WO2024231986A1 - Cellulose derivative and method for producing same, and composition containing cellulose derivative - Google Patents

Abstract

The objective of the present invention is to provide an amide-modified cellulose ether produced by a simple method, and an amide-modified cellulose ether using an aromatic amide.　Provided is a cellulose derivative having a repeating unit represented by formula (1), wherein the total average degree of substitution of a protecting group for a hydroxyl group, a group represented by specific formula (1-a), and a group represented by specific formula (1-b) is 1.5 or more.

Description

Cellulose derivative, its production method, and composition containing the cellulose derivative

The present disclosure relates to a cellulose derivative and a method for producing the same, as well as a composition containing the cellulose derivative.

Cellulose derivatives are semi-synthetic materials obtained by chemically treating cellulose, a natural polymer. By chemically treating cellulose, which does not dissolve in water or common organic solvents, various cellulose derivatives with different solubility, thermal properties, and chemical properties can be obtained. Specific examples include cellulose esters, including cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate phthalate, and nitrocellulose, as well as cellulose ethers, including methylcellulose, ethylcellulose, benzylcellulose, cyanoethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and carboxymethylcellulose.

Among these, for example, carboxymethylcellulose (hereinafter sometimes referred to as CMC) has excellent thickening, water absorption, and water retention properties, and is used in a wide range of applications including food, pharmaceuticals, cosmetics, and construction. Furthermore, by amide-modifying carboxymethylcellulose, its solubility in water and general organic solvents can be changed.

Patent Document 1 describes a method for producing alkylamide-modified carboxymethylcellulose by dissolving carboxymethylcellulose in an ionic liquid, adding an alkylamine having 1 to 6 carbon atoms or ammonia as an amidating agent, and heating at 120°C to 160°C.

Patent Document 2 describes a method for producing an aliphatic amide-modified carboxyl-containing polysaccharide, in particular an aliphatic amide-modified carboxymethylcellulose, by converting carboxymethylcellulose (CMC) into an aliphatic amine salt in an ethanol/water solvent and heating the resulting solid in xylene at 140°C.

Patent Document 3 describes a method for forming a polysaccharide acid amide composition by reacting the hydroxyl groups of a polysaccharide with an alkali metal cyanide compound in the presence of a primary or secondary aliphatic amine.

JP 2009-114437 A Special Publication No. 08-508538 U.S. Pat. No. 5,760,199

In order to obtain amide-modified carboxymethylcellulose, it is generally necessary to use carboxymethylcellulose as a raw material. However, as the degree of substitution of the carboxymethyl group increases, carboxymethylcellulose becomes water-soluble, making it difficult to modify it in the presence of a solvent suitable for amidation, which is a dehydration reaction. When using the ionic liquid described in Patent Document 1, it is difficult to recover the ionic liquid when an amine with a high boiling point, such as an aromatic amine, is used. In addition, there is no description of an example using CMC with a high total average degree of substitution. The methods described in Patent Documents 1 and 2 require a reaction at a high temperature of 120°C or more, making it difficult to carry out in an industrial reaction vessel. The method described in Patent Document 3 requires the use of a cyanide that is highly toxic and requires careful handling, making it difficult to carry out industrially. In addition, none of the documents describes an example using an aromatic amine with low nucleophilicity. This disclosure discloses a method for directly obtaining amide-modified CMC by using a cellulose derivative that is soluble in a general-purpose organic solvent as a raw material and reacting it with an intermediate that reacts at a low temperature.

The object of the present disclosure is to produce an amide-modified cellulose ether by a simple method, and to provide an amide-modified cellulose ether using an aromatic amide.

 
［上記式（１）中、Ｒは、同一又は異なって、水素原子、水酸基の保護基、下記式（１－ａ）で表される基、又は下記式（１－ｂ）で表される基である。尚、上記式（１）で表される繰り返し単位を有するセルロース誘導体に含まれる全てのＲのうち、少なくとも１つは下記式（１－ａ）で表される基である。］

 
（上記式（１－ａ）中、Ｘは、同一又は異なって、水素又はメチル基を示す。また、上記式（１－ａ）中、Ａｒは、単環芳香族炭化水素基又は多環芳香族炭化水素基である。）

 
（上記式（１－ｂ）中、Ｘは、同一又は異なって、水素又はメチル基を示す。また、上記式（１－ｂ）中、Ａｒは、単環芳香族炭化水素基又は多環芳香族炭化水素基である。） A first aspect of the present disclosure relates to a cellulose derivative having a repeating unit represented by the following formula (1), in which the total average substitution degree of a hydroxyl-protecting group, a group represented by the following formula (1-a), and a group represented by the following formula (1-b) is 1.5 or more.

[In the above formula (1), R may be the same or different and is a hydrogen atom, a protecting group for a hydroxyl group, a group represented by the following formula (1-a), or a group represented by the following formula (1-b). Of all R contained in the cellulose derivative having a repeating unit represented by the above formula (1), at least one is a group represented by the following formula (1-a)]

(In the above formula (1-a), X may be the same or different and represents a hydrogen atom or a methyl group. Also, in the above formula (1-a), Ar represents a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.)

(In the above formula (1-b), X may be the same or different and represents a hydrogen atom or a methyl group. Also, in the above formula (1-b), Ar represents a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.)

 
［上記式（２）中、Ｒは、同一又は異なって、水素原子、水酸基の保護基、上記式（１－ａ）で表される基、又は上記式（１－ｂ）で表される基である。尚、上記式（２）で表される繰り返し単位を有するセルロース誘導体に含まれる全てのＲのうち、少なくとも１つは水素原子である。］

 
［上記式（３）中、Ｘは、同一又は異なって、水素又はメチル基を示す。また、上記式（３）中、Ａｒは、単環芳香族炭化水素基又は多環芳香族炭化水素基である。］ A second aspect of the present disclosure is a method for producing the cellulose derivative, comprising the steps of:
The present invention relates to a method for producing a cellulose derivative, the method comprising: a step (i) of reacting a hydroxyl group at the 2-, 3- or 6-position of a cellulose derivative having a repeating unit represented by the following formula (2) with an α-bromocarboxamide represented by the following formula (3) in the presence of a base catalyst.

[In the above formula (2), R is the same or different and is a hydrogen atom, a protecting group for a hydroxyl group, a group represented by the above formula (1-a), or a group represented by the above formula (1-b). At least one of all R contained in the cellulose derivative having a repeating unit represented by the above formula (2) is a hydrogen atom.]

[In the above formula (3), X is the same or different and represents a hydrogen atom or a methyl group. In addition, in the above formula (3), Ar is a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.]

The present disclosure makes it possible to produce amide-modified cellulose ethers using a simple method, and to provide amide-modified cellulose ethers using aromatic amides.

¹ H-NMR measurement data of the cellulose derivative obtained in Example 2 ¹ H-NMR measurement data of the cellulose derivative obtained in Example 8 ¹ H-NMR measurement data of the cellulose derivative obtained in Example 9

 
［上記式（１）中、Ｒは、同一又は異なって、水素原子、水酸基の保護基、下記式（１－ａ）で表される基、又は下記式（１－ｂ）で表される基である。尚、上記式（１）で表される繰り返し単位を有するセルロース誘導体に含まれる全てのＲのうち、少なくとも１つは下記式（１－ａ）で表される基である。］

 
（上記式（１－ａ）中、Ｘは、同一又は異なって、水素又はメチル基を示す。また、上記式（１－ａ）中、Ａｒは、単環芳香族炭化水素基又は多環芳香族炭化水素基である。）

 
（上記式（１－ｂ）中、Ｘは、同一又は異なって、水素又はメチル基を示す。また、上記式（１－ｂ）中、Ａｒは、単環芳香族炭化水素基又は多環芳香族炭化水素基である。） [Cellulose derivatives]
The cellulose derivative of the present disclosure (hereinafter may be referred to as "cellulose derivative (1)") has a repeating unit represented by the following formula (1) (hereinafter may be referred to as a "glucose unit"), and has a total average substitution degree of 1.5 or more for the protecting group of a hydroxyl group, the group represented by the following formula (1-a), and the group represented by the following formula (1-b):

[In the above formula (1), R may be the same or different and is a hydrogen atom, a protecting group for a hydroxyl group, a group represented by the following formula (1-a), or a group represented by the following formula (1-b). Of all R contained in the cellulose derivative having a repeating unit represented by the above formula (1), at least one is a group represented by the following formula (1-a)]

(In the above formula (1-a), X may be the same or different and represents a hydrogen atom or a methyl group. Also, in the above formula (1-a), Ar represents a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.)

