the yield of the target product.

This problem is solved in that in the method for producing esters of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid by transesterification of methyl ester of β- (4-hydroxy-3,5-di-tert-butylphenyl ) propionic acid with polyhydric alcohols in an inert gas stream and at elevated temperature in the presence of alkali metal 2,6-di-tert-butylphenolate, 4- (β-methylcarboxyethyl) -2,6-di-tert-butylphenolate and 2,4- di-tert-butylphenol as a catalyst according to the invention use a catalyst additionally containing sodium acrylate p In the following ratio of components,% wt: sodium 2,6-di-tert-butylphenolate 1.5-3.6; Sodium 4- (β-methylcarboxyethyl) -2,6-di-tert-butylphenolate 4.0-8.6; sodium acrylate 2.1-6.4; 2,6-di-tert-butylphenol rest.

These alkali metal compounds are used in an amount of 0.4-5.1 mol% of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid methyl ester in terms of 4- (β-methylcarboxyethyl) 2,6-di-tert-butylphenolate sodium, 2,6-di-tert-butylphenolate sodium alkali metal and sodium acrylate, while 2,6-di- sodium tert-butylphenolate, and the transesterification process is carried out at a temperature of 130-190 ° C.

The method is as follows.

Esters of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid are separated from the salts of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid and purified by crystallization.

The catalyst is prepared either by mixing its individual components or by heating sodium hydroxide with 2,6-di-tert-butylphenol in methanol in a stream of nitrogen at a temperature of 80-100 ° C for 0.2-0.5 hours, followed by distillation of methanol and water. Then, the calculated amount of methyl acrylate necessary for the formation of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid methyl ester is added to the mixture and the mixture is kept for 40-60 minutes. As a result of this, a catalytic complex is formed of the following composition: sodium 2,6-di-tert-butylphenolate, 4- (β-methylcarboxyethyl) -2,6-di-tert-butylphenolate, sodium acrylate, 2,6-di-tert- butylphenol.

An unexpected effect in the proposed method was the fact that at the initial time, NaOH interacts with 2,6-di-tert-butylphenol to form 2,6-di-tert-butylphenolate. For 20-30 minutes at a temperature of 70-90 ° C, no more than 60% NaOH enters the reaction. Further formation of sodium 2,6-di-tert-butylphenolate does not affect the reaction rate, but the color of the target product deteriorates. With the introduction of methyl acrylate, sodium β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate and sodium acrylate are formed due to the interaction of NaOH residues with methyl acrylate. The formation of sodium acrylate is due to the stronger acidic properties of methyl acrylate compared with 2,6-di-tert-butylphenol, which helps to inhibit the further formation of 2,6-di-tert-butylphenolate and activate the catalytic complex.

The starting reagents must meet the following requirements:

- NaOH - GOST 4328-77;

- 2,6-di-tert-butylphenol - TU 38.103375-80;

- methanol - GOST 2222-78;

- methyl acrylate - GOST 2971-86;

- pentaerythritol - GOST 2168-82.

Β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid ester is added to the obtained catalyst, the mixture is left to stand for 30-40 minutes and then polyhydric alcohol is added, the mixture is heated under inert gas for 3.5- 5 hours at a temperature of 130-190 ° C with a reflux condenser, post-distillation under vacuum. The reaction mass is gradually cooled to 100 ° C. Dissolved in a hydrocarbon solution and cooled to 10-15 ° C. After precipitation, the crystals are filtered.

Example 1

30.95 g (0.15% wt.) Of 2,6-di-tert-butylphenol, 0.5 g (0.014% wt.) Of sodium hydroxide are charged into a three-necked reaction flask equipped with a stirrer and inert gas inlet. a stream of nitrogen (argon) is heated to 95 ° C and incubated for 50-60 minutes with distillation of the water-methanol mixture. Then 1.72 g (0.02% wt.) Of methyl acrylate is pinned into the flask at a temperature of 110 ° C for 30-40 minutes. The result is 33.15 g of a catalytic complex, the composition of which and the content of its alkaline components are confirmed by potentiometric titration and liquid chromatography. Next, 11.18 g of methyl acrylate was added dropwise to the obtained catalyst, held for 30 minutes and then 5.1 g of pentaerythritol was added. In an inert gas stream, the mixture is heated for 3.5 hours at 150 ° C under reflux, trapping methyl alcohol in a condenser during the reaction, and additional distillation under vacuum is carried out for 20-30 minutes. The reaction mass is gradually cooled to 100 ° C, dissolved in a hydrocarbon solvent (or alcohol-hydrocarbon) and cooled to 10 ° C. After precipitation, the crystals are filtered. The yield of pentaerythryl-tetrakis-β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate 47.8 g (98.95%), melting point 116-117 ° C.

