KR101981365B1 - Ionic liquid which has a low cellulose decomposition efficiency - Google Patents

Abstract

The present invention relates to an ionic liquid having a low cellulose degradation rate. The ionic liquid according to the present invention has a similar or better solubility to cellulose than a compatible ionic liquid, and has a significantly low cellulose degradation rate upon dissolution There is an effect useful for maintaining mechanical properties close to that inherent to cellulose.

Description

[0002] Ionic liquids having a low cellulose degradation rate [

The present invention relates to an ionic liquid having a low cellulose degradation rate.

Cellulose is a very versatile raw material. In the textile industry, cellulose is, for example, the most important component of fiber raw materials, especially cotton.

Cellulose can be used without modification or after physical or chemical treatment. When used after physical or chemical treatment, it is advantageous that the cellulose is in a form that is preferably completely dissolved in the solvent. However, cellulose is insoluble in most solvents.

Cellulose is soluble in some copper solutions as a copper chelate complex. The regenerated cellulose can be obtained by precipitation of cellulose. However, when the cellulose is physically or chemically treated, such a copper solution as a solvent for cellulose is not very suitable. As a result, ionic liquids have been proposed particularly in the systems known in the literature as the solvent for cellulose.

Specifically, Patent Literature 1 [US Pat. No. 1,943,176] describes the dissolution of cellulose in benzylpyridinium chloride. As an example of an ionic liquid, benzylpyridinium chloride is a salt that exists in a molten form and is liquid at a relatively low temperature. Patent Document 2 (Korean Patent Laid-Open No. 10-2008-0006550) discloses the use of an ionic liquid for dissolving cellulose. Here, it is important that the ionic liquid should contain a cation containing an alkyl group, especially a quaternary ammonium ion which must be quaternized by methyl.

Non-Patent Document 1 [Materials Chemistry and Physics 128 (2011) 220-227] discloses that when an imidazole-based ionic liquid is used to dissolve cellulose, an anion reacts with the 2-hydrogen of the imidazole to generate an acidic substance Thereby causing degradation of the cellulose. When n-methylimidazole was added to dissolve cellulose by using 1-butyl-3-methylimidazolium chloride, the degree of polymerization was measured over time. As a result, n-methylimidazole stabilized hydrochloric acid, Reduction in the number of workers.

Although the 1-ethyl-2,3-dimethylimidazolium-based compound, which is a compound in which the 2-hydrogen position of imidazole is substituted with a methyl group, is sold in the market, it has a problem that the solubility of cellulose is low and can not be used.

Accordingly, the inventors of the present invention have been studying an ionic liquid having excellent cellulose solubility and low degradation rate of cellulose upon dissolution, and it has been found that the ionic liquid according to the present invention has a similar solubility to cellulose Or more, and the cellulose decomposition rate at the time of dissolution is remarkably low, so that it is useful for maintaining mechanical properties close to that of cellulose. Thus, the present invention has been completed.

An object of the present invention is to provide a salt which constitutes an ionic liquid having an excellent solubility of cellulose and a low decomposition rate of cellulose upon dissolution.

Another object of the present invention is to provide a method for producing the salt.

It is another object of the present invention to provide an ionic liquid as a solvent comprising the salt.

Another object of the present invention is to provide a solution comprising the ionic liquid and cellulose.

In order to achieve the above object, the present invention provides a salt represented by the following general formula (1).

[Chemical Formula 1]

In Formula 1,

R ¹ is C _1-10 linear or branched alkyl or - (CH ₂ ) _n -O-CH ₃ ,

N is an integer of 1-5;

이다. ^- OAc

to be.

The present invention also relates to a process for producing a compound represented by the formula (1)

Reacting a compound represented by the formula (2) and a compound represented by the formula (3) at 10-40 ° C for 10-50 hours to prepare a compound represented by the formula (4) (step 1);

Reacting the compound represented by the formula (4) and the bromoethane prepared in the step 1 at 110-150 ° C for 10-40 hours to prepare a compound represented by the formula (5) (step 2); And

And a step of passing the compound represented by the formula (5) prepared in the step 2 through an anion exchange resin to prepare a compound represented by the formula (1) (step 3).

