HU203314B - Process for separating pentaerithryl-tetrakis/3-(3,5-di/terc-butyl/-4-oxyphenyl)- -propionate/ from the reaction mixture - Google Patents

Abstract

Penta-erythryl-tetrakis -(3-(3,5-ditert.- butyl-4-oxyphenyl) -propionate is recovered from the reaction mass obtd. by the trans-esterification of 3-(3,5-ditert.-butyl -oxyphenyl)-propionic acid methyl ester with pentaerythritol in the presence of an alkali by: (a) treating the reaction mass with cyclohexane at 100-120 deg.C; (b) filtering at 60-75 deg.C; (c) cooling the cyclohexane soln. to 15-20 deg.C to crystallise the prod.; (d) filtering; (e) re-dissolving in n-hydrocarbons at 45-75 deg.C; and (f) re-crystallising at 15-20 deg.C.

Description

The present invention relates to a process for the isolation of pentaerythritol tetrakis [3- (3,5-di-tert-butyl / -4-oxyphenyl) propionate] from the final product, unreacted starting materials, by-products, resinous oxidation products and a reaction mixture of the remainder of the catalyst resulting from the transesterification of the methyl 3- (3,5-di-tert-butyl-4-oxy-phenyl) -propionic acid with pentaerythritol during the preparation of the target product.

Penlaeryl aryl tetrakis [3- (3,5-di-tert-butyl-4-oxyphenyl) proponate] is obtained by transesterification of 3- (3,5-di-tert-butyl / -4-oxyphenyl) ) -propionic acid methyl ester and pentaerythritol in the presence of a basic catalyst. According to a known method, where lithium hydride is used as a catalyst, the reaction mixture is diluted with benzene to isolate the reaction product, the resulting mixture is treated with anhydrous acetic acid and the solid phase containing lithium acetate and unreacted pentaerythritol is separated. a mixture of the reacted ester, by-products, resinous oxidation products and acidic impurities - washed to neutral with water, dried over sodium sulfate, filtered and the benzene distilled. The residue is distilled at 120-140 ° C at 0.0133 kPa to remove the unreacted starting methyl ester. The distillation residue is crystallized from isopropanol and n-hexane; the resulting product melts at 123-125 ° C (U.S. Patent No. 3,644,482).

In another known procedure an alkali metal alcoholate, such as sodium methoxide, lithium methoxide, lithium ethoxide is used as a catalyst in said at ^x szterezés. Anhydrous acetic acid was added to the reaction mixture and the mixture was dissolved in 95% by weight of isopropanol. The final product was crystallized at 5 ° C, filtered and washed first with 95% by weight of isopropanol and then with water. The crystalline product is dissolved in n-heptane, the solution is washed with water, and the water is removed by azeotropic distillation. The dried heptane water is crystallized from the product at 5 ° C; 121-122 ° C (British Patent No. 1,081,789).

The above processes are multi-step processes, time consuming and have the disadvantage of using anhydrous acetic acid and generating large amounts of wastewater due to multiple aqueous washes; organic solutions must either be dried with a solid adsorbent or with azeotropic distillation, which complicates the process and adds energy to the auxiliary material,

SUMMARY OF THE INVENTION An object of the present invention is to provide a process for the preparation of pentaerythritol tetrakis [3- (3,5-di-tert-butyl / -4-oxyphenyl) propionate] with 3- (3,5-di The reaction mixture formed by transesterification of methyl tert-butyl / -4-oxyphenyl) propionic acid with pentaerythritol in the presence of a basic catalyst can be isolated in a short time, in high yield, anhydrous acetic acid, washing with water, drying organic solvents, suitable solvent and suitable solvent. as a result of the choice of circumstances.

According to the invention, this object is solved by not finalizing the final product of the transesterification of the methyl ester of 3- (3,5-di-tert-butyl / -4-oxy-phenyl) -propionic acid with pentaerythritol in the presence of a basic catalyst. an organic solvent is added to the reaction mixture containing the reacted starting materials, the resinous oxidation product and the remainder of the basic catalyst, and the final product is crystallized from n-hydrocarbon. According to the present invention, the organic solvent used is cyclohexane in a ratio of 1: 1.2 to 1: 2 by volume, while the reaction mass is 100 to 120 ° C, unreacted pentaerythritol and 60-75 ° C of the basic catalyst after cyclohexane treatment. After filtration, the final product, the unreacted methyl ester and the by-products in cyclohexane solution were cooled to 1520 ° C, and the crystalline inclusion compound of the final product with cyclohexane was isolated by filtration, using n-hydrocarbon in a weight ratio of 1: 1 to 1: 2. It is dissolved at 4575 ° C and the final product liberated from the decomposition of the inclusion compound is crystallized from hydrocarbon at 15-20 ° C.

