JP2018083882A - Cellulose derivative, metal removal material containing the same, and metal removal method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cellulose derivative capable of selectively adsorbing and recovering a metal. SOLUTION: A cellulose derivative represented by the following formula (1). [R is a group represented by H, formula (a) or formula (b); at least one of R is a group represented by the following formula (a), and at least one is represented by the following formula (b). Group represented by] [Selection diagram] None

Description

  The present invention relates to a novel cellulose derivative, a production method thereof, a metal removing material containing the cellulose derivative, and a metal removing method using the cellulose derivative.

  Heavy metals such as arsenic, cadmium, and lead are used in various fields. For example, arsenic is used as pharmaceuticals, insecticides, rodenticides, preservatives, high-tech industrial materials, and the like. For this reason, the heavy metal may be dissolved in the formation, ocean, river, well water, etc., but it is known that even a trace amount may cause environmental pollution. Therefore, a method for efficiently recovering and removing the heavy metal from soil and seawater contaminated with the heavy metal, industrial waste liquid, mine drainage and the like is desired.

  In Patent Document 1, a cellulose-based adsorbent in which a graft chain is introduced onto the surface of a cellulose-based substrate and a chelate-forming group or an ion-exchange group is bonded to the introduced graft chain is easily compatible with water, and boron and germanium. And adsorbing power of semimetals such as arsenic or heavy metals. The amount of the chelate-forming group or ion exchange group that exerts the adsorptive power of the metal depends on the introduction rate of the graft chain, and if the introduction rate of the graft chain is low, the chelate formation that effectively acts on the metal adsorption It is described that the bonding amount of the group or ion exchange group cannot be ensured sufficiently. However, since cellulose-based substrates have low solubility in organic solvents, it is very difficult to introduce graft chains efficiently, and graft chains can be introduced only by a method using an expensive apparatus such as a radiation graft method. The problem was that the rate could not be improved and the cost increased.

JP 2009-13204 A

Accordingly, an object of the present invention is to provide a novel cellulose derivative that can be produced at low cost, can selectively adsorb and recover a metal, and a method for producing the same.
Another object of the present invention is to provide a metal removing material that can be produced at low cost and can selectively adsorb and recover metals.
Another object of the present invention is to provide a method for selectively adsorbing and recovering metal at a low cost.

  As a result of intensive investigations by the present inventors to solve the above-mentioned problems, acylated cellulose has excellent solubility in organic solvents and can introduce a dithiocarbamate group efficiently and inexpensively. It has been found that a cellulose derivative provided with is excellent in metal adsorption and useful as a metal removal material. The present invention has been completed based on these findings.

［式中、Ｒは、同一又は異なって、水素原子、下記式（ａ）で表される基、又は下記式（ｂ）で表される基である。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（ａ）で表される基であり、少なくとも１つは下記式（ｂ）で表される基である］

（式中、Ｒ¹は単結合又は炭素数１〜１０のアルキレン基を示し、Ｒ²は水素原子又は炭素数１〜１０のアルキル基を示す。Ｒ³、Ｒ⁴は、同一又は異なって、炭素数１〜１０のアルキル基を示す） That is, this invention provides the cellulose derivative which has a repeating unit represented by following formula (1).

[In formula, R is the same or different, and is a hydrogen atom, group represented by the following formula (a), or group represented by the following formula (b). Among all R contained in the cellulose derivative, at least one is a group represented by the following formula (a), and at least one is a group represented by the following formula (b)]

(In the formula, R ¹ represents a single bond or an alkylene group having 1 to 10 carbon atoms, R ² represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R ³ and R ⁴ are the same or different, (It represents an alkyl group having 1 to 10 carbon atoms)

  The present invention also provides the above cellulose derivative, wherein the molar ratio of the group represented by formula (a) to the group represented by formula (b) (the former / the latter) is 1/99 to 99/1. To do.

（式中、Ｒ³は、同一又は異なって、炭素数１〜１０のアルキル基を示し、Ｒ⁵は同一又は異なって、水素原子又は炭素数１〜３のアルキル基を示す。ｎは１〜３の整数を示す） The present invention also provides the above cellulose derivative, wherein the group represented by the formula (a) is a group represented by the following formula (a-1).

(In the formula, R ³ is the same or different and represents an alkyl group having 1 to 10 carbon atoms; R ⁵ is the same or different and represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; Indicates an integer of 3)

  The present invention also provides the above cellulose derivative, wherein the group represented by the formula (b) is an acetyl group.

  In the present invention, the total average substitution degree of the group represented by the formula (a) is 0.2 to 2.1, and the total average substitution degree of the group represented by the formula (b) is 0.9 to The cellulose derivative is 2.8.

