JPH06206717A - Method for separating and purifying high order fullerene - Google Patents

Abstract

PURPOSE:To improve the solubility of the high order fullerene in an eluent and improve the separation of the high order fullerene by using a specific separation column and also using pyridine as the eluent in a liquid chromatography. CONSTITUTION:A separation column filled with the granules of a porous styrene- divinylbenzene copolymer is used, and pyridine or a solvent mixture containing the pyridine is used as an eluent. The solvent mixed with the pyridine includes tetrahydrofuran, dioxane, acetone, chloroform, methylene dichloride, carbon tetrachloride, carbon disulfide, benzene, toluene, ethyl acetate, dimethyl formaldehyde, and quinoline. Especially, tetrahydrofuran is preferable.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for separating and purifying higher fullerenes useful as a novel functional material.

[0002]

BACKGROUND OF THE INVENTION Fullerene, which is a cage compound consisting of only carbon atoms, has attracted attention as a new functional material since its mass production method was announced in 1990, and various studies have been conducted. Generally, these fullerenes have 10
It is obtained by arc-discharging a graphite electrode in helium gas at a pressure of about 0 Torr to generate soot, and then solvent-extracting the soot using benzene or toluene. Since the solvent extract is a mixture of fullerenes such as C ₆₀ and C ₇₀ , it is usually used for various studies after separating and purifying each component.

Up to now, research has been conducted centering on C ₆₀ , which is a spherical molecule which is the most abundant fullerene and which is easy to separate and purify, and is useful for conductivity, superconductivity, photoconductivity, magnetism and the like. It has been found to have various properties. Also, C
_{70, C 76, C 78,} C 82, C 84, C 90, various higher fullerenes carbon number of C ₉₆ or the like is found, there is a growing expectations for their applications. In such a situation, it is essential to obtain a sufficient amount of a single substance in order to further study the properties of these higher fullerenes or to utilize these fullerenes.

Conventionally, C ₆₀ and C ₇₀ are separated and purified by a method of flowing a developing solution consisting of n-hexane in column chromatography using neutral alumina (J. Phys. Chem., 94,
8630-8633 (1990).) Or a method of flowing an eluent composed of benzene in liquid chromatography using a polystyrene gel permeation chromatography (GPC) separation column (Chem. Letters, 1607-1610 (1991).), Etc. Is done by.

For higher fullerenes of C ₇₀ or more, separation and purification by liquid chromatography using a polystyrene-based separation column for GPC has been studied. When benzene was used as the eluent, the solubility of higher-order fullerenes in benzene was low and the separation of higher-order fullerenes was insufficient, so that it was unsuitable for separation and purification of higher-order fullerenes. Therefore, instead of benzene, carbon disulfide, which has a high solubility for higher fullerenes, is used, and C
It became possible to separate and purify higher fullerenes up to about ₁₀₀ (Chem. Phys. Letters, 188, 177-180 (1992).). However, in this method, since the separability is extremely poor, the separation must be repeated many times, and carbon disulfide as an eluent has a problem that it is highly corrosive to metals and rubber.

In addition to the above, a liquid chromatographic measurement using n-hexane as an eluent was carried out using a silica gel-based separation column for reversed-phase chromatography for the purpose of analyzing the composition of a solvent extract of fullerene-containing soot. But
Since the solubility of higher-order fullerenes in n-hexane is extremely low, it was difficult to apply them to separation and purification of higher-order fullerenes.

On the other hand, when extracting fullerenes from soot of fullerenes, it was discovered that fullerenes of C _{100 to} C ₃₀₀ can be extracted by using pyridine or quinoline (J. Phys. Chem., 95, 8449-8451 ( 1992).), It was revealed that these solvents have a high ability to dissolve higher fullerenes.

In liquid chromatography using a separation column packed with porous styrene-divinylbenzene copolymer particles, a method using quinoline as an eluent is known as an analysis method for tar, pitch, etc. Since the separation property of higher fullerenes was extremely poor, it was unsuitable as a method for separating and purifying them.

As an example of using pyridine as an eluent for liquid chromatography, an example of using pyridine as one of a series of eluents used for fractional separation of liquefied coal by silica gel column chromatography (USPatent 41274)
No. 75) can be mentioned, but it is inappropriate to apply this method to high-order fullerenes because high-order fullerenes are easily adsorbed on silica gel.