By using cyclohexane as an organic solvent, an effective separation of unreacted starting pentaerythritol and alkaline catalyst is achieved and the final product is completely separated, since the final product forms an inclusion compound with cyclohexane which can be easily crystallized from other materials, e.g. It can be isolated from by-products, The separation is perfect even if only a relatively small amount (e.g. 25% by weight) of the final product is present in the reaction mass.

The process according to the invention does not require the use of anhydrous acetic acid, washing with water or drying solutions, which means a reduction in the number of steps required. The process is simpler, more efficient and no wastewater is generated. The process is technologically simple and can be implemented with simple devices. The final product is of high quality, m.p. 120-124 ° C.

As mentioned above, the reaction mass is treated with cyclohexane (1: 1.21: 2) at 100-120 ° C.

The use of less than 1: 1.2 by volume cyclohexane is not advisable because the viscosity of the cyclohexane solution will be too high and will make crystallization of the inclusion compound difficult. Exceeding the 1: 2 by volume ratio only increases solvent consumption and reduces process performance.

The reaction mass is treated with cyclohexane at 100-120 ° C. At lower temperatures, the reaction mass would not dissolve sufficiently due to the viscosity of the mixture, and at temperatures above 120 ° C, the pressure in the system would increase significantly.

After treatment with cyclohexane, the unreacted pentaerythritol and residues of the alkaline catalyst are removed by filtration at 6075 ° C. At temperatures below 60 ° C, the viscosity of the solution makes filtration difficult, and filtration at temperatures above 75 ° C is not recommended due to strong pressure rise.

A solution of the final product, unreacted methyl ester, reaction byproducts, and resinous oxidation products in cyclohexane was cooled to 1520 ° C to afford the final product with cyclohexane.

Crystallize the formed inclusion compound -2EN 203314Β. Temperatures below 15'C are not required, additional cooling would only increase power consumption, while temperatures above 20'C would increase the loss of the final product.

The resultant crystalline inclusion compound is dissolved in n-hydrocarbon at a temperature of 45-75 ° C, whereby the weight ratio of inclusion compound to n-hydrocarbon is 1: 1 to 1: 2.

Dissolving below 45'C would be lengthy, while temperatures above 75'C are not recommended due to pressure increase.

The weight ratio of n-hydrocarbon to inclusion compound used for dissolution should be at least 1: 1. For a smaller amount of hydrocarbon, the viscosity of the solution is higher than required, which makes it difficult to crystallize the final product. The use of more than 1: 2 by volume hydrocarbons only increases solvent consumption and reduces process efficiency; no advantage.

The final product is crystallized from hydrocarbon at 15-20 ° C. temperatures below 15 'C are not recommended due to the extra energy required for cooling. Crystallization at temperatures above 20 ° C increases product losses.

The best embodiment of the process according to the invention is described below. The final product, unreacted starting product, by-products, pentaerythritol mono- [3] obtained by transesterification of methyl 3- (3,5-di-tert-butyl-4-oxyphenyl) propionic acid with pentaerythritol in the presence of an alkaline catalyst were obtained. - (3,5-di-tert-butyl-4-oxy-phenyl) -proponate, pentaerythri-bis [3- (3,5-di-tert-butyl-4-oxy) phenylporporionate], pentaerythritris tris [3- (3,5-di-tert-butyl-4-oxy-phenyl) -propinate], and a resinous oxidation product and the remainder of the catalyst After treatment with cyclohexane in a volume ratio of 1: 1.2 to 1: 2 at 100-120 ° C, the temperature of the mixture spontaneously decreases to 60-75 ° C. The solid impurities (pentaerythritol, catalyst residues) are filtered off at 60-70 ° C and the final product, unreacted methyl ester, by-products and resinous oxidation product in a cyclohexane solution is introduced into a crystallizer equipped with a stirrer and thermometer. The solution, which has been cooled to 15-20 C, is preferably left to stand for 6 hours while the inclusion product of the final product with cyclohexane is precipitated. The crystalline product is isolated by filtration, washed on a filter with cyclohexane and added with a crystallizer. In a crystallizer equipped with a stirrer and thermometer, the inclusion compound is dissolved in n-hydrocarbon (e.g., n-hexane, n-heptane, n-octane, gasoline) at 45-75 ° C such that 1: 1 and 1 : 2 by weight. Under these conditions, the inclusion compound decomposes and the final product crystallizes from the solution cooled to 15-20 ° C. The crystallization is preferably continued for 5 hours. The crystalline product is isolated by filtration, washed with hydrocarbon on a filter and dried. The final product is obtained in the form of white crystals, m.p. 120-124 ° C.

