JP4918956B2 - Method for producing boron-based alkali metal salt - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a method for producing a boron-based alkali metal salt.To the lawRelated.
[0002]
[Prior art]
In recent years, the demand for power storage devices has increased due to advances in microelectronics. Attention is paid to lithium secondary batteries and high-capacity capacitors represented by electric double layer capacitors as such power storage devices.
Generally, an electricity storage device such as a lithium secondary battery or an electric double layer capacitor includes an electrolytic solution in which an electrolyte is dissolved in an organic solvent or the like. As the electrolyte, a boron-based alkali metal salt or the like is used. As an example, LiBF is used for lithium secondary batteries._FourBoron-based lithium salts such as are used. As described above, boron-based alkali metal salts are one of important materials in power storage devices and the like, but have a problem that their synthesis is extremely difficult.
For example, regarding the synthesis of lithium catechol borate, which is one of boron-based alkali metal salts, a method of obtaining an anion having boron as a nucleus by using the reaction shown in the following formulas 1 and 2 using boric acid as a raw material is described in J. Electrochem. Soc., P. 2527-2531, Vol. 142, No. 8, (1995).
B (OH)_Four ^-+ C₆H_Four(OH)₂→ [(HO)₂B (C₆H_FourO₂)]^-+ 2H₂O ... Formula 1
[(HO)₂B (C₆H_FourO₂)]^-+ C₆H_Four(OH)₂→ [B (C₆H_FourO₂)₂]^-+ 2H₂O ... Equation 2
[0003]
[Problems to be solved by the invention]
However, in the above method, it is difficult to replace all four hydroxyl groups (—OH) bonded to boron. That is, the equilibrium constant in the reaction of Formula 1 is 2 × 10^FourWhereas it is about L / mol, the equilibrium constant in the reaction of Formula 2 is about 5 L / mol, and the target anion ([B (C₆H_FourO₂)₂]^-) Yield is only around 64%.
This invention is made | formed in view of the said actual condition, and makes it a subject to provide the method which can synthesize | combine the boron alkali metal salt made difficult to synthesize | combine simply and with a high yield.
[0004]
[Means for Solving the Problems]
  The method for producing a boron-based alkali metal salt of the present invention can be exchanged with a first raw material preparation step of preparing a first raw material containing an alkali metal tetraalkylborate and an alkoxy group of the alkali metal tetraalkylborate.And consisting of a chain hydrocarbon compound having at least one of a carboxyl group and a hydroxyl groupPreparing a second raw material containing a ligand, reacting the first raw material and the second raw material, and exchanging the alkoxy group of the alkali metal tetraalkylborate with the ligand; And a synthesis step of synthesizing a boron-based alkali metal salt.
  That is, in the method for producing a boron-based alkali metal salt of the present invention, it is important to use the alkali metal tetraalkyl borate of the present invention described later as one of the raw materials. By using the alkali metal tetraalkylborate of the present invention, the alkoxy group can be easily exchanged with the ligand and all the alkoxy groups bonded to boron can be exchanged by simply reacting with the predetermined ligand. A 4-exchange boron-based alkali metal salt can be obtained. Therefore, the method for producing a boron-based alkali metal salt according to the present invention is a method by which a boron-based alkali metal salt can be synthesized easily and in a high yield.
[0005]
Further, the alkali metal tetraalkylborate of the present invention has a composition formula MB (OR)_Four(M is an alkali metal, and OR is an alkoxyl group). The present inventor has succeeded in synthesizing an alkali metal tetraalkylborate as a very useful substance for the production of a boron-based alkali metal salt, while researching the synthesis of a boron-based alkali metal salt. The use of the alkali metal tetraalkyl borate of the present invention is not particularly limited. However, by using the alkali metal tetraalkyl borate of the present invention as one of the raw materials, a boron-based alkali metal salt can be easily and highly produced. It can be synthesized in a yield.
[0006]
  MaOh, aLucari metal tetraalkyl borateTo manufactureAlkali metal alkoxide and trialkyl borate are reacted to form alkali metal tetraalkyl borate.It is preferable to obtain. In this caseThe useful alkali metal tetraalkylborate of the present invention can be easily produced.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the method for producing a boron-based alkali metal salt of the present invention includes a first raw material preparation step, a second raw material preparation step, and a synthesis step. Hereinafter, the method for producing a boron-based alkali metal salt of the present invention will be described in detail for each step. Further, the alkali metal tetraalkylborate of the present invention and the production method thereof will be described as appropriate in the description of the production method of the boron-based alkali metal salt of the present invention.
