CN115677757A - A method for purifying tris(2,4-di-tert-butylphenyl)phosphite with low chloride ion content - Google Patents

Abstract

The invention relates to a method for purifying tris(2,4-di-tert-butylphenyl)phosphite with low chloride ion content. The method treats tris(2,4-di-tert-butylphenyl) phosphite with a deep eutectic solvent comprising urea or 1,3-dimethyl urea, and has the advantages of less product loss and low chloride ion content in the product, With the advantages of short processing time, high production efficiency, and environmental protection, it is an economically feasible method for purifying tris(2,4-di-tert-butylphenyl)phosphite.

Description

Purification of tris(2,4-di-tert-butylphenyl)phosphite with low chloride ion content method

technical field

The invention relates to the field of chemical industry, in particular to a method for purifying tris(2,4-di-tert-butylphenyl)phosphite with low chloride ion content.

Background technique

Tris (2,4-di-tert-butylphenyl) phosphite is a widely used phosphite antioxidant first developed by Ciba in Switzerland in the late 1970s. The English name is Tris -(2,4-d itertbuty lpheny l)-phosphite, the commonly used trade names are antioxidant 168, Irganox 168, Mark 2112, etc. It is a white powder crystal, tasteless and odorless, with a melting point of 183-186 ° C, at 20 ° C The density is 1.03g/cm ³ , insoluble in strong polar solvents such as water and methanol, slightly soluble in ethanol and acetone, and easily soluble in weak polar solvents such as esters, benzene, toluene and alkanes. Tris (2,4-di-tert-butylphenyl) phosphite is a solid auxiliary antioxidant. When it is used alone as a stabilizer in the resin, it does not show significant activity. When it is used with the main antioxidant When combined with agents such as phenolic antioxidants, they have a strong synergistic effect. Therefore, tris(2,4-di-tert-butylphenyl) phosphite is often used together with antioxidant 1010, antioxidant 1076, antioxidant 1790, etc., as a composite antioxidant for polypropylene, polyethylene, Polystyrene, polyamide and polyester are used as processing stabilizers to prevent thermal degradation and yellowing at processing temperatures, so that the processed products have long-term thermal stability, thereby delaying the oxidation process of polymer materials. Extend product life. Therefore, tris(2,4-di-tert-butylphenyl)phosphite has a strong market demand.

Tris(2,4-di-tert-butyl)phosphite is generally prepared by reacting phosphorus trichloride and 2,4-di-tert-butylphenol with organic amine compound as a catalyst, and is removed by distillation after the reaction Low boiler, and then crystallization in solvents such as methanol. However, the purity and quality of the 2,4-di-tert-butylphenol product produced by this process method are not high, especially if the reaction is not purified properly, it will contain more chloride ions. The higher concentration of chloride ions limits the use of tris(2,4-di-tert-butyl)phosphite and may corrode reaction and storage equipment. Therefore, it is necessary to develop a purification method capable of reducing the chloride ion content in tris(2,4-di-tert-butyl)phosphite.

CN101684130A reports a method of purifying phosphite compounds by adding deionized water followed by extraction, removing the organic solvent by distillation and recrystallizing, whereby a product with a residual chlorine content of 0.01% by weight of chlorine can be obtained. However, this method uses a large amount of solvent, and the use of water may lead to the instability of the phosphite compound and the loss of a part of the valuable product.

WO2015/176929A1 reports a method for reducing the chlorine content of an organic monophosphite by partially or completely dissolving the organic monophosphite in a mixture containing aromatic compounds, alcohols, acetone, ethyl acetate, acetonitrile, ether , in a first solution of a first solvent of water; wherein the first solution comprises dimethylaminobutane or triethylamine or triethanolamine; precipitating the purified organic monophosphite. WO2015/121007A1 reports a method for reducing the chlorine content of an organic bisphosphite, comprising completely dissolving an organic bisphosphite in a first solution comprising a first solvent and a first base, and then introducing the first solution into In the second solution comprising the second solvent and the second alkali, the purified organic bisphosphite is precipitated. CN106928270A reports a method for reducing the chlorine content of an organic tetraphosphite, and the organic tetraphosphite is combined with the contacting a solution of at least one solvent and at least one base, wherein the at least one solvent is selected from the group consisting of aromatic compounds, alcohols, acetone, ethyl acetate, acetonitrile and ether, and wherein the at least one base is selected from the group consisting of amine bases , alkoxides, pyridine, pyridine derivatives, N-methyl-2-pyrrolidone, triethylamine and triethanolamine, then adjust the temperature to a value from -20°C to +15°C to separate the purified organotetraphosphite . However, the above-mentioned methods all have the problems of incomplete removal of chlorine and excessive retention of phosphite in the mother liquor, and the alkali used may remain in the phosphite, thereby causing discoloration of the phosphite.