The invention will now be explained in more detail by the following embodiments.

Example 1

The pentaerythritol tetrakis [3- (3,5-di tert-butyl / 4-oxyphenyl) propionate] is separated from the reaction mass which is 3- (3,5-di tert-butyl / 4-oxy) The methyl ester of phenyl 5-propionic acid was formed by transesterification with pentaerythritol in the presence of an alkaline catalyst in the presence of lithium hydride. The composition of the reaction mass is as follows: 77.321% pentaerythritil tetrakis [3- (3,5-di-tert-butyl / -4-oxyphenyl) propionate], 4.0% 3- (3,5-di- tert-butyl 6- (4-oxyphenyl) propionic acid methyl ester, 14.0% pentaerythril tris [3- (3,5-di-tert-butyl 4-oxyphenyl) propionate], 90% by weight of pentaerythritil bis [3- (3,5-di-tert-butyl / -4-oxyphenyl) propionate], 0.10% by weight of pentaeritrile mono- [3- (3,5-di (tert-butyl / -4-oxyphenyl) propionate], 0.77% w / w resinous oxidation products, 2.911% unreacted pentaerythritol and alkaline catalyst residue.

cm ^{3 of} reaction mass was treated with 75 cm ^{3 of} cyclohexane (1: 1.5 by volume) at 120 ° C. The mixture cooled to 75 ° C. The starting pentaerythritol and residual alkaline catalyst were removed by filtration at the indicated temperature. The cyclohexane solution was fed with stirring and into a crystallizer equipped with a thermometer, where it was cooled to 20 ° C and allowed to stand for 6 hours. The inclusion product of the final product with cyclohexane is precipitated. The crystals were separated by filtration and washed on a filter with 50 µl cyclohexane. After washing, the filter cake weighs 45.3 g. The crystals were transferred to a crystallized desiccator with stirrer and thermometer, whereupon 45.3 g of gasoline (inclusion compound: petrol: 1: 1 weight ratio) were dissolved at 75 ° C. The inclusion compound decomposed under the conditions mentioned. The product gasoline solution was cooled to 15 ° C and allowed to stand at this temperature for 5 hours. The precipitated product was collected by filtration, washed with 30 cm ^{3 of} petrol and dried. 32.85 g of product are obtained in the form of white crystals. Mp 123-124 ° C.

Example 2

The reaction mixture to be worked up was derived from a transesterification similar to that described in Example 1, but using sodium methylate as the basic catalyst. The composition of the reaction mass is as follows:

60.23% by weight of pentaerythritol tetrakis [3- (3,5-di-tert-butyl / -4-oxyphenyl) propionate], 0.50% by weight of unreacted starting methyl ester, 25.40% by weight % pentaerythritol tris, 2.701% pentaerythryl bis ester, 0.231% pentaerythryl monoester, 7.851% resinous oxidation products, 3.101% unreacted pentaerythritol and

100 cm Cyclohexane (1: 2 by volume) was treated at 100 C, whereby the temperature of the mixture was reduced to 60 C. The solid impurities (pentaerythritol, alkaline catalyst residue) are filtered off at 60 ° C and the cyclohexane solution is cooled to 15 ° C with stirring and in a thermocrystallizer and allowed to stand at this temperature for 6 hours. The crystalline inclusion compound of the final product 60 with cyclohexane was separated by filtration and washed with 50 cm @ 2 of cyclohexane on a filter. After washing, the filter cake weighed 34.8 g.

The crystals were dissolved by stirring and in a crystallizer equipped with a thermometer, 41.8 g of n-hexane (65: 1 by weight ratio of product to n-hexane) at 45 ° C. The basic catalyst in n-hexane is a residue. 50 cnr reaction mass

-3HU 203314Β

Solution 6 is cooled to 18 'C and allowed to stand at this temperature for 5 hours. The crystalline product is isolated by filtration, washed with 30 cm <RTI ID = 0.0> n-hexane </RTI> on a filter and dried. 35.28 g of final product are obtained in the form of white crystals, m.p. 121-122 ° C.