[0008]
(1) First raw material preparation step
This step is a step of preparing a first raw material containing an alkali metal tetraalkyl borate. That is, the first raw material contains the alkali metal tetraalkyl borate of the present invention. The alkali metal tetraalkylborate of the present invention has a composition formula MB (OR)_Four(M is an alkali metal, OR is an alkoxyl group), and the alkali metal M to be a cation is not particularly limited. Examples of the alkali metal include Li, K, Na, and the like. In this step, the alkali metal tetraalkylborate of the present invention, which is appropriately selected according to the target boron-based alkali metal salt, may be used. For example, when a boron-based lithium salt is synthesized, a lithium tetraalkyl borate with an alkali metal Li may be employed.
The alkoxy group (—OR) of the alkali metal tetraalkylborate of the present invention is not particularly limited. When used as the first raw material in this step, it is desirable that the alkoxy group has a low electron donating property, considering that boron is an element with strong electrophilicity. That is, since the electron donating property to boron decreases when the number of carbons bonded to oxygen is small, for example, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, or the like is desirable. Further, the bulky alkoxy group may inhibit the nucleophilic attack of the ligand in the ligand exchange reaction described later. Therefore, when these are taken into consideration, the alkoxy group is preferably a methoxy group.
Note that four alkoxy groups are bonded to boron, but one type of alkoxy group may be used, that is, all four may be the same alkoxy group, or two or more types may be mixed. In particular, in consideration of the uniformity of the ligand exchange reaction, it is desirable that the number of alkoxy groups be one. In summary, all four alkoxy groups are preferably methoxy groups. That is, when used as the first raw material in this step, the alkali metal tetraalkyl borate is alkali metal tetramethyl borate (MB (OCH_Three)_Four) Is desirable. Furthermore, for example, when synthesizing a boron-based lithium salt, it is desirable to use lithium tetramethyl borate in which the alkali metal is Li.
[0009]
The method for synthesizing the alkali metal tetraalkylborate of the present invention is not particularly limited. The inventor has conducted extensive research and has established a simple method for synthesizing the alkali metal tetraalkylborate of the present invention. Therefore, according to the present synthesis method, the alkali metal tetraalkylborate of the present invention can be easily synthesized, and the method for producing the boron-based alkali metal salt of the present invention can be further simplified. That is, the method for producing an alkali metal tetraalkyl borate of the present invention is a method for obtaining an alkali metal tetraalkyl borate by reacting an alkali metal alkoxide with a trialkyl borate. The first raw material preparation step in the method for producing a boron-based alkali metal salt of the present invention further includes a step of synthesizing an alkali metal tetraalkyl borate by reacting an alkali metal alkoxide with a trialkyl borate. Can do.
Here, alkali metal alkoxide (M (OR¹)) And trialkyl borate (B (OR²)_Three) (M is alkali metal, OR¹And OR²Is an alkoxy group, and the alkoxy group is not particularly limited. What is necessary is just to select suitably according to the target alkali-metal tetraalkyl borate. For example, the alkali metal tetramethyl borate (MB (OCH_Three)_Four) Are synthesized, both alkoxy groups (OR¹, OR²) Is a methoxy group, alkali metal methoxide and trimethyl borate may be used.
Then, the alkali metal alkoxide and the trialkyl borate may be reacted in equimolar amounts. The reaction time may be about 24 hours. Since this synthesis reaction is an exothermic reaction, it is desirable to carry out the reaction in a solvent in order to suppress the reaction rate. Any solvent may be used as long as it does not react with alkali metal alkoxide and trialkyl borate and can dissolve them. For example, when an alkali metal methoxide and trimethyl borate are reacted, it is desirable to use methanol as a solvent. The amount of solvent is desirably 500 mL or more and 5000 mL or less with respect to 1 mol of tetraalkylborate ions. This is because if the amount is less than 500 mL, the solvent may be boiled due to heat during the reaction, and if it exceeds 5000 mL, the reaction efficiency decreases.
