JPH08201366A - Filler for liquid chromatography - Google Patents

Abstract

PURPOSE: To suppress a water swelling property and satisfactorily split an optical isomer by substantially substituting the inter-layer ions of a clay mineral with optically active cations, and applying hydrophobic treatment to the surface with a silane finishing agent to form a filler. CONSTITUTION: The inter-layer exchangeable ions of a spherical clay mineral are substituted with optically active cations, then surface treatment is applied with a silane finishing agent to obtain a filler. A metal complex, an organic metal, or tetra-ammonium is used for the optically active cations. The metal complex is optically split easily by itself, it is hardly applied with racemization, and it is preferable for use. An organic compound containing nickel or chromium as a metal atom, 1, 10-phenanthroline or amine acid as a ligand, and two or more portions to be coordinate-linked with the metal is used for the metal complex. For the surface treatment, a silane compound is dissolved alone, for example, or it is dissolved in an organic solvent, the spherical clay mineral is dispersed in this solution, it is kept stationary at 10-180 deg.C for 10-150hr, it is filtered and washed by a solvent, then it is dried.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a packing material for liquid chromatography, and more particularly to an improvement of the packing material for separating optically active substances.

[0002]

2. Description of the Related Art With the refinement of research and development, the importance of handling optically active substances in the fields of pharmaceuticals, agricultural chemicals, fragrances, seasonings, feeds, electronics, etc. has been remarkably increased.
Therefore, the need for optical resolution of chiral compounds has increased more and more in recent years. Among the optical resolution methods, the liquid chromatography method can be used to confirm the purity (analysis) and obtain (preparative purification) of the optically active substance. Therefore, at present, the development of column packing materials for the separation of optical isomers It is being actively conducted.

As a column packing material for separating optical isomers, a packing material in which an optically active synthetic molecule, a natural polymer or a derivative thereof is adsorbed or chemically bonded to silica gel or an organic polymer powder is used. Further, a filler in which an optically active ion is supported on a clay mineral is also used.

[0004]

By the way, when a sample dissolved in water or a water-containing organic solvent, such as a biological sample, is optically resolved, or when it is used in combination with a column using a water-containing organic solvent mobile phase, Alternatively, in the case of optically resolving a sample that cannot be optically resolved because it is not retained by an organic solvent, a filler having high water resistance and capable of using a water-containing organic solvent mobile phase is required. However, most of the above-mentioned conventional fillers are fillers using an organic solvent as a mobile phase, and when water is mixed in the mobile phase, the optically active molecules in the filler are eluted and deteriorated.

On the other hand, a filler in which the interlayer ions of the spherical clay mineral are substantially replaced by optically active cations (Japanese Patent Application Laid-Open No. 1-21).
02658) is a filler having a wide range of optical resolution by using an organic solvent mobile phase such as methanol. However, when a water-containing organic solvent-based mobile phase is used, the filler immediately swells, which is also problematic in durability.

In order to modify the clay mineral to suppress water swelling,
There are methods of performing ion exchange with polyvalent metal ions, firing of clay minerals (JP-A-1-199155), and surface treatment. Those whose ion-exchange ability with polyvalent metal ions or whose swelling property is suppressed by firing have lost their ion-exchange ability and cannot support optically active ions. Although there are many surface treatment methods, there is almost no treatment method for suppressing water swelling of clay minerals, and a treatment method with a silicone compound (JP-A-63-
Only 113082) was effective. However, the clay mineral obtained by this method also lacks the ion-exchange ability, and cannot support an optically active ion. In addition, the filler treated with this silicone compound after supporting the optically active ions was confirmed to have optical resolution because the contact between the optically active cation and the sample for optical resolution was cut off by the silicone coating. There wasn't.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide a packing material for liquid chromatography which can be used even in a water-containing organic solvent and has excellent optical resolution. .

[0008]

Means for Solving the Problems As a result of intensive studies by the present inventors in order to achieve the above object, as a result of substantially substituting the interlayer ion of the surface-treated clay mineral with an optically active cation, The inventors have found that they are ion-exchangeable and can suppress water swelling, and have completed the present invention.

That is, the packing material for liquid chromatography according to the present invention is characterized in that the interlayer ion of the clay mineral is substantially replaced with an optically active cation, and the surface is made of a clay mineral having a hydrophobic treatment. Further, in the present invention, it is preferable that the hydrophobizing treatment is performed with a silanizing agent.

In the present invention, the silanizing agent is preferably represented by the following formula (2).