[0010]

As described above, the conventionally known method for separating and purifying fullerenes by liquid chromatography has a problem that the solubility of higher fullerenes in a solvent used as an eluent is low. In addition, even in the method using a solvent having a high ability to dissolve higher-order fullerenes, there are problems such as extremely poor separability or high corrosiveness of the solvent. Was not suitable for separation and purification. Further, with these conventional methods, it was impossible to separate and purify C ₁₀₀ or more fullerenes extracted from pyridine-containing soot with pyridine. Therefore, an object of the present invention is to develop a method for separating and purifying higher fullerenes without the above problems.

[0011]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has found that a specific separation column is used in liquid chromatography and pyridine or a mixed solvent containing pyridine is used as an eluent. , Found that the eluent dissolves high-order fullerenes well and that high-order fullerenes can be separated well in GPC mode.
The present invention has been completed.

That is, the present invention uses a separation column packed with porous styrene-divinylbenzene copolymer particles,
The present invention also provides a method for separating and purifying higher fullerenes by liquid chromatography, which is characterized in that pyridine or a mixed solvent containing pyridine is used as an eluent.

The present invention will be described in detail below. The separation column used in the present invention is a hollow column made of a material such as stainless steel filled with porous styrene-divinylbenzene copolymer particles produced by a known method from divinylbenzene and a styrene monomer. Is. The copolymerization composition of the porous styrene-divinylbenzene copolymer, the pores of the copolymer particles, or the size of the separation column may be appropriately determined according to the purpose and is not particularly limited.

In the present invention, pyridine or a mixed solvent containing pyridine is used as an eluent. Specific examples of the solvent mixed with pyridine include tetrahydrofuran, dioxane, acetone, chloroform, methylene chloride, carbon tetrachloride, carbon disulfide, benzene, toluene, o-dichlorobenzene, ethyl acetate, dimethylformamide, quinoline and the like. However, one kind is usually used from these, but two or more kinds may be used. Tetrahydrofuran is particularly preferred among these solvents.

The pyridine content in the mixed solvent is not necessarily limited to a specific value, but is usually 50 to 10
The range of 0% (volume ratio) is preferable. When the content of pyridine is increased, the separability of each component is slightly lowered, but the solubility of higher fullerenes is improved, so that the content can be selected according to the kind of the component to be separated, its purity or amount, and the like.

In the present invention, when pyridine is used as an eluent, it is preferable to carry out the separation at a temperature of room temperature to 100 ° C. When a mixed solvent containing pyridine is used, the separation temperature varies depending on the mixed solvent. However, when a pyridine-tetrahydrofuran mixed solvent is used as an eluent, the separation is preferably performed at room temperature to 60 ° C.

In the method for separating and purifying high-order fullerenes of the present invention, the use of pyridine in all or part of the eluent increases the solubility of higher-order fullerenes of C ₇₀ or higher, so that the separation of such higher-order fullerenes is increased. The mode is a GPC (gel permeation chromatography) mode in which the modes are separated according to the difference in molecular weight, and the separability is significantly improved. Therefore, higher fullerenes can be efficiently separated and purified with a small amount of solvent and in a short time. That is, the present invention is a very effective method for separating and purifying higher-order C ₇₀ or higher fullerenes including C ₁₀₀ to C ₃₀₀ fullerenes from fullerene-containing soot.

[0018]

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these.

Comparative Example 1 A fullerene-containing extract obtained by toluene extraction from soot obtained by arc-discharging a graphite electrode with a direct current of 200 A in 100 torr helium gas by a known method was used as a separation source. Separation column Shodex
Separation column for preparative packing (column inner diameter 50 mm, column, filled with porous styrene-divinylbenzene copolymer particles, which is a packing material for GPC K-2001 and K-2002 (both are trade names of Showa Denko KK) 700 mm long)
A preparative liquid chromatograph, Shodex AUTOPREP-50 (trade name, manufactured by Showa Denko K.K.), in which two tubes are attached in series, is used to separate toluene at room temperature for eluent, and a higher fullerene of C ₇₀ or more is obtained. A high-order fullerene sample containing a large amount of was prepared. This sample 1
mg was dissolved in 10 ml of an eluent having the following composition to prepare a sample solution, and separation was performed under the following conditions. As a detector, a UV detector Shodex UV-41 (trade name, manufactured by Showa Denko KK) was used. Measurement Conditions Separation Column: Porous Styrene-Divinylbenzene Copolymer Particle Packing Column Shodex GPC KF
-802 (column inner diameter 8 mm, column length 300 mm)
(Showa Denko K.K.) Two columns are connected in series Column temperature: 35 ° C Eluent: Toluene Eluent flow rate: 0.5 ml / min Detection wavelength: 330 nm Sample injection amount: 20 μl The obtained chromatogram is a diagram It was as shown in 1. As shown in this figure, the components exceeding C ₇₀ were hardly separated. The outflow order of each component is
The order is C ₆₀ , C ₇₀ , and higher fullerenes, and the separation mode under this separation condition is not the GPC mode but the distribution adsorption mode.