The present invention also provides a method for producing a cellulose derivative, wherein the cellulose derivative is obtained through the following steps.
[1] Amino group-protected amino acid is reacted with the hydroxyl group of acylated cellulose (total average substitution degree of acyl group: 0.9 to 2.8), and then the amino group protecting group is removed [2 ] the presence of sulfur compounds, quaternary ammonium salt to an amino group deprotection _{^{(N + (R 3) 4}} X -; R 3 are the same or different and each represents an alkyl group having 1 to 10 carbon atoms, X ^- Represents a counter anion)

  The present invention also provides a metal adsorbent containing the cellulose derivative.

  The present invention also provides a metal removal method using the cellulose derivative.

  The cellulose derivative of the present invention can be produced at low cost, and can selectively adsorb and recover metals (for example, heavy metals such as arsenic, cadmium and lead). Further, the cellulose derivative of the present invention is excellent in chemical resistance, heat resistance, and water resistance. Therefore, the cellulose derivative of the present invention is extremely useful as a metal removing material, and is suitably used for the purpose of purifying soil and seawater contaminated with metal, industrial wastewater containing the metal, mine wastewater, hot spring water, etc. can do.

2 is a graph showing an IR spectrum of a cellulose derivative (MI96) obtained in Example 1. FIG. 2 is a graph showing an IR spectrum of a cellulose derivative (MI98) obtained in Example 2. FIG. 6 is a graph showing an IR spectrum of a cellulose derivative (MI77) obtained in Example 4. FIG. 6 is a graph showing an IR spectrum of a cellulose derivative (MI64) obtained in Example 5. FIG. It is a figure which shows the pH dependence of the metal adsorption power of a cellulose derivative. It is a figure which shows the arsenic adsorption power of the cellulose derivative obtained in the Example. It is a figure which shows the adsorptive power with respect to arsenic, cadmium, and lead of a cellulose derivative and acetylcellulose.

［式中、Ｒは、同一又は異なって、水素原子、下記式（ａ）で表される基、又は下記式（ｂ）で表される基である。前記式（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（ａ）で表される基であり、少なくとも１つは下記式（ｂ）で表される基である］

（式中、Ｒ¹は単結合又は炭素数１〜１０のアルキレン基を示し、Ｒ²は水素原子又は炭素数１〜１０のアルキル基を示す。Ｒ³、Ｒ⁴は、同一又は異なって、炭素数１〜１０のアルキル基を示す） [Cellulose derivative]
The cellulose derivative of the present invention has a repeating unit (glucose unit) represented by the following formula (1).

[In formula, R is the same or different, and is a hydrogen atom, group represented by the following formula (a), or group represented by the following formula (b). Among all R contained in the cellulose derivative having a repeating unit represented by the formula (1), at least one is a group represented by the following formula (a), and at least one is the following formula (b). Is a group represented by

(In the formula, R ¹ represents a single bond or an alkylene group having 1 to 10 carbon atoms, R ² represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R ³ and R ⁴ are the same or different, (It represents an alkyl group having 1 to 10 carbon atoms)

Examples of the alkylene group having 1 to 10 carbon atoms in R ¹ include methylene group, methylmethylene group, dimethylmethylene group, ethylene group, 2-methylethylene group, 1,2-dimethylethylene group, propylene group, trimethylene group, A linear or branched alkylene group such as a 2-methyl-trimethylene group can be exemplified.

As R ¹ , the longer the carbon chain between the cellulose main chain skeleton and the dithiocarbamate group, the more the metal adsorbing power tends to be improved.

Examples of the alkyl group having 1 to 10 carbon atoms in R ² , R ³ and R ⁴ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, an s-butyl group, a t-butyl group, A linear or branched alkyl group such as a pentyl group can be exemplified.

R ² is particularly preferably a hydrogen atom. As the R ^3, R ^4, which preferable is an alkyl group having 1 to 3 carbon atoms.

As the group represented by the formula (a), among them, a group represented by the following formula (a-1) (wherein n represents an integer of 1 to 3, R ⁵ is the same or different, An atom or an alkyl group having 1 to 3 carbon atoms, wherein R ³ is the same as above, and particularly preferably, among the groups represented by the following formula (a-1), n in the formula is a group of 2 is there.

More preferably, the group represented by the formula (a) is a group represented by the following formula (a-1 ′) (wherein n represents an integer of 1 to 3, and R ⁵ are the same or different, A hydrogen atom or an alkyl group having 1 to 3 carbon atoms), and particularly preferably, in the group represented by the following formula (a-1 ′), n is a group of 2.