The results of the syntheses with other alcohols and the compositions of the catalytic complex are shown in table 1, the syntheses were carried out analogously to example 1.

The table shows that the proposed method will achieve a yield of esters of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid 99.5% compared with the prototype, where the yield reaches 94%, which will ensure widespread use him as stabilizers in the polymer industry.

Table 1. Example The composition of the catalyst, wt.% The amount of catalyst in the amount of alkali metal compounds, mol. % Time h Polyhydric alcohol Exit, % The resulting compound Melting point, ° С Arona sodium acrylate Phona Phoh 2 5,4 3.9 1,5 89.2 4.70 5,0 pentaertritis 98.6 pentaerythryl-tetrakis [β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate] 116-117 3 6.1 3.3 2,3 88.3 4,55 4,5 diethylene glycol 99.1 diethylene glycol bis [β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate] 92-93 4 7.9 4.6 1.7 85.8 4.10 5,0 thioethylene glycol 99.0 thioethylene glycol bis [β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate] 71 5 8.2 4.0 2,8 85.0 3.60 4.2 triethylene glycol 99,2 ethyl 1,1,1-tris- [methylene-β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate] 107-108 6 8.4 3,1 3.6 84.9 2.90 5.1 pentaerythritol 98.5 pentaerythryl-tetrakis [β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate] 116-117 7 4.9 3.2 3,1 88.8 0.45 6.0 diethylene glycol 98.4 diethylene glycolbis [β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate] 92-93 8 7.1 4.8 3.4 84.7 5.10 4.8 triethylene glycol 99.5 ethyl 1,1,1-tris- [methylene-β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate] 107-108 nine 6.8 2,3 3.0 87.9 4.6 5.3 thioethylene glycol 99.1 thioethylene glycol bis [β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate] 71 10 6.5 5.3 2,8 85,4 3.9 5.1 diethylene glycol 99.0 diethylene glycol bis [β- (4-hydroxy-3,5-di-tert-butylphenyl) propionate] 92-93 Note: ArONa - 4- (β-methylcarboxyethyl) -2,6-di-tert-butylphenolate sodium;
PhOH - 2,6-di-tert-butylphenol; PhONa - 2,6-di-tert-butylphenolate sodium.

Claims (2)

1. A method for producing β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid esters by transesterification of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid methyl ester with polyhydric alcohols in an inert gas stream and at elevated temperature in the presence of alkali metal 2,6-di-tert-butylphenolate, sodium 4- (β-methylcarboxyethyl) -2,6-di-tert-butylphenolate and 2,6-di-tert-butylphenol as a catalyst, characterized in that the use of a catalyst additionally containing sodium acrylate in the following ratio of components . In wt%: Alkali metal 2,6-di-tert-butylphenolate 1.5-3.6 4- (β-Methylcarboxyethyl) -2,6-di-tert-butylphenolate sodium 4.0-8.6 Sodium Acrylate 2.1-6.4 2,6-di-tert-butylphenol Else while these alkali metal compounds are used in an amount of 0.4-5.1 wt.% from methyl ester of β- (4-hydroxy-3,5-di-tert-butylphenyl) propionic acid, calculated on the amount of 4- (β- methyl carboxyethyl) -2,6-di-tert-butylphenolate sodium, 2,6-di-tert-butylphenolate alkali metal and sodium acrylate. 2. The method according to claim 1, characterized in that sodium 2,6-di-tert-butylphenolate is used as the 2,6-di-tert-butylphenolate of the alkali metal, and the transesterification process is carried out at a temperature of 130-190 ° C.