[0010]
Moreover, the alkali metal alkoxide should just select the kind of the alkali metal suitably according to the target alkali metal tetraalkyl borate. For example, when synthesizing lithium tetraalkyl borate, the alkali metal alkoxide may be replaced with lithium alkoxide.
Even when lithium tetraalkylborate is synthesized, an alkali metal alkoxide having an alkali metal other than lithium as a cation can be used. In this case, in the first raw material preparation step, the alkali metal alkoxide having an alkali metal other than lithium as a cation and a trialkyl borate are reacted to form an alkali metal tetraalkyl having an alkali metal other than lithium as a cation. The step of synthesizing the borate, the synthesized alkali metal tetraalkylborate and a lithium salt having lithium as a cation are reacted to replace the alkali metal of the alkali metal tetraalkylborate and lithium of the lithium salt, And a step of synthesizing lithium tetraalkylborate. The same applies to the method for producing an alkali metal tetraalkyl borate of the present invention. If this embodiment is adopted, for example, sodium tetraalkylborate is synthesized using sodium alkoxide which is inexpensive and easily available, and the lithium and tetraalkylborate are easily replaced by replacing the sodium with lithium. Can be synthesized.
In the above embodiment, the lithium salt having lithium as a cation is not particularly limited. For example, lithium chloride, lithium bromide, lithium carbonate, or the like can be used. In particular, it is desirable to use lithium chloride because it is highly soluble in methanol as a solvent and the by-product precipitates as sodium chloride. The reaction between the alkali metal tetraalkyl borate and the lithium salt can be carried out by directly adding the lithium salt to the reaction solution obtained by synthesizing the alkali metal tetraalkyl borate. In this case, in order to accelerate the reaction, it is desirable to add the lithium salt by previously dissolving the lithium salt in a solvent such as methanol used in the synthesis reaction of the alkali metal tetraalkylborate.
[0011]
The first raw material is not particularly limited as long as it contains the alkali metal tetraalkyl borate of the present invention. For example, a predetermined solvent can be added to the alkali metal tetraalkyl borate of the present invention to prepare an alkali metal tetraalkyl borate solution. In this case, the solvent to be added is not particularly limited. Considering that the ligand exchange reaction to be described later proceeds more rapidly, it is desirable that the solvent dissolves at least one of the alkali metal tetraalkylborate and the ligand used as the second raw material. In particular, it is desirable to use tetrahydrofuran (THF) because the ligand used as the second raw material is easily dissolved and can be used as an electrolyte for a lithium secondary battery.
Moreover, the amount of solvent to add is not specifically limited, What is necessary is just to add about 0.5 mL-10 mL with respect to 1 mmol of alkali metal tetraalkyl borate. In particular, in order to advance the ligand exchange reaction quickly, it is desirable that the concentration of the reactant is high, and therefore the solvent to be added is desirably 5 mL or less. Moreover, when there are too few solvents, there exists a possibility that progress of a ligand exchange reaction may become slow for reasons, such as precipitation of the boron-type alkali metal salt which is a target object, or the viscosity of a liquid is high. Therefore, the solvent to be added is desirably 1 mL or more.
In addition, as the solvent to be added in the above embodiment, a solvent that does not dissolve both the alkali metal tetraalkylborate of the present invention and the ligand used as the second raw material can be used. Even in this case, from the viewpoint of allowing the ligand exchange reaction to proceed more rapidly, for example, when lithium tetraalkyl borate is used as the alkali metal tetraalkyl borate, water is further added to form lithium tetraalkyl borate. It is desirable to prepare the first raw material as a lithium tetraalkyl borate solution in which lithium tetraalkyl borate is dissolved. In this case, if water is added excessively, the yield of the target boron-based lithium salt in the subsequent ligand exchange reaction may be reduced. Therefore, it is desirable that the amount of water added is such that lithium tetraalkyl borate is dissolved.