The group represented by the formula (a) is particularly preferably a group represented by the following formula (a-1-1) or (a-1-2), particularly preferably the following formula (a-1- It is a group represented by 2). In the following formula, R ³ is the same as described above.

The group represented by the formula (a) is most preferably a group represented by the following formula (a-1′-1) or (a-1′-2), particularly preferably the following formula (a- It is a group represented by 1′-2).

  Among them, an acetyl group is preferable as the group represented by the formula (b).

  A group represented by formula (a) (preferably a group represented by formula (a-1), more preferably a group represented by formula (a-1 ′), more preferably a group represented by formula (a-1-1) ) And a group represented by (a-1-2), most preferably a group represented by formula (a-1'-1) and (a-1'-2) Group) as the total average substitution degree (total average substitution degree of the above-mentioned groups substituted at the 2, 3 and 6 positions of the glucose units constituting the cellulose), for example, 0.2 to 2.1, preferably 0.2 to 1.8, particularly preferably 0.5 to 1.5. It is preferable that the cellulose derivative contains the group represented by the formula (a) in the above range in that an excellent metal adsorbing power can be exhibited.

  Examples of the total average substitution degree of the group represented by the formula (b) (particularly preferably an acetyl group) (total average substitution degree of the group substituted at the 2, 3 and 6-positions of the glucose units constituting the cellulose) include, for example: It is 0.9 to 2.8, preferably 1.2 to 2.8, particularly preferably 1.5 to 2.5, and most preferably 1.8 to 2.5.

  The cellulose derivative of the present invention has an excellent metal adsorption power (the amount of metal adsorption is, for example, 0.1 μmol / g or more, preferably 0.3 μmol / g or more, particularly preferably 0.5 μmol / g or more). In particular, it has an excellent adsorption capacity for heavy metals such as As (III), Cd (II), and Pb (II). The adsorption amount of As (III) is, for example, 0.1 μmol / g or more, the adsorption amount of Cd (II) is, for example, 0.5 μmol / g or more, and the adsorption amount of Pb (II) is, for example, 0.6 μmol / g or more. It is.

  The shape of the cellulose derivative of the present invention is not particularly limited as long as the effects of the present invention are not impaired, and for example, a sheet shape, a spherical shape (such as a true spherical shape, a substantially true spherical shape, an elliptic spherical shape), a polyhedral shape, a rod shape ( Columnar shape, prismatic shape, etc.), flake shape, and indefinite shape.

  Since the cellulose derivative of the present invention has an excellent metal adsorption force as described above, it can be suitably used, for example, as a metal adsorbent.

  The metal adsorbent containing the cellulose derivative of the present invention (or the metal adsorbent comprising the cellulose derivative of the present invention) is, for example, a metal (in particular, a heavy metal such as As (III), Cd (II), Pb (II)). It can be suitably used for the purpose of purifying soil and seawater contaminated with water, other industrial wastewater containing the metal, mine wastewater, hot spring water, and the like.

  Soil or seawater contaminated with metals (especially heavy metals such as As (III), Cd (II), Pb (II)) using the metal removal method of the present invention, that is, the cellulose derivative of the present invention as a metal adsorbent. In addition, the method for adsorbing and removing metal from industrial wastewater containing the metal, mine wastewater, hot spring water, etc. is not particularly limited, for example, the cellulose derivative of the present invention is packed in a column or the like, and Examples thereof include a method of flowing industrial wastewater and the like, a method of adding the cellulose derivative of the present invention to industrial wastewater and the like, and stirring. In particular, when the cellulose derivative of the present invention exhibits solubility in organic solvents, it can also be used as a homogeneous metal adsorbent (that is, a material that adsorbs and removes metal in a state dissolved in industrial waste water or the like). .

  In the metal removal method of the present invention, adjusting the pH of the cellulose derivative to, for example, 1 to 9 (especially 1 to 7) can further improve the metal adsorption force and efficiently remove the metal. It is preferable in that it can be performed. In addition, pH adjustment of a cellulose derivative can be performed using a well-known and usual pH adjuster (acids, such as nitric acid, and alkalis, such as sodium hydroxide).

  Moreover, a metal can be easily collect | recovered by baking the cellulose derivative which adsorb | sucked the metal, and the collect | recovered metal can be utilized as a useful resource again.

[Method for producing cellulose derivative]
The cellulose derivative of this invention can be manufactured through the following process, for example.
[1] Acylated cellulose (in which a part of hydroxyl groups of cellulose is substituted with an acyl group [—COR ⁴ ] (R ⁴ is the same as above), the total average substitution degree of acyl groups: 0.9-2. 8) reacting an amino group-protected amino acid with the hydroxyl group, and then removing the amino-group-protecting group. [2] In the presence of a sulfur compound, the deprotected amino group is converted to a quaternary ammonium salt (N ⁺ (R ³ ) ₄ X ⁻ ; R ³ is the same or different and represents an alkyl group having 1 to 10 carbon atoms, and X ⁻ represents a counter anion).