Example 1 Instead of the eluent used in Comparative Example 1, an eluent having the following composition was used, and 1 mg of the same sample used in Comparative Example 1 was dissolved in 1 ml of the eluent to prepare a sample solution. Separation was performed under the same separation conditions as in Comparative Example 1 except that the flow rate of the eluent was changed as follows. Eluent: pyridine + tetrahydrofuran mixed solvent (mixing ratio = 50: 50 (volume ratio)) Eluent flow rate: 1.0 ml / min The obtained chromatogram was as shown in FIG. As shown in this figure, the components of C ₇₆ or higher flowed out before C ₆₀ and in descending order of molecular weight. Moreover, the separability of each component was good.

Example 2 Separation was performed under the same separation conditions as in Example 1 except that the eluent having the following composition was used instead of the eluent used in Example 1. Eluent: pyridine + tetrahydrofuran mixed solvent (mixing ratio = 75: 25 (volume ratio)) The obtained chromatogram was as shown in FIG. As shown in this figure, the peak intensity was increased and the solubility in higher fullerenes of C ₇₆ or higher was improved.

Example 3 Instead of the eluent used in Comparative Example 1, an eluent having the following composition was used, and 10 mg of the same sample as that used in Comparative Example 1 was used.
Was dissolved in 1 ml of an eluent to give a sample solution, and separation was performed under the same separation conditions as in Comparative Example 1 except that the flow rate of the eluent was changed as follows. Eluent: Pyridine Eluent flow rate: 0.8 ml / min The obtained chromatogram was as shown in FIG. As shown in this figure, the sample throughput is 1 as compared with the second embodiment.
Although it was 0 times, the separability of each component of the higher fullerene was good.

Example 4 Separation was carried out under the same separation conditions as in Example 1 except that the following separation column was used instead of the separation column used in Example 1. Separation column: Porous styrene-divinylbenzene-based copolymer particle packing column Shodex GPC KF
-801 and KF-802 (both column inner diameter 8
mm, column length 300 mm) (Showa Denko KK product name) are connected in series. The obtained chromatogram is as shown in FIG. 5, and the separability of each component is as good as in the case of Example 1. there were.

Example 5 Separation was carried out under the same separation conditions as in Example 1 except that the following separation column was used instead of the separation column used in Example 1. Separation column: Porous styrene-divinylbenzene-based copolymer particle packing column Shodex GPC KF
-802 and KF-803 (both column inner diameter 8
mm, column length 300 mm) (trade name of Showa Denko KK) are connected in series. The obtained chromatogram is as shown in FIG. 6, and the separability of each component is as good as in Example 1. there were.

[0025]

According to the method for separating and purifying high-order fullerenes of the present invention, since the high-order fullerenes having a C _{70 or} higher solubility in the eluent to be used are highly soluble and the respective components can be separated easily, Can be efficiently separated and purified with a small amount of solvent and in a short time. Since the eluent used in the present invention has low corrosiveness, it can be used for separation and purification of high-order fullerenes on an industrial scale.

[Brief description of drawings]

FIG. 1 is a chromatogram showing the results of Comparative Example 1.

FIG. 2 is a chromatogram showing the results of Example 1.

FIG. 3 is a chromatogram showing the results of Example 2.

FIG. 4 is a chromatogram showing the results of Example 3.

5 is a chromatogram showing the results of Example 4. FIG.

FIG. 6 is a chromatogram showing the results of Example 5.

[Explanation of symbols]

1 Unidentified fullerene peak 2 C ₈₄ peak 3 C ₇₈ peak 4 C ₇₆ peak 5 C ₆₀ peak 6 C ₇₀ peak

Claims (1)

[Claims] 1. A high-order fullerene by liquid chromatography, characterized by using a separation column packed with porous styrene-divinylbenzene copolymer particles and using pyridine or a mixed solvent containing pyridine as an eluent. Separation and purification method.