(In the above formula (1-b), X may be the same or different and represents a hydrogen atom or a methyl group. Also, in the above formula (1-b), Ar represents a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.)

(Degree of substitution)
In the cellulose derivative (1), the total average substitution degree of the hydroxyl-protecting group, the group represented by the following formula (1-a), and the group represented by the following formula (1-b) is 1.5 or more, preferably 1.7 or more, more preferably 2.0 or more, and even more preferably 2.5 or more, and may be 3 or less.

In this disclosure, the average degree of substitution refers to the average value of the degree of substitution of hydrogen atoms of hydroxyl groups at positions 2, 3, and 6 of glucose units constituting a cellulose derivative with groups other than hydrogen atoms, and in particular, the total average degree of substitution refers to the sum of the average degrees of substitution of the protecting groups of hydroxyl groups, the group represented by the following formula (1-a), and the group represented by the following formula (1-b).

At least one of all Rs contained in the cellulose derivative (1) is a group represented by the above formula (1-a), and the average degree of substitution of the group represented by the above formula (1-a) may be greater than 0. The average degree of substitution of the group represented by the above formula (1-a) is preferably 0.1 or more, more preferably 0.5 or more, and even more preferably 1.8 or more, and may be 3 or less.

The average substitution degree of the hydroxyl protecting groups in the cellulose derivative (1) may be 0 or less than 3. The average substitution degree of the hydroxyl protecting groups is preferably 2.5 or less, more preferably 2.2 or less, and even more preferably 1.1 or less.

When the protecting group for the hydroxyl group in the cellulose derivative (1) contains the following acetyl group, the average substitution degree of the acetyl group is preferably 1.5 or more and less than 3.0, more preferably 1.5 or more and 2.5 or less, even more preferably 1.7 or more and 2.5 or less, and particularly preferably 1.7 or more and 2.2 or less.

When the protecting group for the hydroxyl group in the cellulose derivative (1) contains the following trityl group, the average substitution degree of the trityl group is greater than 0 and preferably 2.5 or less, more preferably 2.2 or less, and even more preferably 1.1 or less.

(Group represented by (1-a))
In the above formula (1-a), X may be the same or different and represents a hydrogen atom or a methyl group, and it is preferable that at least one of X is a methyl group, and it is particularly preferable that all of X are methyl groups, because the cellulose derivative (1) of the present disclosure can be obtained in a particularly excellent yield in the following step (i) or (iii) in the method for producing the cellulose derivative (1).

In the above formula (1-a), Ar is a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group. In this disclosure, the monocyclic aromatic hydrocarbon group includes monocyclic aromatic hydrocarbon groups in which hydrogen in an aromatic hydrocarbon is replaced with another group and unsubstituted monocyclic aromatic hydrocarbon groups, and the polycyclic aromatic hydrocarbon group includes polycyclic aromatic hydrocarbon groups in which hydrogen in a polycyclic aromatic hydrocarbon is replaced with another group and unsubstituted polycyclic aromatic hydrocarbon groups. In addition, the polycyclic aromatic hydrocarbon group is a group having a hydrocarbon in which two or more aromatic rings are condensed.

  In the above formula (1-a), Ar is not an aliphatic hydrocarbon group but a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group, which makes it easier to produce an α-ketoaziridine derivative represented by the following formula (3-a), which is an intermediate in the reaction in the following step (i) or (iii) in the production method for cellulose derivative (1) of the present disclosure, and makes it possible to obtain cellulose derivative (1) in an excellent yield.

Examples of monocyclic aromatic hydrocarbon groups include unsubstituted phenyl groups, and substituted monocyclic aromatic hydrocarbon groups, such as monocyclic aromatic hydrocarbon groups in which the hydrogen atom in the phenyl group is substituted with a halogen atom, an alkyl group having 1 to 24 carbon atoms, an alkenyl group having 1 to 24 carbon atoms, an alkynyl group having 1 to 24 carbon atoms, an alkoxy group having 1 to 24 carbon atoms, an acyl group having 1 to 24 carbon atoms, an alkoxycarbonyl group (ester group) having 1 to 24 carbon atoms, etc., a trifluoromethyl group, or a nitro group. The number of substituents in the monocyclic aromatic hydrocarbon group may be 1, 2, 3, 4, or 5, and the position of the substituent is not limited. As the monocyclic aromatic hydrocarbon group, a phenyl group is preferred from the viewpoint of chemical stability. Furthermore, from the viewpoint of improving the plasticity as a resin, an alkyl group-substituted monocyclic aromatic hydrocarbon group is preferred.

Examples of polycyclic aromatic hydrocarbon groups include monovalent substituents in which one hydrogen atom has been replaced from unsubstituted polycyclic aromatic hydrocarbons such as naphthalene, anthracene, phenanthrene, pyrene, triphenylene, and tetracene, as well as substituted polycyclic aromatic hydrocarbon groups such as polycyclic aromatic hydrocarbon groups in which a hydrogen atom in the polycyclic aromatic hydrocarbon has been replaced with a halogen atom, an alkyl group having 1 to 24 carbon atoms, an alkenyl group having 1 to 24 carbon atoms, an alkynyl group having 1 to 24 carbon atoms, an alkoxy group having 1 to 24 carbon atoms, an acyl group having 1 to 24 carbon atoms, an alkoxycarbonyl group (ester group) having 1 to 24 carbon atoms, etc., a trifluoromethyl group, or a nitro group. The number of substituents in the polycyclic aromatic hydrocarbon group may be any number from 1 to 12, and the position of the substituent is not limited.

(Hydroxyl-protecting group)
The above-mentioned hydroxyl-protecting group includes well-known and commonly used protecting groups, for example, silyl-based protecting groups such as trimethylsilyl, triethylsilyl, triisopropylsilyl, triphenylsilyl, t-butyldimethylsilyl, dimethylthexylsilyl, and t-butyldiphenylsilyl; acetal-based protecting groups such as tetrahydropyranyl and methoxymethyl; aralkyl groups having 6 to 15 carbon atoms such as benzyl and p-methoxybenzyl;
These include alkenyl groups such as allyl group, ether-based protecting groups such as trityl group and methoxytrityl group, aliphatic acyl groups having 1 to 5 carbon atoms, such as acetyl group, pivaloyl group, benzoyl group and trimethylbenzoyl group, or aromatic acyl groups having 6 to 15 carbon atoms, and ester-based protecting groups such as p-toluenesulfonyl group. Among these, the acetyl group or trityl group is preferred from the viewpoints that it can be subjected to weakly basic reaction conditions, the cellulose derivative as the raw material becomes soluble in a commonly used organic solvent, and it can be deprotected with an inexpensive acid or base.

(Group represented by (1-b))
Among all R contained in the cellulose derivative (1) of the present disclosure, at least one may be a group represented by the following formula (1-b), and the average substitution degree of the group represented by the following formula (1-b) may be greater than 0 but is preferably 1 or less, more preferably 0.6 or less.

 
　（上記式（１－ｂ）中、Ｘは、同一又は異なって、水素又はメチル基を示す。また、上記式（１－ｂ）中、Ａｒは、単環芳香族炭化水素基又は多環芳香族炭化水素基である。） In addition, in R at the 6-position of the cellulose derivative (1), the group represented by the following formula (1-b) is preferably 50 mol % or less, more preferably 30 mol % or less, and even more preferably 20 mol % or less, based on the total number of moles of the group represented by the following formula (1-a) and the group represented by the following formula (1-b).