  The acylated cellulose having a total average substitution degree of acyl groups used in the step [1] of 0.9 to 2.8 is obtained by, for example, reacting a hydroxyl group of cellulose with an acylating agent to form a hydroxyl group of cellulose. Can be produced by deacylating a part of the acyl group in the obtained triacylated cellulose (see, for example, JP-A-56-59801).

  As the cellulose, for example, wood pulp (softwood pulp, hardwood pulp), cellulose derived from cotton linter pulp, or the like can be suitably used. These can be used alone or in combination of two or more. The pulp may contain a different component such as hemicellulose. Cellulose is preferably used in a finely pulverized state, for example, by pulverization.

  The total average substitution degree of acyl groups in the acylated cellulose is 0.9 to 2.8, preferably 1.2 to 2.8, particularly preferably 1.5 to 2.5, and most preferably 1.8 to 2.5. When an acylated cellulose having a total average degree of substitution of acyl groups in the above range is used as a reaction substrate, an acylated cellulose having a total average degree of substitution of acyl groups in the above range is out of the above range. Compared with acylated cellulose, it has better solubility in solvents and can be reacted with amino acids whose amino groups are protected in an organic solvent, improving the introduction rate of the group represented by formula (a) It is possible to produce a cellulose derivative that exhibits excellent metal adsorbing power.

  Examples of acylated cellulose include commercially available products such as trade names “L-20”, “L-30”, “L-50”, and “L-70” (above, acetylcellulose, manufactured by Daicel Corporation). It can be preferably used.

The amino acid in which the amino group is protected is represented, for example, by the following formula (3).
HOOC-R ¹ -NHY (3)
R ¹ in the formula (3) corresponds to R ¹ in the formula (a). Y is a protecting group for protecting an amino group, and examples thereof include a t-butoxycarbonyl group (Boc) and a 9-fluorenylmethyloxycarbonyl group (Fmoc). As the amino-protecting group, Fmoc is particularly preferable because it can be deprotected under mild conditions.

The amino acid before protecting the amino group is represented by the following formula (3 ′).
HOOC-R ¹ —NH ₂ (3 ′)
R ¹ in the formula (3 ') in correspond to R ¹ in the formula (a). Examples of the amino acid before protecting the amino group (= compound represented by the formula (3 ′)) include, for example, L-alanine, β-alanine, 4-aminobutyric acid, 5-aminopentanoic acid, and 7-aminoheptanoic acid. Etc.

  The reaction between the acylated cellulose and an amino group-protected amino acid is preferably performed in the presence of a catalyst. Examples of the catalyst include triethylamine, pyridine, N, N-dimethyl-4-aminopyridine (DMAP), and the like. These can be used alone or in combination of two or more.

  The amount of the catalyst used is, for example, about 0.01 to 1.0 mol with respect to 1 mol of amino acid in which the amino group is protected.

  The reaction is preferably performed in the presence of a condensing agent. Examples of the condensing agent include 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (EDC-HCl), N, N′-dicyclohexylcarbodiimide, N, N′-diisopropylcarbodiimide and the like. it can. These can be used alone or in combination of two or more.

  The amount of the condensing agent used is, for example, about 0.01 to 1.0 mol with respect to 1 mol of the amino acid whose amino group is protected.

  The reaction is preferably performed in the presence of a solvent. Examples of the solvent include aliphatic hydrocarbons such as hexane, heptane, and octane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; chloroform, dichloromethane, 1,2- Halogenated hydrocarbons such as dichloroethane; ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran, and dioxane; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as methyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate; N, N -Amides such as dimethylformamide and N, N-dimethylacetamide; Nitriles such as acetonitrile, propionitrile and benzonitrile; Alcohols such as methanol, ethanol, isopropyl alcohol and butanol; Sulfoxide, and the like. These can be used individually by 1 type or in combination of 2 or more types.

  The amount of the solvent used is, for example, about 0.5 to 30 times the total amount of the reaction substrate. When the usage-amount of a solvent exceeds the said range, the density | concentration of a reaction component will become low and there exists a tendency for reaction rate to fall.

Through the reaction, from acylated cellulose (1-1), at least one part of hydroxyl group (OH group) in acylated cellulose is —OOC—R ¹ —NHY group (Y is an amino group protecting group, The compound (1-2) substituted with Y in formula (3) is obtained.

