JP2736265B2 - Method for producing α-crystal tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane having excellent powder properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is useful as an excellent antioxidant for polyolefins and the like, and has novel powder characteristics of α-crystal tetrakis [3- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane.

[Conventional technology]

Currently commercially available tetrakis [3- (3,5-di-t
The product of -butyl-4-hydroxyphenyl) propionyloxymethyl] methane is a fine powder and has poor powder properties such as (1) low bulk specific gravity and poor fluidity, and (2) easy scattering during handling. There is a problem in correctness, weighability and work environment, and improvement thereof is desired. Tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane has a property called polymorphism in crystallography. There are no or metastable crystals, and several crystal forms defined by α-crystal, β-crystal, γ-crystal, δ-crystal and the like have been known.

Among them, the α-crystal belongs to the stable crystallization, and
No. 617, No. 42-19083, JP-A-60-156645, etc., ie, recrystallization from n-heptane, n-hexane, methanol or the like.

However, as a result of detailed follow-up tests by the present inventors,
In recrystallization from n-heptane and n-hexane, (1)
Recrystallization yield is good, but purification effect is small, that is,
There are problems such as the inability to obtain a high-purity product, and (2) poor powder characteristics in the form of powder. In addition, recrystallization from methanol provides (1) a good purification effect and high purity. However, there are problems such as a poor recrystallization yield and (2) poor powder characteristics due to fine powder, and it cannot be a desired product at present.

In order to improve the above-mentioned disadvantages, (1) JP-B-60-1301
Nos. 7 and 60-13018 disclose a method of improving the drawbacks of α-crystals and commercially available β-crystals by converting them into δ-crystals, which are metastable, and (2) JP-A-62-258343. In the gazette, a method has been proposed in which a crystal form is a metastable β crystal, but recrystallized under specific conditions to obtain a crystal expressed as an independent particulate crystal.

However, these methods require (a) the addition of β- (3,5-di-t-butyl-4-hydroxybenzyl) glutaric acid diester during the transesterification reaction, and (ii) tetrakis [3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionyloxymethyl]
It is necessary to isolate the molecular adduct of methane and isopropanol, so that the isolation and purification are duplicated. (C) The starting material 3- (3,5-di-t-butyl-4-hydroxy) is recrystallized and purified. This is not an economical or industrial method, since it is necessary to contain a phenyl) propionic acid methyl ester and a tris-substituted intermediate which has not been reacted.

[Problems to be solved by the invention]

The present invention belongs to a stable crystal structure, and has high purity, excellent powder properties and good fluidity, and has good fluidity, α-tetrakis [3- (3,5-di-
[tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane.

[Means for solving the problem]

The present inventors have conducted intensive studies on the α-crystal of tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane, and as a result, the particle shape is different from that of the known α-crystal. In the present invention, α-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane having high stability and excellent powder properties and excellent fluidity is obtained with high purity. Has been reached.

That is, the present invention relates to tetrakis [3- (3,5-di-t
-Butyl-4-hydroxyphenyl) propionyloxymethyl] methane is excellent in powder characteristics characterized by being crystallized from a mixed solvent of methanol or hydrated methanol and a small amount of an aliphatic saturated hydrocarbon having 6 to 10 carbon atoms. Was α
The present invention relates to a method for producing crystalline tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane.

Tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane is the same as methyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate. It is produced by subjecting pentaerythritol to a transesterification reaction. Moreover, it is also possible to use a commercial item. When using transesterification reactants, the content may be 85-98%.

The water content in hydrated methanol as a recrystallization solvent is 1 to 15% by weight based on methanol. Examples of the aliphatic saturated hydrocarbon solvent having 6 to 10 carbon atoms include n-hexane, n-heptane, and isopar (trade name of Eccrine Chemical).
The mixing ratio of the hydrocarbon solvent to methanol or hydrated methanol is preferably 2 to 5% by weight. The crystallization is performed by cooling or cooling from about 60 ° C. to about 20 ° C.

[Action]

Tetrakis [3- (3,5-di-) obtained by the present invention
[t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane is the X-ray (Cu-K) shown in FIG.
α) From the diffraction and the melting point, the crystal structure is judged to be the crystal structure of α crystal. The bulk specific gravity is as large as 0.50 to 0.55, and as shown in the micrograph showing the crystal structure in FIG. It can be seen that the particle form is clearly distinguished from the crystal.

Since the main solvent at the time of crystallization is methanol, it is purified with high purity, narrow in the particle size distribution, and the target substance with a large bulk specific gravity is obtained. It greatly contributes to improvement in operability and work environment, and is easy to manufacture.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited thereto.

Example 1 3- (3,5-di-tert-butyl-) was placed in a 1-volume 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer and a pressure-reducing valve.
479.5 g of methyl 4-hydroxyphenyl) propionate,
54.5 g of pentaerythritol and 0.25 g of dibutyltin oxide were added, and the mixture was reacted at 195 ° C. under atmospheric pressure for 2 hours, and methanol as a by-product was distilled off. Subsequently, the reaction was carried out at 195 ° C. under a reduced pressure of 40 mmHg for 2 hours and further at 195 ° C. under a reduced pressure of 2 to 5 mmHg for 12 hours, and methanol produced as a by-product was distilled off to complete the reaction.
The weight of the reaction product after returning to atmospheric pressure with nitrogen was 483 g, and as a result of HPLC analysis, the target substance, tetrakis [3- (3,5-di-
[tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane.

