JP3041116B2 - Separating agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a separating agent using a polysaccharide derivative has shown an excellent resolving ability for a 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 be well adapted to the structure of the racemic compound, and that various adsorptive interactions work effectively between the two. However, it is a fact that there are compounds that are difficult to resolve even when using a polysaccharide derivative having an excellent resolution ability.

[0003] Therefore, the present inventors have focused on chitosan, which is a polysaccharide in which β-D-glucosamine is 1 → 4 linked. Hitherto, it has been known that chitosan derivatives have an optical resolution ability, but the resolution ability was 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 made intensive studies on the synthesis of chitosan derivatives and the resolution thereof, and as a result, have completed the present invention. That is, the present invention relates to a method in which the amino group of chitosan has an aromatic aldehyde.
To form a hydrate compound and an imino bond, there is provided a separating agent composed of chitosan derivatives represented by the general formula and the remaining hydroxyl groups have been derivatized (1).

[0005]

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Hereinafter, the present invention will be described in detail. In the present invention, chitosan is crustacean-derived N-acetyl-β-
D-glucosamine represented by the following general formula (2) obtained by deacetylating chitin, which is D-glucosamine, is a polysaccharide having a repeating unit of 1 → 4, and the degree of deacetylation. Is 80 to 100%, preferably 95% or more. The binding 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 although there is no particular upper limit, it is preferably 500 or less for ease of handling.

[0007]

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(In the formula, n represents the above-mentioned meaning.) Chitosan has two types of active hydrogens, a hydroxyl group and an amino group, in its repeating unit. It refers to the conversion of each type of active hydrogen by different means.

<Synthesis Method> A: Derivatization of Amino Group Amino group is derivatized by applying a reaction that reacts a primary amine with an aldehyde to form an imino bond, which can be generally used in an organic synthesis reaction. be able to. That is, the amino group of chitosan is derivatized by reacting chitosan with an aromatic aldehyde in the presence of an acid or a base. Acids that can be used in the reaction include protic acids such as acetic acid and hydrochloric acid,
It is also possible to use Lewis acids such as boron trifluoride etherate, zinc chloride and the like. As the base, potassium hydroxide or the like is generally used.

B: Derivatization of hydroxyl group Derivatization of hydroxyl group is carbamate derivatization . Departure
The synthesis of carbamate derivatives of chitosan involved in Akira,
The usual reaction for producing urethane from alcohol and isocyanate can be applied as it is. For example, it can be obtained by reacting a corresponding isocyanate (3 equivalents to 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. Can be. In addition, the synthesis of isocyanate can be easily obtained , for example, by allowing phosgene to act on the amino group of the corresponding aniline derivative.
You.

<Separating Agent> The chitosan derivative of the present invention is a very useful substance as a functional material, and is particularly useful as a filler for optical resolution, ie, a separating agent. To separate a mixture of compounds or a mixture of optical isomers using the separating agent of the present invention, gas chromatography, liquid chromatography, thin-layer chromatography, and supercritical chromatography using a column packed with the separating agent of the present invention. Although it is suitable to use a chromatography method such as the above, it is also possible to perform membrane separation.

In order to use the chitosan derivative of the present invention as a packing material for liquid chromatography, the chitosan derivative is used as it is after being crushed, physically adsorbed to a carrier, chemically bonded to a carrier, or used in the form of beads. be able to. The carrier used in the present invention includes a porous organic carrier or a porous inorganic carrier, and is preferably a porous inorganic carrier. Suitable examples of the porous organic carrier include a polymer substance composed of polystyrene, polyacrylamide, polyacrylate, and the like. Suitable examples of the porous inorganic carrier include silica, alumina, magnesia, glass, kaslion, titanium oxide, silicate, etc., and have improved affinity with carbamate derivatives and improved surface characteristics of the carrier itself. In order to improve the quality, a porous inorganic carrier whose surface is treated may be used. Examples of the surface treatment method include a silanization treatment using an organic silane compound and a surface treatment method using plasma polymerization.

There are no particular restrictions on the developing solvent used in liquid chromatography or thin layer chromatography, except for those that dissolve or react with the chitosan derivative. On the other hand, in the case of performing thin layer chromatography, the separating agent comprising particles of about 0.1 μm to 0.1 mm and, if necessary, a thickness comprising a small amount of a binder.
A layer having a thickness of 0.1 mm to 100 mm may be formed in a support plate shape. When performing membrane separation, it is used as a hollow fiber or film.