[Reaction Scheme 1]

In the above Reaction Scheme 1,

R ¹ and ^- OAc is as defined in claim 1 in the formula (1) independently,

X is halogen.

Further, the present invention provides an ionic liquid as a solvent containing the salt represented by the above formula (1).

The present invention also provides a solution comprising the ionic liquid and cellulose.

The ionic liquid according to the present invention has a similar or better solubility to cellulose than a compatible ionic liquid, and has a remarkably low decomposition rate of cellulose at the time of dissolution, so that the ionic liquid has a useful effect for maintaining mechanical properties close to that of cellulose.

Fig. 1 is a photograph showing the solubility of the ionic liquid prepared in Example 1-2 and Comparative Example 1-9 for cellulose. Fig.

Hereinafter, the present invention will be described in detail.

The present invention provides a salt represented by the following formula (1).

[Chemical Formula 1]

In Formula 1,

R ¹ is C _1-10 linear or branched alkyl or - (CH ₂ ) _n -O-CH ₃ ,

N is an integer of 1-5;

이다. ^- OAc

to be.

Preferably,

R ¹ is C _1-5 linear or branched alkyl or - (CH ₂ ) _n -O-CH ₃ ,

And n is an integer of 1-3.

More preferably,

R ¹ is methyl or - (CH ₂ ) _n -O-CH ₃ ,

N is an integer of 2.

Most preferably, the salt represented by the formula (1) is any one selected from the following group.

(1) 1-ethyl-2- (methoxymethyl) -3-methylimidazolium acetate; And

(2) 1-Ethyl-2 - ((2-methoxyethoxy) methyl) -3-methylimidazolium acetate.

The present invention also relates to a process for producing a compound represented by the formula (1)

Reacting a compound represented by the formula (2) and a compound represented by the formula (3) at 10-40 ° C for 10-50 hours to prepare a compound represented by the formula (4) (step 1);

Reacting the compound represented by the formula (4) and the bromoethane prepared in the step 1 at 110-150 ° C for 10-40 hours to prepare a compound represented by the formula (5) (step 2); And

And a step of passing the compound represented by the formula (5) prepared in the step 2 through an anion exchange resin to prepare a compound represented by the formula (1) (step 3).

[Reaction Scheme 1]

In the above Reaction Scheme 1,

R ¹ and ^- OAc is the same as defined in the formula (1) independently,

X is halogen.

Hereinafter, the process for preparing the salt represented by the formula (1) according to the present invention will be described in detail.

In step (1), the compound represented by formula (2) and the compound represented by formula (3) are reacted at 10-40 ° C for 10-50 hours to obtain a salt represented by formula ≪ / RTI > compound.

At this time, the reaction temperature is preferably 20-30 ° C, more preferably 23-27 ° C, and most preferably 25 ° C. If the reaction temperature is lower than 10 ° C, the reaction can not be easily induced, and if the reaction temperature is higher than 40 ° C, the amount of by-products to be produced increases.

The reaction time is preferably 20 to 40 hours. If the reaction time is less than 10 hours, the reaction may not proceed completely, and if the reaction time exceeds 50 hours, the amount of by-products may be increased.

Further, X may use a halogen atom, but preferably Cl, Br or I can be used, more preferably Br or I can be used, and most preferably, I can be used.

In the process for preparing a salt represented by the general formula (1) according to the present invention, the compound represented by the general formula (4) prepared in the step (1) and the bromoethane are reacted at 110-150 ° C for 10-40 hours, Is a step of preparing a compound represented by the formula

At this time, the reaction temperature is preferably 120-140 ° C, more preferably 125-135 ° C, and most preferably 130 ° C. If the reaction temperature is lower than 110 ° C, the reaction can not be easily induced. If the reaction temperature is higher than 150 ° C, the amount of by-products to be produced increases.

The reaction time is preferably 20-30 hours, most preferably 24 hours. If the reaction time is less than 10 hours, the reaction may not proceed completely. If the reaction time exceeds 40 hours, the amount of produced by-products increases.

In the process for preparing a salt represented by the formula (1) according to the present invention, the compound represented by the formula (5) prepared in the above step 2 is passed through an anion exchange resin (Ambersep 900-OAc) , Wherein Br ^- is replaced with ^- OAc of the compound represented by formula (5). Specifically, the anion exchange resin is passed through a column tube filled with an anion exchange resin at a rate of about 3-4 times the number of moles of the compound, passed through the column at least once, and the molecular weight of the compound passed through the column is confirmed. .