In the reaction for removing the amino protecting group, the amino group protecting group (Y) in the compound (1-2) obtained through the above reaction is removed, and at least one part of the hydroxyl group (OH group) in the acylated cellulose is removed. , -OOC-R ¹ —NH ₂ is a reaction for obtaining a compound (1-3) substituted with a group. The reaction for removing the protecting group is preferably selected as appropriate according to the kind of the protecting group. For example, when Y is Fmoc, the protecting group can be quickly removed by reacting with a secondary amine such as pyridine. When Y is Boc, the protecting group can be quickly removed by reacting with a strong acid such as trifluoroacetic acid.

In the step [2], the deprotected amino group, that is, the —OOC—R ¹ —NH ₂ group in the compound (1-3) obtained through the step [1] The cellulose of the present invention is reacted with a quaternary ammonium salt (N ⁺ (R ³ ) ₄ X ⁻ ; R ³ is the same or different and represents an alkyl group having 1 to 10 carbon atoms, and X ⁻ represents a counter anion). This is a step of obtaining a derivative.

Examples of the counter anion (X ⁻ ) in the quaternary ammonium salt include OH ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , F ⁻ , SO ₄ ²⁻ , BH ₄ ⁻ , BF ₄ ⁻ , PF ₆ ^{− and the} like. Is mentioned.

  Examples of the quaternary ammonium salt include tetramethylammonium hydroxide and tetraethylammonium hydroxide.

  The amount of the quaternary ammonium salt used is, for example, about 20 to 500 parts by weight with respect to 100 parts by weight of the compound (1-3).

  Examples of the sulfur compound include carbon disulfide. The usage-amount of a sulfur compound is 100 weight part or more with respect to 100 weight part of said compounds (1-3), for example.

  The reaction in step [2] is preferably performed in the presence of a solvent. Examples of the solvent include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; alcohols such as methanol, ethanol, 2-propanol, isopropyl alcohol, and butanol; N-methylpyrrolidone, dimethyl sulfoxide, N, N-dimethylformamide, and the like. Is mentioned. These can be used individually by 1 type or in combination of 2 or more types. The amount of solvent used is, for example, about 0.5 to 30 times the total amount of the reaction substrate.

  The reaction temperature of process [2] is about 10-100 degreeC, for example. The reaction time is, for example, about 1 to 24 hours. After completion of the reaction, the obtained reaction product can be separated and purified by separation means such as filtration, concentration, distillation, extraction, crystallization, adsorption, recrystallization, column chromatography, etc., or a separation means combining these.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by these Examples.

Example 1 (Preparation of cellulose derivative (MI96))
In a nitrogen atmosphere, acetylcellulose (total average substitution degree of acetyl groups: 2.4, 6% viscosity: 53 mPa · s) (4.02 g, 15.3 mmol) was placed in a two-necked eggplant flask and vacuumed at 80 ° C. for 2 hours. Dried. Fmoc-β-alanine (3.13 g, 10.1 mmol), dichloromethane (76 mL), and DMAP (1.23 g, 10.1 mmol) were added to the reaction vessel, and then the reaction system was cooled to 0 ° C.
Further, EDC-HCl (1.93 g, 10.1 mmol) was added, and then the reaction system was returned to room temperature and stirred overnight.
After the solvent was distilled off under reduced pressure, a DMSO / piperidine mixed solvent (DMSO / piperidine = 80/20 (v / v), 76 mL) was added under nitrogen, and the mixture was stirred at room temperature for 2 hours. The precipitated solid was washed with methanol and collected by centrifugation. Vacuum drying was performed to obtain a compound represented by the following formula (I) as a white solid (3.30 g, 71%). ^From the result of ¹ H-NMR measurement, the total average substitution degree of Fmoc-β-alanine was calculated to be 0.47.
¹ H-NMR (500 MHz, DMSO-d6): δ5.61-3.26 (glucose ring, CH ₂ ), 2.92-2.70 (CH ₂ ), 2.21-1.69 (Acetyl)

To a mixed solution of toluene (320 mL), 2-propanol (32 mL), CS ₂ (64 mL), 10% tetramethylammonium hydroxide (8 mL), the compound represented by the above formula (I) (2.04 g, 6. 67 mmol) in DMSO (32 mL) was slowly added dropwise and stirred at room temperature for 2 hours under light shielding. The progress of the reaction was confirmed by the appearance of C═S absorption at 1489 cm ⁻¹ by IR measurement (see FIG. 1). The precipitated solid was washed with methanol and collected by centrifugation. Vacuum drying gave MI96 (2.15 g, 82%) as a white solid. From the result of elemental analysis (S), the total average substitution degree of the dithiocarbamate group (—CS ₂ ⁻ ) of MI96 was calculated to be 0.13.