Contents of the invention

In order to solve the above problems in the prior art, the present invention provides a method for purifying tris(2,4-di-tert-butylphenyl) phosphite, which can significantly reduce tris(2,4-di Chloride ion content in tert-butylphenyl) phosphite.

The invention provides a method for purifying tris(2,4-di-tert-butylphenyl)phosphite, comprising:

Mix tris (2,4-di-tert-butylphenyl) phosphite with a deep eutectic solvent containing urea or 1,3-dimethyl urea, make a slurry, and separate the solid from the liquid, and wash the collected solid with an organic solvent After washing and drying, purified tris(2,4-di-tert-butylphenyl)phosphite was obtained.

As the tris(2,4-di-tert-butylphenyl)phosphite to be purified in the present invention, according to its source, it can contain more than 10ppm of chloride ion content, or more than 30ppm, or more than 50ppm, or more than 80ppm, Or more than 100ppm chloride ion content, more preferably more than 200ppm chloride ion content; preferably, its chloride ion content is below 2000ppm, or below 1000ppm, or below 500ppm, or below 300ppm. The object of the present invention is to reduce the chloride ion content of tris(2,4-di-tert-butylphenyl)phosphite through a purification process. The present invention finds that the above purification process can reduce the chloride ion content in tris(2,4-di-tert-butylphenyl)phosphite to be lower than that of tris(2,4-di-tert-butylphenyl) to be purified The degree of chloride ion content in the phosphite; preferably, the chloride ion content in the purified tris (2,4-di-tert-butylphenyl) phosphite is less than 100ppm, preferably less than 80ppm, or less than 50ppm, or less than 30ppm , or less than 10ppm, or less than 5ppm.

In one embodiment, the deep eutectic solvent containing urea or 1,3-dimethylurea comprises hydrogen bond acceptors not containing chlorine and urea or 1,3-dimethylurea in a molar ratio of 1:2-6. Dimethyl urea is a deep eutectic solvent. Wherein, the chlorine-free hydrogen bond acceptor includes at least one of betaine or its derivatives, tetraethylammonium bromide, tetrabutylammonium bromide, and methyltriphenylphosphine bromide. Preferably, the molar ratio of hydrogen bond acceptor to urea or 1,3-dimethylurea is 1:3-5, more preferably 1:4. When the deep eutectic solvent is formed at the molar ratio, it has a lower melting point. In the present invention, the melting point of the deep eutectic solvent can be lower than 40°C, or lower than 30°C, lower than 20°C, or even below 15°C.

In one embodiment, the deep eutectic solvent is prepared via the following method:

The chlorine-free hydrogen bond acceptor is mixed with urea or 1,3-dimethylurea according to the molar ratio, heated to 70-100° C., and stirred until the solution is completely transparent.

In one embodiment, the mass ratio of tris(2,4-di-tert-butylphenyl)phosphite to the deep eutectic solvent is 1:1.5-4, preferably 1:2-3. When the ratio is too low, three (2,4-di-tert-butylphenyl) phosphite cannot be completely dispersed in the deep eutectic solvent, and the purification effect is poor; when the ratio is too high, there are economic benefits Lowering the problem.

In one embodiment, the temperature during beating is lower than 40°C, or lower than 30°C, preferably, beating is performed at room temperature.

In one embodiment, the beating time is 0.5-4 hours, preferably 1-3 hours.

In one embodiment, the solid-liquid separation method includes at least one of sedimentation, centrifugation, and filtration.

In one embodiment, the organic solvent is selected from solvents with low solubility for tris(2,4-di-tert-butylphenyl)phosphite, such as methanol, ethanol, acetone, preferably methanol.

In one embodiment of the present invention, the present invention also relates to the step of reusing the deep eutectic solvent, the deep eutectic solvent of the present invention can be directly used in the next batch of tris(2,4 - In the purification of di-tert-butylphenyl) phosphite. Therefore, purification method of the present invention can also comprise following reuse step:

After the solid-liquid separation, the deep eutectic solvent of the liquid phase is collected, and the three (2,4-di-tert-butylphenyl) phosphite to be purified is added to the deep eutectic solvent, and the beating and solidification of the present invention are repeated. Liquid separation, washing, and drying processes to obtain purified tris(2,4-di-tert-butylphenyl)phosphite and the used deep eutectic solvent.

