KR102705428B1 - Novel tetra-substituted diphosphate-boron trifluoride based compound and method for preparing the same - Google Patents

Abstract

The present invention relates to a novel tetra-substituted diphosphate-boron trifluoride compound represented by the following chemical formula 1 and a method for producing the same. More specifically, the present invention relates to a method for producing a tetra-substituted diphosphate compound by reacting a halogen-substituted diphosphate with an alcohol compound in the presence of a solvent and a base, and then adding boron trifluoride (BF3) thereto.
[Chemical Formula 1]

In the above chemical formula 1, n is 1 or 2, and R1 to R4 are as defined in the description of the invention.

Description

{Novel tetra-substituted diphosphate-boron trifluoride based compound and method for preparing the same}

The present invention relates to a novel tetra-substituted diphosphate-boron trifluoride compound represented by the following chemical formula 1 and a method for producing the same. More specifically, the present invention relates to a method for producing a tetra-substituted diphosphate compound by reacting a halogen-substituted diphosphate with an alcohol compound in the presence of a solvent and a base, and then adding boron trifluoride (BF3) thereto.

[Chemical Formula 1]

In the above chemical formula 1, n is 1 or 2, and R1 to R4 are as defined in the description of the invention.

Among secondary battery technologies, lithium-ion batteries, which theoretically have the highest energy density, are receiving attention.

Recently, various materials have been developed in the lithium-ion battery field, and basic raw materials for the development of these materials are also being developed.

Lithium-ion batteries, which are widely used as batteries for mobile phones and electric vehicles, use electrolytes that contain a large amount of flammable organic solvents. The demand for electrolytes is also increasing as they have moved beyond the simple auxiliary role of helping the smooth movement of lithium ions and become functional electrolytes that can improve the performance and safety of batteries. Recently, as lithium secondary batteries with high energy storage characteristics are being applied to various purposes, issues regarding battery ignition and explosion are gradually increasing.

Here, in order to prevent accidental accidents due to battery fires, electrolytes containing various flame retardants are used, and one of the flame retardants that can be used for this purpose is phosphoric acid propargyl esters. The phosphoric acid propargyl ester compounds can be easily manufactured by reacting phosphorus oxychloride and propargyl alcohol.

However, new materials or raw materials are required as electrolyte additives that can obtain better charge/discharge capacities, long cycle life, and ensure stability, and among them, research is being conducted on various phosphate compounds.

Domestic registration patent No. 10-0585219 (registration date 2006.05.24.) US Patent Publication No. US 2003/0113635 A1 (Published on June 19, 2003) Chinese Publication Patent CN 110066291 A (Published on 2019.07.30.) Domestic Publication Patent No. 10-2023-0001107 (Published on 2023.01.04.) Japanese Publication of Patent No. 2002-198092 (Published on July 12, 2002)

Gi K. Cheung et al, “A convenient preparation of pyrophosphoryl chloride and its use in vilsmeier formylation”, SYNLETT, January 1992, p77-78.

As described above, the present invention aims to provide a novel tetra-substituted diphosphate-boron trifluoride compound.

In addition, the present invention aims to provide a method for producing a novel tetra-substituted diphosphate-boron trifluoride compound in high yield through a simple and economical synthetic process.

The present invention provides a tetra-substituted diphosphate-boron trifluoride compound represented by the following chemical formula 1.

[Chemical Formula 1]

In the above chemical formula 1, n is 1 or 2, R ₁ to R ₄ are the same as or different from each other, and are each independently selected from a substituted or unsubstituted alkyl group, an alkenyl group, an alkynyl group, an aryl group, an arylalkyl group, a heteroaryl group, and a heteroarylalkyl group having m or less carbon atoms.

In the above R ₁ to R ₄ , the number of carbon atoms m is 50 or less.

As a more preferred example, the tetra-substituted diphosphate-boron trifluoride compound represented by the above chemical formula 1 may be a compound represented by the following chemical formulas 1-1 and 1-2.