The above reaction product (150 g) was charged into a 500 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel, and heated in an oil bath to an internal temperature of 125 ° C. to completely melt the reaction product.

While stirring this melt, 63 g of methanol and Isopar E4.
5 g of the mixture was added dropwise under reflux for about 15 minutes. The internal temperature became about 65 ° C., and the internal solution became a clear solution.

Separately, 92.5% methanol water 126 was added to a 500 ml four-necked flask equipped with a stirrer, reflux condenser, thermometer and dropping funnel.
g and a small amount of α-crystal as a seed crystal. Under stirring, the above methanol solution of tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane was added. After the addition, the internal temperature was maintained at about 40 ° C. for 1 hour, and then 11 g of water was added dropwise, and the temperature was maintained at that temperature for 1 hour. After that, 11.5 g of water is further dropped, and the internal temperature is 55-60 ° C.
For 10 hours.

Thereafter, the mixture was allowed to cool to an internal temperature of 20 ° C., and then subjected to solid-liquid separation, followed by drying to obtain 135 g of white crystals having good fluidity.

The melting point of this crystal was 121.5 to 124 ° C., and it was confirmed from the X-ray diffraction spectrum that it was an α-crystal. The properties of the obtained crystals are shown in Table 1 in comparison with the commercially available products and the α crystals obtained by the additional test of the conventional method.

Example 2 Commercially available tetrakis [3- (3,5-di-t-butyl-4)
As shown in FIG. 2, the product of -hydroxyphenyl) propionyloxymethyl] methane has a β crystal structure from the X-ray diffraction spectrum, and has a melting point of 112 to 114 ° C., and the crystal shape shows the crystal structure of FIG. It is a fine powder as shown in the micrograph.

The procedure was the same except that tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane used in Example 1 was changed to the above-mentioned commercially available fine powder product. Good white crystals 14
2 g were obtained. The melting point of this crystal was 122 to 124 ° C., and it was confirmed from the X-ray diffraction spectrum (FIG. 3) that it was an α crystal. Table 1 shows the properties of the obtained crystals.

Example 3 The procedure of Example 1 was repeated except that n-heptane was used instead of Isopar E. As a result, 134 g of white crystals were obtained.

The melting point of this crystal was 122 to 124 ° C., and it was confirmed from the X-ray diffraction spectrum that it was an α-crystal. The properties of the obtained crystals are shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated except that Isopar E was not added. As a result, 137 g of white powdery crystals were obtained.

The melting point of this crystal was 121.5 to 124 ° C., and it was confirmed from the X-ray diffraction spectrum (FIG. 5) that it was an α-crystal. The properties of the obtained crystals are shown in Table 1.

Comparative Example 2 The procedure of Example 2 was repeated except that Isobar E was not added, and as a result, 139 g of white powdery crystals were obtained.

The melting point of this crystal was 122 to 124 ° C., and it was confirmed from the X-ray diffraction spectrum that it was an α crystal. The properties of the obtained crystals are shown in Table 1.

Example 4 Tetrakis [3- (3,5-di-t) obtained in Example 1
The mechanical strength of the crystal particles of [-butyl-4-hydroxyphenyl) propionyloxymethyl] methane was tested by the shaking method.

100 g of a sample is placed in a 1000 ml flask and shaken for 7 hours.
Table 2 shows the particle size distribution before and after shaking.

Since the particle size distribution before and after shaking hardly changes, it can be seen that the mechanical strength of the crystal particles is high.

[Effects of the Invention] According to the method of the present invention, a novel α-crystal tetrakis [3- (3) which is highly purified, has a narrow particle size distribution and a large bulk specific gravity of 0.50 to 0.55, that is, has excellent powder properties. , 5-Di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane is produced industrially.

[Brief description of the drawings]

FIG. 1 shows the X-ray diffraction spectrum of the compound of the present invention obtained in Example 1, FIG. 2 shows the X-ray diffraction spectrum of the commercial product used in Example 2, and FIG. FIG. 4 shows an X-ray diffraction spectrum of the compound of the present invention, and FIG. 4 is a micrograph showing the crystal structure of α-crystal obtained by the present invention.
FIG. 5 is a micrograph showing the crystal structure of the α-crystal obtained by the conventional method, FIG. 6 is a micrograph showing the crystal structure of a commercially available product, and FIG. 7 is a diagram showing a hopper used for measuring the falling velocity. It is.

Claims (3)

(57) [Claims] 1. A method for preparing tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane from methanol or water-containing methanol, and a small amount of a saturated aliphatic hydrocarbon having 6 to 10 carbon atoms. A process for producing α-crystal tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane having excellent powder characteristics, characterized by crystallization from a mixed solvent of 2. The method according to claim 1, wherein the water content in the hydrated methanol is 1 to 15% by weight based on the methanol. 3. The method according to claim 1, wherein the amount of the aliphatic saturated hydrocarbon having 6 to 10 carbon atoms is 2 to 5% by weight based on methanol or hydrated methanol.