JPS6013018B2 - Tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane with a novel crystal structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides tetrakis [3-(3,5-
It relates to di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane (formula (1)).

It is well known that the compound represented by the above formula (1) is used as an antioxidant for polyolefins, for example.

This compound (1) is commercially available, but the powder form of the commercially available product is a white fine powder with a high specific gravity and a low specific gravity.
It is extremely unsatisfactory in terms of transportability, workability, and weighability, such as scattering into the air when handled, low fluidity, and poor weighability when melt-mixed with polyolefin in an extruder. On the other hand, various methods for producing compound (1) have been proposed.

Specifically, the details of Tsubaki Kosho No. 42-18617, the details of Hakama Kosho No. 42-19083, and Tokuseki Sho 49-1946.
This is the specification of Publication No. 44. The method proposed in these prior art uses propionate ester (0) represented by the following formula (0).
and (in the formula, R is a lower alkyl group.

) The main point is to carry out a transesterification reaction with pentaerythritol to obtain compound (1).

However, according to detailed follow-up tests by the present inventors, the compound (1) obtained by the methods disclosed in these prior art
) could not solve the drawbacks of commercially available products.

First, in Example 2 a of Tsubaki Publication No. 42-18617, a transesterification reaction mixture of propionic acid methyl ester (0) and pentaerythritol is subjected to chromatography while eluting with hexane to remove hexane. It is described that compound (1) is obtained as a transparent amber glassy material (softening temperature 50-600) by
1) A mechanical crushing process is required to produce a product in the form of powder or granules, which is not a desirable form.

In addition, in C of the same example, it is described that compound (1) with a high melting point (119-1220) is obtained by recrystallization with hebutane from the reaction mixture after neutralization. ) is colored yellow and cannot be sold on the market.

Another description of Example C shows that when cyclohexane is used as the recrystallization solvent, a compound with a low melting point (80-90oo) (
Although it is described that 1) can be obtained, the product obtained by this method is also extremely colored and cannot be marketed.

In Example 1 of the specification of Tsubakiko Sho 42-190, after neutralizing the transesterification reaction mixture, 95% isopropanol was added to release a molecular addition compound of compound (1) and isopropanol, and then There is a statement that compound (1) with a melting point of 121 to 122°C is obtained by recrystallizing with heptane, but the compound obtained by this method (
1) is also colored yellow and cannot be marketed.

Furthermore, in Example 4 of the specification of Japanese Patent Publication No. 49-94644, methyl acrylate is slowly added to 2,6-di-t-butylphenol in the presence of an alkali catalyst at a high temperature of 100 to 104°C, while propionic acid is added. Acid methyl ester (0
), followed by a transesterification reaction with pentaerythritol without isolating the ester (0), and recrystallization from the neutralized reaction mixture with ethanol to obtain compound (1). However, the compound (1) obtained by this method has low purity and is colored yellow and cannot be marketed.

As mentioned above, the compound (1) obtained by the method disclosed in the prior art is glassy, yellow-colored, has low purity, or has poor powder properties. However, it cannot overcome the drawbacks of current commercially available products or replace them.

However, the present inventor discovered that 3-(3,
A step of transesterifying 5-di-t-butyl-4-hydroxyphenyl)propionic acid ester and pentaerythritol is carried out in the presence of a compound represented by the following formula (m), and then the transesterification reaction product is By adding an alcohol that forms a molecular addition compound with compound (1) to form a molecular addition compound, and recrystallizing with methanol or/and ethyl alcohol, a product that is purified and has good properties is obtained. Compound (1) as pongee grain
I discovered that it is possible to obtain

(In the formula, R2 and R3 are lower alkyl groups having 1 to 6 carbon atoms, respectively.) Furthermore, the present inventors have conducted detailed research on the compound (1) obtained by the above method, and found that A new crystal structure that has never been obtained (hereinafter sometimes referred to as 6 mice).

), and that the hexagonal compound (1) essentially has the following outstanding advantages as attributes, leading to the completion of the present invention. 1
It can be obtained as fine particles with good properties such as high bulk specific gravity and excellent fluidity.

Therefore, transportability and weighability are significantly improved compared to conventional products.

Furthermore, when obtaining the 6 crystals by the recrystallization method, separation from the mother liquor is extremely easy. 2. Compound (1) can be obtained as a purified and uncolored product.