[0012]
  (2) Second raw material preparation step
  This step is a step of preparing a second raw material containing a ligand exchangeable with an alkoxy group of an alkali metal tetraalkylborate. Ligand can be exchanged for alkoxy groupChain hydrocarbon compoundsIf it is, it will not specifically limit.The chain hydrocarbon compound used as the ligand is preferably a compound that can form a cyclic structure with an alkali metal tetraalkylborate,For example, a substance having a nucleophilic functional group such as a carboxyl group, a sulfonic acid group, an imide group, a hydroxyl group, or an alkoxy group under a more nucleophilic condition can be used. The ligand isThese twoWhat is necessary is just to have the above. The number of functional groups is not particularly limited, and the number of functional groups may be one or two or more. Among the ligands, in particular, because the ligand exchange reaction described later easily proceeds,Consists of chain hydrocarbon compoundsIt is desirable to use a chelate compound.TheAs a chelate compound,It is preferably at least one selected from the group consisting of oxalic acid, fumaric acid, malonic acid, succinic acid, and pyruvic acid.
Although not within the scope of the present invention, the chelate compound used as the ligand isPhthalic acid,Dicarboxylic acid such as hydroxyphthalic acid, catechol, 2-2'biphenyldiol, diol such as 2-2'binaphthol, salicylIt may be an acid or the like.
  A 2nd raw material will not be specifically limited if the said ligand is included. For example, it is possible to prepare a ligand solution by adding a predetermined solvent to the ligand. In this case, the solvent to be added is not particularly limited as described above. As described above, it is desirable to use tetrahydrofuran (THF) as the solvent for reasons such as allowing the ligand exchange reaction to proceed more rapidly. In addition, what is necessary is just to add about 0.5 mL-10 mL with respect to 1 mmol of ligands for the solvent amount to add.
[0013]
(3) Synthesis process
This step is a step of synthesizing a boron-based alkali metal salt by reacting the first raw material and the second raw material and exchanging the alkoxy group of the alkali metal tetraalkylborate and the ligand.
The reaction between the first raw material and the second raw material may be performed by mixing both prepared raw materials. The mixing ratio of the first raw material and the second raw material may be determined stoichiometrically according to the target boron-based alkyl metal salt. For example, when synthesizing a 4-exchanged boron-based alkali metal salt in which all alkoxy groups bonded to boron are exchanged with a ligand, and the ligand is monovalent, an alkali metal tetra What is necessary is just to mix so that a ligand may become 4 equivalent with respect to 1 equivalent of alkyl borate. Moreover, if a ligand is a bivalent thing, what is necessary is just to mix so that a ligand may become 2 equivalent with respect to 1 equivalent of alkali metal tetraalkyl borate.
In consideration of the reaction rate, the subsequent purification efficiency, and the like, it is desirable to mix the second raw material so that the ligand is excessive with respect to the alkali metal tetraalkylborate. Specifically, if the ligand is monovalent with respect to 1 equivalent of the alkali metal tetraalkylborate, it is desirable that the ligand be 4 equivalents or more and 6 equivalents or less. This is because if the ligand is less than the stoichiometric amount, an intermediate product is easily generated in the ligand exchange reaction. On the other hand, if an excessive amount is added, purification of the product becomes difficult.
The reaction does not specifically limit the reaction conditions. For example, the reaction temperature may be about room temperature. If the ligand exchange reaction is difficult to proceed depending on the raw materials used for the reaction, refluxing under heating or the like, removal of by-products by distillation, extraction, or the like may be performed. Further, when a solvent is used as a raw material, a boron-based alkali metal salt can be obtained by removing the solvent after the ligand exchange reaction. Furthermore, it is desirable to remove impurities such as raw materials added excessively by purifying the reaction product. Impurities can be removed, for example, by vacuum drying the reaction product.
[0014]
In addition, it is also possible to synthesize a boron-based lithium salt using the alkali metal tetraalkyl borate of the present invention having an alkali metal other than lithium as a cation as the first raw material. In this case, after the synthesis step, the boron-based alkali metal salt obtained is reacted with a lithium salt having lithium as a cation to exchange the alkali metal of the boron-based alkali metal salt with lithium of the lithium salt. A mode including the step of making it should just be adopted. That is, after the boron-based alkali metal salt is once synthesized, a step of replacing the alkali metal that is a cation of the boron-based alkali metal salt with lithium may be added. As the lithium salt used in this embodiment, lithium chloride or the like can be used as described above.
[0015]
(4) Acceptance of other embodiments
The embodiment of the method for producing a boron-based alkali metal salt of the present invention described so far, the alkali metal tetraalkylborate used therein and the method for producing the same are merely examples, and the method for producing the boron-based alkali metal salt of the present invention, The alkali metal tetraalkylborate used and the method for producing the alkali metal can be implemented in various modified and improved forms based on the knowledge of those skilled in the art including the above-described embodiment.
