JP2535446B2 - Method for producing optical resolving agent - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an optical resolving agent, and particularly to high performance liquid chromatography by polymerizing a vinyl derivative of a polysaccharide such as cellulose on a porous carrier (particle). The present invention relates to a method for advantageously producing an optical resolving agent suitable as a filler for a graphic.

BACKGROUND ART Traditionally, polysaccharides such as starch, dextran,
Cellulose, cellulose derivatives and the like have a specific optical resolution, useful as an optical resolution agent,
JP-A-60-40952, JP-A-60-82858, and "Separation of optical isomers" edited by The Chemical Society of Japan [Quarterly Chemical Review No. 6]
From pages 167 to 175 (1989) and the like, it is well known. Among them, a derivative obtained by esterifying a hydroxyl group of cellulose, for example, a chemically modified cellulose such as cellulose triacetate is more preferable than cellulose itself.
It is generally accepted that the optical resolution performance is high.

By the way, in the direct resolution of optical isomers by liquid chromatography, when a substance having the above optical resolution is directly used as a packing material for liquid chromatography, swelling due to pressure resistance and the solvent used From the aspect of shrinkage, the range of usage conditions is narrow, so
A method in which the above substance is supported on a carrier that does not cause such a problem is generally considered.

Under such circumstances, as a method of supporting the substance on a carrier by the simplest method, an impregnation adsorption method which is a physical method, that is, after immersing the carrier in a solution in which the substance is dissolved, the carrier is taken out, A method of drying is conceivable, but the weak point of this method is that the solvent species that dissolve the above substances are difficult to use, and the width of the solvent that can be used during the chromatographic measurement operation is narrow. It becomes larger in chemically modified polysaccharides. That is, since the modified polysaccharide is easily dissolved in an organic solvent, it is necessary to use a developing solution that does not dissolve it, and there is a significant restriction on the selection of separation conditions. However, there is an inherent problem that the theoretical plate number is remarkably reduced only by injecting a good solvent into the polysaccharide derivative by about several μ.

Further, as a method for eliminating the weak point in such a physical method, a method of chemically bonding a carrier and a polysaccharide derivative can be considered. However, a polysaccharide derivative can be used while maintaining its excellent optical resolution. So far, no specific method has been proposed for chemically binding to a carrier. For example, the above-mentioned JP-A-60
In Japanese Patent Publication No.-82858, as a method for holding a polysaccharide derivative on a carrier, a chemical method can be adopted in addition to a physical method. , No specific details have been disclosed.

(Problem to be Solved) Here, the present invention has been made in view of such circumstances, and its object is to achieve optical resolution with few restrictions on a developing solution or a solvent for dissolving a sample in liquid chromatography. An object of the present invention is to provide a method for producing an optical resolution carrier using an agent, particularly a chemically modified polysaccharide (polysaccharide derivative).

(Solution) That is, as a result of intensive studies by the present inventors, for the purpose of insolubilizing a polysaccharide used as an optical resolving agent, in particular, a chemically modified polysaccharide, the hydroxyl group of such a polysaccharide has a predetermined vinyl group. By chemically modifying with a modifier, a polysaccharide derivative in which a vinyl group is introduced through an ester bond or a urethane bond is polymerized on the surface of the porous carrier, thereby improving the conventional chemically modified polysaccharide. The present invention has been completed by finding a method capable of obtaining a polymer optically active carrier that is completely insoluble even in a solvent having high solubility such as ethyl acetate, tetrahydrofuran, methylene chloride, chloroform, and acetone. Was reached.

Therefore, the optical resolving agent targeted by the present invention is a polysaccharide derivative obtained by introducing a vinyl group into a hydroxyl group site of a polysaccharide through an ester bond or a urethane bond, and polymerized on the surface of the porous carrier. A layer formed of a polymerization product of a saccharide derivative is formed on the surface of the porous carrier, and particularly preferably, such a polysaccharide derivative has a vinyl group-introduced porous carrier. It is copolymerized to form a layer of a polymerization product produced by the copolymerization on the surface of the porous carrier.

Then, in the production method according to the present invention, in order to obtain an optical resolving agent as described above, a polysaccharide derivative having a vinyl group introduced through an ester bond or a urethane bond to the hydroxyl group site of the polysaccharide is attached to the surface of the porous carrier. Or, after adsorbing, polymerizing such a polysaccharide derivative, or polymerizing such a polysaccharide derivative and copolymerizing at least a part thereof with a vinyl group of the porous carrier is the gist thereof. is there.