(In the above formula (1-b), X may be the same or different and represents a hydrogen atom or a methyl group. Also, in the above formula (1-b), Ar represents a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.)

In the above formula (1-b), it is preferable that each X is a methyl group. This is because the cellulose derivative (1) can be obtained in a particularly excellent yield in the following step (i) or (iii) in the method for producing the cellulose derivative (1) of the present disclosure.

In the above formula (1-b), Ar is not an aliphatic hydrocarbon group but a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group, which makes it easier to produce the α-ketoaziridine derivative represented by the above formula (3-a), which is an intermediate in the reaction in the production method of the cellulose derivative (1) of the present disclosure, and makes it possible to obtain the cellulose derivative (1) in an excellent yield.

Examples of monocyclic aromatic hydrocarbon groups and polycyclic aromatic hydrocarbon groups include the same ones exemplified as Ar in formula (1-a) above.

The form of the cellulose derivative (1) disclosed herein is not particularly limited and can be used as a resin molding material, for example, in the form of powder, fiber, granules, or sheet.

Cellulose-based materials generally have the properties of being water-soluble, having excellent water permeability, and being stain-resistant. At least one of all R contained in the cellulose derivative (1) of the present disclosure is a group represented by the above formula (1-a) and has an amide group, so in addition to these properties, the cellulose derivative (1) of the present disclosure has excellent alkali resistance. In particular, it has better alkali resistance than cellulose esters. Therefore, the cellulose derivative (1) of the present disclosure is suitable as a material for water treatment membranes, which require alkali resistance and chemical resistance.

[Composition]
The composition of the present disclosure is a composition containing the above-mentioned cellulose derivative (1).

The above composition may contain optional components other than the above cellulose derivatives depending on the application. Examples of the optional components include plasticizers, stabilizers (e.g., antioxidants, UV absorbers, heat stabilizers, light resistance stabilizers, etc.), colorants (e.g., dyes, pigments, etc.), flame retardants, antistatic agents, lubricants, antiblocking agents, dispersants, fluidizing agents, drip prevention agents, and antibacterial agents.

Examples of the plasticizer include di-C _1-12 alkyl phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, and di-2-ethylhexyl phthalate; C _1-6 alkoxy C _1-12 alkyl phthalates such as dimethoxyethyl phthalate; C _1-12 alkyl-aryl-C _1-3 alkyl phthalates such as butyl benzyl phthalate; C _1-6 alkyl phthalyl C _2-4 alkylene glycolates such as ethyl phthalyl ethylene glycolate and butyl phthalyl butylene glycolate; tri-C _1-12 alkyl esters of trimellitic acid such as trimethyl trimellitate, triethyl trimellitate, trioctyl trimellitate, and tri-2-ethylhexyl trimellitate; and tetra-C pyromellitic acid such as tetraoctyl pyromellitate. The plasticizer may contain aromatic carboxylate esters such as _1-12 alkyl esters; azelaic acid esters such as diethyl azelate, dibutyl azelate, dioctyl azelate, etc., sebacic acid esters such as dibutyl sebacate, dioctyl sebacate, etc., fatty acid esters such as butyl oleate, methylacetyl ricinoleate, etc.; triacetin, diglycerin tetraacetate, etc.; lower fatty acid esters of polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol, sorbitol, etc.; benzoic acid esters of polyhydric alcohols such as glycol ester dipropylene glycol dibenzoate, etc.; citric acid esters such as acetyl tributyl citrate, etc.; amides such as N-butylbenzenesulfonamide, etc.; ester oligomers such as caprolactone oligomers, etc. These plasticizers may be used alone or in combination of two or more.

[Method of producing cellulose derivatives]
The cellulose derivative (1) of the present disclosure can be produced, for example, by the following production method: A method for producing a cellulose derivative, comprising a step (i) of reacting a hydroxyl group at the 2-, 3- or 6-position of a cellulose derivative having a repeating unit represented by the following formula (2) (hereinafter, sometimes referred to as "cellulose derivative (2)") with an α-bromocarboxamide represented by the following formula (3) in the presence of a base catalyst.

 
［上記式（２）中、Ｒは、同一又は異なって、水素原子、水酸基の保護基、上記式（１－ａ）で表される基、又は上記式（１－ｂ）で表される基である。尚、上記式（２）で表される繰り返し単位を有するセルロース誘導体に含まれる全てのＲのうち、少なくとも１つは水素原子である。］ (Cellulose derivative (2))
The cellulose derivative (2) of the present disclosure has a repeating unit represented by the following formula (2).

[In the above formula (2), R is the same or different and is a hydrogen atom, a protecting group for a hydroxyl group, a group represented by the above formula (1-a), or a group represented by the above formula (1-b). At least one of all R contained in the cellulose derivative having a repeating unit represented by the above formula (2) is a hydrogen atom.]

(Degree of substitution)
When at least one of all R contained in the cellulose derivative (2) is a hydrogen atom and at least one of them is a hydroxyl-protecting group or a group represented by the above formula (1-a), the total average substitution degree of the hydroxyl-protecting group, the group represented by the above formula (1-a), and the group represented by the above formula (1-b) is preferably 1.5 or more, more preferably 1.7 or more, even more preferably 2.0 or more, and particularly preferably 2.5 or more, and may be less than 3.

The average substitution degree of the hydroxyl protecting groups in the cellulose derivative (2) may be 0 or less than 3. The average substitution degree of the hydroxyl protecting groups is preferably 2.5 or less, more preferably 2.2 or less, and even more preferably 1.1 or less.

When the protecting group for the hydroxyl group in the cellulose derivative (2) contains the following acetyl group, the average substitution degree of the acetyl group is preferably 1.5 or more and less than 3.0, more preferably 1.5 or more and 2.5 or less, even more preferably 1.7 or more and 2.5 or less, and particularly preferably 1.7 or more and 2.2 or less.

When the protecting group for the hydroxyl group in the cellulose derivative (2) contains the following trityl group, the average substitution degree of the trityl group is greater than 0 and preferably 2.5 or less, more preferably 2.2 or less, and even more preferably 1.1 or less.

The average degree of substitution of the group represented by the above formula (1-a) in the cellulose derivative (2) may be 0.

The cellulose derivative (2) is not limited as long as it has the repeating unit represented by the above formula (2), but specific examples of cellulose derivatives that are soluble in general-purpose organic solvents such as acetonitrile (hereinafter sometimes referred to as AN) and tetrahydrofuran (hereinafter sometimes referred to as THF) include cellulose acetate, trityl cellulose, cellulose acetate propionate, and cellulose acetate butyrate.

(Group represented by (1-a))
When the cellulose derivative (2) has a group represented by the above formula (1-a), the explanation for the group represented by the above formula (1-a) in the cellulose derivative (2) is the same as the explanation for the group represented by the above formula (1-a) in the cellulose derivative (1).

(Hydroxyl-protecting group)
When the cellulose derivative (2) has a hydroxyl-protecting group, specific examples of the hydroxyl-protecting group in the cellulose derivative (2) are the same as those in the cellulose derivative (1) described above. In addition, the hydroxyl-protecting group in the method for producing the cellulose derivative (1) of the present disclosure is preferably an acetyl group or a trityl group, from the viewpoints that the cellulose derivative as the raw material is soluble in a general-purpose organic solvent and can be deprotected with an inexpensive acid or base.

 
［上記式（３）中、Ｘは、同一又は異なって、水素又はメチル基を示す。また、上記式（３）中、Ａｒは、単環芳香族炭化水素基又は多環芳香族炭化水素基である。］ (α-bromocarboxamide)
The α-bromocarboxamide of the present disclosure is represented by the following formula (3):

[In the above formula (3), X is the same or different and represents a hydrogen atom or a methyl group. In addition, in the above formula (3), Ar is a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.]

In the above formula (3), X may be the same or different and represents a hydrogen atom or a methyl group. It is preferable that at least one of X is a methyl group, and it is particularly preferable that all X are methyl groups. This is because the yield of the cellulose derivative (1) obtained by the production method of the present disclosure can be further increased.