[Chemical Formula 1-1]

[Chemical Formula 1-2]

In addition, the present invention includes a method for producing a tetra-substituted diphosphate-boron trifluoride compound represented by the chemical formula 1, the method including: 1) a step of preparing a halogen-substituted diphosphate; 2) a step of reacting the halogen-substituted diphosphate with an alcohol compound in the presence of a solvent and a base to produce a tetra-substituted diphosphate compound; and 3) a step of mixing boron trifluoride (BF3) and an ether with the tetra-substituted diphosphate to produce a tetra-substituted diphosphate-boron trifluoride compound.

The alcohol compound in the above step 2) is characterized in that it is propargyl alcohol, and the tetra-substituted diphosphate is tetra(prop-2-yn-1-yl)diphosphate.

The solvent in the above step 2) is characterized in that it is one or a mixture of two or more solvents selected from dimethyl ether, diethyl ether, diisopropyl ether, dichloromethane, dichloroethane, nitrile, dioxane solvents, etc., and the base is characterized in that it is one or a mixture of two or more solvents selected from triethylamine, dimethylethylamine, pyridine, etc.

The above step 2) is characterized in that it is performed through the steps of: first, introducing the alcohol compound and the solvent into the reactor, and cooling the temperature of the reactor to 0°C to 10°C (step 2-1); after the cooling step, introducing the base and stirring (step 2-2); and after the stirring step, introducing the pyrophosphoryl chloride prepared in step 1) into the reactor (step 2-3).

In addition, the present invention can be used as an additive for a lithium ion battery electrolyte including the tetra-substituted diphosphate-boron trifluoride compound.

In addition, the present invention can be used as an electrolyte for a lithium secondary battery, including a lithium salt; an organic solvent; and an additive for the electrolyte; wherein the additive for the electrolyte includes a tetra-substituted diphosphate-boron trifluoride compound.

The present invention provides a novel tetra-substituted diphosphate-boron trifluoride compound.

In addition, the present invention provides a method for producing a novel tetra-substituted diphosphate-boron trifluoride compound in high yield through a simple and economical synthetic process.

In addition, the compound according to the present invention has low volatility and thermal stability, and is therefore industrially useful as an electrolyte additive for lithium ion batteries.

Figure 1 is a reaction flow diagram dividing the manufacturing process of the present invention into steps.

Hereinafter, the present invention will be described in detail using preferred embodiments. However, the scope of the rights of the present invention is not limited by these embodiments. In addition, even if it is a configuration that is absolutely necessary for carrying out the present invention, a detailed description will be omitted for matters that are introduced in the prior art or can be easily carried out by a person skilled in the art from known techniques.

Terms or words used in the specification and claims of the present invention are not to be construed as limited to their usual or dictionary meanings, and should be interpreted as meanings and concepts that conform to the technical idea of the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her own invention in the best manner.

Throughout the specification of the present invention, when a part is said to "include" a certain component, this does not exclude other components, unless otherwise specifically stated, but rather means that other components may be included. Throughout the specification of the present invention, "A and/or B" means A or B, or A and B.

As used herein, the terms "preferred" and "preferably" refer to embodiments of the invention that can provide certain advantages under certain circumstances. However, other embodiments may also be preferred under the same or different circumstances. Additionally, the mention of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

Pyrophosphoric acid is an inorganic compound with the chemical formula [(HO) ₂ P(O)] ₂ O, and is also called diphosphoric acid. In the present invention, it was used as a starting material by substituting it with a halogen.

Hereinafter, the present invention aims to provide a tetra-substituted diphosphate-boron trifluoride compound represented by the following chemical formula 1.

[Chemical Formula 1]

In the above chemical formula 1, n is 1 or 2, R ₁ to R ₄ are the same as or different from each other, and are each independently selected from a substituted or unsubstituted alkyl group, an alkenyl group, an alkynyl group, an aryl group, an arylalkyl group, a heteroaryl group, and a heteroarylalkyl group having m or less carbon atoms.