(Specific Structure / Action) By the way, in the present invention, as the polysaccharide into which the vinyl group is introduced, any known one having optical resolution is targeted, and cellulose is a typical one. In addition, polysaccharides such as dextran, amylose, curdlan, pullulan and the like can be used appropriately. In addition, chemically modified cellulose obtained by chemically modifying cellulose as a polysaccharide has a high molecular weight, which increases the viscosity of the solution, which makes it difficult to uniformly adhere and adsorb to the porous carrier surface. In order to uniformly coat the surface of the porous carrier with the uniform cellulose derivative, in the present invention, it is desirable to use cellulose having a low molecular weight, particularly one having a number average degree of polymerization of 100 or less.

Then, in order to chemically modify such a polysaccharide to introduce a vinyl group, a vinyl group (specifically, via its ester bond or urethane bond) is attached to its hydroxyl group so as not to impair its excellent optical resolution. Specifically, it is necessary to introduce a vinyl group-containing organic group).

In addition, in order to chemically modify such a polysaccharide, a known vinyl compound that reacts with a hydroxyl group of the polysaccharide to form an ester bond or a urethane bond is appropriately selected,
Examples thereof include unsaturated acid halides such as acryloyl chloride, methacryloyl chloride, and vinylbenzoyl chloride, and unsaturated isocyanates such as vinyl phenyl isocyanate, and compounds having one vinyl group in such a molecule. Not only can compounds with multiple vinyl groups be used as required, but even when a vinyl compound having a structure in which vinyl groups are bonded to the benzene ring is used, the bonding position of the vinyl groups ,
If polymerization is possible, no significant disadvantage will be exhibited regardless of the position of vinyl group bonded to ortho, meta or para.

Further, regarding the number of introduction into the polysaccharide structural unit when chemically modifying the polysaccharide with a compound having a vinyl group, in the compound having a vinyl group, all the hydroxyl groups present in the structural unit of the polysaccharide, for example cellulose In the above, it is not necessary to completely chemically modify the three hydroxyl groups, and after the chemical modification, the chemical modification is performed to such an extent that it can be dissolved in a good solvent such as methylene chloride to achieve the desired polymerization on the carrier surface. It is possible.

On the other hand, in the present invention, as the porous carrier to which the vinyl group-introduced polysaccharide is applied, silica, alumina, magnesia, titanium oxide, glass, silicates, porous inorganic carriers such as kaolin, polystyrene, polyamide, poly There are well-known porous organic carriers such as acrylates, but generally, porous particles such as silica (silica gel) and glass (porous glass) are preferably used.

In the present invention, such a porous carrier is used as it is, and in order to more effectively support a vinyl group-introduced polysaccharide, a vinyl group is introduced into such a porous carrier to introduce a vinyl group. Copolymerization between the polysaccharide and the vinyl group-introduced porous carrier can be achieved, and an even more effective organic solvent-insoluble optical resolving agent can be provided.

When introducing a vinyl group into the porous carrier,
Various known methods are adopted, and like the above-mentioned method of binding a vinyl group to a polysaccharide, vinyl having a plurality of vinyl groups or vinyl groups at various bonding positions is provided to the extent that the function of copolymerization is not affected. A compound is used to react such a vinyl compound with a predetermined porous carrier, preferably with respect to a chemically modifiable carrier such as silica gel or porous glass, and chemically bond it. ,
The desired vinyl group will be introduced.

Here, a more specific method of introducing the vinyl group into the porous carrier will be described below by taking silica gel as an example.

I. Method of reacting a silylating agent having a vinyl group with a hydroxyl group of silica gel II. A method of bonding a vinyl group to the surface of silica gel after introducing a functional group that reacts with a compound having a vinyl group onto the surface of silica gel. III. Method to bind silica gel after binding silylating agent and vinyl group Since the present invention uses a porous carrier as described above, the method for synthesizing an optical resolution agent obtained by polymerizing a vinyl group-introduced polysaccharide as described above is a porous carrier having a vinyl group bonded thereto. Is roughly divided into a method using a carrier and a method using a carrier having no vinyl group. Regarding these synthesizing methods, the vinyl group-introduced carrier and the unmodified carrier have different polarities on the carrier surface. Although the degree of desorption of vinylated polysaccharide may be different, the same method can be applied to the adsorption method and the polymerization conditions, for example, a solution of a vinyl group-introduced polysaccharide is applied to the surface of a carrier to attach or Is adsorbed, then radical polymerization,
Polymerization is carried out using a polymerization technique such as ionic polymerization or plasma polymerization.