3 Compound (1) can be recovered at a high yield through the recrystallization step.

Thus, according to the present invention, the diffraction pattern measured by X-rays (Cu-KQ), that is, the diffraction X-ray intensity at a diffraction angle of 2, shows the pattern shown in Table 1, particularly at a diffraction angle of 28:
Tetrakis [3-(3
, 5-di-tert-butyl-4-hydroxyphenyl)propionyloxymethyl]methane. Table 1 X-ray (Cu-Ko) The diffraction pattern in Table 1 was measured using the powder method, and the value of the diffraction angle 28 clearly satisfies the Bragg reflection condition, and is approximately ±0 in the measurement. Contains an error of .050.

The intensity of diffracted X-rays follows the counting method, and the diffraction angle is 20:1.
8.9? Table 1 shows the relative values when the strength at M.5 is 100, but it is inevitable that some errors will occur depending on the type of measuring bag, measuring operation, etc.
Figure 1 of the drawings shows the diffraction angle 2 of the 8-crystal compound (1) of the present invention.
A spectrum showing the relationship between 0 (axis) and the intensity of diffracted X-rays is shown.

The number of each peak corresponds to the number in Table 1. That is, Table 1
The value of the diffraction angle is determined as the value corresponding to each peak in Figure 1, and the relative intensity is determined using line a (dashed line), which is a straight line connecting two points on the 28:100 and 300 spectrum lines, as the reference line. , was determined by measuring the distance between the peak position of each number and the reference line.

Although Table 1 and FIG. 1 describe the range of the diffraction angle 28 from oo to 34o, diffraction X-rays can also be measured at diffraction angles of 340 or more.

However, the above range is sufficient to specify the hexagonal compound (1) of the present invention. The basic operations for X-ray diffraction using the powder method can be found in, for example, the "X
Line Crystallography" 5th edition.

The melting point of the hexagonal compound (1) of the present invention varies slightly depending on the measuring method, but is in the range of about 111 to about 110. According to the research of the present inventor, compound (1) has a property called polymorphism in terms of crystallography, and there are various stable or metastable crystal forms despite having the same chemical structural formula. It is. All of the crystal forms of compound (1) disclosed in the above-mentioned prior art documents are completely different from the crystal form of the present invention, and are any of the Q crystal, 3 crystal, and y crystal defined by the present inventors. These can be determined by measuring diffraction X-rays, melting points, etc., or even by measuring infrared absorption spectra.
It is clearly distinguished from crystal. The existence of the hexa-crystal compound (1) of the present invention cannot be predicted from the above-mentioned prior art documents, and it is also difficult to predict the excellent attributes of the hex-crystal compound (1). Here, the Q-crystal compound (1) has a diffraction X-ray spectrum shown in FIG. 2 when measured by the powder method described above.

The horizontal koji and vertical axis in Figure 2 are exactly the same as in Figure 1.
The spectrum of the Q crystal is completely different from that of the hexagonal crystal, and many peaks are observed. In particular, the diffraction angle 20 of the Q crystal is 50 to 100.
Two peaks that are not observed in the 6-crystal are observed in the range of
It is characteristic that it is not recognized by Akira. Also, the melting point is about 1
It has a melting point of 20 to 125o0, which is higher than that of hexagonal crystals.
Such Q-crystal compound (1) is disclosed in the above-mentioned Japanese Patent Publication No. 42-18
C of Example 2 of Publication No. 617 specification or Japanese Patent Publication No. 42-1
It can be obtained by the method described in Example 1 of Publication No. 9083, that is, by using hebutane as a recrystallization solvent.

However, the Q crystal compound (1) obtained by these methods is colored as described above and is not purified. Alternatively, an alcohol such as isopropanol is added to the transesterification reaction mixture to liberate a molecular addition compound with compound (1), and the molecular addition compound is recrystallized using ethanol instead of hebutane as a solvent. The present inventor has found that by carrying out this process, it is possible to obtain highly pure compound (1) without coloration as a Q crystal with a good rate, but in this case, it can only be obtained as a powder with low bulk specific gravity and poor fluidity. Can not. In other words, compound (1) as a Q crystal has the property that there is little loss due to recrystallization, that is, it can be obtained at a high yield,
It is difficult to satisfy both the requirements of powder having good properties and being refined and highly pure. Another crystalline form of compound (1), crystal 8, is identified by the diffraction X-ray spectrum shown in FIG. The axis and vertical axis in Figure 3 are exactly the same as in Figure 1. At first glance, it is clearly different from the hexagonal crystal of the present invention or from the crystal. Similar to the Q-crystal, the a-crystal has many more intense diffraction X-ray peaks than the hex-crystal. In particular, the diffraction angle 2a of the 8-crystal is in the range of 5o to 10.5o, and there are five peaks due to diffraction X-rays that are not observed in the 6-crystal. 1
ship. It is characteristic that the peak in 1) is not observed in the 8-crystal. The melting point of compound (1) of crystal 8 is approximately the same as that of compound (1) of crystal 6, and is about 112 to 115°C.

