SU1012569A1 - Method of extracting and purifying pentaerythryl-tetra-(3,5-ditret-butyl-4-oxyphenyl)-propyonotases - Google Patents

Description

This invention relates to the field of organic chemistry, specifically to an improved method for the isolation and purification of pentaerythryltetra and c- / 9- (3,5-di-tert-butyl-4-hydroxyphenyl) propyrnate 1, which is a highly effective non-staining thermal stabilizer for polymeric materials.

Pentaerythryltetrakis-i / 3 - (3,5-di-tert-buti / -4-hydroxyphenyl) -propionate) is obtained by transesterification of methyl ester / 3 (3,5-di-tert-butyl-4-hydroxyphenyl) -propionic acid with pentaerythritol in the presence of alkaline catalysts at elevated temperatures. The reaction mass at the same time. in addition to the target product, it contains the starting methyl ester, (3.5-di-tert-butyl4-hydroxyphenyl) propionic acid, products of partial esterification of pentaerythritol, and resinous oxidation products, which makes it difficult to isolate the target product in its individual form.

A known method for isolating the desired product consists in dissolving the reaction mass in benzene, neutralizing catalyst (acetic acid, distilling off benzene). The residue is diluted with hexanoM, filtered from the solid residues of the catalyst, the chromatograph of alumina and the solvent is distilled off. Get the product in the form of a vitreous mass, t.razm, 50-60 ° C.

The disadvantages of this method are the necessity of destroying the catalyst with acid, isolating the target product from the reaction mass by chromatography on alumina, obtaining a finished product of poor quality,

The closest to the proposed method is the separation and purification of the target product by acidifying the reaction mixture with glacial acetic acid, followed by dissolving in isopropyl alcohol at 60 ° C, cooling and crystallization at 5 ° C.

The precipitated crystals are dissolved in heptane with heating, washed with water, dried the heptane solution by azeotropic distillation of water, boiled at 70 ° C and cooled to 5 ° C. Get the crystals of the target product, so pl. 121-122 ° C.

However, this method is multistage, long lasting and is accompanied by the formation of wastewater.

The aim of the invention is to simplify and intensify the process.

This goal is achieved by the method consisting in dissolving the reaction mass at 90-100 ° C in cyclohexane, filtering it from the catalyst and cooling the solution to 15-20 ° C. The precipitate is filtered off and dissolved at 45-50 ° C in normal hydrocarbons (n-hexane, gasoline). The precipitate of the desired product which precipitated out at 15-20 ° C is filtered and dried. Pentaerythritol tetraester is obtained, m.p. 120-124 ° C.

Distinctive features of the process are the dissolution of the reaction mass at 90-100 ° C in cyclohexane, separation of the catalyst by filtration, cooling the solution to 15-20 ° C, followed by separating the precipitate and dissolving it in a normal hydrocarbon at 45-50 ° C and separating the crystalline target product at 15-20 ° C.

In this case, the following occurs: tetraether and triether of pentaerythritol with cyclohexane form readily crystallizing inclusion compounds, while mono- and di-esters of pentaerythritol, which do not form such compounds, remain in solution along with unreacted methyl ether b- {3.5 -di-tert-butyl-4-hydroxyphenyl) -propionic acid and resinous oxidation products.

The filter cake is dissolved when it is heated in normal hydrocarbons (n-hexane, gasoline), the inclusion compounds are destroyed and, when cooled to 20 ° C, the pentaerythritol tetraester is released as crystals, while the triether having the best solubility in hydrocarbons, remains in solution.

Example 1. To 50 g of the reaction mass,

containing,%: 77.32 tetraether, 15.0 three ethers, 4 methyl esters of - (3,5-di-1-methyl 1-hydroxyphenyl) -propionic acid.

2.91 alkaline canalizer and 0.67 resinous products, 75 ml of cyclohexane is added at 100 ° C and stirred for 15 minutes, while the temperature is reduced to

60 ° C. The alkaline catalyst is filtered off, cooled with stirring to 20 ° C and kept for 5-6 hours until the end of the crystallization process of the inclusion compounds. The precipitate is filtered off, washed with 30 ml of cyclohexane. The resulting paste is dissolved at 45-50 ° C in 60 ml of Galosh gasoline, and the solution is cooled to 20 ° C and stirred for 5 hours until crystallization of the tetraester is complete. The precipitate is filtered off, washed with 20 ml of gasoline and dried.

Obtain 32.85 g of the desired product in the form of white crystals, so pl. 123-124 ° C. Example 2. 50 g of the reaction mass,

containing,%: 60.23 tetraether, -25.63 triether, 2.7 diester of pentaerythritol, 0.5 methyl ester of 8- (3,5-di-tert-butyl-4-oxyphenyl) -propionic acid, 3.1 mixtures of alkaline catalyst and source

pentaerythritol and 7.84 resinous products are treated, as in Example 1, decomposition of the inclusion compound by n-hexane.

Obtain 25.28 g of the desired product, so pl. 121-122C.

PRI me R 3. 50 g of the reaction mass containing,%: 40 those; rastefra, 38,5 triether, 1.5 diester of pentaerythritol, 4.5 methyl esters - {3,5-di-tert-butyl-4-hydroxyphenyl) -propionic acid, 1.8 alkaline catalyst and the starting pentaerythritol and 1.37 resinous products, treated as in Example 1, decomposition of the inclusion compound by n-octane,

Obtain 76.4 g of the desired product, so pl.

120-121 ° C.

Example 4. 50 g of the reaction mass, containing,%: 25.0 tetraether, 35.5 triester, 16.8 diester and 4.0 monoether pentaerythritol, 8.2 methyl ether

 (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid, 3.5 alkaline catalyst and pentaerythritol and 7.0 resinous products, are treated as in Example 1.

9.38 g of white tetraether crystals are obtained, m.p. 121-122 ° C.

The advantage of the proposed method for the isolation and purification of pentaerythryltetrakis-G / 5- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate1 is the possibility

isolating an individual target high-quality product from complex, by composition, masses with different contents of the target product; simplifying the method of removing alkaline alkali 510125696

the catalyst from the reaction mass; pro-from water; the time consistency of carrying out the process of isolating the process of secession and azeot-duct production without a process, which leads to an increase in the dry weight of the reaction mass and the productivity of labor.

Claims (1)

(54X57) METHOD FOR ISOLATION AND PURIFICATION OF PENTAerythrityl tetraKIS - [/? - (3.5-DI TRET-BUTYL-4-OXYPHENYL) PROPION ATA}, from the reaction mass by removing residual alkaline catalyst by crystallization of the target product from organic solvents, characterized in that. that, in order to simplify and intensify the process, the reaction mass is dissolved at 90-100 ° C in cyclohexane, the catalyst is separated by filtration, the solution is cooled to 15-20 ° C, and then the precipitate is dissolved at 45-50 ° C in a normal hydrocarbon and after cooling to 15-20 ° C, the crystalline target product is separated.