[0016]
【Example】
Based on the said embodiment, the alkali metal tetraalkyl borate of this invention was synthesize | combined and the boron type | system | group alkali metal salt was manufactured variously. And according to the manufacturing method of this invention, it confirmed that a boron type | system | group alkali metal salt was compoundable simply and with a high yield. Hereinafter, the synthesis of the alkali metal tetraalkyl borate as the first raw material and the synthesis of the boron-based alkali metal salt will be described in order.
[0017]
<Synthesis of alkali metal tetraalkylborate>
In this example, lithium tetramethyl borate (LiB (OCH_Three)_Four) And sodium tetramethylborate (NaB (OCH_Three)_FourAnd each was used as the first raw material in the production of boron-based alkali metal salts. Hereinafter, the synthesis method will be described.
Sodium methoxide was used as an alkali metal alkoxide with sodium as a cation. First, 193 g of sodium methoxide was dissolved in methanol to prepare a 28 wt% sodium methoxide-methanol solution. This solution was placed in a three-neck flask exchanged with nitrogen, and 200 mL of methanol was further added. Next, 103.9 g of trimethyl borate as a trialkyl borate was dropped into the above solution with an isobaric dropping funnel to obtain sodium tetramethyl borate. The dropping time was 30 minutes. This reaction is shown in Formula 3 below.
NaOCH_Three+ B (OCH_Three)_Three  → NaB (OCH_Three)_Four... Formula 3
On the other hand, 42.4 g of lithium chloride as a lithium salt was dissolved in 200 mL of methanol, and water-cooled for 30 minutes to prepare a lithium chloride solution. The reaction solution was allowed to stand for about 3 hours, and after the exothermic reaction converged to room temperature, a lithium chloride solution was added to the reaction solution with an isobaric dropping funnel. At this time, heat of reaction and white precipitation were confirmed. The flame reaction of the white precipitate showed an orange color and it reacted with the aqueous silver nitrate solution, confirming that the precipitate was NaCl. This reaction is shown in Formula 4 below.
NaB (OCH_Three)_Four+ LiCl → LiB (OCH_Three)_Four+ NaCl Formula 4
Further, the reaction solution was allowed to stand at room temperature for 12 hours, and then NaCl was filtered off and the resulting solution was recrystallized. As a result, 88.8 g of white needle crystals were obtained. This crystal shows a red flame reaction. Further, from the spectrum of IR measurement, lithium tetramethylborate (LiB (OCH_Three)_Four).
[0018]
<Synthesis of boron-based alkali metal salts>
The following (1), (2), (3), (4), (9) are manufacturing methods as reference examples, and (5), (6), (7), (8) are the manufacturing methods of the present invention. The method.
(1) Synthesis of lithium dicatechol borate
(A)As a reference exampleSynthesis by manufacturing method
  Lithium dicatechol borate was synthesized from the synthesized lithium tetramethyl borate. The reaction formula is shown in the following formula 5.
[Chemical 1]
  First, 7.2 g (equivalent to 50 mmol) of lithium tetramethylborate (LiB (OCH_Three )_Four ) Was added to a three-necked flask, and 100 mL of tetrahydrofuran (THF) was added to prepare a first raw material. Next, 11.0 g (corresponding to 50 × 2 mmol) of catechol having two hydroxyl groups as a ligand exchangeable with a methoxy group was dissolved in 100 mL of THF to prepare a second raw material. The second raw material was added to the three-necked flask containing the first raw material, heated for about 5 hours, and then allowed to stand for about 24 hours. Then, THF was removed by an evaporator until the reaction solution reached about 15 mL, and then 1 L of n-hexane was added to perform reprecipitation treatment. The obtained precipitate was vacuum-dried at 120 ° C. to obtain 8.6 g (corresponding to 35 mmol) of dark brown lithium dicatechol borate. The yield was about 85%. The absence of catechol in the product was confirmed by gel permeation chromatography. Furthermore, it was confirmed from IR measurement and elemental analysis that the product was lithium dicatechol borate. In this example, the yield is a value calculated by the following equation. Yield = weight of product obtained (g) / theoretical synthetic weight of product (g) × 100 (%)
(B) Synthesis by conventional methods
  For comparison, lithium dicatechol borate was synthesized by a conventional method. The reaction formula is shown in the following formula 6.
