JPH05163164A - Separation agent - Google Patents

Abstract

PURPOSE:To provide a separation agent composed of a specific chitosan derivative obtained by modifying the amino group of chitosan with an aldehyde, etc., having excellent optical resolution performance and separation performance and useful for optical resolution, etc. CONSTITUTION:The objective separation agent is composed of a chitosan derivative expressed by formula (R is 4-30C aliphatic residue or aromatic residue; R' and R'' are H, 4-30C aliphatic residue or aromatic residue; (n) is >=5), containing >=70% of the amino groups of chitosan forming imino bond with aldehyde and ketone and having >=70% of the remaining hydroxyl group in a modified state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chromatographic separating agent, and more particularly to a separating agent comprising a specific polysaccharide derivative, which is useful as an optical resolving agent for racemic compounds.

[0002]

Conventionally, a separating agent using a polysaccharide derivative has shown an excellent resolving ability for a wide variety of racemic compounds as a stationary phase for liquid chromatography. It is considered important for the resolution that the higher order structure of the polysaccharide derivative is well adapted to the structure of the racemic compound and that various adsorptive interactions work effectively between them. However, it is a fact that some compounds are difficult to be resolved even if a polysaccharide derivative having excellent resolution is used.

Therefore, the present inventors have focused on chitosan, which is a polysaccharide in which β-D-glucosamine is 1 → 4 linked. Conventionally, it has been known that chitosan derivatives have optical resolution, but their resolution is low (Y.Okamoto et al., J. Am. Chem. So.
c., 106, 5357 (1984)).

[0004]

Means for Solving the Problems In order to solve the above problems, the present inventors have conducted intensive studies on the synthesis of chitosan derivatives and their resolving ability, and as a result, the present invention has been completed. That is, the present invention provides a chitosan derivative represented by the general formula (1) in which 70% or more of the amino groups of chitosan form an imino bond with aldehydes and ketones, and 70% or more of the remaining hydroxyl groups are derivatized. To provide a separating agent.

[0005]

[Chemical 2]

(Wherein R represents an aliphatic or aromatic residue having 4 to 30 atoms derived from a compound which reacts with a hydroxyl group, and R'and
R "are the same or different and each represents a hydrogen atom, or an aliphatic or aromatic residue having 4 to 30 atoms derived from an aldehyde or a ketone, and n represents an integer of 5 or more."
The present invention will be described in detail. Chitosan in the present invention is a repeating unit of D-glucosamine represented by the following general formula (2), which is deacetylated chitin which is N-acetyl-β-D-glucosamine derived from crustacean, and its repeating unit. Is a polysaccharide in which 1 → 4 is linked, and its deacetylation degree is 80 to 100%, preferably 95% or more. The bond form of D-glucosamine, which is a repeating unit, is a β-1,4-glucoside bond in which the β-position is substituted. The number of repeating units is 5 or more, preferably 10 or more, and there is no particular upper limit, but it is preferably 500 or less in view of easy handling.

[0007]

[Chemical 3]

(In the formula, n has the above-mentioned meaning.) Since chitosan has two types of active hydrogens, a hydroxyl group and an amino group, in its repeating unit, the introduction of a functional group in the present invention means the introduction of these two groups. It means that each type of active hydrogen is converted by different means.

A: Derivatization of amino group In the general formula (1), R ′ and R ″ are each a hydrogen atom or an aldehyde or ketone-derived atom number of 4 to 30.
Any of those selected from the aliphatic or aromatic residues may be used. In addition, R'and R "do not have to be the same. When derivatizing an aldehyde, R'and R"
One of them becomes a hydrogen atom, and the other has 4 to 30 atoms.
To become an aliphatic or aromatic residue. Specific examples of these residues, a methyl group (-CH _3), ethyl group (-C ₂ H _5),

[0010]

[Chemical 4]

On the other hand, when a ketone is used, both R ′ and R ″ are aliphatic or aromatic residues having 4 to 30 atoms derived from the ketone, and specific examples of these residues include a methyl group (- CH ₃ ),
Ethyl group (-C ₂ H _5), a vinyl group (-CH = CH _2),

[0012]

[Chemical 5]

The introduction rate of these functional groups is 70% of all amino groups.
It is -100%, preferably 80% or more.

