CN115677757B - Method for purifying tri (2, 4-di-tert-butylphenyl) phosphite ester with low chloride ion content - Google Patents

Abstract

The invention relates to a method for purifying tris (2, 4-di-tert-butylphenyl) phosphite ester with low chloride ion content. The method for treating the tris (2, 4-di-tert-butylphenyl) phosphite by using the eutectic solvent containing urea or 1, 3-dimethyl urea has the advantages of less product loss, low chloride ion content in the product, short treatment time, high production efficiency, environmental protection and the like, and is an economically feasible purification method for the 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

三(2,4-二叔丁基苯基)亚磷酸酯是20世纪70年代末由瑞士汽巴公司首先开发出的一种具有广泛用途的亚磷酸酯类抗氧化剂，英文名为Tr i s-(2,4-d itertbuty lpheny l)-phosphite，常用商品名为抗氧剂168、I rganox 168、Mark 2112等，为白色粉末晶体，无味无臭，熔点为183-186℃，20℃时密度为1.03g/cm ³ ，不溶于水、甲醇等极性较强的溶剂，微溶于乙醇、丙酮，易溶于酯类、苯、甲苯、烷烃类等弱极性溶剂。 Tris(2,4-di-tert-butylphenyl)phosphite is a solid auxiliary antioxidant, which does not show significant activity when it is used alone as a stabilizer in resins, but it has a strong synergistic effect when combined with primary antioxidants such as phenolic antioxidants. 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 as a processing stabilizer to prevent thermal degradation and yellowing at the processing temperature, so that the processed product has long-term thermal stability, thereby delaying the oxidation process of polymer materials and prolonging the service life of the product. 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 as raw materials with organic amine compounds as catalysts. After the reaction, the low boilers are removed by distillation, and then obtained by 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, wherein the organic monophosphite is partially or completely dissolved in a first solution comprising a first solvent selected from aromatic compounds, alcohols, acetone, ethyl acetate, acetonitrile, ether, water; wherein the first solution comprises dimethylaminobutane or triethylamine or triethanolamine; and the purified organic monophosphite is precipitated. WO2015/121007A1 reports a method for reducing the chlorine content of an organic bisphosphite, comprising completely dissolving an organic bisphosphite in a first solution containing a first solvent and a first base, then introducing the first solution into a second solution containing a second solvent and a second base, and precipitating the purified organic bisphosphite CN106928270A reports a method for reducing the chlorine content of an organic tetraphosphite. contacting, 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, and then adjusting the temperature to a value from -20°C to +15°C, and isolating the purified organic tetraphosphite. 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 the chloride ion content in tris(2,4-di-tert-butylphenyl)phosphite.

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

Mixing tris(2,4-di-tert-butylphenyl)phosphite with a deep eutectic solvent containing urea or 1,3-dimethylurea, beating, and separating solid and liquid, washing the collected solid with an organic solvent, and drying to obtain purified tris(2,4-di-tert-butylphenyl)phosphite.

As the three (2,4-di-tert-butylphenyl) phosphite to be purified in the present invention, according to its source, it can contain more than 10 ppm of chloride ion content, or more than 30 ppm, or more than 50 ppm, or more than 80 ppm, or more than 100 ppm of chloride ion content, more preferably more than 200 ppm of chloride ion content; preferably, its chloride ion content is below 2000 ppm, or below 1000 ppm, or below 500 ppm, or 3 00ppm or less. 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-mentioned purification process can reduce the content of chloride ions in tris (2,4-di-tert-butylphenyl) phosphite to a level lower than the content of chloride ions in tris (2,4-di-tert-butylphenyl) phosphite to be purified; ppm.

In one embodiment, the deep eutectic solvent containing urea or 1,3-dimethylurea includes a deep eutectic solvent formed by a hydrogen bond acceptor not containing chlorine and urea or 1,3-dimethylurea in a molar ratio of 1:2-6. 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 lower than 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, tris(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 is a problem of reduced economic benefits.