[0014]

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

Example 1 Phenylcarbame of N- (2-salicylidene) chitosan
(1) Synthesis of N- (2-salicylidene) chitosan 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). To this solution was added a solution of 2-salicylaldehyde (2.26 g; 18.6 mmol; manufactured by Aldrich) in methanol (10 ml), and the mixture was stirred at room temperature for 24 hours. This solution was added to methanol (500 ml), and the resulting precipitate was collected by filtration, 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 phenylcarbamate of N- (2-salicylidene) chitosan (3) N- (2-salicylidene) chitosan (1.0 g) obtained in (1)
Was added to 50 ml of pyridine, and phenyl isocyanate (2.69 g; 22.6 mmol) was added thereto, followed by heating and stirring at 100 ° C. for 24 hours under a nitrogen stream. Add 50 parts of this reaction solution.
Poured into 0 ml of methanol, the resulting precipitate was filtered off, washed,
This was dried under reduced pressure at 60 ° C. to obtain the desired product.

(3) Synthesis of phenyl carbamate of N- (2-salicylidene) chitosan (3) Synthesis of filler filled on a carrier The phenyl carbamate of N- (2-salicylidene) chitosan obtained in (2) ) 1 part (parts by weight, same hereafter) 8
Silica gel (manufactured by Fuji Devison; FD-1000, 10μ)
m) After mixing with 10 parts, tetrahydrofuran was distilled off under reduced pressure to obtain a filler.

Example 2 Phenyl of N- (9-anthrylmethylidene) chitosan
Synthesis of filler having carbamate (4) supported on a carrier (1) Synthesis of N- (9-anthrylmethylidene) chitosan Chitosan (1.0 g), 9 −
Ansulfaldehyde (3.83 g; 18.6 mmol; manufactured by Aldrich)
Thus, the target compound was synthesized. (2) Synthesis of phenylcarbamate (4) of N- (9-anthrylmethylidene) chitosan N- (9-anthrylmethylidene) chitosan (1 g) and phenylcarbamate (1 g) were synthesized in the same manner as in (2) of Example 1. The target compound was synthesized from isocyanate (2.04 g; 17.19 mmol). (3) Synthesis of phenylcarbamate of N- (9-anthrylmethylidene) chitosan (4) Synthesis of fillers supported on a carrier Phenyl of N- (9-anthrylmethylidene) chitosan obtained in (2) The filler was synthesized in the same manner as in Example 1, (3) using carbamate (4).

Example 3 N- (1-pyrenylmethylidene) chitosan phenylca
Synthesis of Filler Supporting Rubamate (5) on Carrier (1) Synthesis of N- (1-pyrenylmethylidene) chitosan Chitosan (1.0 g), 1 −
Pyrene carboxaldehyde (4.29 g; 18.6 mmol; Aldr
ich) was synthesized. (2) Synthesis of phenyl carbamate (5) of N- (1-pyrenylmethylidene) chitosan N- (1-pyrenylmethylidene) chitosan (1.0 g) was synthesized in the same manner as in (2) of Example 1. Phenyl isocyanate (1.
91 g; 16.1 mmol) to synthesize the desired product. (3) Synthesis of a filler comprising N- (1-pyrenylmethylidene) chitosan phenylcarbamate (5) supported on a carrier Phenyl of N- (1-pyrenylmethylidene) chitosan obtained in (2) The filler was synthesized in the same manner as in Example 1, (3) using carbamate (5).

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

Example 5 N- (1-naphthylmethylidene) chitosan phenylca
Synthesis of filler having rubamate (7) supported on carrier (1) Synthesis of N- (1-naphthylmethylidene) chitosan Chitosan (1.0 g), 1-
Naphthaldehyde (2.90 g; 18.6 mmol; manufactured by Aldrich)
Thus, the target compound was synthesized. (2) Synthesis of phenyl carbamate (7) of N- (1-naphthylmethylidene) chitosan N- (1-naphthylmethylidene) chitosan (1.0 g) was synthesized in the same manner as in (2) of Example 1. The target compound was synthesized from isocyanate (2.39 g; 20.1 mmol). (3) Synthesis of filler having N- (1-naphthylmethylidene) chitosan phenylcarbamate (7) supported on a carrier Phenylcarbamate of N- (1-naphthylmethylidene) chitosan obtained in (2) Using 7), the filler was synthesized in the same manner as in Example 1, (3).

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

[0023]

[Table 1]

Note) * 1: Introduction rate of imino group * 2: Numbers in parentheses are theoretical values.

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

[0026]

(Equation 1)

[0027]

[Table 2]

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

[0029]

[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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C07B 57/00 C08B 37/08 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A separating agent comprising a chitosan derivative represented by the general formula (1) in which an amino group of chitosan forms an imino bond with an aromatic aldehyde and the remaining hydroxyl group is derivatized. Embedded image