KR101373109B1 - A Method for Screening ionic liquid Capable of dissolving cellulose - Google Patents

Abstract

The present invention relates to a method for searching for an ionic liquid capable of dissolving cellulose, specifically collecting solubility data from ionic liquids capable of dissolving cellulose (step 1); Optimizing the geometry of the ionic liquids applied to the solubility data collection of step 1 to derive a geometry that is a global minimum (step 2); Deriving molecular presenters of an ionic liquid capable of dissolving cellulose from the geometry derived in step 2 (step 3); And a step (step 4) of deriving the objective function consisting of molecular descriptors from the molecular descriptors derived in step 3 and the solubility data collected in step 1 (step 4). Provide a way to. The method for searching for an ionic liquid capable of dissolving cellulose according to the present invention derives the presenter from ionic liquids known as a solvent capable of dissolving cellulose, and then uses the derived presenter value to determine the ionic liquid. By deriving the objective function which can be expressed, the ionic liquid which can satisfy | fill the said objective function and can dissolve a cellulose can be searched out. In addition, the ionic liquids searched according to the present invention can exhibit better solubility compared to ionic liquids that have been used as solvents of conventional cellulose.

Description

A method for screening ionic liquid capable of dissolving cellulose

The present invention relates to a method of searching for an ionic liquid capable of dissolving cellulose.

As the price increases and global warming accelerate due to the depletion of fossil fuels, the production of alcohols for the production of fuels and chemicals from natural resources is being considered. Cellulose, which makes up about 40% of biomass, is a renewable natural resource that is abundant in nature. Cellulose is an aggregate of D-glucose (glucose) having β-1,4-glycosidic bonds and is composed of about 100 to 3000 D-glucose. Each D-glucose has three hydroxyl groups, thus having a very high affinity with other substances but having α-1,4-glycosidic bonds due to the crystal structure consisting of strong hydrogen bonds between or within molecular chains. Unlike starch, it does not dissolve easily in water or organic solvents. Due to the characteristics of such cellulose, it is difficult to utilize cellulose as a fuel or a chemical, and tertiary amine oxide is most widely used among solvents capable of preparing a cellulose solution by destroying the structure of the cellulose.

On the other hand, environmental regulations, which have been tightened since the early 1980s, are becoming increasingly strict, and in particular, as the severity of air pollution increases, regulations on the use of volatile organic compounds (VOCs) are tightened. In addition, in the fine chemical process, energy consumption and cost for solvent separation and recovery are rapidly increasing. Therefore, there is a need for a green alternative technology that can simultaneously solve environmental and energy problems. However, such a clean alternative solvent technology is still in the early stages of the world and is currently a clean alternative solvent. Research into fluids, liquid polymers, and the like has been conducted.

Among these next-generation solvents, ionic liquids refer to liquids consisting solely of ions, and are generally composed of large cations containing nitrogen and smaller anions. This structure reduces the lattice energy of the crystal structure and consequently has a low melting point. In particular, ionic liquids present as liquids at room temperature are called room temperature ionic liquids (RTILs). Ionic liquids are not only used as clean solvents and catalysts in various organic chemical reactions due to their unique properties different from conventional organic solvents, but also for various purposes such as electrolytes, lubricating oils, heating media, extraction and separation media in fuel cells and solar cells. Can be utilized.

In addition, the ionic liquid has been attracting attention as a solvent capable of dissolving cellulose since Rogers of the University of Alabama reported the world's first possibility of dissolving cellulose using ionic liquid. And

For example, Korean Patent Publication Nos. 10-2008-0006550 (published January 16, 2008), 10-2008-0104053 (published November 28, 2008), and 10-2008-0006550 (January 16, 2008) a method of dissolving cellulose using an ionic liquid as a solvent has been disclosed.

However, the solubility of the ionic liquid capable of dissolving cellulose remains a room for further development, and research on this has been actively conducted.

Accordingly, the present inventors, while researching to improve the solubility of the ionic liquid capable of dissolving cellulose, derive a descriptor representing the characteristics of the ionic liquid capable of dissolving cellulose, and then the derived expression. We have developed a method for searching for an ionic liquid capable of dissolving cellulose using a ruler value and completed the present invention.