In addition, in the above formula (3), when one of X is hydrogen and the other is a methyl group, it is called α-methylcarboxamide, and when both X are methyl groups, it can be rephrased as α-dimethylcarboxamide.

In the above formula (3), Ar is a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group. In the above formula (3), Ar is not an aliphatic hydrocarbon group but a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group, which makes it easier to produce the α-ketoaziridine derivative represented by the following formula (3-a), which is an intermediate in the reaction of the following step (i) or (iii), and the cellulose derivative (1) can be obtained in high yield. Therefore, by changing the substituent of the monocyclic aromatic hydrocarbon group or the polycyclic aromatic hydrocarbon group, it is possible to produce cellulose derivatives (1) having various substituents.

Specific examples of the monocyclic aromatic hydrocarbon group and polycyclic aromatic hydrocarbon group in the above formula (3) and the explanation of suitable substituents thereamong are the same as the explanation of the specific examples of the monocyclic aromatic hydrocarbon group and polycyclic aromatic hydrocarbon group in the above formula (1-a) and the explanation of suitable substituents thereamong.

In the above step (i), the amount of α-bromocarboxamide represented by the above formula (3) used is preferably 1 to 3 molar equivalents, more preferably 1 to 2 molar equivalents, and even more preferably 1 to 1.5 molar equivalents per mole of the total hydroxyl groups at the 2-, 3- or 6-positions of the entire cellulose derivative (2).

(Base Catalyst)
The base catalyst used in the above step (i) is not particularly limited as long as it can catalyze the reaction in the above step (i), and examples thereof include non-nucleophilic inorganic bases such as carbonates including sodium carbonate, potassium carbonate, and cesium carbonate, and phosphates such as sodium phosphate, potassium phosphate, and cesium phosphate. Among these, carbonates and phosphates are preferred from the viewpoint of suppressing the decomposition reaction of α-bromocarboxamide, and as the metal ion, potassium salts are preferred from the viewpoint of increasing the activation effect in the reaction, and cesium salts are more preferred. Cesium carbonate is particularly preferred.

The amount of base catalyst used in step (i) above is preferably 1 to 5 molar equivalents, more preferably 1 to 3 molar equivalents, and even more preferably 1 to 2 molar equivalents per mole of α-bromocarboxamide used.

(solvent)
The reaction in the step (i) is preferably carried out in the presence of a solvent. As the solvent, an aprotic solvent can be used, and specifically, for example, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, etc.; halogenated hydrocarbons such as chloroform, dichloromethane, 1,2-dichloroethane, etc.; ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxane, etc.; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.; esters such as methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, etc.; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, etc.; nitriles such as acetonitrile, propionitrile, benzonitrile, etc.; dimethyl sulfoxide, etc. These can be used alone or in combination of two or more. Among these, aromatic hydrocarbons, ethers, esters, and nitriles are preferred from the viewpoint of less occurrence of side reactions, and acetonitrile or tetrahydrofuran is more preferred from the viewpoint of low boiling point, easy recovery, and excellent versatility.

When the reaction in step (i) is carried out in the presence of a solvent, the amount of the solvent used may be, for example, 1 to 20 mL, preferably 1 to 10 mL, and more preferably 1 to 5 mL per 1 mmol of the raw cellulose derivative, in order to increase the reaction rate.

The atmosphere for the reaction in step (i) above is not particularly limited as long as it does not inhibit the reaction, and may be, for example, an air atmosphere, a nitrogen atmosphere, an argon atmosphere, etc.

The reaction temperature in step (i) above can be adjusted appropriately depending on the solvent used, and may be, for example, 20°C (room temperature) to 150°C, 20°C (room temperature) to 100°C, and preferably about 20°C (room temperature) to 60°C. The reaction time is, for example, 3 to 24 hours, preferably 5 to 24 hours, but may be 24 hours or longer.

The reaction mechanism of the above step (i) is that the α-ketoaziridine derivative represented by the above formula (3-a), which is a reaction intermediate, is generated from the α-bromocarboxamide represented by the above formula (3) in the presence of a base catalyst, and the α-ketoaziridine derivative reacts with the hydroxyl group at the 2-, 3- or 6-position of the cellulose derivative (2) to produce the cellulose derivative (1).

  As shown in the following reaction formula, in the reaction of an α-ketoaziridine derivative with a hydroxyl group at the 2-, 3- or 6-position of a cellulose derivative (2), the reaction may be substituted with a group represented by the above formula (1-b), and the resulting cellulose derivative (1) may have a group represented by the above formula (1-b) in addition to the group represented by the above formula (1-a).

According to the above step (i), the cellulose derivative (1) can be produced in an excellent yield. The yield in the above step (i) may be 30% or more, preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more. The yield in the above step (i) refers to the ratio of the number of moles of the cellulose derivative (1), which is the product of the above step (i), to the number of moles of the cellulose derivative having the repeating unit represented by the above formula (2) charged in the above step (i).

In addition, when at least one of all R contained in the cellulose derivative (2) of the present disclosure is a protecting group for a hydroxyl group, the method for producing the cellulose derivative (1) may include, after the step (i), a step (ii) of removing the protecting group for the hydroxyl group and replacing it with a hydroxyl group.

The method for removing the protecting group for the hydroxyl group and substituting it with a hydroxyl group can be a method known for each of the well-known and conventional protecting groups mentioned above. For example, when the protecting group is a silyl group, it is a method of treating with a fluoride; when the protecting group is an acetal-based protecting group, it is a method of treating with an acid such as hydrochloric acid, acetic acid, or hydrogen bromide; when the protecting group is a _C1-5 aliphatic acyl group or a _C6-15 aromatic acyl group, it is a method of treating under basic conditions such as treating with potassium carbonate in an alcohol/water such as methanol; when the protecting group is an ether-based protecting group, it is a _C7-15 aralkyl group, allyl group, or the like, it is a method of treating by hydrogenation in the presence of a catalyst such as palladium/carbon; and when the protecting group is a trityl group, it is a method of treating with an acid such as acetic acid or hydrochloric acid.

The case where the protecting group for the hydroxyl group in step (ii) contains a trityl group and the trityl group is eliminated will be described below. The acid used in step (ii) above is not particularly limited as long as it can eliminate the trityl group and replace it with a hydroxyl group, but examples include hydrochloric acid, hydrobromic acid, a hydrobromic acid/acetic acid solution, and hydroiodic acid. Among these, a hydrobromic acid/acetic acid solution is preferred from the viewpoints of high compatibility with organic solvents and easy reaction progress.

The reaction in step (ii) is preferably carried out in the presence of a solvent. Examples of the solvent include halogenated hydrocarbons such as chloroform and dichloromethane.

When the reaction in step (ii) is carried out in the presence of a solvent, the amount of the solvent used may be, for example, 1 to 20 mL, preferably 1 to 10 mL, and more preferably 1 to 5 mL per 1 mmol of the raw cellulose derivative, in order to increase the reaction rate.

The atmosphere for the reaction in step (ii) above is not particularly limited as long as it does not inhibit the reaction, and may be, for example, an air atmosphere, a nitrogen atmosphere, an argon atmosphere, etc.

The reaction temperature in step (ii) above can be adjusted appropriately depending on the solvent used, and may be, for example, room temperature to 60°C or room temperature to 40°C, with room temperature of about 25°C being preferred. The reaction time may be, for example, 5 to 180 minutes, 5 to 60 minutes, or 5 to 30 minutes.

　The above explains the case where the hydroxyl-protecting group in step (ii) contains a trityl group and the trityl group is eliminated.

Even when the above step (ii) is included, the cellulose derivative (1) can be produced in an excellent yield. The yield in the above step (ii) may be 30% or more, preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more. The yield in the above step (ii) refers to the ratio of the number of moles of the cellulose derivative (1), which is the product of the above step (ii), to the number of moles of the cellulose derivative having the repeating unit represented by the above formula (2) charged in the above step (i).