Example 2 (Preparation of cellulose derivative (MI98))
Under a nitrogen atmosphere, acetylcellulose (total average substitution degree of acetyl groups: 1.7) (2.02 g, 8.63 mmol) was placed in a two-necked eggplant flask and vacuum dried at 80 ° C. for 2 hours. Fmoc-β-alanine (3.80 g, 12.2 mmol), dichloromethane (42 mL), and DMAP (1.50 g, 12.3 mmol) were added to the reaction vessel, and then the reaction system was cooled to 0 ° C. Further, EDC-HCl (2.34 g, 12.2 mmol) was added, and then the reaction system was returned to room temperature and stirred overnight. After the solvent was distilled off under reduced pressure, a DMSO / piperidine mixed solvent (DMSO / piperidine = 80/20 (v / v), 42 mL) was added under nitrogen, and the mixture was stirred at room temperature for 2 hours. The precipitated solid was washed with methanol and collected by centrifugation. Vacuum drying was performed to obtain a compound represented by the following formula (II) as a white solid (2.16 g, 77%). ^From the result of ¹ H-NMR measurement, the total average substitution degree of Fmoc-β-alanine was calculated to be 1.01.
¹ H-NMR (500 MHz, DMSO-d6): δ 5.45-3.18 (glucose ring, CH ₂ ), 2.86-2.59 (CH ₂ ), 2.10-1.79 (Acetyl)

To a mixed solution of toluene (160 mL), 2-propanol (16 mL), CS ₂ (32 mL), 10% tetramethylammonium hydroxide (4 mL), a compound represented by the above formula (II) (1.0 g, 3. (08 mmol) in DMSO (15.4 mL) was slowly added dropwise, and the mixture was stirred at room temperature for 2 hours in the dark. Progress of the reaction was confirmed by the appearance of C = S absorption at 1489 cm ⁻¹ by IR measurement (see FIG. 2). The precipitated solid was washed with methanol and collected by centrifugation. Vacuum drying gave MI98 (0.89 g, 56%) as a white solid. From the results of elemental analysis (S), the total average substitution degree of the dithiocarbamate group (—CS ₂ ⁻ ) of MI98 was calculated to be 0.33.

Example 3 (Preparation of cellulose derivative (MI101))
Instead of acetyl cellulose (total average substitution degree of acetyl groups: 2.4, 6% viscosity: 53 mPa · s), acetyl cellulose (total average substitution degree of acetyl groups: 2.4, 6% viscosity: 132 mPa · s) In the same manner as in Example 1 except that was used, MI101 was obtained as a white solid. From the results of elemental analysis (S), the total average substitution degree of the dithiocarbamate group (—CS ₂ ⁻ ) of MI101 was calculated to be 0.13.

Example 4 (Preparation of cellulose derivative (MI77))
Under a nitrogen atmosphere, acetylcellulose (total average substitution degree of acetyl group 2.4) (5.02 g, 19.1 mmol) was placed in a two-necked eggplant flask and vacuum dried at 80 ° C. for 2 hours. Boc-L-alanine (3.24 g, 17.1 mmol), DMSO (95 mL), DMAP (2.10 g, 17.1 mmol) were added to the reaction vessel, and then the reaction system was cooled to 0 ° C. Further, EDC-HCl (3.32 g, 17.3 mmol) was added, and then the reaction system was returned to room temperature and stirred overnight. A solid precipitated by reprecipitation in a mixed solvent of MeOH / H ₂ O (80/20, v / v) was collected by centrifugation. It vacuum-dried at 60 degreeC and the compound represented by following formula (III) was obtained as a white solid (5.60g, 80%). ^From the result of ¹ H-NMR measurement, the total average substitution degree of Boc-L-alanine was calculated to be 0.30.
¹ H-NMR (500 MHz, DMSO-d6) δ7.23-6.59 (NH), 5.56-3.35 (glucose ring, CH), 2.14-1.75 (Acetyl), 1.47-1.35 (Boc), 1.35-1.04 (CH ₃ )

Under a nitrogen atmosphere, a compound represented by the above formula (III) (2.26 g, 6.18 mmol), dichloromethane (64 mL), trifluoroacetic acid (1.48 mL, 19.3 mmol) was placed in a two-necked eggplant flask at room temperature. And stirred overnight. After removing the supernatant of the gelled reaction system, the gel was dissolved in MeOH and reprecipitated in a saturated aqueous sodium bicarbonate solution. The precipitated solid was collected by centrifugation and vacuum-dried to obtain a compound represented by the following formula (IV) as a white solid (1.95 g, 103%).
¹ H-NMR (500 MHz, DMSO-d6) δ7.22-6.53 (NH ₂ ), 5.73-3.28 (glucose ring, CH), 2.28-1.64 (Acetyl), 1.35-1.01 (CH ₃ )