Such an 8-crystal compound (1) was produced in
As in the method described in Example 4 of the Specification of Publication No. 644, ethanol was directly added without adding isoprobanol or the like to the transesterification reaction mixture of propionic acid ester (b) and pentaerythritol to release the molecular adduct. However, the yield is poor.

Moreover, the 8-crystal compound (1) thus obtained is yellow in color. That is, the 8-crystal compound (1) cannot be obtained in good yield by the recrystallization method, nor can it be obtained even if it is purified. Y-crystal, which is another form of compound (1), is defined as having a melting point or softening point of 100 qC or less.

Such y-crystals can be produced by the method described in Example 2 a of the specification of the Fin Kosho No. 42-18617, or by the method described in Example 2
It is obtained by a method of recrystallizing c from cyclohexazo. In addition, an alcohol such as isopropanol is added to the transesterification reaction mixture to take out the molecular addition compound, and the amorphous compound (1) is obtained by heating under reduced pressure to about 6,000 ml to remove isopropanol. The obtained X-ray diffraction pattern is shown in FIG. This type of y-crystal compound (1) is glassy and requires a pulverization process to form a powder, and may be extremely colored.

To produce the hexagonal compound (1) of the present invention, the formula (1) is as follows:
) Tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane represented by general formula (0) is converted into 3-(3,5-di-t-butyl -4-Hydroxyphenyl)propionic acid alkyl ester and pentaerythritol are subjected to a transesterification reaction in the presence of the compound represented by the general formula (m), and then a molecular addition compound is formed with compound (1). This is accomplished by adding alcohols to the transesterification process product to form a molecular addition compound, followed by recrystallization from methanol or/and ethanol.

Performing the transesterification reaction step in the presence of compound (m) is an extremely important requirement for obtaining hexagonal compound (1).

The amount of compound (m) present is usually about 0.3 to about 2% by weight, preferably about 0.3% to about 1.0% by weight, based on propionate ester (0).

The presence of a large amount of compound (m) reduces the yield of compound (1), and the presence of a small amount of compound (m) makes it impossible to obtain compound (1) as hexagonal crystals. R2 or R of compound (D)
3 each represents a lower alkyl group having 1 to 6 carbon atoms, specifically, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a t-butyl group, a s-butyl group,
Examples include isobutyl group, bentyl group, hexyl group, etc., but industrially preferred are methyl group and ethyl group.

Monron R and R2 may be different alkyl groups. Although it is recommended that compound (m) be present from the beginning of the transesterification reaction, it may be added at an intermediate stage.

Further, R in the propionate ester (D) is a lower alkyl group, preferably a methyl group or an ethyl group.

Therefore, the propionic acid ester (0) is preferably the methyl ester of 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid, the ethyl ester, and mixtures thereof. The propionate ester may be used in a slightly excess stoichiometric amount relative to pentaerythritol, that is, about 4.2 to 4.4 parts by mole of the propionate may be used per 1 mole part of pentaerythritol. preferable.

In the transesterification reaction step, known catalysts are used as catalysts, specifically hydrides of alkali metals or alkali metals such as sodium hydride, calcium hydride, lithium hydride; lithium methoxide, sodium methoxide; Lower alkoxides of alkali metals such as potassium methoxide, lithium ethoxide, sodium ethoxide, potassium ethoxide, sodium t-butoxide, and potassium t-butoxide; other examples include sodium metal and potassium metal, among which alkaline metals The use of lower alkoxides is preferred.

It is sufficient to use such a catalyst in a conventionally known amount, usually 0.4 to 8 parts by weight, preferably 0.8 to 5 parts by weight, per 100 parts by weight of propionic acid ester (0).
Use parts by weight.

It is preferable to use a solvent in the transesterification reaction step. Solvents that can be used include dimethyl sulfoxide, dimethyl formamide, tetrahydrofuran,
Examples include dioxane, diglyme, dimethylacetamide, hexamethylphosphoamide, 1,2-dimethoxyethane, acetonitrile, propionitrile, t-butyl alcohol, among others, dimethylformamide and dimethylsulfoxide are preferably used. . The amount of solvent used is usually a maximum of 5 parts by weight per 1 part by weight of propionate (0), preferably 0.1 parts by weight.
None, 1 part by weight is used. The transesterification reaction essentially involves the reaction of the compounds of formulas (0) and (m) with pentaerythritol to produce R, OH, R20, R30.
It is carried out until the production of lower alcohols such as days is finished,
It is usually carried out at a temperature of 80 to 140 qo for 5 to 10 hours.