In the above R ₁ to R ₄ , the number of carbon atoms m can be 50 or less, 25 or less, or 12 or less.

The definitions of the functional groups mentioned in this specification are as follows.

The above “substituted or unsubstituted” means substituted or unsubstituted with one or more substituents selected from the group consisting of a halogen group, a cyano group, a nitro group, a hydroxy group, a carbonyl group, an ester group, an imide group, an amino group, an amidino group, a carboxyl group or a salt thereof, a sulfonyl group, a sulfamoyl group, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a phosphine group, a phosphine oxide group, a thiol group, a thioxy group, a phosphonate group, an alkoxy group, an aryloxy group, an alkylthioxy group, an arylthioxy group, a hydrazine group, a hydrazone group, a silyl group, a boron group, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an arylalkyl group, a heteroaryl group, and a heteroarylalkyl group.

The above “alkyl” means a fully saturated branched or unbranched (or straight-chain or linear) hydrocarbon, including a cycloalkyl form. Non-limiting examples of the above “alkyl” include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, neopentyl, iso-amyl, n-hexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl, and the like. At least one hydrogen atom of the above “alkyl” may be substituted with at least one substituent selected from the group consisting of a halogen group, a cyano group, a nitro group, a hydroxy group, a carbonyl group, an ester group, an imide group, an amino group, an amidino group, a carboxyl group or a salt thereof, a sulfonyl group, a sulfamoyl group, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a phosphine group, a phosphine oxide group, a thiol group, a thioxy group, a phosphonate group, an alkoxy group, an aryloxy group, an alkylthioxy group, an arylthioxy group, a hydrazine group, a hydrazone group, a silyl group, a boron group, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an arylalkyl, a heteroaryl group, and a heteroarylalkyl group.

The above “alkenyl” means a branched or unbranched hydrocarbon having at least one carbon-carbon double bond, including a cyclo form. Non-limiting examples of “alkenyl” include vinyl, allyl, butenyl, isopropenyl, isobutenyl, and the like. In addition, one or more hydrogen atoms in the alkenyl may be substituted with the same substituents as in the case of the above-described alkyl group.

The above “alkynyl” means a branched or unbranched hydrocarbon having at least one carbon-carbon triple bond, including a cyclo form. Non-limiting examples of the above “alkynyl” include ethynyl, butynyl, isobutynyl, isopropynyl, and the like. In addition, one or more hydrogen atoms in the above alkynyl may be substituted with the same substituent as in the case of the above-described alkyl group.

The above “aryl” is used alone or in combination, and means an aromatic hydrocarbon containing one or more aromatic rings. In addition, a form in which two or more rings are simply attached to each other (pendant) or condensed may also be included. Non-limiting examples of the above “aryl” include phenyl, naphthyl, tetrahydronaphthyl, etc. In addition, one or more hydrogen atoms in the above “aryl” may be substituted with a substituent similar to the case of the above-described alkyl group.

The above “arylalkyl” means alkyl substituted with aryl. Examples of arylalkyl include benzyl (C6H5CH2-), phenyl (-CH2CH2-), or phenethyl (C6H5CH2CH2-).

The above “heteroaryl” refers to a monocyclic or bicyclic organic compound containing one or more heteroatoms selected from N, O, P, S or Se, and the remaining ring atoms are carbon. The heteroaryl may contain, for example, 1-5 heteroatoms and may contain 5-10 ring members. The S or N may be oxidized to have various oxidation states. One or more hydrogen atoms in the above “heteroaryl” may be substituted with a substituent similar to the case of the above-described alkyl group.

The above “heteroarylalkyl” means alkyl substituted with heteroaryl.

As an embodiment of the present invention, compounds having a structure in which all R1 to R4 substituents of diphosphate are substituted with propargyl groups are tetra-substituted diphosphate-boron trifluoride compounds represented by the following chemical formulas 1-1 and 1-2.

[Chemical Formula 1-1]

[Chemical Formula 1-2]

Among these, the compound according to the most preferred embodiment is tetra(prop-2-yn-1-yl) diphosphate-boron trifluoride represented by the chemical formula 1-1.