Furthermore, the method for producing the cellulose derivative (1) of the present disclosure may include a step (iii) of reacting, in the presence of a base catalyst, the hydroxyl group at the 2-, 3-, or 6-position of the cellulose derivative obtained by the step (ii) above, including the hydroxyl group substituted with a hydrogen atom from the protecting group by the step (ii) above, with an α-bromocarboxamide represented by the formula (3) above.

The base catalyst used in the above step (iii) is not particularly limited as long as it can catalyze the reaction in the above step (iii), and the same catalyst as in the above step (i) can be used. As the base catalyst used in the above step (iii), cesium carbonate is preferable from the viewpoint of suppressing the decomposition reaction of α-bromocarboxamide.

In the above step (iii), the amount of base catalyst used is preferably 1 to 5 molar equivalents, more preferably 1 to 3 molar equivalents, and even more preferably 1 to 2 molar equivalents, per mole of α-bromocarboxamide used.

The reaction in step (iii) is preferably carried out in the presence of a solvent, and the same solvent as in step (i) can be used. As the solvent used in step (iii), acetonitrile or tetrahydrofuran is preferred because of its low boiling point, ease of recovery, and versatility.

When the reaction in step (iii) is carried out in the presence of a solvent, the amount of the solvent used may be, for example, 1 to 20 mL, preferably 1 to 10 mL, and more preferably 1 to 5 mL per 1 mmol of the raw cellulose derivative, in order to increase the reaction rate.

The atmosphere for the reaction in step (iii) above is not particularly limited as long as it does not inhibit the reaction, and may be, for example, an air atmosphere, a nitrogen atmosphere, an argon atmosphere, etc.

The reaction temperature in step (iii) above can be adjusted appropriately depending on the solvent used, and may be, for example, 20°C (room temperature) to 150°C, or 20°C (room temperature) to 100°C, with room temperature of about 20°C (room temperature) to 60°C being preferred. The reaction time is, for example, 3 to 24 hours, preferably 5 to 24 hours, but may be 24 hours.

Even when the above step (iii) is included, the cellulose derivative (1) can be produced in an excellent yield. The yield in the above step (iii) may be 30% or more, preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more. The yield in the above step (iii) refers to the ratio of the number of moles of the cellulose derivative (1), which is the product of the above step (iii), to the number of moles of the cellulose derivative having the repeating unit represented by the above formula (2) charged in the above step (i).

The reaction products obtained by steps (i), (ii), and (iii) can be separated and purified by separation means such as reprecipitation, filtration, drying, concentration, distillation, extraction, crystallization, adsorption, recrystallization, column chromatography, or a combination of these.

The above configurations and combinations of the present disclosure are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate without departing from the spirit of the present disclosure. The present disclosure is not limited by the embodiments, but only by the scope of the claims.

Furthermore, each aspect disclosed herein may be combined with any other feature disclosed herein.

 
［上記式（１）中、Ｒは、同一又は異なって、水素原子、水酸基の保護基、下記式（１－ａ）で表される基、又は下記式（１－ｂ）で表される基である。尚、上記式（１）で表される繰り返し単位を有するセルロース誘導体に含まれる全てのＲのうち、少なくとも１つは下記式（１－ａ）で表される基である。］

 
（上記式（１－ａ）中、Ｘは、同一又は異なって、水素又はメチル基を示す。また、上記式（１－ａ）中、Ａｒは、単環芳香族炭化水素基又は多環芳香族炭化水素基である。）

 
（上記式（１－ｂ）中、Ｘは、同一又は異なって、水素又はメチル基を示す。また、上記式（１－ｂ）中、Ａｒは、単環芳香族炭化水素基又は多環芳香族炭化水素基である。）
［項目２］
　上記式（１－ａ）又は（１－ｂ）中、Ａｒが単環芳香族炭化水素基である、項目１に記載のセルロース誘導体。
［項目３］
　上記式（１－ａ）又は（１－ｂ）中、Ａｒが多環芳香族炭化水素基である、項目１に記載のセルロース誘導体。
［項目４］
　上記総平均置換度が１．７以上である、項目１～３の何れか一項に記載のセルロース誘導体。
［項目５］
　上記水酸基の保護基がアセチル基又はトリチル基である、項目１～４の何れか一項に記載のセルロース誘導体。
［項目６］
　上記式（１）で表される繰り返し単位を有するセルロース誘導体に含まれる全てのＲのうち、少なくとも１つは上記式（１－ｂ）で表される基である、項目１～５の何れか一項に記載のセルロース誘導体。
［項目７］
　項目１～６の何れか一項に記載のセルロース誘導体を含む組成物。
［項目８］
　項目１に記載のセルロース誘導体の製造方法であって、
塩基触媒の存在下、下記式（２）で表される繰り返し単位を有するセルロース誘導体の２、３又は６位の水酸基に、下記式（３）で表されるαブロモカルボキサミドを反応させる工程（ｉ）を含む、セルロース誘導体の製造方法。

 
［上記式（２）中、Ｒは、同一又は異なって、水素原子、水酸基の保護基、上記式（１－ａ）で表される基、又は上記式（１－ｂ）で表される基である。尚、上記式（２）で表される繰り返し単位を有するセルロース誘導体に含まれる全てのＲのうち、少なくとも１つは水素原子である。］

 
［上記式（３）中、Ｘは、同一又は異なって、水素又はメチル基を示す。また、上記式（３）中、Ａｒは、単環芳香族炭化水素基又は多環芳香族炭化水素基である。］
［項目９］
　上記式（２）で表される繰り返し単位を有するセルロース誘導体に含まれる全てのＲのうち、少なくとも１つが水酸基の保護基、上記式（１－ａ）で表される基、又は上記式（１－ｂ）で表される基であって、上記式（２）で表される繰り返し単位を有するセルロース誘導体は、上記水酸基の保護基、上記式（１－ａ）で表される基、及び上記式（１－ｂ）で表される基の総平均置換度が１．５以上である、項目８に記載のセルロース誘導体の製造方法。
［項目１０］
　上記式（３）中、Ａｒが単環芳香族炭化水素基である、項目８又は９に記載のセルロース誘導体の製造方法。
［項目１１］
　上記式（３）中、Ａｒが多環芳香族炭化水素基である、項目８又は９に記載のセルロース誘導体の製造方法。
［項目１２］
　上記式（２）で表される繰り返し単位を有するセルロース誘導体に含まれる全てのＲのうち、少なくとも１つが水酸基の保護基であって、
上記工程（ｉ）の後、上記水酸基の保護基を脱離して水酸基に置換する工程（ｉｉ）を含む、項目８～１１の何れか一項に記載のセルロース誘導体の製造方法。
［項目１３］
　上記水酸基の保護基がアセチル基又はトリチル基である、項目８～１２の何れか一項に記載のセルロース誘導体の製造方法。
［項目１４］
　上記工程（ｉｉ）により得られたセルロース誘導体における、上記工程（ｉｉ）により置換された水酸基を含む２、３又は６位の水酸基に、塩基触媒の存在下、上記式（３）で表されるαブロモカルボキサミドを反応させる工程（ｉｉｉ）を含む、項目１２又は１３に記載のセルロース誘導体の製造方法。 The following items enumerate preferred aspects of the present disclosure, but the present invention is not limited to the following items.
[Item 1]
A cellulose derivative having a repeating unit represented by the following formula (1), in which the total average substitution degree of a hydroxyl-protecting group, a group represented by the following formula (1-a), and a group represented by the following formula (1-b) is 1.5 or more.

[In the above formula (1), R may be the same or different and is a hydrogen atom, a protecting group for a hydroxyl group, a group represented by the following formula (1-a), or a group represented by the following formula (1-b). Of all R contained in the cellulose derivative having a repeating unit represented by the above formula (1), at least one is a group represented by the following formula (1-a)]

(In the above formula (1-a), X may be the same or different and represents a hydrogen atom or a methyl group. Also, in the above formula (1-a), Ar represents a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.)