It is an object of the present invention to provide a method for searching for an ionic liquid capable of dissolving cellulose.

In order to achieve the above object,

Collecting solubility data from ionic liquids capable of dissolving cellulose (step 1);

Optimizing the geometry of the ionic liquids applied to the solubility data collection of step 1 to derive a geometry that is a global minimum (step 2);

Deriving molecular presenters of an ionic liquid capable of dissolving cellulose from the geometry derived in step 2 (step 3); And

Deriving the objective function of the solubility consisting of molecular descriptors from the molecular descriptors derived in step 3 and the solubility data collected in step 1 (step 4); Provide a way to navigate.

The method for searching for an ionic liquid capable of dissolving cellulose according to the present invention derives the presenter from ionic liquids known as a solvent capable of dissolving cellulose, and then uses the derived presenter value to determine the ionic liquid. By deriving the objective function which can be expressed, the ionic liquid which can satisfy | fill the said objective function and can dissolve a cellulose can be searched out. In addition, the ionic liquids searched according to the present invention can exhibit better solubility compared to ionic liquids that have been used as solvents of conventional cellulose.

1 is graphs shown for deriving values of presenters;
2 is a regression analysis graph for deriving maximum solubility.

The present invention

Collecting solubility data from ionic liquids capable of dissolving cellulose (step 1);

Optimizing the geometry of the ionic liquids applied to the solubility data collection of step 1 to derive a geometry that is a global minimum (step 2);

Deriving molecular presenters of an ionic liquid capable of dissolving cellulose from the geometry derived in step 2 (step 3); And

Deriving the objective function of the solubility consisting of molecular descriptors from the molecular descriptors derived in step 3 and the solubility data collected in step 1 (step 4); Provide a way to navigate.

Hereinafter, the ionic liquid searching method according to the present invention will be described in detail for each step.

In the ionic liquid search method according to the present invention, step 1 is a step of collecting solubility data from ionic liquids capable of dissolving cellulose.

Collecting solubility data in step 1 is to derive a correlation between the structure and solubility of ionic liquids (anionic liquids and cationic liquids) known to be able to dissolve cellulose, wherein the solubility in step 1 For the ionic liquid used for data collection, it is preferable to select materials having similar conditions, means, and the like for dissolving cellulose. That is, not all ionic liquids dissolve cellulose under the same conditions and means, but can dissolve cellulose through specific temperature conditions or means (heating, sonication, microwave treatment, etc.). At this time, if such conditions or means make a list of similar ionic liquids and derive a correlation with solubility from their structure, the ionic liquid capable of dissolving cellulose can be searched from this.

Therefore, in step 1 of the ionic liquid search method according to the present invention, anionic liquids and cationic liquids, which are ionic liquids having similar conditions for dissolving cellulose, are selected, and solubility data is collected from the selected ionic liquids.

In the ionic liquid search method according to the present invention, step 2 is a step of optimizing the geometry of the ionic liquids applied to the solubility data collection of step 1 to derive a geometry having a global minimum.

As described above, the present invention seeks to search for the ionic liquid showing the maximum solubility by deriving solubility from the structure of the conventional ionic liquids capable of dissolving cellulose. Solubility data of the liquids were collected. In step 2, the geometry of the ionic liquids applied to the solubility data collection in step 1 is optimized to derive the geometry with the minimum energy state.

At this time, the minimum energy state geometry is the only minimum energy structure (Global minimum) having a lower energy than several local energy structures (Local minima), the most likely to exist in the ionic liquid state in the Boltzmann distribution (Boltzmann distribution) It is a large structure and these structures can be used in the selection of a solvent to dissolve cellulose. In particular, since the ionic liquid is composed of cations and anions, the structures of the two ions, cation and anion, are optimized separately to obtain respective minimum energy structures. At this time, deriving the geometry of the minimum energy state in step 2 may be performed by the AM1 (Austin Model 1), a semi-empirical molecular orbital method, the geometry of step 2 Derivation is not limited to this.