In one embodiment, the used deep eutectic solvent can be reused until the chloride ion content in the obtained tris(2,4-di-tert-butylphenyl)phosphite does not meet the requirements. Preferably, the deep eutectic solvent is reused until the chloride ion content in tris (2,4-di-tert-butylphenyl) phosphite is higher than the set qualified chloride ion content, and the number of times of repeated use is 1- 10 times.

Therefore, the purification method of the present invention may also include: repeating the above-mentioned reuse steps, and simultaneously detecting the content of chloride ions in the obtained tris(2,4-di-tert-butylphenyl)phosphite, when the content is at 100ppm In the above, the obtained tris(2,4-di-tert-butylphenyl)phosphite is treated with a fresh deep eutectic solvent or a deep eutectic solvent with a small number of cycles to reduce its chloride ion content to less than 100ppm.

Preferably, reuse until the content of chloride ion is more than 80ppm, or more than 50ppm, or more than 30ppm, or more than 10ppm, or more than 5ppm; and the obtained three (2,4-di-tert-butylphenyl) phosphite Treatment with fresh deep eutectic solvent or low number of cycles of deep eutectic solvent to reduce its chloride ion content to less than 80 ppm, or less than 50 ppm, or less than 30 ppm, or less than 10 ppm, or less than 5 ppm.

In one embodiment, the present invention also includes the process of combining and then regenerating the non-recyclable deep eutectic solvent.

Beneficial effect

The invention provides a method for purifying tris(2,4-di-tert-butylphenyl) phosphite, the method treats tris(2) with a deep eutectic solvent containing urea or 1,3-dimethyl urea , 4-di-tert-butylphenyl) phosphite. Deep eutectic solvent is a kind of low-temperature melting mixture, which is mainly composed of hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA) in different molar ratios through hydrogen bonds. The melting point of the mixture is much lower than that of each component. Melting point, has many advantages such as low melting point, low cost, easy synthesis, high atom economy, biodegradability, environmental friendliness, low biotoxicity, easy recycling, and reusability. On the one hand, three (2,4-di-tert-butylphenyl) phosphite has low solubility in the deep eutectic solvent, so its dissolution in the deep eutectic solvent is less, reducing the loss of products; On the other hand, the deep eutectic solvent of the present invention can combine chloride ions therein into the solvent in the process of processing tris(2,4-di-tert-butylphenyl) phosphite, thereby greatly reducing the tris(2 , 4-di-tert-butylphenyl) phosphite chloride ion content, three (2,4-di-tert-butylphenyl) phosphite can be basically completely removed. Furthermore, compared with the crystallization method, the treatment process of the present invention not only does not need to use alkali, but also avoids the defects of long time consumption, many types of solvents, and incomplete removal of chloride ions in the recrystallization method, and the treatment time is short and the production efficiency is high. At the same time, the deep eutectic solvent can be reused many times, and can also be recycled and regenerated, which meets the requirements of green and environmental protection chemistry. Therefore, the purification method of the present invention is an economically feasible method for purifying tris(2,4-di-tert-butylphenyl)phosphite.

Detailed ways

A clear and complete description will be made below in conjunction with the technical solutions of the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

The experimental methods in the following examples are conventional methods unless otherwise specified. If no specific technique or condition is indicated in the examples, it shall be carried out according to the technique or condition described in the literature in this field, or according to the product specification.

Example 1:

Add 1 mol of betaine and 4 mol of urea into a reactor with a magnetic device, heat to 80° C. and keep stirring until the solution is completely transparent to obtain 357 g of a deep eutectic solvent. Cool to 30°C, add 150g of tris(2,4-di-tert-butylphenyl)phosphite (containing about 150ppm of chloride ions, the same below), beat for 1 hour; after the beating is finished, the speed is 2000-3000rpm The solid was collected by centrifugation, and the solid was washed with methanol. After drying, 146.1 g of purified tris(2,4-di-tert-butylphenyl)phosphite was obtained, and no chloride ion was detected by an instrument with a detection limit of 2 ppm.