(In the above formula (1-b), X may be the same or different and represents a hydrogen atom or a methyl group. Also, in the above formula (1-b), Ar represents a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.)
[Item 2]
2. The cellulose derivative according to item 1, wherein in formula (1-a) or (1-b), Ar is a monocyclic aromatic hydrocarbon group.
[Item 3]
2. The cellulose derivative according to item 1, wherein in the formula (1-a) or (1-b), Ar is a polycyclic aromatic hydrocarbon group.
[Item 4]
4. The cellulose derivative according to any one of items 1 to 3, wherein the total average degree of substitution is 1.7 or more.
[Item 5]
5. The cellulose derivative according to any one of items 1 to 4, wherein the protecting group for the hydroxyl group is an acetyl group or a trityl group.
[Item 6]
6. The cellulose derivative according to any one of items 1 to 5, wherein at least one of all R contained in the cellulose derivative having a repeating unit represented by the formula (1) is a group represented by the formula (1-b).
[Item 7]
7. A composition comprising the cellulose derivative according to any one of items 1 to 6.
[Item 8]
A method for producing the cellulose derivative according to item 1, comprising the steps of:
A method for producing a cellulose derivative, comprising: a step (i) of reacting a hydroxyl group at the 2-, 3- or 6-position of a cellulose derivative having a repeating unit represented by the following formula (2) with an α-bromocarboxamide represented by the following formula (3) in the presence of a base catalyst.

[In the above formula (2), R is the same or different and is a hydrogen atom, a protecting group for a hydroxyl group, a group represented by the above formula (1-a), or a group represented by the above formula (1-b). At least one of all R contained in the cellulose derivative having a repeating unit represented by the above formula (2) is a hydrogen atom.]

[In the above formula (3), X is the same or different and represents a hydrogen atom or a methyl group. In addition, in the above formula (3), Ar is a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.]
[Item 9]
Item 9. The method for producing a cellulose derivative according to item 8, wherein at least one of all R contained in the cellulose derivative having a repeating unit represented by formula (2) is a protecting group for a hydroxyl group, a group represented by formula (1-a), or a group represented by formula (1-b), and the cellulose derivative having a repeating unit represented by formula (2) has a total average substitution degree of the protecting group for a hydroxyl group, the group represented by formula (1-a), and the group represented by formula (1-b) of 1.5 or more.
[Item 10]
Item 10. The method for producing a cellulose derivative according to item 8 or 9, wherein in formula (3), Ar is a monocyclic aromatic hydrocarbon group.
[Item 11]
Item 10. The method for producing a cellulose derivative according to item 8 or 9, wherein, in formula (3), Ar is a polycyclic aromatic hydrocarbon group.
[Item 12]
At least one of all R contained in the cellulose derivative having a repeating unit represented by the above formula (2) is a protecting group for a hydroxyl group,
12. The method for producing a cellulose derivative according to any one of items 8 to 11, further comprising, after the step (i), a step (ii) of removing the protecting group for the hydroxyl group and replacing it with a hydroxyl group.
[Item 13]
13. The method for producing a cellulose derivative according to any one of items 8 to 12, wherein the protecting group for the hydroxyl group is an acetyl group or a trityl group.
[Item 14]
Item 14. A method for producing a cellulose derivative according to item 12 or 13, comprising a step (iii) of reacting, in the presence of a base catalyst, an α-bromocarboxamide represented by formula (3) with a hydroxyl group at the 2-, 3- or 6-position of the cellulose derivative obtained in the step (ii), including the hydroxyl group substituted in the step (ii).

The present disclosure will be explained in more detail below with reference to examples, but the present disclosure is not limited to these examples.

Example 1
Cellulose acetate (1 in the following reaction formula (R1), product name "LL-10" (manufactured by Daicel Corporation, average substitution degree of acetyl group about 1.7, 0.10 g, 0.41 mmol) was placed in a two-necked eggplant flask as a raw cellulose derivative, and acetonitrile (0.86 mL) was added under a nitrogen atmosphere and stirred to dissolve. α-bromodimethylacetanilide (2 in the following reaction formula (R1), 0.24 g, 0.80 mmol, 1.5 equivalents) and cesium carbonate (0.52 g, 1.60 mmol, 3.0 equivalents) were added as α-bromocarboxamide, and the mixture was stirred at room temperature (hereinafter also referred to as "rt"; 25°C) for 5 hours. The reaction solution was poured into an aqueous methanol solution (1/1, v/v) to cause reprecipitation, and the resulting solid was collected by suction filtration. The resulting solid was washed with diethyl ether and dried in vacuum to obtain cellulose derivative (1) (0.146 g, yield: 92%) having a repeating unit represented by 3 in the following reaction formula (R1) as a pale orange solid. Note that the term "equivalent" used herein means the relative amount to 1 mole of the total hydroxyl groups at the 2-, 3- or 6-positions of the entire raw cellulose derivative (the same applies to the following Examples and Comparative Examples).

From the results of ¹ H-NMR measurement, the average degree of substitution of the acetyl group in the obtained cellulose derivative (1) was calculated to be about 1.7, the average degree of substitution of the group represented by the above formula (1-a) or (1-b) to be about 1.3, and the total average degree of substitution to be about 3.0.

The chemical shift values of the ¹ H-NMR spectrum of the cellulose derivative obtained in Example 1 are shown below.
¹ H-NMR (500 MHz, CDCl ₃ , r.t.): δ 8.4-8.7 (br), 7.6 (br), 7.2-7.4 (br, overlapped with CHCl ₃ ), 6.3-6.9 (br), 2.8-5.9 (br, CH, CH ₂ : cellulose), 1.8-2.2 (br, CH ₃ : acetyl), 1.2-1.8 (br, CH ₃ : (1-a) or (1-b))

Example 2
Cellulose acetate (1 in the following reaction formula (R1), product name "FL-70" (manufactured by Daicel Corporation, average substitution degree of acetyl group about 2.1, 0.10 g, 0.40 mmol) was placed in a two-necked eggplant flask as a raw cellulose derivative, and tetrahydrofuran (0.86 mL) was added under a nitrogen atmosphere and stirred to dissolve. As α-bromocarboxamide, α-bromodimethylacetanilide (2 in the following reaction formula (R1), 0.13 g, 0.54 mmol, 1.5 equivalents) and cesium carbonate (0.35 g, 0.11 mmol, 3.0 equivalents) were added and stirred at room temperature for 24 hours. The reaction solution was poured into an aqueous methanol solution (1/1, v/v) and reprecipitated, and the resulting solid was collected by suction filtration. The obtained solid was washed with diethyl ether and dried in vacuum to obtain cellulose derivative (1) (0.151 g, yield: 86%) having a repeating unit represented by 3 in the following reaction formula (R1) as a pale orange solid.

From the results of ¹ H-NMR measurement, the average degree of substitution of the acetyl group in the obtained cellulose derivative was calculated to be about 2.1, the average degree of substitution of the group represented by the above formula (1-a) or (1-b) was about 0.9, and the total average degree of substitution was calculated to be about 3.0.

 

 

The ¹ H-NMR spectrum data of the cellulose derivative obtained in Example 2 is shown in FIG. 1, and the chemical shift values are shown below.
¹ H-NMR (500 MHz, CDCl ₃ , r.t.): δ 8.4-8.7 (br), 7.6 (br), 7.2-7.4 (br, overlapped with CHCl ₃ ), 6.3-6.9 (br), 2.8-5.9 (br, CH, CH ₂ : cellulose), 1.8-2.2 (br, CH ₃ : acetyl), 1.2-1.8 (br, CH ₃ : (1-a) or (1-b))

Example 3
Trityl cellulose (4 in the following reaction formula (R2), average substitution degree of trityl group about 1.0, 0.16 g, 0.40 mmol) was placed in a two-necked eggplant flask as a raw cellulose derivative, and tetrahydrofuran (0.86 mL) was added under a nitrogen atmosphere and stirred to dissolve. α-bromodimethylacetanilide (2 in the following reaction formula (R2), 0.29 g, 1.20 mmol, 1.5 equivalents) and cesium carbonate (0.78 g, 2.40 mmol, 3.0 equivalents) were added as α-bromocarboxamide, and the mixture was stirred at room temperature for 24 hours. The reaction solution was poured into an aqueous methanol solution (1/1, v/v) and the resulting solid was collected by suction filtration. The obtained solid was washed with diethyl ether and dried in vacuum to obtain a cellulose derivative (1) (0.250 g, yield: 86%) having a repeating unit represented by 5 in the following reaction formula (R2) as a pale orange solid.