The produced alcohol is removed from the reaction system. The removal method may be any conventional means used in transesterification reactions, such as distillation under reduced pressure of 5 to 5 mHg. No special equipment is required, and any equipment can be used as long as it is equipped with a flywheel equipment, a heating equipment, or a reaction vessel equipped with the above-mentioned alcohol distillation equipment. The product from the transesterification step detailed above is subsequently subjected to the following steps.

That is, the product is first added with an alcohol that forms a molecular addition compound with compound (1) to form a molecular addition compound of compound (1) and the alcohol, and then recrystallized with ethanol or/and methanol. conduct. The series of operations adopted in this process is the hexa-crystalline compound (1).
This is an essential requirement for obtaining When the operation for forming a molecular addition compound is omitted and recrystallization is performed using ethanol or/and methanol, the compound is obtained as 8 crystals, and the yield is low and the compound is colored yellow. Moreover, when hexane or heptane is used as a recrystallization solvent, the obtained compound (1) is a Q crystal and is colored yellow. Preferred examples of the alcohols forming the molecular addition compound include lower alcohols having 3 to 4 carbon atoms such as n-pro/enol, isopro/enol, n-butanol, s-butanol, and isobutanol. Methanol and ethanol do not form molecular adducts. Such alcohols usually contain about 100% to about 1% per 100% of compound (1) present in the transesterification process product.
000, preferably without 300, or above 600 and uniformly dissolved at a temperature of about 70 oo or higher.

Note that the solubility varies depending on the type of alcohol, so the dissolution temperature is appropriately selected depending on the type of alcohol. Upon subsequent cooling, a molecular addition compound begins to precipitate at a temperature of about 55 to about 8 pi, depending on the type of alcohol, and is further cooled to complete precipitation, after which it is separated by filtration. If necessary, a ripening operation may be performed at a temperature of 55 to 80°C. The separated molecular addition compound is subjected to a recrystallization method using methanol or ethanol as a recrystallization solvent to obtain compound (1) as hexagonal crystals.

Note that the molecular addition compound may be heated under reduced pressure to once remove alcohols, and then a recrystallization operation may be performed.The methanol and/or ethanol used does not need to be completely purified. For example, commercially available ethanol, which contains about 4% water by weight, can be used and yields highly desirable fine granules.Methanol and/or ethanol usually contain from about 100 to about
After heating to make a homogeneous solution, complete precipitation of compound (1) by cooling to room temperature or below room temperature. Compound (1) is obtained.

Note that the above purification step is usually performed after neutralizing the alkali catalyst contained in the product of the transesterification step.

It is recommended that the operation for removing the salt produced by neutralization be performed before and after the step of producing the molecular addition compound. The acid used for neutralization is a carboxylic acid such as acetic acid, or another organic sulfonic acid, and is used in an amount equivalent to that of the alkali catalyst. The hexagonal compound (1) produced in the above recrystallization step is pongee grains with good properties, and can be separated from the mother liquor very easily.

After separation from the mother liquor, it is dried to obtain a hexacrystalline compound (1) as a product. Hexagonal compound of the present invention (1)
is a refined white string grain with excellent properties such as a high transverse specific gravity reaching about 0.6 and high fluidity, and is significantly superior to the secondary product.

Furthermore, its function as an antioxidant is equivalent to or better than that of conventional products.

Examples will be specifically described below.

Example 1 50 equipped with a rope strainer, reflux condenser, thermometer, and nitrogen inlet pipe
0 [50 Z of dimethylformamide in 40 flasks,
Potassium t-ptoxide 2.83 times, methyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (compound (2)) 124.0 times, bentaerythritol 13.12 times and R2 and R in the compound (prisoner)
Add 0.62% of a compound in which 3 is a methyl group (0.5% by weight based on compound (0)), heat at 870°C for 10 minutes, and then heat at 90qo/3cmHg for 1 hour to form a The resulting methanol was distilled off.