Further, when using an unmodified porous carrier, if the degree of polymerization is increased to such an extent that it does not dissolve in a good solvent such as methylene chloride, the purpose of not dissolving in such a good solvent can be achieved, but on the other hand, There is an inherent possibility that the polysaccharide derivative will elute if the degree of polymerization is low. In addition, when a carrier having a vinyl group introduced is used, even when the polymerization does not reach a degree of polymerization that does not dissolve in a good solvent, the polysaccharide derivative will bind to the carrier, and thus elution should be avoided. I can do it.

Furthermore, since it is considered that the polysaccharide derivative and all vinyl groups bonded to the surface of the carrier are not polymerized and disappear by one-time polymerization, the optical resolving agent obtained by the polymerization treatment further contains vinyl groups. It is also possible to employ a method of adsorbing the polysaccharide bound with the compound to increase the introduced amount of the polysaccharide derivative and polymerizing the compound to further improve the degree of polymerization. In the method of carrying out such polymerization a plurality of times, in addition to the polysaccharide having a vinyl group bonded, a compound having a plurality of vinyl groups, for example, divinylbenzene, ethylenediamine dimethacrylate,
It is also possible to employ a means for promoting the crosslinking reaction using a crosslinking agent such as ethylene glycol diacrylate to reduce the solubility in a good solvent.

As the polymerization conditions in the method for synthesizing the polymerization type optical resolving agent according to the present invention, the conditions used in general suspension polymerization can be applied, but when water is used as a medium,
The ester group bonded to the polysaccharide may be hydrolyzed, and further, the vinyl group-introduced polysaccharide adsorbed to the porous carrier by hydrogen bond may cause the hydrogen between the polysaccharide and the porous carrier due to the intervention of water. When the bond is broken, it is expected to fall off the surface of the porous carrier. The loss of a functional group containing a vinyl group introduced into the polysaccharide leads to a decrease in optical resolution, and a decrease in the amount of vinylated polysaccharide adsorbed on the porous surface in the polymerization step causes a decrease in the amount of adsorption on the porous surface. It is thought to cause a decrease in the introduction efficiency of the polysaccharide derivative. From the above, the polymerization of the polysaccharide derivative on the porous surface should be performed without hydrolyzing the ester bond or urethane bond and reducing the adsorption amount of the polysaccharide derivative as compared with the method using water as a medium. It is desirable to select a suitable solvent.

Further, as a polymerization medium which does not inhibit the decomposition of such ester bond or urethane bond and hydrogen bond,
The use of an organic solvent with low polarity can be mentioned, but considering that the polysaccharide derivative is soluble in a relatively large amount of organic solvent and that the reaction temperature required for radical polymerization is secured, the boiling point is 90 ° C or higher. Furthermore, a solvent that is liquid at room temperature is desirable. From these, it is considered that an alkyl hydrocarbon is the most suitable organic solvent as a medium used for the synthesis of the desired optical resolving agent, and a specific alkyl hydrocarbon solvent has a carbon number of A mixture of straight-chain hydrocarbons such as heptane, octane, nonane, decane, etc. having a number of 7 or more, branched hydrocarbons such as isooctane, cyclic hydrocarbons such as decalin, and hydrocarbons such as kerosene is advantageous for polymerization. Will be used.

In this way, by polymerizing the vinyl group-introduced polysaccharide derivative adhered or adsorbed to the surface of the porous carrier, on the surface of the porous carrier, a polymerization product of such a polysaccharide derivative is obtained. Is formed, especially when the vinyl group is introduced into the porous carrier,
Copolymerization is also carried out between such a carrier and a polysaccharide derivative, which is no longer soluble in an organic solvent, so that an optical resolving agent insoluble in an organic solvent is advantageously obtained here. Of.

In fact, as a result of applying the insoluble polysaccharide polymerization type optically active carrier obtained by the production method according to the present invention to a packing material for high performance liquid chromatography, a chemically modified type polysaccharide is prepared using conventional silica gel as a base material. With the optical resolving agent just adsorbed, the polysaccharide derivative is dissolved, and even under mobile phase conditions in which no resolving ability is expressed, optical resolution can be achieved, and with respect to the polysaccharide derivative before polymerization, Even if methylene chloride, which is a representative of a good solvent, is injected and passed, the performance does not deteriorate and it becomes a polymer type carrier that maintains the optical resolution.
It has been confirmed.

(Example) In order to more specifically clarify the present invention,
Examples of the present invention will be given, but it goes without saying that the present invention is not limited by the description of such examples. Further, in the present invention,
In addition to the following embodiments, in addition to the above specific description, various changes, modifications, improvements, etc. may be added based on the knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that there is.