From the results of ¹ H-NMR measurement, the average degree of substitution of the trityl group in the obtained cellulose derivative was calculated to be about 1.0, the average degree of substitution of the group represented by the above formula (1-a) or (1-b) to be about 2.0, and the total average degree of substitution to be about 3.0.

 

 

The chemical shift values of the ¹ H-NMR spectrum of the cellulose derivative obtained in Example 3 are shown below.
¹ H-NMR (500 MHz, CDCl ₃ , r.t.): δ 8.9-9.8 (br, NH), 6.8-8.0 (br, overlapped with CHCl ₃ ), 6.3-6.8 (br), 2.8-6.0 (br, CH, CH ₂ : cellulose), 0.7-1.8 (br, CH ₃ : (1-a) or (1-b))

Example 4
The same procedure as in Example 3 was carried out except that α-bromodimethylaceto(3,4,5-trimethoxy)anilide (6 in the following reaction formula (R3), 0.40 g, 1.20 mmol, 1.5 equivalents) was used instead of α-bromodimethylacetanilide as the α-bromocarboxamide, to obtain a cellulose derivative (1) (0.214 g, yield: 59%) having a repeating unit represented by 7 in (R3) as a pale orange solid.

  From the results of ¹ H-NMR measurement, the average degree of substitution of the trityl group in the obtained cellulose derivative was calculated to be about 1.0, the average degree of substitution of the group represented by the above formula (1-a) or (1-b) to be about 2.0, and the total average degree of substitution to be about 3.0.

The chemical shift values of the cellulose derivative obtained in Example 4 are shown below.
¹ H-NMR (500 MHz, CDCl ₃ , r.t.): δ 9.1-9.4 (br, NH), 8.4 (s), 6.6-7.8 (br, overlapped with CHCl ₃ ), 6.8 (s), 6.2-6.6 (br), 2.3-5.0 (br, CH, CH ₂ : cellulose), 3.85 (s), 3.80 (s), 1.3-1.7 (br, CH ₃ : (1-a) or (1-b)).

Example 5
The same procedure as in Example 3 was carried out except that α-bromodimethylaceto(4-trifluoromethyl)anilide (8 in the following reaction formula (R4), 0.37 g, 1.20 mmol, 1.5 equivalents) was used instead of α-bromodimethylacetanilide as the α-bromocarboxamide, to obtain a cellulose derivative (1) (0.288 g, yield: 72%) having a repeating unit represented by 9 in (R2) as a pale orange solid.

  From the results of ¹ H-NMR measurement, the average degree of substitution of the trityl group in the obtained cellulose derivative was calculated to be about 1.0, the average degree of substitution of the group represented by the above formula (1-a) or (1-b) to be about 2.0, and the total average degree of substitution to be about 3.0.

The chemical shift values of the cellulose derivative obtained in Example 5 are shown below.
¹ H-NMR (500 MHz, CDCl ₃ , r.t.): δ 9.3-9.8 (br, NH), 6.8-8.2 (br, overlapped with CHCl ₃ ), 6.2-6.6 (br), 2.5-5.7 (br, CH, CH ₂ : cellulose), 0.7-2.3 (br, CH ₃ : (1-a) or (1-b))

Example 6
The same procedure as in Example 3 was carried out except that 1-(α-bromodimethylacetoxy)aminopyrene (10 in the following reaction formula (R5), 0.44 g, 1.20 mmol, 1.5 equivalents) was used instead of α-bromodimethylacetanilide as the α-bromocarboxamide, to obtain cellulose derivative (1) (0.260 g, yield: 67%) having a repeating unit represented by 11 in (R5) as a pale orange solid.

  From the results of ¹ H-NMR measurement, the average degree of substitution of the trityl group in the obtained cellulose derivative was calculated to be about 1.0, the average degree of substitution of the group represented by the above formula (1-a) or (1-b) to be about 2.0, and the total average degree of substitution to be about 3.0.

The chemical shift values of the cellulose derivative obtained in Example 6 are shown below.
^1H -NMR (500MHz, CDCl ₃ , rt.): δ 9.5-10.2 (br, NH), 7.6-8.4 (br), 6.6-7.6 (br, overlapped with CHCl ₃ ), 2.5-5.0 (br, CH, CH ₂ :cellulose), 0 .8-2.0 (br, CH ₃ : (1-a) or (1-b), overlapped with H ₂ O)

(Example 7)
The same procedure as in Example 3 was carried out except that α-bromoacetanilide (12 in the following reaction formula (R6), 0.26 g, 1.20 mmol, 1.5 equivalents) was used instead of α-bromodimethylacetanilide as the α-bromocarboxamide, to obtain a cellulose derivative (1) (0.187 g, yield: 70%) having a repeating unit represented by 13 in (R6) as a pale orange solid.

  From the results of ¹ H-NMR measurement, the average degree of substitution of the trityl group in the obtained cellulose derivative was calculated to be about 1.0, the average degree of substitution of the group represented by the above formula (1-a) or (1-b) to be about 2.0, and the total average degree of substitution to be about 3.0.

The chemical shift values of the cellulose derivative obtained in Example 7 are shown below.
¹ H-NMR (500 MHz, CDCl ₃ , r.t.): δ 6.8-7.7 (br, overlapped with CHCl ₃ ), 2.3-4.8 (br, CH, CH ₂ : cellulose), 4.6 (s, CH ₂ : (1-a) or (1-b))

(Example 8)
The cellulose derivative (1) obtained in Example 3 (5, 0.15 g, 0.20 mmol of the following reaction formula (R7)) was placed in a two-necked eggplant flask as a raw cellulose derivative, and chloroform (1 mL) was added under a nitrogen atmosphere and stirred to dissolve. A 30 wt % hydrogen bromide solution in acetic acid (0.4 mL, 2 mmol) was added and stirred at room temperature (25 ° C) for 5 minutes. The reaction solution was poured into an aqueous methanol solution (1/1, v/v) to reprecipitate the solid obtained, which was collected by suction filtration and washed with ethanol. The obtained solid was vacuum dried to obtain a cellulose derivative (1) (0.080 g, yield: 82%) having a repeating unit represented by 14 in the following reaction formula (R7) as a pale orange solid.

From the results of ¹ H-NMR measurement, the average degree of substitution of the group represented by the above formula (1-a) or (1-b) in the obtained cellulose derivative was calculated to be about 2.0, and the total average degree of substitution was calculated to be about 2.0.

 

 

The ¹ H-NMR measurement data of the cellulose derivative obtained in Example 8 is shown in FIG. 2, and the chemical shift values are shown below.
¹ H-NMR (500MHz, DMSO-d6, rt.): δ 9.5-10.0 (br, NH), 7.6 (br), 7.25 (br), 7.0 (br) 6.4-6.8 (br), 2.5-5.5 (br, CH, CH ₂ :cellulose, overlapped wi th H ₂ O), 0.8-1.7 (br, CH ₃ : (1-a) or (1-b))

(Example 9)
The cellulose derivative obtained in Example 7 (14 in the following reaction formula (R8), 0.096 g, 0.20 mmol) was placed in a two-necked eggplant flask as a raw cellulose derivative, and tetrahydrofuran (0.86 mL) was added under a nitrogen atmosphere and stirred to dissolve. As an α-bromocarboxamide, α-bromodimethylacetanilide (2 in the following reaction formula (R8), 0.073 g, 0.30 mmol, 1.5 equivalents) and cesium carbonate (0.20 g, 0.60 mmol, 3.0 equivalents) were added and stirred at room temperature (25° C.) for 18 hours. The reaction solution was poured into an aqueous methanol solution (1/1, v/v) to reprecipitate the solid obtained, which was collected by suction filtration and washed with diethyl ether. The obtained solid was vacuum dried to obtain a cellulose derivative (1) (0.044 g, yield: 34%) having a repeating unit represented by 15 in the following reaction formula (R8) as a pale orange solid.