B: Derivatization of Hydroxyl Group In the general formula (1), R may be any aliphatic or aromatic residue having 4 to 30 atoms derived from a compound that reacts with a hydroxyl group. Examples of the bonding mode are ester bond, urethane bond, ether bond and the like. The introduction rate of these functional groups is 70 to 100%, preferably 80% or more of all hydroxyl groups.

<Synthesis Method> A: Derivatization of Amino Group The derivatization of an amino group is a reaction which is generally used in an organic synthesis reaction to react a primary amine with an aldehyde or a ketone to form an imino bond. Can be applied. That is, the amino group of chitosan is derivatized by reacting chitosan with an aldehyde and a ketone in the presence of an acid or a base. The acid that can be used in the reaction may be a protic one such as acetic acid or hydrochloric acid, or a Lewis acid such as boron trifluoride etherate or zinc chloride. As the base, potassium hydroxide or the like is generally used.

B: Derivatization of Hydroxyl Group Derivatization of a hydroxyl group includes ester derivatization, carbamate derivatization, ether derivatization and the like shown below. 1) Ester Derivatization To synthesize the ester derivative of chitosan according to the present invention, the corresponding carboxylic acid is converted to an acid chloride using thionyl chloride, oxalyl chloride, etc., and this reagent is used in an amount of 3 equivalents based on all hydroxyl groups of chitosan. Then, it is easily obtained by reacting chitosan with the acid chloride in a pyridine solvent.

2) Carbamate Derivatization For the synthesis of the carbamate derivative of chitosan according to the present invention, the usual reaction for producing urethane from alcohol and isocyanate can be applied as it is. For example, it is obtained by reacting a corresponding isocyanate (3 equivalents based on all hydroxyl groups of chitosan) with chitosan in a suitable solvent using a Lewis base such as a tertiary amine or a Lewis acid such as a tin compound as a catalyst. You can Moreover, the synthesis of isocyanate can be easily obtained, for example, by reacting phosgene with the amino group of the corresponding aniline derivative.

3) Ether Derivatization The synthesis of the ether derivative of chitosan according to the present invention is carried out by reacting the corresponding halide (3 equivalents based on all the hydroxyl groups of chitosan) and chitosan as a base in a solvent such as dioxane or pyridine. It can be obtained by reacting with potassium hydroxide, potassium tert-butoxide or the like.

<Separator> The chitosan derivative of the present invention is a substance that is extremely useful as a functional material, and is particularly useful as a filler for optical resolution, that is, a separator. For separating a mixture of compounds or a mixture of optical isomers using the separating agent of the present invention, gas chromatography using a column packed with the separating agent of the present invention, liquid chromatography, thin layer chromatography and supercritical chromatography. Chromatography methods such as are suitable, but membrane separation is also possible.

To use the chitosan derivative of the present invention as a packing material for liquid chromatography, it is used by crushing as it is, physically adsorbed on a carrier, chemically bound to a carrier, or in the form of beads. be able to. The carrier used in the present invention may be a porous organic carrier or a porous inorganic carrier, preferably a porous inorganic carrier. Suitable examples of the porous organic carrier include polymer substances made of polystyrene, polyacrylamide, polyacrylate and the like. Suitable as the porous inorganic carrier are silica, alumina, magnesia, glass, kasulion, titanium oxide, silicate, etc. Also, the affinity with the carbamate derivative is improved and the surface properties of the carrier itself are improved. In order to improve the quality, it is possible to use the porous inorganic carrier whose surface is treated. Examples of the surface treatment method include a silanization treatment with an organic silane compound and a surface treatment method by plasma polymerization.