The mixture was then maintained at 100% and 140qo/2% Hg for 6 hours to distill off small amounts of methanol and dimethylformamide and complete the transesterification reaction. After cooling the reaction product to 120 qo, nitrogen gas was introduced to return it to atmospheric pressure, neutralize it by adding 1.7 g of glacial acetic acid, dissolve it by adding 350 g of benzene, and wash and desalt with hot water. did.

Next, benzene was distilled off, 50 pieces of isopropanol was added to the obtained yellow glassy substance, and the mixture was heated and dissolved to 75 qo, and then cooled to room temperature to precipitate a molecular addition compound.
It was filtered and washed with 200 g of isopropanol. After removing isopropanol adhering to the molecular addition compound by drying it in a 45qo vacuum dryer, 350°C of ethanol (water content: about 4% by weight) was added and heated to 70°C to homogenize. After making a solution, the resulting crystals were cooled to room temperature and separated in a furnace and dried to obtain Compound (1) as a fine white powder (yield: 100%). This is a high yield of 95% based on compound (1) contained in the transesterification product. This compound (
1) was confirmed to be a hexagonal crystal by X-ray diffraction. The melting point measured using a microscope-attached melting point measuring device was about 112-114°C. Further, analysis by liquid chromatography showed that the purity was about 99%. Next, 10 parts of compound (1) were dissolved in toluene to prepare exactly 100 solutions, and the transmittance of the solution was measured using 425 visible light beams using a cell in 1. %Met.

In addition, the high specific gravity and falling speed of the powder were measured.

Incidentally, the falling speed was measured according to the following method. That is,
In FIG. 5 of the attached drawings, a sample 200' was charged into a hopper consisting of a hollow cylindrical portion 18 and a vice principal-shaped conical portion 19, and the number of seconds for the entire amount to flow out was measured, and the number of seconds was taken as the falling speed. A large number of seconds indicates poor fluidity. The diameter of the sample outlet (conical head) 20 is 8 sails, the diameter of the cylindrical part 18 is 83 ribs, and the joint part 2 between the conical part and the cylindrical part.
1 and the sample outlet 20 was 65 kites. The above results are listed in Table 2 along with other examples.

Comparative Example 1 The same operations as in Example 1 were performed except that compound (m) was not added at all. The results are listed in Table 2. Comparative Example 2 The same operation as in Example 1 was performed except that hexane (Comparative Example 2) was used as the recrystallization solvent, and a yellow colored compound (1) was obtained.

Other results are shown in Table 2. Comparative Example 3 The same procedure as in Comparative Example 1 was performed except that hebutane was used as the recrystallization solvent, and a yellow colored compound (
1) was obtained.

Other results are shown in Table 2. Comparative Example 4 The step of adding isopropanol to precipitate a molecular addition compound in Comparative Example 1 was omitted, and the yellow glassy material after benzene was removed was recrystallized with ethanol.

Even if the ethanol solution is cooled to room temperature, only a small amount of the compound (
Since 1) did not precipitate, the precipitated compound was separated by furnace after being left in an atmosphere at 5° C. for 1 hour. Table 2 shows the yield, properties of the obtained compound (1), and others. Comparative example
5 The same operations as in Comparative Example 4 were performed except that the transesterification reaction was carried out without adding any compound (m).

The results are shown in Table 2. Comparative Example 6 In Comparative Example 5, cyclohexane was used instead of ethanol as the recrystallization solvent.

However, only a small amount of compound (1) was precipitated even after being left in an atmosphere at 5°C for one hour, so it was left in an atmosphere at 5°C for an additional week. Other operations were performed in the same manner as in Comparative Example 5. The results are shown in Table 2. Comparative Example 7 Commercially available Compound (1) (Irganox 1010, manufactured by Ciba-Geigy) was measured by X-ray diffraction and was found to be a mixture of Q crystal and 8 crystal.

The properties of this powder as a powder and the transmittance of visible light were measured.

High specific gravity had poor reproducibility and varied between 0.04 and 0.39. Other results are also listed in Table 2. Ship (Fujie Koi Naka Sato Nuclear ``≦ Do.

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[Brief explanation of the drawing]

Figure 1 shows the novel crystalline form (6 crystals) of compound (1) of the present invention.
This is the X-ray diffraction pattern of FIG. 2, FIG. 3, and FIG. 4 are X-ray diffraction patterns of compound (1) of Q crystal, 8 crystal, and SO crystal, respectively. FIG. 5 is a conceptual diagram of an apparatus used to test the fluidity of powder in Examples and Comparative Examples. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1 Tetrakis [3-(3 ,5-G-
t-Butyl-4-hydroxyphenyl)propionyloxymethyl]methane.