Further, the present invention provides an ionic liquid as a solvent containing the salt represented by the above formula (1).

The following experiment was conducted to confirm whether the ionic liquid according to the present invention had an excellent solubility of cellulose in comparison with a compatible ionic liquid and an improvement in the cellulose degradation rate upon dissolution.

Specifically, experiments were conducted to evaluate the solubility of the ionic liquids prepared in Example 1 and Example 2 for cellulose. As a result, it was found that the ionic liquids prepared in Example 1 and Example 2 of the present invention, (See Fig. 1 of Experimental Example 1) in comparison with Comparative Example 7-9 which is an ionic liquid.

Experiments were carried out to evaluate the degree of degradation of the cellulose when the cellulose was dissolved in the ionic liquids prepared in Examples 1 and 2. As a result, the ionic liquid prepared in Examples 1 and 2 (See Table 3 in Experimental Example 2). The results are shown in Table 3. < tb > < TABLE >

Therefore, the ionic liquid according to the present invention is similar to or better in solubility of cellulose than a compatible ionic liquid, and has a remarkably low decomposition rate of cellulose upon dissolution, so that it is useful for maintaining mechanical properties close to that of cellulose .

Furthermore, the present invention provides a solution comprising the ionic liquid and cellulose.

Hereinafter, the present invention will be described in detail with reference to Examples and Experimental Examples.

However, the following examples and experimental examples are illustrative of the present invention, and the present invention is not limited thereto.

Example 1 Preparation of 1-ethyl-2- (methoxymethyl) -3-methylimidazolium acetate

step 1: 2 - ( Methoxymethyl )-One- Methylimidazole  Produce

5.00 g (44.6 mmol) of 2-hydroxymethyl-1-methylimidazole and 4.28 g (178 mmol) of sodium hydride were added to 50 mL of tetrahydrofuran and cooled to 0 占 폚. 3.05 mL (49.0 mmol) of methyl iodide was slowly added to the cooled reaction solution, the ice bath was removed, and the mixture was stirred at room temperature for 40 hours. After completion of the reaction, the reaction solution was removed by distillation under reduced pressure, dissolved in water and extracted several times with hexane. The water layer was collected and extracted several times with dichloromethane, and the organic layer was collected and magnesium sulfate was added. The magnesium sulfate was removed with a vacuum filter, and the obtained solution was collected by vacuum distillation, and then purified by column chromatography using eluent dichloromethane: methanol = 95: 5 to obtain 4.79 g (yield: 85%) of the product. NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 6.95 (s, 1H), 6.87 (s, 1H), 4.53 (s, 2H), 3.69 (s, 3H), 3.33 (s, 3H).

LRMS (ESI-) m / z: 127 (M + H).

Step 2: Preparation of 1-ethyl-2- (methoxymethyl) -3-methylimidazolium bromide

1.52 g (12.0 mmol) of 1-ethyl-2- (methoxymethyl) -1-methylimidazole and 2.70 mL (36.2 mmol) of bromoethane were added to 30 mL of acetonitrile and stirred for 24 hours Respectively. After completion of the reaction, the reaction mixture was distilled under reduced pressure and vacuum dried to obtain 2.64 g of product (yield = 94%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.76 (d, j = 2.0, 1H), 7.65 (d, j = 2.4, 1H), 4.95 (s, 2H), 4.40 (q, j = 7.2 , 2H), 4.07 (s, 3H), 3.52 (s, 3H), 1.57 (d, J = 7.2,3H).

LRMS (ESI-) m / z: 315 [M + ( ^- Br)], 551 [2M + ( ^- Br)], 785 [3M + ( ^- Br)].

Step 3: Preparation of 1-ethyl-2- (methoxymethyl) -3-methylimidazolium acetate

2.64 g (11.2 mmol) of 1-ethyl-2- (methoxymethyl) -1-methylimidazolium bromide was dissolved in water and passed through an anion exchange resin (Ambersep 900-OAc). The collected products were collected by vacuum distillation And then dried at 70 ° C under vacuum to obtain 2.07 g of product (yield = 88%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.77 (d, j = 2.0, 1H), 7.61 (d, j = 2.0, 1H), 4.89 (s, 2H), 4.37 (q, j = 7.2 , 2H), 4.03 (s, 3H), 3.49 (s, 3H), 1.86 (s, 3H), 1.53 (d, J = 7.2, 3H).