Hereinafter, a method for producing a tetra-substituted diphosphate - boron trifluoride compound represented by the chemical formula 1 is described step by step.

First, the first stage of synthesis is the step of preparing a halogen-substituted diphosphate as a starting material according to the following reaction scheme 1. This can be synthesized by substituting a halogen (e.g., Cl) on diphosphoric acid according to a known method (see Synlett, Jan. 1992, p77-78). 4 to 5 moles of halogen acid can be used per mole of diphosphoric acid compound in the reactor. Alternatively, dichloromethane and dimethylformamide can be used for phosphoryl chloride to shorten the reaction time.

<Reaction Formula 1>

In the second step of synthesis, a tetra-substituted diphosphate compound can be prepared by reacting the halogen-substituted diphosphate (e.g., pyrophosphoryl chloride) synthesized in the first step with an alcohol compound in the presence of a solvent (e.g., dichloromethane) and a base (e.g., triethylamine). For example, when the alcohol compound is propargyl alcohol, tetra(prop-2-yn-1-yl)diphosphate can be synthesized.

<Reaction Formula 2>

Propargyl alcohol (or 2-propyn-1-ol) is an organic compound with the chemical formula C3H4O. It is the simplest and most stable alcohol containing an alkyne functional group, and is a colorless, viscous liquid that is miscible with water and most polar organic solvents.

The above two steps can be further divided into the following:

It can be carried out through the steps of: first, introducing the alcohol compound and the solvent into the reactor, and cooling the temperature of the reactor to 0°C to 10°C (step 2-1); after the cooling step, introducing the base and stirring (step 2-2); and after the stirring step, introducing the pyrophosphoryl chloride prepared in step 1 into the reactor (step 2-3).

The above step 2 may be performed at a temperature range of 0°C to 25°C or less. At this time, the reaction time may be appropriately varied depending on the type and amount of reactants, alcohol, base, and solvent used. More specifically, the above step may be performed at a temperature range of 0°C to 25°C or less for 2 to 24 hours.

Non-limiting examples of the solvent include one or more mixed solvents selected from dimethyl ether, diethyl ether, diisopropyl ether, dichloromethane, dichloroethane, nitrile solvents, dioxane solvents, etc. The amount of the solvent used is not limited, but in order to achieve an economical industrial process, the solvent may be used in the range of 1 to 100 parts by weight based on 1 part by weight of the starting material, and more specifically, it is preferable to use the solvent in the range of 5 to 50 parts by weight.

Non-limiting examples of the base include one or a mixture of two or more selected from triethylamine, dimethylethylamine, pyridine, etc. Preferably, triethylamine is used. The equivalent amount of the base may be 1 to 2 equivalents, but the most suitable amount to be used is preferably 1.2 equivalents.

After the above 2 steps, the reaction can be completed after confirming that the starting material has been consumed through TLC (Thin Layer Chromatograph), GC (Gas Chromatography), etc. When the reaction is completed, the solvent can be removed under reduced pressure through simple distillation. In addition, the intermediate target product from which the reactant (mixture) has been removed can be separated and purified through a conventional method such as column chromatography. In addition, the intermediate target product can be separated and purified through reduced pressure distillation.

The yield of the intermediate target tetra-substituted diphosphate compound synthesized through the above steps can be 60% or more. Preferably, it can be 95% or more. The yield and purity can be improved depending on the type of base used.

In the third step of the synthesis, boron trifluoride (BF3) is added to the tetra(prop-2-yn-1-yl)diphosphate synthesized in the second step, thereby ultimately producing tetra(prop-2-yn-1-yl)diphosphate-boron trifluoride. This is a novel solid-state compound which is the final target product of the present invention, and its thermal stability has been confirmed.

Here, tetra(prop-2-yn-1-yl)diphosphate-boron trifluoride can be said to be the most preferred form of tetra-substituted diphosphate-boron trifluoride compound.