The developing solvent for liquid chromatography or thin layer chromatography is not particularly limited, except for those which dissolve the chitosan derivative or react with it. On the other hand, when performing thin layer chromatography, the thickness of the separating agent consisting of particles of about 0.1 μm to 0.1 mm and a small amount of binder if necessary.
A layer having a thickness of 0.1 mm to 100 mm may be formed in the shape of a supporting plate. When performing membrane separation, it is used as a hollow fiber or a film.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 Phenylcarbamme of N- (2-salicylidene) chitosan
(1) Synthesis of N- (2-salicylidene) chitosan in which carrier (3) is supported on a carrier (1) Chitosan (1.0 g; 100% deacetylated; manufactured by Katokichi) in 40 ml of 0.5% acetic acid aqueous solution. Was dissolved at room temperature and this was diluted with methanol (40 ml). A solution of 2-salicylaldehyde (2.26 g; 18.6 mmol; manufactured by Aldrich) in methanol (10 ml) was added to this solution, and the mixture was stirred at room temperature overnight. This solution was added to methanol (500 ml), the precipitate formed was filtered off, washed with ethanol and ether, and dried (60 ° C).
/ Under reduced pressure; 4 hours) to obtain 1.64 g of the desired product.

(2) Synthesis of phenyl carbamate (3) of N- (2-salicylidene) chitosan N- (2-salicylidene) chitosan (1.0 g) obtained in (1)
Was added to 50 ml of pyridine, phenylisocyanate (2.69 g; 22.6 mmol) was added thereto, and this was heated and stirred at 100 ° C. for 24 hours under a nitrogen stream. This reaction solution is 500
It was poured into ml of methanol, the precipitate formed was filtered off, washed,
This was dried at 60 ° C. under reduced pressure to obtain the desired product.

(3) Synthesis of a filler comprising N- (2-salicylidene) chitosan phenylcarbamate (3) supported on a carrier (2) N- (2-salicylidene) chitosan phenylcarbamate (3) ) 1 part (part is by weight, the same applies hereinafter) is 8
Silica gel dissolved in some parts of tetrahydrofuran and treated with diphenylsilane (manufactured by Fuji Devison; FD-1000, 10μ
After mixing with 10 parts of m), tetrahydrofuran was distilled off under reduced pressure to obtain a filler.

Example 2 Phenyl N- (9-anthrylmethylidene) chitosan
Synthesis of filler in which carbamate (4) is supported on carrier (1) Synthesis of N- (9-anthrylmethylidene) chitosan Chitosan (1.0 g), 9 in the same manner as in Example 1 (1). −
Anthraldehyde (3.83g; 18.6mmol; Aldrich)
Then, the target product was synthesized. (2) Synthesis of phenyl carbamate (4) of N- (9-anthrylmethylidene) chitosan N- (9-anthrylmethylidene) chitosan (1 g) and phenyl were prepared in the same manner as in (2) of Example 1. The target product was synthesized from isocyanate (2.04 g; 17.19 mmol). (3) Synthesis of a phenyl carbamate of N- (9-anthrylmethylidene) chitosan (4) supported on a carrier Phenyl of N- (9-anthrylmethylidene) chitosan obtained in (2) Using the carbamate (4), the filler was synthesized in the same manner as in (3) of Example 1.

Example 3 N- (1-pyrenylmethylidene) chitosan phenylca
Synthesis of filler comprising rubamate (5) supported on carrier (1) Synthesis of N- (1-pyrenylmethylidene) chitosan Chitosan (1.0 g), 1 in the same manner as in Example 1 (1). −
Pyrenecarboxaldehyde (4.29g; 18.6mmol; Aldr
(manufactured by ich) was used to synthesize the target product. (2) Synthesis of phenyl carbamate (5) of N- (1-pyrenylmethylidene) chitosan In the same manner as in (2) of Example 1, N- (1-pyrenylmethylidene) chitosan (1.0 g), Phenyl isocyanate (1.
91 g; 16.1 mmol), the target compound was synthesized. (3) N- (1-pyrenylmethylidene) chitosan phenyl carbamate (5) Synthesis of a packing material which is carried on a carrier (2) N- (1-pyrenylmethylidene) chitosan phenyl Using the carbamate (5), the filler was synthesized in the same manner as in (3) of Example 1.