LRMS (ESI-) m / z: 273 [M + ( ^- OAc)], 487 [2M + ( ^- OAc)], 701 [3M + ( ^- OAc)].

Example 2 Synthesis of 1-ethyl-2 - ((2-methoxyethoxy) methyl) -3-methylimidazolium acetate

step 1: 2 -((2- Methoxyethoxy ) methyl )-One- Methylimidazole  Produce

5.00 g (44.6 mmol) of 2-hydroxymethyl-1-methylimidazole and 4.28 g (178 mmol) of sodium hydride were added to 70 mL of tetrahydrofuran and cooled to 0 占 폚. After 4.61 mL (49.0 mmol) of bromoethyl methyl ether was added slowly to the cooled reaction solution, the ice bath was removed, and the mixture was stirred at room temperature for 20 hours. After completion of the reaction, the reaction solution was removed by distillation under reduced pressure, dissolved in water and extracted several times with hexane. The water layer was collected and extracted several times with dichloromethane, and the organic layer was collected and magnesium sulfate was added. The magnesium sulfate was removed with a vacuum filter, and the obtained solution was collected by vacuum distillation, and purified by column chromatography using eluent dichloromethane: methanol = 95: 5 to obtain 3.28 g of the product (yield = 50%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 6.94 (s, 1H), 6.87 (s, 1H), 4.64 (s, 2H), 3.71 (s, 3H), 3.60 (m, 2H), 3.52 (m, 2H).

LRMS (ESI +) m / z: 171 (M + H), 193 (M + Na).

Step 2: Preparation of 1-ethyl-2 - ((2-methoxyethoxy) methyl) -3-methylimidazolium bromide

4.24 g (24.9 mmol) of 2 - ((2-methoxyethoxy) methyl) -1-methylimidazole and 5.60 mL (75.0 mmol) of bromoethane were added to 30 mL of acetonitrile, Lt; / RTI > After completion of the reaction, the reaction mixture was distilled under reduced pressure and vacuum dried to obtain 6.72 g of the product (yield = 97%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.68 (d, j = 2.0, 1H), 7.59 (d, j = 2.0, 1H), 5.08 (s, 2H), 4.40 (q, j = 7.2 , 2H), 4.07 (s, 3H), 3.82 (m, 2H), 3.58 (m, 2H), 3.35 (s, 3H), 1.58 (t,

LRMS (ESI-) m / z: 359 [M + ( ^- Br)], 639 [2M + ( ^- Br)], 917 [3M + ( ^- Br)].

Step 3: Preparation of 1-ethyl-2 - ((2-methoxyethoxy) methyl) -3-methylimidazolium acetate

6.72 g (24.1 mmol) of 1-ethyl-2 - ((2-methoxyethoxy) methyl) -1-methylimidazolium bromide was dissolved in water, passed through an anion exchange resin (Ambersep 900-OAc) The collected water was distilled off under reduced pressure, and vacuum dried at 70 ° C to obtain 5.19 g of product (yield: 83%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.79 (d, j = 2.0, 1H), 7.64 (d, j = 2.0, 1H), 5.04 (s, 2H), 4.38 (q, j = 7.2 , 2H), 4.05 (s, 3H), 3.79 (m, 2H), 3.57 (m, 2H), 3.35 (s, 3H), 1.87 (s, 3H), 1.54 (t,

LRMS (ESI-) m / z: 317 [M + ( ^- OAc)], 575 [2M + ( ^- OAc)], 833 [3M + ( ^- OAc)].

The chemical structures of the compounds prepared in Example 1-2 are summarized in Table 1 below.