From the results of ¹ H-NMR measurement, the average degree of substitution of the group represented by the above formula (1-a) or (1-b) of the obtained cellulose derivative was calculated to be about 3.0, and the total average degree of substitution was calculated to be about 3.0.

 

 

The ¹ H-NMR spectrum of the cellulose derivative obtained in Example 9 is shown in FIG. 3, and the chemical shift values are shown below.
¹ H-NMR (500MHz, DMSO-d6, rt.): δ 9.6-10.4 (br, NH), 7.6 (br), 7.25 (br), 7.0 (br) 6.3-6.6 (br), 3.0-6.1 (br, CH, CH ₂ :cellulose, overlapped wi th H ₂ O), 0.9-1.8 (br, CH ₃ : (1-a) or (1-b))

(Comparative Example 1)
Trityl cellulose (4 in the following reaction formula (R9), average substitution degree of trityl group about 1.0, 0.315 g, 0.78 mmol) was placed in a two-necked eggplant flask as a raw material cellulose derivative, and pyridine (3.1 mL) was added under a nitrogen atmosphere and stirred to dissolve. 3-Phenylpropionic acid chloride (described in the following reaction formula (R9), 0.58 mL, 3.90 mmol, 5 equivalents) was added and stirred at 80°C for 24 hours. The reaction solution was poured into methanol for reprecipitation, and the resulting solid was collected by suction filtration. The obtained solid was washed with methanol and dried in vacuum to obtain a 3-phenylpropanoyl cellulose derivative (0.493 g, yield: 94%) having a repeating unit represented by 16 in the following reaction formula (R9) as a pale orange solid.

From the results of ¹ H-NMR measurement, the average degree of substitution of the trityl group in the obtained cellulose derivative was calculated to be about 1.0, the average degree of substitution of the 3-phenylpropanoyl group to be about 2.0, and the total average degree of substitution to be about 3.0.

 

 

The chemical shift values of the ¹ H-NMR spectrum of the cellulose derivative obtained in Comparative Example 1 are shown below.
¹ H-NMR (500 MHz, CDCl ₃ , r.t.): δ 6.2-7.8 (br, overlapped with CHCl ₃ ), 1.7-5.4 (br, CH, CH ₂ : cellulose, CH ₂ : 3-phenylpropanoyl)

The results of the above examples and comparative examples are shown in Table 1.

 

 

Table 1 shows that aromatic amide-modified cellulose with a high degree of substitution was obtained in good yield.

(evaluation)
The cellulose derivative (1) obtained in Example 3 and the 3-phenylpropanoyl cellulose derivative obtained in Comparative Example 1 were subjected to a hydrolysis reaction, and the alkali resistance was evaluated from the change over time in the average substitution degree of the substituents by the following method.

The cellulose derivative obtained in Example 3 (0.071 g, 0.1 mmol) or the 3-phenylpropanoyl cellulose derivative obtained in Comparative Example 1 (0.067 g, 0.1 mmol) was placed in a two-necked eggplant flask as a raw cellulose derivative, and tetrahydrofuran (1 mL) was added and stirred under a nitrogen atmosphere to dissolve. A 10 wt % aqueous sodium hydroxide solution (0.1 mL) was added and stirred at room temperature. After 24 hours, a saturated ammonium chloride solution was added to stop the reaction. The target substance was extracted from the aqueous layer with dichloromethane, dried with sodium sulfate, and the solvent was distilled off with an evaporator. The residue was dried in vacuum, and the degree of substitution was evaluated by ¹ H-NMR measurement. The results are shown in Table 2.

 

 

As shown in Table 2, the cellulose derivative (1) obtained in Example 3 did not show a decrease in the average degree of substitution even when subjected to alkaline hydrolysis conditions, and it is clear that the alkali resistance is improved by converting it into amide-modified cellulose.

Claims (14)

A cellulose derivative having a repeating unit represented by the following formula (1), in which the total average substitution degree of a hydroxyl-protecting group, a group represented by the following formula (1-a), and a group represented by the following formula (1-b) is 1.5 or more.

[In the above formula (1), R may be the same or different and is a hydrogen atom, a protecting group for a hydroxyl group, a group represented by the following formula (1-a), or a group represented by the following formula (1-b). Of all R contained in the cellulose derivative having a repeating unit represented by the above formula (1), at least one is a group represented by the following formula (1-a)]

(In the above formula (1-a), X may be the same or different and represents a hydrogen atom or a methyl group. Also, in the above formula (1-a), Ar represents a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.)

(In the above formula (1-b), X may be the same or different and represents a hydrogen atom or a methyl group. Also, in the above formula (1-b), Ar represents a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.) The cellulose derivative according to claim 1, wherein Ar in formula (1-a) or (1-b) is a monocyclic aromatic hydrocarbon group. The cellulose derivative according to claim 1, wherein Ar in the above formula (1-a) or (1-b) is a polycyclic aromatic hydrocarbon group. The cellulose derivative according to claim 1, wherein the total average degree of substitution is 1.7 or more. The cellulose derivative according to claim 1, wherein the protecting group for the hydroxyl group is an acetyl group or a trityl group. The cellulose derivative according to claim 1, in which at least one of all R contained in the cellulose derivative having the repeating unit represented by formula (1) is a group represented by formula (1-b). A composition comprising the cellulose derivative according to any one of claims 1 to 6. A method for producing the cellulose derivative according to claim 1, comprising the steps of:
A method for producing a cellulose derivative, comprising: a step (i) of reacting a hydroxyl group at the 2-, 3- or 6-position of a cellulose derivative having a repeating unit represented by the following formula (2) with an α-bromocarboxamide represented by the following formula (3) in the presence of a base catalyst.

[In the above formula (2), R is the same or different and is a hydrogen atom, a protecting group for a hydroxyl group, a group represented by the above formula (1-a), or a group represented by the above formula (1-b). At least one of all R contained in the cellulose derivative having a repeating unit represented by the above formula (2) is a hydrogen atom.]

[In the above formula (3), X is the same or different and represents a hydrogen atom or a methyl group. In addition, in the above formula (3), Ar is a monocyclic aromatic hydrocarbon group or a polycyclic aromatic hydrocarbon group.] The method for producing a cellulose derivative according to claim 8, wherein at least one of all R contained in the cellulose derivative having a repeating unit represented by formula (2) is a protecting group for a hydroxyl group, a group represented by formula (1-a) or a group represented by formula (1-b), and the cellulose derivative having a repeating unit represented by formula (2) has a total average substitution degree of 1.5 or more for the protecting group for a hydroxyl group, the group represented by formula (1-a) and the group represented by formula (1-b). The method for producing a cellulose derivative according to claim 8, wherein in formula (3), Ar is a monocyclic aromatic hydrocarbon group. The method for producing a cellulose derivative according to claim 8, wherein in formula (3), Ar is a polycyclic aromatic hydrocarbon group. At least one of all R contained in the cellulose derivative having a repeating unit represented by the above formula (2) is a protecting group for a hydroxyl group,
The method for producing a cellulose derivative according to claim 8, further comprising, after the step (i), a step (ii) of removing the protecting group for the hydroxyl group and replacing it with a hydroxyl group. The method for producing a cellulose derivative according to any one of claims 8 to 12, wherein the protecting group for the hydroxyl group is an acetyl group or a trityl group. The method for producing a cellulose derivative according to claim 12, comprising a step (iii) of reacting the hydroxyl group at the 2-, 3- or 6-position, including the hydroxyl group substituted in step (ii), in the cellulose derivative obtained in step (ii) with an α-bromocarboxamide represented by formula (3) in the presence of a base catalyst.