[Chemical 2]
  First, 500 g of catechol, 95.27 g of lithium hydroxide monohydrate, and 140.31 g of boric acid were added to 250 mL of distilled water and refluxed at 105 ° C. in an argon atmosphere. Then, it was left at room temperature for 14 hours and recrystallized at -3 ° C. The obtained crystal was vacuum-dried at 115 ° C. for 50 hours to remove crystal water, and 323.9 g of lithium dicatechol borate was obtained. The yield was about 61%.
(C)Reference exampleComparison of manufacturing methods with conventional methods
  the aboveReference exampleWhen comparing the production method and the conventional method,Reference exampleThe manufacturing method was higher than 20%. Also,Reference exampleIn this production method, since THF is used as a reaction solvent, there is no mixing of water, and it is not necessary to remove crystal water from the product. This is very useful when lithium dicatechol borate is used as an electrolyte for a lithium secondary battery. Therefore,Reference exampleThis production method was confirmed to be a method by which a boron-based alkali metal salt can be synthesized in a simple and high yield.
[0019]
(2) Synthesis of lithium bis (2-2'biphenyldiol) borate
Similarly to (1) above, lithium bis (2-2'biphenyldiol) borate was synthesized from lithium tetramethyl borate. The reaction formula is shown in the following formula 7.
[Chemical Formula 3]
First, 7.2 g (equivalent to 50 mmol) of lithium tetramethylborate (LiB (OCH_Three)_Four) Was placed in a three-necked flask, and 100 mL of THF was added to prepare a first raw material. Next, 18.6 g (corresponding to 50 × 2 mmol) of 2-2 ′ biphenyldiol having two hydroxyl groups as a ligand exchangeable with a methoxy group was dissolved in 100 mL of THF to prepare a second raw material. The second raw material was added to the three-necked flask containing the first raw material, heated for about 5 hours, and then allowed to stand for about 24 hours. The precipitated white substance was dried at 100 ° C. to obtain 18.3 g of a crude product with respect to the theoretical amount of 19.3 g. When separation by molecular size was performed by GPC, a peak derived from 2-2'biphenyldiol was detected in addition to a peak considered to be an object. From the peak intensity, 2-2 'biphenyldiol was 1% or less. The crude product was washed twice with 100 mL of toluene to remove 2-2'biphenyldiol, and lithium bis (2-2'biphenyldiol) borate was obtained. The yield was 17.4 g, and the yield was about 90%.
[0020]
(3) Synthesis of lithium disalicylate boroxide
Similarly to (1) above, lithium disalicylate boroxide was synthesized from lithium tetramethylborate. The reaction formula is shown in the following formula 8.
[Formula 4]
First, 7.2 g (equivalent to 50 mmol) of lithium tetramethylborate (LiB (OCH_Three)_Four) Was placed in a three-necked flask, and 100 mL of THF was added to prepare a first raw material. Subsequently, 12.6 g (corresponding to 50 × 2 mmol) of salicylic acid having one hydroxyl group and one carboxyl group as a ligand exchangeable with a methoxy group was dissolved in 50 mL of THF to prepare a second raw material. The second raw material was added to the three-necked flask containing the first raw material and left at room temperature. After 30 minutes, LiB (OCH_Three)_FourDisappeared, confirming that the reaction had proceeded. Furthermore, after leaving to stand for 2 days, it filtered and THF was removed by the evaporator and about 10 mL colorless and highly viscous liquid was obtained. To this liquid, 1000 mL of n-hexane was added and left for 12 hours for reprecipitation treatment. The white precipitate was filtered off, dried in vacuo at 60 ° C., and then unreacted salicylic acid was removed using a sublimation purification apparatus. As a result of measuring by GPC with respect to the obtained white powder, it was confirmed that it was a lithium disalicylate boroxide. The yield was 13.5 g, and the yield was about 91%.
[0021]
(4) Synthesis of boroxide of lithium diphthalate
As in (1) above, lithium diphthalate boroxide was synthesized from lithium tetramethylborate. The reaction formula is shown in the following formula 9.