Example 1 Acetyl cellulose was hydrolyzed to have a low molecular weight, and then the acetyl group was removed to obtain low molecular weight cellulose (polymerization degree: about 36).
The mixture was dispersed in ml, 89.0 g of 4-vinylbenzoyl chloride was added, and the mixture was heated to 80 ° C. and reacted for 10 hours while stirring.
After the reaction, the reaction solution was poured into 1000 ml of methanol to precipitate 4-vinylbenzoylated cellulose, which was washed with methanol while sucking and filtering, and dried at 50 ° C. After this drying, it was dissolved in 500 ml of methylene chloride, the insoluble material was filtered off, the methylene chloride was distilled off, and methanol was added to precipitate a solid. In the cellulose derivative thus obtained, absorption of a carbonyl group was observed by measurement of FT-IR spectrum, and it was confirmed that the hydroxyl group of glucose, which is a constituent unit of cellulose, was derivatized.

Next, using the obtained 4-methylbenzoylated cellulose, 4 g of silica gel as a porous carrier was added to a solution obtained by dissolving 1 g thereof in 50 ml of methylene chloride, and the mixture was dispersed at 30 ° C. The methylene chloride was distilled off under reduced pressure to attach and adsorb the cellulose derivative on the silica gel surface.

Then, 3 g of the silica gel on which 4-vinylated cellulose was adsorbed was dispersed in 50 ml of n-heptane, 30 mg of benzoyl peroxide was further added, and the mixture was stirred at 80 ° C. for 4 hours.
By polymerizing for 4 hours, 4
A layer consisting of the polymerization product of vinylbenzoylated cellulose was formed. After the polymerization reaction, the silica gel on which the polymerization product layer was formed was washed with methylene chloride and dried under reduced pressure.

The thus obtained silica gel on which the phase of the polymerization product of 4-vinylbenzoylated cellulose was formed was, as a result of the dissolution test, only acetyl cellulose, low molecular weight cellulose or 4-vinylbenzoylated cellulose was adsorbed on the surface. It was found that the organic solvent showed excellent insolubility in an organic solvent as compared with the silica gel alone, and that even when the adsorbed cellulose derivative was polymerized, its optical resolution could be sufficiently maintained.

Example 2 N-acryloylaminopropylated silica gel was synthesized as a vinyl group-introduced porous carrier as follows.

That is, first, 2 g of silica gel dried under reduced pressure was dispersed in 100 ml of toluene, 2 g of aminopropyltriethoxysilane as a silylating agent was added, and then ethanol produced by the reaction of the silylating agent and silanol was mixed with toluene. First, aminopropylated silica gel was synthesized by reacting for 5 hours while distilling off. After the reaction, the mixture was washed with methanol, 80% methanol, methanol and chloroform in this order and dried under reduced pressure.

Then, such aminopropyl silylated silica gel
2 g was dispersed in 50 ml of chloroform, 2 ml of acryloyl chloride was added thereto, and the mixture was reacted at 80 ° C. for 2 hours to obtain N-acryloylaminopropyl silica gel. After the reaction,
Methanol and chloroform were washed in this order and dried under reduced pressure.

Then, using the N-acryloylaminopropylated silica gel thus obtained, in order to adsorb the 4-vinylbenzoylated cellulose synthesized in Example 1 on the surface thereof, such a cellulose derivative was prepared.
Dissolve 1 g in 50 ml of methylene chloride and add to it the above N
-Acryloylaminopropylated silica gel was added and dispersed, and then methylene chloride was evaporated under reduced pressure at 30 ° C to adsorb the cellulose derivative on the silica gel surface.

Furthermore, after that, 3 g of the N-acryloylaminopropyl silica gel on which the 4-vinylbenzoylated cellulose was adsorbed was dispersed in 50 ml of n-heptane, and 30 mg of benzoyl peroxide was added thereto, and the mixture was stirred at 80
Polymerization at 4 ° C. for 4 hours to perform copolymerization between acryloyl group (vinyl group) introduced into silica gel and 4-vinylbenzoylated cellulose, and a polymerization type in which a cellulose derivative is chemically bonded to the surface of the silica gel. The following optical resolving agent was obtained.