Example Chemical structural formula Example Chemical structural formula One

2

< Comparative Example  1 > 1-ethyl-2,3- Dimethylimidazolium  Preparation of chloride

step 1: 1 -Ethyl-2,3- Dimethylimidazolium  Manufacture of bromide

10.0 mL (0.11 mol) of 2,3-dimethylimidazole and 25.0 mL (0.34 mol) of bromoethane were added to 50 mL of acetonitrile, and the mixture was stirred for 24 hours while being heated to 140 ° C. After completion of the reaction, the reaction solution was removed by distillation under reduced pressure, dissolved in methanol, and then excess ethyl acetate was added, followed by precipitation at 0 ° C. The precipitated solids were filtered off under reduced pressure and vacuum dried at 70 ° C to give 19.29 g of product (yield = 83%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.67 (d, j = 2.4, 1H), 7.57 (d, j = 2.4, 1H), 4.33 (q, j = 7.2, 2H), 4.01 (s , 3H), 2.83 (s, 3H), 1.53 (t, J = 7.2, 3H).

LRMS (ESI-) m / z: 285 [M + ( ^- Br)], 491 [2M + ( ^- Br)], 695 [3M + ( ^- Br)].

step 2: 1 -Ethyl-2,3- Dimethylimidazolium  Preparation of chloride

4.84 g (23.5 mmol) of 1-ethyl-2,3-dimethylimidazolium bromide was dissolved in water and passed through an anion exchange resin (Ambersep 900-Cl). The collected water was collected by vacuum distillation, Drying gave 3.48 g of product (yield = 92%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.80 (d, j = 2.0, 1H), 7.67 (d, j = 2.0, 1H), 4.36 (q, j = 7.2, 2H), 4.03 (s , 3H), 2.84 (s, 3H), 1.53 (t, J = 7.2,3H).

LRMS (ESI-) m / z: 195 [M + ( ^- Cl)], 357 [2M + ( ^- Cl)], 517 [3M + ( ^- Cl)].

< Comparative Example  2 > 1-ethyl-2,3- Dimethylimidazolium  acetate

4.10 g (20.0 mmol) of 1-ethyl-2,3-dimethylimidazolium bromide was dissolved in water and then passed through an anion exchange resin (Ambersep 900-OAc). The collected water was collected by vacuum distillation, Drying gave 3.36 g of product (Yield = 91%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.73 (d, j = 2.0, 1H), 7.59 (d, j = 2.4, 1H), 4.27 (q, j = 7.2, 2H), 3.93 (s , 3H), 2.72 (s, 3H), 1.82 (s, 3H), 1.48 (t, s = 7.2, 3H).

LRMS (ESI-) m / z: 243 [M + ( ^- OAc)], 427 [2M + ( ^- OAc)], 611 [3M + ( ^- OAc)].

COMPARATIVE EXAMPLE 3 Preparation of 1-ethyl-2-hydroxymethyl-3-methylimidazolium chloride

step 1: 2 - Hydroxymethyl -One- Methylimidazole  Produce

30.0 g (0.36 mol) of n-methylimidazole, 30.0 g of paraformaldehyde and 50 mL of acetonitrile were placed in an Aton parr pressure vessel and stirred for 24 hours while heating to 110 ° C. After completion of the reaction, the resulting solids were removed with a vacuum filter, and the passing solution was collected and removed by distillation under reduced pressure. The concentrated product was dissolved in methanol and then excess ethyl acetate was added and precipitated at 0 &lt; 0 &gt; C. The precipitated solids were collected by vacuum filtration and vacuum dried to give 25.84 g of product (yield = 63%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 6.85 (. S 1H), 6.80 (s, 1H), 4.62 (s, 2H), 3.72 (s, 3H).

LRMS (ESI-) m / z: 111 (M-H).

Step 2: Preparation of 1-ethyl-2-hydroxymethyl-3-methylimidazolium bromide

3.00 g (26.8 mmol) of 2-hydroxymethyl-1-methylimidazole and 4.00 mL (53.6 mmol) of bromoethane were added to 30 mL of acetonitrile and the mixture was stirred for 20 hours while heating at 140 占 폚. After completion of the reaction, the reaction solution was distilled off under reduced pressure, the concentrated product was dissolved in methanol, and then excess ethyl acetate was added thereto, followed by precipitation at 0 ° C. The precipitated solids were collected by vacuum filtration and vacuum dried to give 5.56 g of product (yield = 94%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.41 (s, 1H), 7.38 (s, 1H), 4.91 (s, 2H), 4.39 (q, j = 7.2, 2H), 4.02 (s, 3H), 1.53 (t, J = 7.2, 3H).