[Chemical formula 5]
First, 7.2 g (equivalent to 50 mmol) of lithium tetramethylborate (LiB (OCH_Three)_Four) Was placed in a three-necked flask, and 100 mL of THF was added to prepare a first raw material. Next, 16.6 g (corresponding to 50 × 2 mmol) of phthalic acid having two carboxyl groups as a ligand exchangeable with a methoxy group was dissolved in 50 mL of THF to prepare a second raw material. The second raw material was added to the three-necked flask containing the first raw material and refluxed. About 1 hour after refluxing, LiB (OCH_Three)_FourDisappeared, confirming that the reaction had proceeded. The reaction solution was filtered and cooled at 0 ° C. to precipitate a white solid. This solid was collected and vacuum dried at 80 ° C. to obtain 7.9 g of a white powder. The yield was about 46%. From the results of IR measurement, it was confirmed that the substance was boroxide of lithium diphthalate.
[0022]
(5) Synthesis of boroxide of lithium dipyruvate
As in (1) above, lithium dipyruvate boroxide was synthesized from lithium tetramethylborate. The reaction formula is shown in the following formula 10.
[Chemical 6]
First, 7.2 g (50 mmol) of lithium tetramethylborate (LiB (OCH_Three)_Four) Was placed in a three-necked flask, and 100 mL of THF was added to prepare a first raw material. Next, 8.8 g (100 mmol) of pyruvic acid having a carboxyl group and a hydroxyl group as a ligand exchangeable with a methoxy group was prepared as a second raw material. The second raw material was added to the three-necked flask containing the first raw material, and reacted for 5 hours while refluxing THF at 64 ° C. Thereafter, insoluble components in the reaction solution were filtered off to obtain about 100 mL of a light yellow liquid. As a result of GPC measurement of this liquid, it was confirmed that it was one component. Further, the reaction solvent was distilled off, followed by vacuum drying at 80 ° C. to obtain 4.5 g of white powdery lithium dipyruvate boroxide. The yield was about 54%.
[0023]
(6) Synthesis of lithium dimalonate boroxide
As in (1) above, lithium dimalonic acid boroxide was synthesized from lithium tetramethylborate. The reaction formula is shown in the following formula 11.
[Chemical 7]
First, 3.6 g (corresponding to 25 mmol) of lithium tetramethylborate (LiB (OCH_Three)_Four) Was placed in a three-necked flask, and 50 mL of THF was added to prepare the first raw material. Next, 5.2 g (corresponding to 50 × 2 mmol) of malonic acid having two carboxyl groups as a ligand exchangeable with a methoxy group was dissolved in 50 mL of THF to prepare a second raw material. The second raw material was added to the three-necked flask containing the first raw material and refluxed. About 1 hour after refluxing, LiB (OCH_Three)_FourDisappeared and lithium dimalonate boroxide precipitated as a white powder. 20 mL of water was added to the reaction solution to dissolve the precipitate once, and then cooled at 0 ° C. to precipitate white needle crystals again. The crystals were collected and vacuum-dried at 80 ° C. to obtain 3.3 g of a white solid. From the results of IR measurement, it was confirmed that the substance was a lithium dimalonate boroxide. The yield was about 54%.
[0024]
(7) Synthesis of lithium disuccinate boroxide
Similarly to (1) above, lithium disuccinate boroxide was synthesized from lithium tetramethylborate. The reaction formula is shown in the following formula 12.
[Chemical 8]
First, 3.6 g (corresponding to 25 mmol) of lithium tetramethylborate (LiB (OCH_Three)_Four) Was placed in a three-necked flask, and 50 mL of THF was added to prepare the first raw material. Next, 5.9 g (equivalent to 50 × 2 mmol) of succinic acid having two carboxyl groups as a ligand exchangeable with a methoxy group was dissolved in 50 mL of THF to prepare a second raw material. The second raw material was added to the three-necked flask containing the first raw material and refluxed. About 1 hour after refluxing, LiB (OCH_Three)_FourDisappeared and lithium disuccinate boroxide precipitated as a white powder. 20 mL of water was added to the reaction solution to dissolve the precipitate once, and then cooled at 0 ° C. to precipitate white needle crystals again. The crystals were collected and vacuum dried at 80 ° C. to obtain 3.4 g of a white solid. From the results of IR measurement, it was confirmed that this substance was a lithium disuccinate boroxide. The yield was about 53%.