The polymerization type optical resolving agent thus obtained was used as a packing material to be packed in a column of a high performance liquid chromatography device, and the effect of methylene chloride injection on its theoretical plate number and retention was determined by simply adding 4-vinylbenzoylated cellulose. The comparison was carried out in comparison with the case where an optical resolving agent consisting of silica gel just adsorbed on the surface was used as an adsorption type filler. That is, the influence of the injection of methylene chloride on the theoretical plate number of benzene and the retention time of stilbene oxide in the adsorption type and polymerization type cellulose derivative fillers was examined, and the results are shown in FIGS. 1 and 2.

As is clear from FIGS. 1 and 2, in the adsorption type filler, at the time of injecting 20 μm of methylene chloride,
The number of theoretical plates has dropped from about 8300 to about 3000
At the time of μ injection, the number of theoretical plates decreased below 1000. This can be presumed to be because the injection of methylene chloride partially dissolved the cellulose derivative and disturbed the stationary phase, resulting in a decrease in the number of theoretical plates. Regarding the retention time, it is considered that the injection of about 20 to 50 μm does not affect the retention time and the elution of the cellulose derivative does not occur. However, when 100 μm or more of methylene chloride was injected at one time, the retention was sharply decreased, and the elution of the cellulose derivative was observed. From this result, it is impossible to use methylene chloride as a solvent for dissolving the sample in the adsorption type packing material, and such a decrease is caused by the solubility parameter.
It can be inferred that the solvent around 18 to 25 is similarly generated.

On the other hand, in the above-mentioned chemically-bonded polymerizable filler obtained according to the method of the present invention, the retention time, the theoretical plate number,
No difference was observed in the optical resolution, and it became clear that the filler was extremely excellent in resistance to organic solvent dissolution.

In addition, as a result of examining the presence or absence of optical resolution in a mobile phase using tetrahydrofuran, which is a good solvent, as an additive to the cellulose derivative, as shown in FIGS. 3 (a) and 3 (b), according to the present invention. When the obtained polymerizable filler is used, the optical resolution is exhibited even in the mobile phase containing 30% tetrahydrofuran (THF), and even if the addition amount is increased to 50%, the optical resolution is increased. It was confirmed to be maintained. The liquid chromatography conditions were as follows:
It was as follows.

Column: Polymerized vinyl benzoyl cellulose Column size: 4.6 mm (inner diameter) -150 mm (length) Mobile phase: Fig. 3 (a) Hexane / THF = 7/3 Fig. 3 (b) Hexane / THF = 5/5 Flow rate: 1.0 ml / min Detection: UV254 nm Sample: Warfarin On the other hand, when using an adsorption type filler which is simply adsorbed 4-vinylbenzoylated cellulose,
Even with the addition of 30% tetrahydrofuran, elution of the stationary phase was observed, due to reduced retention and disturbed baseline,
Chromatographic analysis was not possible.

(Effect of the invention) As is apparent from the above description, according to the present invention, the optical resolving agent obtained by polymerizing the polysaccharide derivative on the surface of the porous carrier is prepared by adsorbing on the surface of the conventional porous carrier. In addition to having the same optical resolution as that of the adsorption type, the elution of the polysaccharide derivative is not observed even in the organic solvents that cannot be used with such conventional adsorption type resolving agents, and a wide range of organic solvents can be used. It is extremely useful as a polysaccharide derivative-type resolving agent that can be used.

[Brief description of drawings]

FIG. 1 and FIG. 2 are graphs showing changes in the theoretical plate number and the retention ratio with respect to the injection amount of methylene chloride, which were obtained in Example 2, respectively, and FIGS.
3 is a chromatogram when the composition of the mobile phase obtained in Example 2 is changed.

Claims (4)

(57) [Claims] 1. A polysaccharide derivative in which a vinyl group is introduced into a hydroxyl group site of a polysaccharide through an ester bond or a urethane bond is attached or adsorbed on the surface of a porous carrier,
A method for producing an optical resolving agent, which comprises polymerizing such a polysaccharide derivative. 2. A polysaccharide derivative in which a vinyl group is introduced into a hydroxyl group site of a polysaccharide through an ester bond or a urethane bond is adhered or adsorbed onto the surface of a porous carrier into which a vinyl group is introduced, and then the polysaccharide derivative is introduced. Polymerize the saccharide derivative,
A method for producing an optical resolving agent, which comprises copolymerizing at least a part thereof with a vinyl group of a porous carrier. 3. The method for producing an optical resolving agent according to claim 1, wherein the polysaccharide is cellulose or chemically modified cellulose having a number average degree of polymerization of 100 or less. 4. The method for producing an optical resolving agent according to any one of claims 1 to 3, wherein the porous carrier is silica gel or porous glass.