Embedded image R _4-n SiX _n n = 1,2,3 (R: a hydrocarbon group having 1 to 32 carbon atoms, or some or all of the hydrogen atoms thereof are substituted with fluorine atoms) However, those having a carbon number of 1 and n = 1 are excluded.X: an alkoxy group, a hydrogen atom, a hydroxyl group, a phenoxy group,
Alternatively, it is a diethylamino group. )

The structure of the present invention will be described in more detail below. The spherical clay mineral preferably used in the present invention is
For example, those disclosed in JP-A-1-202658 can be used. What is used for analytical packing material is
It is preferable that the particles are classified to have an average particle diameter of about 5 μm.

The surface treatment agent used in the present invention is
A silanating agent may be used, but a silanizing agent represented by the following chemical formula 3 is particularly preferable.

Embedded image R _4-n SiX _n n = 1,2,3 (R: a hydrocarbon group having 1 to 32 carbon atoms,
Some or all of the hydrogen atoms are replaced with fluorine atoms. However, those having 1 carbon atom and n = 1 are excluded. X: alkoxy group, hydrogen atom, hydroxyl group, phenoxy group,
It is a diethylamino group. )

As an example of this silanizing agent, 3,3,3-
Trifluoropropylmethoxysilane, n-octadecyltriethoxysilane, n-octadecyltrimethoxysilane, n-octadecylsilane, n-octylmethyldimethoxysilane, n-octylsilane, n-octyltriethoxysilane, n-butyltrimethoxysilane ,
Examples thereof include n-propyltrimethoxysilane, ethyltriethoxysilane, ethyltrimethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane, and n-octadecyldimethylmethoxysilane.

Examples of the optically active cation used in the present filler include optically active metal complexes, organic metals, and quaternary ammonium. Among them, metal complexes are particularly preferable. The metal complex is composed of a metal atom and a ligand, and may be any cation that is inactive to the substitution of the ligand. Among them, an optically active metal complex based on a coordination structure can be suitably used because it is easy to optically resolve itself and is unlikely to undergo racemization. Examples thereof include metal atoms such as nickel, osmium, ruthenium, platinum, cobalt, iron, copper and chromium, and ligands such as 1,10-phenanthroline, 2,2′-bipyridyl and amino acids, which are coordinated with metals. Examples thereof include organic compounds having two site-bonding sites.

The method for obtaining the filler according to the present invention includes:
A method of subjecting spherical clay minerals to a surface treatment with a silanizing agent, and then substituting exchangeable ions and optically active cations between layers of spherical clay minerals, and exchangeable ions and optically active cations between layers of spherical clay minerals. After substituting with, there is a method of performing surface treatment with a silanizing agent. Both methods yield fillers of the same quality. Various methods can be adopted as the surface treatment method of the spherical clay mineral. For example, the spherical clay mineral is dispersed in a liquid obtained by dissolving the silane compound alone or in an organic solvent (for example, chloroform, hexane, benzene, toluene, xylene, acetone),
After being kept constant at 180 ° C. for 10 minutes to 150 hours, the spherical clay mineral can be surface-treated by filtering, washing with the above solvent and drying. Further, the spherical clay mineral can be surface-treated by heating the dispersion liquid to evaporate the solvent instead of filtration and washing.

Of the above silanizing agents, the volatile ones are
Surface treatment (abbreviated as vapor phase treatment) can also be carried out by contacting with spherical clay mineral in the form of steam. Explaining specifically the basic mode of gas phase treatment, spherical clay mineral and silanizing agent are placed in separate containers in a closed room (preferably having a thermostatic function), and the upper part of each is placed. All you have to do is open it. The upper space is not particularly limited, but is occupied by the vaporized silanizing agent containing air, an inert gas, or water vapor, and the partial pressure thereof is preferably 1 atm or less. In this state, the silanizing agent vaporizes at the partial pressure at that temperature and maintains adsorption equilibrium on the spherical clay mineral. On the spherical clay mineral, the binding reaction between the silanating agent and the surface of the spherical clay mineral, and the polymerization reaction between the silanizing agents proceed, and the partial pressure of the silanating agent on the surface of the spherical clay mineral decreases, so The silanizing agent is vaporized and supplied. Since the surface treatment occurs in this order, the silanizing agent is supplied in a necessary amount in this system, and there is no waste. Moreover, since the vapor phase treatment is based on such a simple principle, no special device is required. Any enclosed room can be used, such as a desiccator or a constant temperature bath. However, ideally, a device capable of degassing after the treatment is preferable, and a gas sterilization device is preferably used.
The spherical clay mineral in the closed chamber may be agitated continuously or intermittently to make contact between the spherical clay mineral and the silanizing agent desirable.

According to another aspect of the gas phase treatment, only the powder to be treated is placed in a closed chamber having a boiling point of the silanizing agent or lower, and the silanizing agent is vaporized at a predetermined partial pressure to obtain a spherical clay mineral. The vaporized silanizing agent can be introduced, for example, by a pipe into the chamber in which is inserted. The system pressure (excluding the partial pressure of the silanizing agent) is not particularly limited, but the treatment is preferably carried out at a pressure of 200 mmHg or less, preferably 100 mmHg or less. In either embodiment, the treatment time is 30 minutes to 150 hours, after which the unreacted silanizing agent is removed by degassing (drying) to give the desired product.