LRMS (ESI-) m / z: 301 [M + ( ^- Br)], 523 [2M + ( ^- Br)], 743 [3M + ( ^- Br)].

Step 3: Preparation of 1-ethyl-2-hydroxymethyl-3-methylimidazolium chloride

5.20 g (23.5 mmol) of 1-ethyl-2-hydroxymethyl-3-methylimidazolium bromide was dissolved in water and then passed through an anion exchange resin (Ambersep 900-Cl). The collected water was collected by vacuum distillation And dried in vacuo at 70 [deg.] C to give 3.82 g of product (yield = 92%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.47 (s, 1H), 7.40 (s, 1H), 4.91 (s, 2H), 4.47 (q, j = 7.2, 2H), 4.10 (s, 3H), 1.55 (t, J = 7.2, 3H).

LRMS (ESI-) m / z: 211 [M + ( ^- Cl)], 389 [2M + ( ^- Cl)], 565 [3M + ( ^- Cl)].

&Lt; Comparative Example 4 > Preparation of 1-ethyl-2-hydroxymethyl-3-methylimidazolium acetate

After dissolving 4.60 g (20.8 mmol) of 1-ethyl-2-hydroxymethyl-3-methylimidazolium bromide in water, passing through an anion exchange resin (Ambersep 900-OAc), collecting the passed water and removing by vacuum distillation Vacuum drying at 70 [deg.] C gave 4.14 g of the product (Yield = 99%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.28 (m, 2H), 5.04 (s, 2H), 4.43 (q, j = 7.2, 2H), 4.03 (s, 3H), 1.90 (s, 3H), 1.53 (t, J = 7.2, 3H).

LRMS (ESI-) m / z: 259 [M + ( ^- OAc)], 459 [2M + ( ^- OAc)], 659 [3M + ( ^- OAc)].

Comparative Example 5 Preparation of 1-ethyl-2- (methoxymethyl) -3-methylimidazolium acetate

2.37 g (10.0 mmol) of 1-ethyl-2- (methoxymethyl) -3-methylimidazolium bromide was dissolved in water and then passed through an anion exchange resin (Ambersep 900-Cl). The collected water was collected by vacuum distillation And then vacuum-dried at 70 DEG C to obtain 1.70 g of product (yield = 88%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.73 (d, j = 2.0, 1H), 7.60 (d, j = 2.0, 1H), 4.95 (s, 2H), 4.40 (q, j = 7.2 , 2H), 4.08 (s, 3H), 3.51 (s, 3H), 1.56 (d, J = 7.2,3H).

LRMS (ESI-) m / z: 225 [M + ( ^- Cl)], 417 [2M + ( ^- Cl)], 607 [3M + ( ^- Cl)].

Comparative Example 6 Preparation of 1-ethyl-2 - ((2-methoxyethoxy) methyl) -3-methylimidazolium chloride

2.95 g (10.5 mmol) of 1-ethyl-2 - ((2-methoxyethoxy) methyl) -3-methylimidazolium bromide was dissolved in water and then passed through an anion exchange resin (Ambersep 900- The collected water was distilled off under reduced pressure and vacuum dried at 70 ° C to obtain 2.30 g of product (yield: 92%). NMR and Mass measurement results of the obtained ionic liquid are as follows.

_{^{1 H-NMR (CDCl 3 400MHz}} ): δ (ppm) 7.76 (s, 1H), 7.63 (s, 1H), 5.08 (s, 2H), 4.40 (q, j = 7.2, 2H), 4.07 (s, 3H), 3.82 (m, 2H), 3.58 (m, 2H), 3.35 (s, 3H), 1.56 (t, J = 7.2, 3H).

LRMS (ESI-) m / z: 269 [M + ( ^- Cl)], 505 [2M + ( ^- Cl)], 739 [3M + ( ^- Cl)].

< Comparative Example  7> 3-ethyl-1- Methylimidazolium  Preparation of chloride (compatible ionic liquid 1)

The compound of Comparative Example 7 was prepared by purchasing from Sigma Aldrich.

< Comparative Example  8 > 3-ethyl-1- Methylimidazolium  Acetate (compatible ionic liquid 2)

The compound of Comparative Example 8 was purchased from Sigma Aldrich.