<Reaction Formula 3>

Here, boron trifluoride (BF3) is a colorless, toxic, and irritating odor-emitting compound at room temperature. It is heavier than air and reacts with air to produce a white, toxic gas, so it is a substance that must be handled with extreme care.

The above boron trifluoride may be in at least one of a gaseous or solution state.

Therefore, in the present invention, it is used in a mixture with ether, and non-limiting examples of the ether include diisopropyl ether, isopropyl sec-butyl ether, sec-butyl ether, isoamyl ether, isopropyl isoamyl ether, sec-butyl isoamyl ether, etc., and among them, diisopropyl ether, which is commercially available and economical, is particularly preferable.

Since the reaction of mixing ether into boron trifluoride is an exothermic reaction, it is desirable to remove the heat of reaction to reduce the risk of explosion. It is generally known that it is better to perform the reaction at a low temperature of 10℃ or less.

Hereinafter, the present invention will be described in more detail through examples. These examples are provided to more completely explain the present invention to a person having average knowledge in the art.

Synthesis step 1: Synthesis of pyrophosphoryl chloride

Prepare a 250 mL flask that has been washed and dried, and maintain a nitrogen atmosphere in the flask. Add phosphoryl chloride (46 g, 0.3 mol) to the flask, and cool to 5°C. Dissolve pyrophosphoric acid (10.62 g, 0.06 mol), which is a starting material, in 100 mL of dichloromethane (MC), which is a solvent, and add dropwise to the flask. Then, add 1 mL of dimethylformamide dropwise, and gradually heat the temperature in the reactor to reflux.

The above reaction is completed by confirming that the starting material, phosphoryl chloride, has been consumed using gas chromatography (GC). Finally, the remaining excess phosphoryl chloride is removed by distillation, and 7 g of the desired product, pyrophosphoryl chloride, is obtained. The yield at this time is 46% (under conditions of 0.1 torr and 65°C).

Synthesis step 2: Synthesis of Tetra(prop-2-yn-1-yl)diphosphate

Prepare a 250 ml flask that has been washed and dried, and maintain a nitrogen atmosphere in the flask. Add propargyl alcohol (9.0 g, 0.16 mol) to the flask, add 100 g of dichloromethane as a solvent, and cool the temperature inside the reactor to 5°C. While maintaining the temperature inside the reactor, slowly add triethylamine (16.20 g, 0.16 mol) dropwise, and stir for 30 minutes. Dissolve the pyrophosphoryl chloride (10 g, 0.04 mol) synthesized in Step 1 in 50 g of dichloromethane as a solvent, and slowly add dropwise to the reactor for 30 minutes. Confirm that triethylamine hydrochloride is produced in the reaction solution, and proceed with the reaction for 1 hour. Maintain the reaction temperature at room temperature, and stir for 3 hours. The progress of the reaction is confirmed by gas chromatography, and terminated. After completion of the reaction, the solution was washed twice with _H2O ml, the organic layer was dehydrated with _MgSO4 , and the dichloromethane solvent was removed by distillation under reduced pressure. Finally, purification was performed using chromatography on silica gel (Silica gel, 230-400mesh; Hexane:EA (=3:1)). Then, 8.2 g of tetra(prop-2-yn-1-yl)diphosphate was obtained. The yield at this time was 65%.

1H NMR(CDCl3-d6)=δ 4.55(dd, 8H), 2.72 (t, 4H).

Synthesis step 3: Synthesis of Tetra (prop-2-yn-1-yl) diphosphate-Boron trifluoride

Prepare a 250 mL washed and dried flask, and maintain a nitrogen atmosphere in the flask. Add 100 mL of n-hexane to the flask, and add 5 g of boron trifluoride-ether solution. Add 8.2 g of tetra(prop-2-yn-1-yl)diphosphate synthesized in the above step 2, cool the flask, and stir for 3 hours. The produced solid was separated, washed with n-hexane solution, and then vacuum dried at 45°C to obtain 9.0 g of the target product (tetra(prop-2-yn-1-yl)diphosphate-boron trifluoride). The yield at this time was 91%.