In the ionic liquid search method according to the present invention, step 3 is a step of deriving molecular descriptors of the ionic liquid capable of dissolving cellulose from the geometry derived in step 2.

In conducting theoretical studies on the physical properties and properties of ionic liquids, recently, Monte Carlo simulation or CODESSA program has been conducted to investigate the correlations between the structure and physical properties and characteristics of ionic liquids. have. In this case, the CODESSA program is a kind of molecular descriptors calculation software, and the descriptors are values defined to reflect the properties of the molecules themselves, the binding environment of atoms, and the like, for example, the CODESSA program. Is a structural presenter, a topological presenter, a geometrical presenter, an electrostatic presenter, a quantum chemical presenter, and a thermodynamic presenter. Depending on the type of molecule (or atom), up to 400 or more descriptors can be used to represent a molecule.

Thus, in step 3 according to the present invention, molecular descriptors of ionic liquids can be derived from the geometry derived in step 2, and the minimum energy state geometry derived in step 2 can be expressed through the derived molecular descriptors. Molecular descriptors can be derived.

In the method for searching for an ionic liquid according to the present invention, step 4 is a step of deriving an object function related to solubility of molecular descriptors from the molecular descriptors derived in step 3 and the solubility data collected in step 1.

The molecular presenters derived in step 3 represent an ionic liquid capable of dissolving cellulose, and when the molecular presenter and the solubility data collected in step 1 are statistically analyzed, the cellulose solubility of the ionic liquid is And it can derive the objective function for solubility consisting of molecular descriptors representing the correlation of the molecular descriptors. Therefore, in step 4, the objective function consisting of molecular descriptors derived from step 3 and the solubility data collected in step 1 is derived, and the ionic liquid capable of dissolving cellulose can be searched from the objective function. Can be.

In this case, the objective function of step 4 may be derived by a MARS (Multivariate Adaptive Regression Spline) regression method. The MARS regression analysis is an extension of the regression model that automatically detects the main variables and patterns of model predictions and can flexibly respond to nonlinear data. In addition, there is a feature that the resulting results are easy to understand and easy to interpret.

By applying the molecular descriptors derived in step 3 and the solubility data collected in step 1 to the MARS model known to have such advantages, an objective function composed of molecular descriptors representing the cellulose solubility of the ionic liquid is obtained. Can be derived. At this time, the derivation of the objective function is a method of sequentially selecting the most important bases based on the data points of each presenter as knots and generating a linear spline for each knot. Through this, it is possible to derive the objective function indicating the cellulose solubility of the ionic liquid by selecting the key markers related to solubility and knots for the key markers.

On the other hand, the objective function of step 4 is

Bonding information content (BIC) represented by Equations 1 and 2 below;

Average of atomic valency of a carbon atom;

Fractional hydrogen acceptors surface area (FHASA) represented by the following formula (3);

Max atomic state energy for a C atom;

Fractional partial positively charged surface area (FPSA) represented by Equation 4 below; And

Hydrogen acceptor charged surface area (HACA);

&Quot; (1) "

&Quot; (2) "

&Quot; (3) "

&Quot; (4) "

(In the above formulas 1 and 2,

N _i is the number of atoms in the i th class,

N is the total number of atoms in the molecule,

K is the number of atomic layers in the coordination sphere around a given atom,

q is the number of edges in the molecular graph.)

The presenters can use the presenters as an important presenter related to solubility to prepare an objective function relating to the cellulose solubility of the ionic liquid and to search for an ionic liquid capable of dissolving cellulose from the prepared objective function.

On the other hand, the ionic liquid search method according to the invention may further comprise the step of deriving the maximum solubility from the objective function.

That is, by analyzing the cellulose solubility of the ionic liquid by using the derived objective function, it is possible to derive the maximum solubility that can ultimately dissolve the cellulose to the maximum, through which the ion solubility improved than the conventional ionic liquid The sex liquid can be retrieved. The cellulose solution of high concentration can be prepared using the ionic liquid found as described above, and the high concentration of cellulose solution prepared using the ionic liquid found can be applied to various fields, particularly biomaterials.

Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples are intended to illustrate the present invention, but the scope of the present invention is not limited by the following examples.

Example 1 Ionic Liquid Search with Maximum Solubility

Step 1: Various forms of cellulose [MCC (250), MCC, Avicel, cellulose, Eucalyptus pre-hydrolysis sulfate pulp, α-cellulose, spruce sulfite pulp (593), cotton linters (1198), pulp (650), cotton linters , Kraft pulp, pulp cellulose (1000), commercial collulose, etc.] in ionic liquids, varying the temperature conditions, dissolution means (heating, sonication, microwave treatment), The calculated solubility data were reviewed and the ionic liquid solubility data with the most similar experimental conditions were prepared.

At this time, the ionic liquids used for preparing the solubility data are ionic liquids capable of dissolving cellulose (avicel, Avicel) at a temperature of 110 ° C (or 90, 100 ° C) and dissolution conditions by heating. The list of ionic liquids used is shown in Table 1 below.

Ionic liquid Temperature
(℃) Solubility
(weight%) Ionic liquid Temperature
(℃) Solubility
(weight%) [C ₄ mim] HCOO 110 8 [C ₆ mim] Cl 100 6 [Bu ₄ P] HCOO 110 6 [C ₇ mim] Cl 100 5 [Bu ₄ N] HCOO 110 1.5 [C ₇ mim] Cl 100 5 [Amm110] HCOO 110 0.5 [C ₈ mim] Cl 100 4 [C ₂ mim] OAc 110 15 [C ₉ mim] Cl 100 2.5 [C ₂ mim] OAc 100 8 [C ₉ mim] Cl 100 2 [C ₄ mim] Oac 100 12 [Me (OEt) ₂ -Et-Im] Cl 110 2 [Me (OEt) ₂ -Et-Im] OAc 110 12 [C ₅ mim] Cl 100 1.5 [Me (OEt) ₄ -Et-Im] OAc 110 10 [C ₅ mim] Cl 100 One [Me (OEt) ₃ -Et ₃ N] OAc 110 10 [H (OEt) ₂ -Me-Im] Cl 110 One [Me (OEt) ₂ -Et ₃ N] OAc 110 10 [C ₃ mim] Cl 100 0.5 [H (OEt) ₂ -Me-Im] OAc 110 5 [C ₃ mim] Cl 100 0 [Me (OEt) ₇ -Et-Im] OAc 110 3 [C ₁₀ mim] Cl 100 0.5 [H (OEt) ₃ -Me-Im] OAc 110 2 [Amm110] Cl 110 0.5 [C ₈ mim] OAc 110 One [C ₅ mim] Br 100 1.5 [Me (OEt) ₃ -MeOEtOMe-Im] OAc 110 0.5 [C ₆ mim] Br 100 1.5 [Me (OPr) ₃ -Et-Im] OAc 110 0.5 [C ₇ mim] Br 100 One [Amm110] OAc 110 0.5 [C ₈ mim] Br 100 One [Me (OEt) ₃ -Bu-Im] OAc 110 0.5 [C ₄ mim] I 100 1.5 [MM (EtOH) NH] OAc 110 0.5 [C ₂ mim] F 100 2 [(MeOEt) ₂ NH ₂ ] OAc 110 0.5 [P66614] DCA 110 0.5 [MM (MeOEt) NH] OAc 110 0.5 [Amm110] DCA 110 0.5 [M (MeOEt) ₂ NH] OAc 110 0.5 [C ₁ mim] (MeO) ₂ PO ₂ 100 10 [C ₂ mim] (EtO) ₂ PO ₂ 100 13

Step 2: After separating the ionic liquids selected in Step 1 into cations and anions, the geometries of the separated cations and anions were optimized using AM1, which is a semi-experimental calculation method. Was used. In addition, in order to confirm that the molecule with the optimized geometry is the lowest energy structure, the lowest energy structure (Global minimum) was derived by using GaussView.

Step 3: The presenters were derived from the geometry derived in step 2 through the CODESSA program.