Example 4 Phenyl N- (4-biphenylmethylidene) chitosan
Synthesis of filler in which carbamate (6) is supported on carrier (1) Synthesis of N- (4-biphenylmethylidene) chitosan Chitosan (1.0 g), 4-in the same manner as (1) of Example 1.
Biphenylcarboxaldehyde (3.39g; 18.6mmol;
The target product was synthesized from Aldrich. (2) Synthesis of phenyl carbamate (6) of N- (4-biphenylmethylidene) chitosan In the same manner as (2) of Example 1, N- (4-biphenylmethylidene) chitosan (1.0 g), phenylisocyanate The target product was synthesized from (2.69 g; 22.6 mmol). (3) Synthesis of a filler comprising N- (4-biphenylmethylidene) chitosan phenylcarbamate (6) supported on a carrier (2) N- (4-biphenylmethylidene) chitosan phenylcarbamate (6) Using (6), the filler was synthesized in the same manner as in (3) of Example 1.

Example 5 N- (1-naphthylmethylidene) chitosan phenylca
Synthesis of filler containing rubamate (7) supported on carrier (1) Synthesis of N- (1-naphthylmethylidene) chitosan In the same manner as in Example 1, (1), chitosan (1.0 g), 1-
Naphthaldehyde (2.90g; 18.6mmol; Aldrich)
Then, the target product was synthesized. (2) Synthesis of phenyl carbamate (7) of N- (1-naphthylmethylidene) chitosan In the same manner as in (2) of Example 1, N- (1-naphthylmethylidene) chitosan (1.0 g) and phenyl The desired product was synthesized from isocyanate (2.39 g; 20.1 mmol). (3) Synthesis of a filler comprising N- (1-naphthylmethylidene) chitosan phenylcarbamate (7) supported on a carrier (2) N- (1-naphthylmethylidene) chitophenyl phenylcarbamate obtained in (2) Using (7), the filler was synthesized in the same manner as in (3) of Example 1.

As described above, the phenylcarbamate derivatives (3) of N- (allylidene) chitosan synthesized in Examples 1 to 5
Table 1 shows the elemental analysis values and the imino group introduction rate of (7).

[0031]

[Table 1]

Note) * 1: Imino group introduction rate * 2: Numbers in parentheses are theoretical values.

Application Example The separating agent obtained in Examples 1 to 5 was packed by a slurry method into a stainless steel column having an inner diameter of 0.46 cm and a length of 25 cm.
The racemic compounds shown in Tables 2 and 3 were separated using this column. Table 2 shows the results of optical resolution by a column for liquid chromatography using as a stationary phase the packing material obtained by supporting the phenyl carbamate (3) of N- (2-salicylidene) chitosan obtained in Example 1 on a carrier. Optical resolution by a column for liquid chromatography using as a stationary phase a packing material obtained by supporting the phenylcarbamate derivatives (4) to (7) of N- (allylidene) chitosan obtained in Examples 2 to 5 on a carrier. The results are shown in Table 3. The capacity ratio (k ′) and the separation coefficient (α) in the table are defined by the following equations, respectively.

[0034]

[Equation 1]

[0035]

[Table 2]

Note) * 1 Mobile phase conditions; A: Hexane B: Hexane / 2-propanol = 99/1 C: Hexane / 2-propanol = 98/2

[0037]

[Table 3]

Note) * 1 Mobile phase conditions; A: Hexane B: Hexane / 2-propanol = 99/1 C: Hexane / 2-propanol = 98/2 D: Hexane / 2-propanol = 95/5 E: Hexane / 2-Propanol = 9/1

Claims (1)

[Claims] 1. A chitosan derivative represented by the general formula (1), wherein 70% or more of the amino groups of chitosan form an imino bond with aldehydes and ketones, and 70% or more of the remaining hydroxyl groups are derivatized. Become a separating agent. [Chemical 1] (In the formula, R is 4 to 4 atoms derived from a compound that reacts with a hydroxyl group.
30 represents an aliphatic or aromatic residue, R ′ and R ″ are the same or different and each represents a hydrogen atom, or an aldehyde or ketone-derived aliphatic or aromatic residue having 4 to 30 atoms, n represents an integer of 5 or more.)