1H NMR(DMSO-d6)=δ 4.77(dd, 4H), 4.55(dd, 4H), 2.72 (t, 4H).

The tetra-substituted diphosphate-boron trifluoride compound synthesized in this way is useful as an additive for lithium-ion battery electrolyte.

In particular, since the compounds represented by the chemical formulas 1-1 to 1-2 have a propargyl functional group in their structure, when this functional group is reduced and decomposed, a SEI film having a high passivation ability is formed on the surface of the negative electrode, which can not only improve the high-temperature durability of the negative electrode itself, but also reduce the amount of transition metal deposited on the negative electrode itself. Furthermore, the propargyl group can have a function of making it difficult to elute the metallic impurities contained in the positive electrode by adsorbing them on the surface, thereby suppressing an internal short circuit that may occur when the eluted metal ions are deposited on the negative electrode. Furthermore, since the propargyl group is easily reduced on the surface of the negative electrode, a stable film can be formed on the surface of the negative electrode, thereby preventing a self-discharge reaction of a graphite-based or silicon-based negative electrode caused by an additional reduction and decomposition reaction of the electrolyte caused by the instability of the SEI film.

In addition, in one embodiment of the present invention, an electrolyte for a lithium secondary battery is provided, which comprises a lithium salt; an organic solvent; and an electrolyte additive, wherein the additive of the electrolyte is at least one compound represented by the chemical formula 1.

The lithium salt included as the above electrolyte may be any one commonly used in electrolytes for lithium secondary batteries without limitation.

The organic solvent mentioned above is not limited as long as it can minimize decomposition by oxidation reactions, etc. during the charging and discharging process of the secondary battery, and can exhibit the desired properties together with additives. For example, ether solvents, ester solvents, or amide solvents can be used alone or in combination of two or more.

Although the present invention has been described in detail above with reference to examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and the scope of the present invention should not be construed as being limited to the examples described above.

Claims (8)

In a tetra-substituted diphosphate-boron trifluoride compound represented by the following chemical formula 1,
[Chemical Formula 1]

The compound represented by the above chemical formula 1 is a compound represented by the following chemical formulas 1-1 to 1-2:
[Chemical Formula 1-1]

[Chemical Formula 1-2]

In the above chemical formula 1, n is 1 or 2, and R ₁ to R ₄ are all 2-propynyl groups. delete A method for producing a tetra-substituted diphosphate-boron trifluoride compound represented by the chemical formula 1 of claim 1,
1) A step of preparing a halogen-substituted diphosphate;
2) a step of producing tetra(prop-2-yn-1-yl)diphosphate by reacting the halogen-substituted diphosphate with propargyl alcohol in the presence of a solvent and a base; and
3) A method including a step of preparing a tetra-substituted diphosphate-boron trifluoride compound by mixing boron trifluoride (BF3) and ether into the tetra(prop-2-yn-1-yl)diphosphate; delete In claim 3, a method characterized in that the solvent in step 2) is one or more mixed solvents selected from dimethyl ether, diethyl ether, diisopropyl ether, dichloromethane, dichloroethane, nitrile-based solvents, and dioxane-based solvents, and the base is one or more mixed solvents selected from triethylamine, dimethylethylamine, and pyridine. In claim 3, step 2) is
First, a step of introducing the propargyl alcohol and solvent into the reactor and cooling the temperature of the reactor to 0°C to 10°C (step 2-1);
After the cooling step, a step of adding the base and stirring (step 2-2); and
A method characterized in that it is performed by going through the step (step 2-3) of introducing pyrophosphoryl chloride prepared in step 1) into the reactor after the above stirring step. Additive for lithium ion battery electrolyte comprising the tetra-substituted diphosphate-boron trifluoride compound of claim 1 A lithium secondary battery electrolyte comprising: a lithium salt; an organic solvent; and an additive for an electrolyte; wherein the additive for the electrolyte is an additive for a lithium ion battery electrolyte according to claim 7.