Step 4: The objective function (R-square is 0.8487) and the maximum of cellulose represented by Equation 1 by applying the solubility data of step 1 and the solubility data of step 1 to MARS regression analysis Solubility was derived, and the MARS model with interaction was used to derive the maximum solubility. In this case, the presenters applied to the objective function are shown in the graph of FIG. 1 and Table 2 below, and the values of the presenters applied to the maximum solubility derivation are shown in Table 2 below.

&Quot; (1) "

Solubility (%) = 10.19543 + 219.02773 × max (0.0169-(FHASA, Fractional HASA (HASA / TMSA) [Quantum-Chemical PC]), 0)-24.51059 × max ((Max atomic state energy for a C atom)-103.568 , 0)-39.08106 × max (103.568-(Max atomic state energy for a C atom), 0)-2.15486 × max (3.8048-(Bonding Information content (order 1)), 0)-48.08038 × max ((Bonding Information content (order 1))-3.8048, 0) × max ((FHASA, Fractional HASA (HASA / TMSA) [Quantum-Chemical PC])-0.0169, 0)-194.90408 × max ((Bonding Information content (order 1)) -3.8048, 0) × max ((Avg atomic valency of a C atom)-3.8735, 0) + 66.12931 × max ((Bonding Information content (order 1))-3.8048, 0) × max (0.9316- (FPSA-1 , Fractional PPSA (PPSA-1 / TMSA) [Zefirov's PC]), 0) + 0.22651 × max (3.8048-(Bonding Information content (order 1)), 0) × max (11.2246-(HASA-1 [Zefirov's PC] ), 0)-2.41683 × max ((Bonding Information content (order 1))-3.8048, 0) × max ((HACA-2 [Zefirov's PC]), 0)

Expresser Derived value Combined Information Content Maximum value (9.9501) Average valence of carbon atoms 3.8735 or less Fraction of hydrogen acceptor surface area Minimum value (0) Maximum atomic state energy of a carbon atom Minimum value (0.8456) Fraction of surface area partially charged Minimum value (0) Surface area to which hydrogen receptors are transferred 103.568

On the other hand, the maximum solubility value of the cellulose derived through the MARS regression analysis was found to be 48.4% by weight. In other words, currently known experimental solubility can dissolve about 15% by weight of cellulose, while the maximum solubility value derived from the present invention was found to reach three times that. Through this, it can be seen that the search method according to the present invention can search for the ionic liquid having a better cellulose solubility value than the conventional ionic liquid.

Claims (5)

Collecting solubility data from ionic liquids capable of dissolving cellulose (step 1);
Optimizing the geometry of the ionic liquids applied to the solubility data collection of step 1 to derive a geometry that is a global minimum (step 2);
Deriving molecular presenters of an ionic liquid capable of dissolving cellulose from the geometry derived in step 2 (step 3); And
Deriving the objective function of the solubility consisting of molecular descriptors from the molecular descriptors derived in step 3 and the solubility data collected in step 1 (step 4); How to navigate.
According to claim 1, wherein the objective function of step 4
Bonding information content (BIC) represented by Equations 1 and 2 below;
Average of atomic valency of a carbon atom;
Fractional hydrogen acceptors surface area (FHASA) represented by the following formula (3);
Max atomic state energy for a C atom;
Fractional partial positively charged surface area (FPSA) represented by Equation 4 below; And
Method for searching for an ionic liquid capable of dissolving cellulose, characterized in that the hydrogen acceptor charged surface area (HACA);

&Quot; (1) "

&Quot; (2) "

&Quot; (3) "

&Quot; (4) "

(In the above formulas 1 and 2,
N _i is the number of atoms in the i th class,
N is the total number of atoms in the molecule,
K is the number of atomic layers in the coordination sphere around a given atom,
q is the number of edges in the molecular graph).
The method of claim 1, wherein the objective function of step 4 is derived by a multivariate adaptive regression spline (MARS) regression method.
The method of claim 1, wherein the geometry of step 2 is derived by the AM1 method, which is a semi-experimental molecular orbital method.
The method of claim 1, further comprising the step of deriving maximum solubility from the objective function of step 4. The method for searching for an ionic liquid capable of dissolving cellulose.

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