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, and the deep eutectic solvent of the present invention can be directly used in the purification of the next batch of tris(2,4-di-tert-butylphenyl)phosphite without regeneration. 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, the tris(2,4-di-tert-butylphenyl)phosphite to be purified is added to the deep eutectic solvent, and the beating, solid-liquid separation, washing and drying processes of the present invention are repeated to obtain the 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 used repeatedly 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 to 10 times.

Therefore, the purification method of the present invention may further 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, and when the content is above 100ppm, treating the obtained tris(2,4-di-tert-butylphenyl)phosphite with a fresh deep eutectic solvent or a deep eutectic solvent with a small number of cycles to reduce the chloride ion content to less than 100ppm.

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

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 uses a deep eutectic solvent containing urea or 1,3-dimethyl urea to treat tris(2,4-di-tert-butylphenyl)phosphite. Deep eutectic solvent is a kind of low-temperature melting mixture, which is mainly composed of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) through hydrogen bonding in different molar ratios. The melting point of this mixture is far lower than the melting point of each component. It has many advantages such as low melting point, low cost, easy synthesis, high atom economy, biodegradability, environmental friendliness, low biological toxicity, 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; phenyl) phosphite can be removed substantially completely. Furthermore, compared with the crystallization method, the treatment process of the present invention not only does not require the use of alkali, but also avoids the defects of long time-consuming recrystallization method, many types of solvents used, and incomplete removal of chloride ions. 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

The technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, 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 chloride ion, the same below), and beat for 1 hour; after beating, centrifuge at a speed of 2000-3000rpm to collect the solid, wash the obtained solid with methanol, and dry to obtain 146.1g of purified tris(2,4-di-tert-butylphenyl)phosphite, no chloride ion was detected by the instrument with a detection limit of 2ppm .

In the deep eutectic solvent after separation, add 150g tris (2,4-di-tert-butylphenyl) phosphite again, repeat above-mentioned steps, obtain the purified tris (2,4-di-tert-butylphenyl) phosphite of multiple batches, its product output and chloride ion content are shown in the table below:

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 chloride ions) to it, and beat for 1 hour; after beating, centrifuge at a speed of 2000-3000rpm to collect the solid, wash the obtained solid with methanol, and dry to obtain 196.6g of purified tris(2,4-di-tert-butylphenyl)phosphite. No chloride ion was detected by an instrument with a detection limit of 2ppm.

In the deep eutectic solvent after separation, add again the three (2,4-di-tert-butylphenyl) phosphite of 200g, repeat above-mentioned steps, obtain the purified tris (2,4-di-tert-butylphenyl) phosphite of multiple batches, its product output 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 (9)

1. A process for 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, separating solid from liquid, washing the collected solid with an organic solvent, and drying to obtain purified tris (2, 4-di-tert-butylphenyl) phosphite;

the eutectic solvent comprising urea or 1, 3-dimethyl urea is selected from the group consisting of a molar ratio of 1:4 with urea or 1, 3-dimethylurea, said hydrogen bond acceptor containing no chlorine being selected from betaines.

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

3. The method according to claim 1, wherein the eutectic solvent is prepared via the following method:

mixing the hydrogen bond acceptor without chlorine with urea or 1, 3-dimethyl urea according to the molar ratio, heating to 70-100 ℃, and stirring until the solution is completely transparent.

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

5. The method according to claim 1, wherein the mass ratio of tris (2, 4-di-t-butylphenyl) phosphite to the eutectic solvent is 1:2 to 3.

6. The method according to claim 1, wherein beating is performed at room temperature for a period of 0.5 to 4 hours.

7. The method according to claim 1, wherein the organic solvent is selected from the group consisting of methanol, ethanol, acetone.

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

9. The method of claim 8, wherein the purification method further comprises: the above reuse step is repeated while detecting the content of chloride ions in the obtained tris (2, 4-di-t-butylphenyl) phosphite, and when the content is 100ppm or more, the obtained tris (2, 4-di-t-butylphenyl) phosphite is treated with a fresh eutectic solvent or a eutectic solvent having a small number of cycles to reduce the chloride ion content thereof to less than 100ppm.