Compound (1) represented by the above formula (IV) finely crushed in a mortar into a mixed solution of toluene (160 mL), 2-propanol (16 mL), CS ₂ (32 mL), 10% tetramethylammonium hydroxide (4 mL) 0.000 g, 3.27 mmol) was added, and the mixture was stirred at room temperature for 2 hours under light shielding. The progress of the reaction was confirmed by the appearance of C═S absorption at 1489 cm ⁻¹ by IR measurement (see FIG. 3). The solid in the reaction system was washed with methanol and collected by centrifugation. Vacuum drying gave MI77 (1.00 g, 87%) as a white solid.

Example 5 (Preparation of cellulose derivative (MI64))
Under a nitrogen atmosphere, acetylcellulose (total average substitution degree of acetyl group 1.7) (3.01 g, 12.9 mmol) was placed in a two-necked eggplant flask and vacuum dried at 80 ° C. for 2 hours. Boc-L-alanine (4.71 g, 24.9 mmol), DMSO (64 mL), DMAP (3.07 g, 25.1 mmol) were added to the reaction vessel, and the reaction system was cooled to 0 ° C. Furthermore, after adding EDC-HCl (4.77 g, 24.9 mmol), the reaction system was returned to room temperature and stirred overnight. A solid precipitated by reprecipitation in a mixed solvent of MeOH / H ₂ O (70/30, v / v) was collected by centrifugation. The mixture was heated at 60 ° C. and vacuum dried to obtain a compound represented by the following formula (V) as a white solid (4.13 g, 71%). ^From the result of ¹ H-NMR, the degree of substitution of Boc-L-alanine was calculated to be 0.91.
¹ H-NMR (500 MHz, DMSO-d6) δ 7.31-6.16 (NH), 5.39-3.38 (glucose ring, CH), 2.24-1.66 (Acetyl), 1.48-1.35 (Boc), 1.34-1.07 (CH ₃ )

Under a nitrogen atmosphere, a compound represented by the above formula (V) (2.00 g, 4.40 mmol), dichloromethane (44 mL), trifluoroacetic acid (2.17 mL, 28.4 mmol) was added to a two-necked eggplant flask at room temperature. And stirred overnight. After removing the supernatant of the gelled reaction system, the gel was dissolved in MeOH and reprecipitated in a saturated aqueous sodium bicarbonate solution. The precipitated solid was collected by centrifugation and vacuum dried to obtain a compound represented by the following formula (VI) as a white solid (0.593 g, 41%).
¹ H-NMR (500 MHz, DMSO-d6) δ7.96-7.66 (NH), 5.26-3.33 (glucose ring, CH), 2.26-1.70 (Acetyl), 1.33-1.01 (CH ₃ )

In the above formula (VI) finely crushed in a mortar into a mixed solution of toluene (64 mL), 2-propanol (6.4 mL), CS ₂ (12.8 mL), 10% tetramethylammonium hydroxide (1.60 mL). The compound represented (0.378 g, 1.16 mmol) was added, and the mixture was stirred at room temperature for 2 hours in the dark. The progress of the reaction was confirmed by the appearance of C═S absorption at 1489 cm ⁻¹ by IR measurement (see FIG. 4). The solid in the reaction system was washed with methanol and collected by centrifugation. Vacuum drying gave MI64 (0.350 g, 72%) as a white solid.

Evaluation [1] The pH dependence of the metal adsorption force of the cellulose derivative was evaluated by the following method.
1. Preparation of sample solution and buffer solution Diarsenic trioxide (As (III)) (special grade; manufactured by Wako Pure Chemical Industries, Ltd.), disodium hydrogen arsenate heptahydrate (As (V)) (special grade; sum A sample solution was prepared by dissolving sodium cacodylate (DMA (V)) (for electron microscope; manufactured by Nacalai Tesque) in 0.01 M NaOH solution. For the buffer solution, the following reagents were dissolved in purified water to prepare a 0.1M buffer solution, and the pH was adjusted by adding a small amount of 1M nitric acid or 1M NaOH solution.