According to another embodiment of the gas phase treatment, the spherical clay mineral is surface-treated by supplying and contacting the silanizing agent with the surface of the spherical clay mineral in the form of a mixed gas of the silanizing agent and a carrier gas. be able to. The mixing of the silanizing agent and the carrier gas is performed by heating the silanizing agent as needed until the vapor pressure of the silanizing agent becomes 1 mmHg or more, preferably 100 mmHg or more, and then the carrier gas flow is used in the silanizing agent or silanizing It can be carried out by introducing it onto the surface of the agent. The supply rate of the carrier gas flow is
It can be appropriately determined depending on the vapor pressure of the silanizing agent, the type and amount of the spherical clay mineral, and the volume of the processing container. It is preferable that the treatment can be performed in 30 minutes to 150 hours. The carrier gas is preferably an inert gas such as nitrogen, argon or helium, but it is also possible to use air or a mixed gas obtained by mixing water vapor, methanol vapor or ethanol vapor in the inert gas in a molecular state. When a gas such as hydrogen that may cause an explosion is generated during the treatment, an inert gas containing no silanizing agent may be supplied at the same time.

The method of exchanging interlayer cations is described in JP-A 1-2
The method described in 02658 is preferably used. In optical resolution using the filler according to the present invention, the target substance may be any chiral compound as long as it is soluble in a solvent. In particular, it is suitable for optically resolving a small molecule compound (for example, 2-methoxy-α-methylbenzyl alcohol) which shows almost no optical isomer separation with other fillers.

As the mobile phase used in the present filler, any solvent can be used except for an electrolyte (including intramolecular dissociation) solvent and a solution in which ions are dissolved. For optical resolution of neutral compounds, water / methanol, water / acetonitrile,
Preferred are methanol, acetonitrile, methanol / acetonitrile. To optically resolve an acidic compound, it is necessary to add 0.1 to 10% of acetic acid to the above mobile phase.
On the other hand, in order to optically resolve the basic compound, it is necessary to add 0.1 to 10% of amine to the above mobile phase. Further, even when these solvents are used, there is no elution of the optically active cation and the swelling of the filler, and the present filler can be used for a long time.

As described above, the packing material according to the present invention is a packing material for liquid chromatography, which is characterized in that it is possible to separate optical isomers in a water-containing organic solvent mobile phase. In liquid chromatography, the water-containing organic solvent mobile phase is most often used, and it can be combined with other columns for epoch-making analysis. By subjecting this filler to a surface treatment, without impairing the optical isomer recognition ability,
By using the water-containing organic solvent mobile phase, it is possible to easily separate the optical isomers even for the compounds which were difficult to separate with the untreated filler. Especially effective for small molecules. From the above, the present packing material is a packing material for liquid chromatography, which is extremely useful for analysis and separation of optically active substances.

[0022]

EXAMPLES Next, the present invention will be explained based on examples. The present invention is not limited to these examples. Example 1 10 g of a spherical clay mineral contained in a separate container and 5 ml of ethyltrimethoxysilane were placed in a closed container having an internal volume of 100 ml, and a nitrogen atmosphere was created. Then, close this sealed container to 105
It was placed in a constant temperature bath at ℃ and left for 16 hours.

After this, the spherical clay mineral was taken out and left in a thermostat at 105 ° C. for 16 hours. 0.1 g of the above-mentioned silane-treated spherical clay mineral was dispersed in 10 ml of water, and the presence or absence of swelling was determined. 5 meq of Λ-tris (1,10-phenanthroline) ruthenium (II) chloride in methanol 1
Dissolve in 00 ml, disperse all the remaining silane-treated spherical clay mineral, reflux for 1 hour, and then observe the supernatant,
The presence or absence of ion exchange capacity was judged (if the supernatant is colorless,
It has an ion exchange capacity, and if it is colored, there is no ion exchange capacity).

Then, the mixture was filtered, washed with methanol, and then dried at 105 ° C. overnight. The packing material thus obtained was packed in a column having an inner diameter of 4.6 mm and a length of 250 mm by a slurry method to carry out resolution of optical isomers. It was confirmed that the separation ability was improved by using the water-containing organic solvent mobile phase in all the samples. Examples 2 to 7 and Comparative Example 1 Spherical clay minerals were treated with the treatment agents shown in Table 1. The processing conditions and the evaluation method at this time are the same as in Example 1.

Example 8 10 g of a spherical clay mineral was dispersed in 30 ml of n-octadecyldimethylmethoxysilane, and the mixture was kept at 180 ° C. for 3 hours in a nitrogen stream.
Stir for 0 minutes. After cooling to room temperature, it was filtered and washed with chloroform. The evaluation method is the same as in Example 1.