Add 150g of tris(2,4-di-tert-butylphenyl)phosphite again to the separated deep eutectic solvent, repeat the above steps to obtain multiple batches of purified tris(2,4-di-tert Butylphenyl) phosphite, its product yield and chloride ion content are shown in the following table:

repeat times 1 2 3 4 5 Yield (g) 146.3 147.9 148.4 148.7 148.9 Chloride ion content (ppm) not detected not detected 3.7 6.1 8.8

Example 2:

Add 1 mol of betaine and 4 mol of 1,3-dimethylurea into a reactor with a magnetic device, heat to 80°C and keep stirring until the solution is completely transparent to obtain 469 g of deep eutectic solvent. Cool to 30°C, add 200g of tris(2,4-di-tert-butylphenyl)phosphite (containing about 150ppm of chloride ion), beat for 1h; centrifuge at 2000-3000rpm after beating, The solid was collected, washed with methanol, and dried to obtain 196.6 g of purified tris(2,4-di-tert-butylphenyl)phosphite, and no chloride ion was detected by an instrument with a detection limit of 2 ppm.

Add 200g of tris(2,4-di-tert-butylphenyl)phosphite again to the separated deep eutectic solvent, repeat the above steps to obtain multiple batches of purified tris(2,4-di-tert Butylphenyl) phosphite, its product yield and chloride ion content are shown in the following table:

repeat times 1 2 3 4 5 Yield (g) 196.7 198.1 198.3 198.7 198.6 Chloride ion content (ppm) not detected 2.2 4.5 7.6 9.8

The preferred embodiments of the present invention have been described above, but they are not intended to limit the present invention. Modifications and changes to the embodiments disclosed herein may be made by those skilled in the art without departing from the scope and spirit of the invention.

Claims (10)

1. A method of purifying tris (2,4-di-tert-butylphenyl) phosphite comprising:

mixing tris (2,4-di-tert-butylphenyl) phosphite with a eutectic solvent containing urea or 1,3-dimethyl urea, pulping, performing solid-liquid separation, washing the collected solid with an organic solvent, and drying to obtain purified tris (2,4-di-tert-butylphenyl) phosphite.

2. The process of claim 1 wherein the tris (2,4-di-tert-butylphenyl) phosphite to be purified has a chloride content of 10ppm or more and the purified tris (2,4-di-tert-butylphenyl) phosphite has a chloride content that is lower than the chloride content of the tris (2,4-di-tert-butylphenyl) phosphite to be purified.

3. The method according to claim 1, wherein the eutectic solvent comprising urea or 1,3-dimethyl urea comprises a mixture of urea and 1,3-dimethyl urea in a molar ratio of 1: 2-6 hydrogen bond acceptors without chlorine and urea or 1,3-dimethyl urea.

4. A method according to claim 3, wherein the chlorine-free hydrogen bond acceptor comprises at least one of betaine or a derivative thereof, tetraethylammonium bromide, tetrabutylammonium bromide, methyl triphenylphosphonium bromide.

5. The method according to claim 3 or 4, characterized in that the eutectic solvent is prepared via the following method:

and mixing the chlorine-free hydrogen bond acceptor with urea or 1,3-dimethyl urea according to the molar ratio, heating to 70-100 ℃, and stirring until the solution is completely transparent.

6. The method of claim 1, wherein the mass ratio of tris (2,4-di-tert-butylphenyl) phosphite to eutectic solvent is 1:1.5 to 4, preferably 1:2 to 3.

7. The method according to claim 1, characterized in that the temperature during beating is lower than 40 ℃ and the beating time is 0.5-4 h.

8. The method according to claim 1, wherein the organic solvent is selected from methanol, ethanol, acetone, preferably methanol.

9. The method of claim 1, wherein the purification method further comprises the following reuse steps: collecting the liquid-phase eutectic solvent after solid-liquid separation, adding the tris (2,4-di-tert-butylphenyl) phosphite to be purified into the eutectic solvent, and repeating the processes of beating, solid-liquid separation, washing and drying to obtain the purified tris (2,4-di-tert-butylphenyl) phosphite and the used eutectic solvent.

10. The method of claim 9, wherein the purification method further comprises: repeating the recycling steps, detecting the content of chloride ions in the obtained tris (2,4-di-tert-butylphenyl) phosphite, and when the content is more than 100ppm, treating the obtained tris (2,4-di-tert-butylphenyl) phosphite with a fresh eutectic solvent or a eutectic solvent with a small number of cycles to reduce the content of chloride ions to less than 100ppm.