< Comparative Example  9> 3-Butyl-1- Methylimidazolium  Preparation of chloride (compatible ionic liquid 3)

The compound of Comparative Example 9 was purchased from Sigma Aldrich.

Table 2 summarizes the chemical structures of the compounds prepared in Comparative Examples 1-9.

Comparative Example Chemical structural formula Comparative Example Chemical structural formula One

6

2

7

3

8

4

9

5

< Experimental Example  1> Evaluation of cellulose solubility

The following experiments were performed to evaluate the solubility of the ionic liquids prepared in Example 1 and Example 2 for cellulose.

The ionic liquids prepared in Example 1-2 and Comparative Example 1-9 were vacuum dried at 80 占 폚 for 24 hours before use. After vacuum drying, 0.1 g of cellulose (DP 850 pulp) was added and mixed at 80 ° C for 24 hours. Thereafter, the reaction was carried out at 100 DEG C for 5 hours to visually observe cellulose dissolution. The results are shown in Fig.

Fig. 1 is a photograph showing the solubility of the ionic liquid prepared in Example 1-2 and Comparative Example 1-9 for cellulose. Fig.

As shown in FIG. 1, the ionic liquids prepared in Example 1 and Example 2 of the present invention were found to have better or similar cellulose solubility as compared to Comparative Example 7-9, which is a compatible ionic liquid.

< Experimental Example  2> Cellulose Degradability  evaluation

The following experiments were carried out to evaluate the degree of degradation of the cellulose when the cellulose was dissolved in the ionic liquids prepared in Example 1 and Example 2.

The cellulose dissolved in the ionic liquids prepared in Example 1-2 and Comparative Example 8 was precipitated in ethanol at 150 deg. C, followed by vacuum drying. The dried solids were soxhleted with ethanol, dried, dissolved in DMAC (Dimethylacetamide) / LiCl solvent, and the molecular weight was measured by GPC (Gel Permeation Chromatography) using DMAC as an eluent . The results are shown in Table 3 below.

Number average molecular weight (Mn) Weight average molecular weight (Mw) Example 1 33,500 62,200 Example 2 34,800 85,300 Comparative Example 8 21,500 55,800

As shown in Table 3, the ionic liquids prepared in Example 1 and Example 2 at 150 ° C were significantly lower in cellulose degradability than the ionic liquids of Comparative Example 8.

Therefore, the ionic liquid according to the present invention is similar to or better in solubility of cellulose than a compatible ionic liquid, and has a remarkably low decomposition rate of cellulose upon dissolution, so that it is useful for maintaining mechanical properties close to that of cellulose .

Claims (10)

A salt selected from the group consisting of the following compounds:
(1) 1-ethyl-2- (methoxymethyl) -3-methylimidazolium acetate; And
(2) 1-Ethyl-2 - ((2-methoxyethoxy) methyl) -3-methylimidazolium acetate.
delete delete delete As shown in Scheme 1 below,
Reacting the compound represented by formula (2) and the compound represented by formula (3) at 10-40 ° C for 10-50 hours to prepare a compound represented by formula (4) (step 1);
Reacting the compound represented by the formula (4) and the bromoethane prepared in the step 1 at 110-150 ° C for 10-40 hours to prepare a compound represented by the formula (5) (step 2); And
A step of passing the compound represented by the formula (5) prepared in the step 2 through an anion exchange resin to prepare a compound represented by the formula (1) (step 3); and Method of preparing phosphorus salt:
[Reaction Scheme 1]

(In the above Reaction Scheme 1,
R ¹ and ^- OAc is the same as the range of the substituent of the compound according to claim 1 wherein independently and,
And X is halogen.
6. The method of claim 5,
The reaction temperature of step 1 is 20-30 ° C; And
Wherein the reaction temperature in step 2 is 120-140 占 폚.
6. The method of claim 5,
The reaction time of step 1 is 20-40 hours; And
Wherein the reaction time of step 2 is 20-30 hours.
An ionic liquid as a solvent comprising a salt selected from the group consisting of the compounds of claim 1.
9. The method of claim 8,
Wherein the ionic liquid has a low decomposition rate of cellulose when the cellulose is dissolved.
A solution comprising the ionic liquid of claim 8 and cellulose.

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