[0026]

[Table 1] ──────────────────────────────────── Treatment agent Water swellability Ion exchange capacity ── ────────────────────────────────── Unprocessed Yes Yes ──────────── ──────────────────────── Example 1 Ethyltrimethoxysilane No Yes Example 2 n-Propyltrimethoxysilane No Yes Example 3 n-Butyl Trimethoxysilane No Yes Example 4 Methyltrimethoxysilane No Yes Example 5 3,3,3-Trifluoropropyltrimethoxysilane No Yes Example 6 Dimethyldimethoxysilane No Yes Example 7 Diethyldiethoxysilane No Yes Example 8 n-octadecyldimethylmethoxysilane None Yes ───────────────────── ────────────── Comparative Example 1 1,3,5,7-Tetramethylcyclotetrasiloxane No No Comparative Example 2 No trimethylchlorosilane No No Comparative Example 3 Octadecyldimethylchlorosilane No No Comparative Example 4 Hexamethyldisilazane Yes Yes Comparative Example 5 Trimethylmethoxysilane Yes Yes Comparative Example 6 Trimethylsilane Yes Yes Comparative Example 7 Trimethylsilanol Yes Yes ───────────────────── ────────────────

From Comparative Example 1, when silicone or a silanizing agent having a chloro group added thereto as in Comparative Examples 2 to 3 was used, water swellability was lost, but ion exchange capacity was lost. . On the other hand, when trimethylsilane is used as a silanizing agent as in Comparative Examples 4 to 7, it has an ion-exchange ability, but water swelling property remains, which is not preferable. Therefore, when the carbon number of R is 1, n = 1 is excluded. Next, an example of chromatography in which an optically active substance is separated using the packing material of the present invention will be described.

FIG. 1 shows an example in which 2-methoxy-α-methylbenzyl alcohol is separated.
Indicates that the filler described in Example 1 was used, and the same figure (A) indicates that the clay mineral filler that had not been silanized was used. When the silanization treatment is not performed, the filler swells when the aqueous mobile phase is used. Therefore, methanol is used as the mobile phase, and when the filler of Example 1 is used, the aqueous mobile phase is used. However, since the filler does not swell, 30% water / methanol is used as the mobile phase.

As shown in FIG. 3A, when a filler which was not silanized was used, almost no optical resolution could be achieved. On the other hand, as shown in FIG. 6B, when the filler of Example 1 was used, clear optical resolution could be achieved. further,
2 and 3 show examples of optical separation of 2,3-epoxypropylbenzene and methyl mandelate under the same conditions.

FIG. 4 shows an example of optical resolution of ibuprofen using a mobile phase added with 1% acetic acid. FIG. 5 shows an example of optical resolution of indapamide using a mobile phase added with 0.1% diethylamine. In each case, it is understood that the filler according to the present invention provides extremely clear optical resolution.

[0031]

As described above, according to the packing material for liquid chromatography of the present invention, the interlayer ions of the clay mineral are substantially replaced with the optically active cations, and the surface of the clay mineral is hydrophobized. As a result, good optical isomer resolution can be achieved while suppressing the water swelling property.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example in which 2-methoxy-α-methylbenzyl alcohol is optically resolved using the filler according to Example 1 of the present invention.

[Fig. 2] Fig. 2 is a graph showing the results of using the filler according to Example 1 of the present invention.
FIG. 6 is an explanatory diagram of an example in which optical resolution of epoxypropylbenzene is performed.

FIG. 3 is an explanatory diagram of an example in which optical resolution of methyl mandelate is performed using the filler according to Example 1 of the present invention.

FIG. 4 is an explanatory diagram of an example in which ibuprofen is optically resolved using the filler according to Example 1 of the present invention.

FIG. 5 is an explanatory diagram of an example in which indapamide is optically resolved using the filler according to Example 1 of the present invention.

Claims (3)

[Claims] 1. A packing material for liquid chromatography, which comprises a clay mineral in which interlayer ions of the clay mineral are substantially substituted with an optically active cation and the surface is subjected to a hydrophobic treatment. 2. The packing material for liquid chromatography according to claim 1, wherein the hydrophobizing treatment is performed by a silanizing agent. 3. The packing material for liquid chromatography according to claim 2, wherein the silanizing agent is represented by the following formula 1. Embedded image R _4-n SiX _n n = 1,2,3 (R: a hydrocarbon group having 1 to 32 carbon atoms, or some or all of the hydrogen atoms thereof are substituted with fluorine atoms) However, those having a carbon number of 1 and n = 1 are excluded.X: an alkoxy group, a hydrogen atom, a hydroxyl group, a phenoxy group,
Alternatively, it is a diethylamino group. )