2. Preparation of solid phase column and solid phase extraction About 1 g of the cellulose derivative (MI96) obtained in Example 1 was transferred to a mortar and ground with a pestle until the particle size was about 2 mm or less. The parts that were hard and could not be crushed with a pestle were cut with scissors.
0.050 g of the pulverized cellulose derivative (MI96) was weighed, filled into a Teflon (registered trademark) tube having an inner diameter of 2 mm and a length of 3 cm, and Teflon (registered trademark) wool was packed at both ends to prepare a solid phase column. .
A silicon tube having an inner diameter of 2 mm was connected to the obtained solid phase column, and each solution was fed by a tube pump (Perista Pump, manufactured by ASONE Corporation). First, 10 mL of 0.1 M buffer solution was sent to the solid phase column to adjust the pH in the column, and then 5 mL of 10-5 M sample solution was passed at a flow rate of 5 mL / min to perform solid phase extraction of arsenic. 1 mL of 1M HCl was added to 5 mL of the eluate and stored. The metal concentration in each eluate was quantified by ICP-OES (Thermo Fisher Scientific Co., Ltd., iCAP6300DUO), and the amount of adsorption by the solid phase was determined. The results are shown in FIG. From FIG. 5, it was found that the cellulose derivative of the present invention can exhibit particularly excellent metal adsorbing power in the pH range of 1-7.

[2] The arsenic adsorption power in each cellulose derivative was evaluated by the following method.
A sample solution was prepared by dissolving diarsenic trioxide (As (III)) (special grade; manufactured by Wako Pure Chemical Industries, Ltd.) in a 0.01 M NaOH solution.
Using the cellulose derivative obtained in the example, a solid phase column was prepared in the same manner as described above, and 5 mL of the sample solution was passed through the solid phase column at 5 mL / min. The amount was determined (however, the pH in the column was 2.5 or 3). The results are shown in FIG. From FIG. 6, it was found that the longer carbon chain between the cellulose main chain skeleton and the dithiocarbamate group has better arsenic adsorption power.

[3] Adsorption power of each cellulose derivative for each metal was evaluated by the following method.
As a sample solution, 10 ⁻⁵ M As (III), Pb (II), Cd (II) /0.1M MES buffer solution (pH 3) was prepared.
Cellulose derivative (MI64) obtained in Example 5, acetylcellulose (total average substitution degree of acetyl group 1.7) (= AC (1.7)), and acetylcellulose (total average substitution degree of acetyl group 2. 4) Using (= AC (2.4)), a solid phase column was prepared in the same manner as described above, and 5 mL of the sample solution was passed through the solid phase column at 5 mL / min. , Cadmium, and lead adsorption were determined. The results are shown in FIG. From FIG. 7, it was found that the cellulose derivative of the present invention has a remarkably superior adsorptive power for arsenic, cadmium, and lead as compared with acetylcellulose.

Claims (8)

A cellulose derivative having a repeating unit represented by the following formula (1).

[In formula, R is the same or different, and is a hydrogen atom, group represented by the following formula (a), or group represented by the following formula (b). Among all R contained in the cellulose derivative, at least one is a group represented by the following formula (a), and at least one is a group represented by the following formula (b)]

(In the formula, R ¹ represents a single bond or an alkylene group having 1 to 10 carbon atoms, R ² represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R ³ and R ⁴ are the same or different, (It represents an alkyl group having 1 to 10 carbon atoms)   The cellulose derivative according to claim 1, wherein the molar ratio (the former / the latter) of the group represented by the formula (a) and the group represented by the formula (b) is 1/99 to 99/1. The cellulose derivative according to claim 1 or 2, wherein the group represented by the formula (a) is a group represented by the following formula (a-1).

(In the formula, R ³ is the same or different and represents an alkyl group having 1 to 10 carbon atoms; R ⁵ is the same or different and represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; Indicates an integer of 3)   The cellulose derivative according to any one of claims 1 to 3, wherein the group represented by the formula (b) is an acetyl group.   The total average substitution degree of the group represented by the formula (a) is 0.2 to 2.1, and the total average substitution degree of the group represented by the formula (b) is 0.9 to 2.8. The cellulose derivative according to any one of claims 1 to 4. The manufacturing method of a cellulose derivative which obtains the cellulose derivative of any one of Claims 1-5 through the following process.
[1] Amino group-protected amino acid is reacted with the hydroxyl group of acylated cellulose (total average substitution degree of acyl group: 0.9 to 2.8), and then the amino group protecting group is removed [2 ] the presence of sulfur compounds, quaternary ammonium salt to an amino group deprotection _{^{(N + (R 3) 4}} X -; R 3 are the same or different and each represents an alkyl group having 1 to 10 carbon atoms, X ^- Represents a counter anion)   The metal adsorbent containing the cellulose derivative of any one of Claims 1-5.   The metal removal method using the cellulose derivative of any one of Claims 1-5.

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