Example 3

The reaction mixture to be worked up is derived from a transesterification similar to that described in Example 1, but lithium ethylate is used as the alkaline catalyst. The composition of the reaction mass is as follows: 40.03% by weight of pentaerythritol tetrakis [3- (3,5-di-tert-butyl / -4-oxyphenyl) propionate], 7.501% of unreacted starting methyl ester, 36.861%. % pentaerythryl tris tris, 7.32 wt% pentaerythryl bis ester, 1.82 wt% pentaerythryl mono ester, 3.671% resinous oxidation products, 2.8% unreacted pentaerythritol and residual alkaline catalyst is removed by filtration, the cyclohexane solution was transferred to a crystallizer equipped with a thermometer with stirring, where it was cooled to 15 ° C and allowed to stand at this temperature for 6 hours. The precipitated compound was collected by filtration and washed with 30 cm ^{3 of} cyclohexane on a filter. After washing, the filter cake weighed 22.7 g.

The crystalline filter cake was dissolved in 45.4 g of n-octane (1: 2 by weight) at 70 ° C with stirring and in a thermometer, and the solution was cooled to 15 ° C and allowed to stand for 5 hours. During this time, the final product crystallizes out. The crystals are filtered off, washed on a filter with 20 cm <^{3> of} n-octane and then dried. 16.4 g of the expected product are obtained in the form of white crystals, m.p. 120-121 ° C.

Example 4

The reaction mixture to be worked up was derived from a transesterification similar to that described in Example 1, but using sodium hydroxide as the alkaline catalyst. The composition of the reaction mass is as follows: 25.0% by weight of pentaerythritol tetrakis [3- (3,5-di-tert-butyl / -4-oxyphenyl) propionate], 14.2% by weight of unreacted starting material methyl ester, 35.5% by weight pentaerythritol tris, 10.8% by weight pentaerythryl bisester, 4.01% pentaerythryl monoester, 7.01% resinous oxidation products, 3.51% unreacted pentaerythritol and alkaline catalyst residue.

cm ³ reaction mass 60 cm ³ of cyclohexane at 120 ° C (which is 1: 1.2 corresponding to volume ratio) treated in the reaction mass temperature cooled to 75 'decreases. The unreacted pentaerythritol and the residue of the alkaline catalyst are separated by filtration, the cyclohexane solution is stirred and introduced into a crystallizer with thermometer, where it is cooled to 18 ° C and left to stand at this temperature for 6 hours. The crystalline precipitate is isolated by filtration and washed with 20 cm ^{3 of} cyclohexane on a filter. After washing, the filter cake weighed 12.9 g.

The inclusion compound is dissolved in 12.9 g (1: 1) gasoline (75% by weight) in a crystallizer with a thermometer and the solution is cooled to 20 ° C and left to stand at this temperature for 5 hours. The precipitated crystalline product is filtered off, washed with 10 cm ^{3 of} petrol on a filter and dried. 9.38 g of product are obtained in the form of white crystals, m.p. 121-122 ° C.

The process of the present invention allows the reaction product to be isolated from the reaction mixture containing varying proportions of the final product in a few operations; no wastewater is generated and the use of auxiliaries and energy is reduced compared to known processes. An area of industrial application of the process is the recovery of pentaerythritol tetrakis [3- (3,5-di-tert-butyl / -4-oxyphenyl) propionate] from a reaction mixture which is 3- (3,5-di / tert-butyl). The methyl ester of butyl-6- (4-oxyphenyl) propionic acid is formed by transesterification with pentaerythritol in the presence of an alkaline catalyst. Said end product can be used as an effective, non-toxic antioxidant of polyolefins, polystyrene and other polymers which does not color the polymer.

Claims (1)

Patent Claim Point A process for isolating pentaerythritol tetrakis [3- (3,5-di-tert-butyl / -4-oxyphenyl) propionate] with 30 reaction mixtures formed during the transesterification of 3- (3,5-di-tert-butyl / -4-oxyphenyl) propionic acid methyl ester with pentaerythritol in the presence of an alkaline catalyst during the synthesis of said product, from unreacted starting materials, It consists of by-products, resinous oxidation products, and residues of an alkaline catalyst in which the reaction mass is treated with an organic solvent and the final product is crystallized from n-hydrocarbons, As the solvent 40, cydohexane was used in a ratio of 1: 1.2 to 1: 2 by volume, while the reaction mass was 100-120 ° C, unreacted pentaerythritol after cyclohexane treatment and the basic catalyst filtered at 6045 75 ° C. after removal of the final product, the unreacted starting methyl ester, by-product and resinous oxidation products in cyclohexane solution to 15-20 ° C, the cyclohexane crystalline inclusion compound of the final product was isolated by filtration in a weight ratio of 1: 1 to 1: 2. Dissolve the final product liberated during the decomposition of the inclusion compound at 15-20 ° C to crystallize from the n-hydrocarbon.