[0025]
(8) Synthesis of lithium disoxalate boroxide
As in (1) above, lithium disoxalate boroxide was synthesized from lithium tetramethylborate. The reaction formula is shown in the following formula 13.
[Chemical 9]
First, 7.2 g (equivalent to 50 mmol) of lithium tetramethylborate (LiB (OCH_Three)_Four) Was placed in a three-necked flask, and 100 mL of THF was added to prepare a first raw material. Next, 10 g (corresponding to 110 mmol) of oxalic acid having two carboxyl groups as a ligand exchangeable with a methoxy group was dissolved in 100 mL of THF to prepare a second raw material. The second raw material was added to the three-necked flask containing the first raw material and refluxed. About 24 hours after refluxing, LiB (OCH_Three)_FourDisappeared. Here, when the components of the reaction solution were separated by the gel permeation chromatograph method, the reaction intermediate was confirmed, and the reaction was allowed to proceed at room temperature for 3 weeks. After 3 weeks, the reaction solution was filtered and THF was distilled off to obtain a solid product. The product was then vacuum dried at 100 ° C. for 2 days to completely sublimate and evaporate excess oxalic acid. As a result, 4.4 g of a brown powder was obtained. From the results of IR measurement, it was confirmed that the substance was lithium disoxalate boroxide. The yield was about 45%.
[0026]
(9) Synthesis of sodium dicatechol borate
Sodium dicatechol borate was synthesized from the sodium tetramethyl borate synthesized above. The reaction formula is shown in the following formula 14.
[Chemical Formula 10]
First, 3.9 g (corresponding to 25 mmol) of sodium tetramethylborate (NaB (OCH_Three)_Four) Was placed in a three-necked flask, and 50 mL of THF was added to prepare a first raw material. Next, 11.0 g (corresponding to 50 × 2 mmol) of catechol having two hydroxyl groups as a ligand exchangeable with a methoxy group was dissolved in 50 mL of THF to prepare a second raw material. The second raw material was added to the three-necked flask containing the first raw material and allowed to stand for about 1 hour. Then NaB (OCH_Three)_FourSince the reaction solution was confirmed to disappear, the reaction solution was filtered, THF was removed by an evaporator, and the obtained solid was vacuum-dried at about 80 ° C. After drying, 3.6 g of a pale yellow solid was obtained. From the IR measurement, it was confirmed that this solid was lithium dicatechol borate. The yield was about 60%.
[0027]
【The invention's effect】
  The method for producing a boron-based alkali metal salt of the present invention uses the alkali metal tetraalkyl borate of the present invention as one of raw materials, and reacts with a predetermined ligand to produce a 4-substituted boron-based alkali metal salt. It is a method to do. According to the production method of the present invention, a boron-based alkali metal salt that is difficult to synthesize can be synthesized simply and in high yield.The

Claims (8)

A first raw material preparation step of preparing a first raw material containing an alkali metal tetraalkylborate;
A second raw material preparation step of preparing a second raw material that is exchangeable with an alkoxy group of the alkali metal tetraalkylborate and includes a ligand made of a chain hydrocarbon compound having at least one of a carboxyl group and a hydroxyl group ; ,
A boron-based process comprising: synthesizing a boron-based alkali metal salt by reacting the first material and the second material and exchanging the alkoxy group and the ligand of the alkali metal tetraalkylborate. A method for producing an alkali metal salt. The method for producing a boron-based alkali metal salt according to claim 1, wherein the chain hydrocarbon compound is a compound that can form a cyclic structure with the alkali metal tetraalkylborate . The method for producing a boron-based alkali metal salt according to claim 2, wherein the chain hydrocarbon compound is at least one selected from the group consisting of oxalic acid, fumaric acid, malonic acid, succinic acid, and pyruvic acid . The method for producing a boron-based alkali metal salt according to any one of claims 1 to 3, wherein the alkali metal tetraalkyl borate is alkali metal tetramethyl borate, and the alkoxy group is a methoxy group. 5. The method for producing a boron-based alkali metal salt according to claim 1, wherein the first raw material preparation step includes a step of synthesizing the alkali metal tetraalkyl borate by reacting an alkali metal alkoxide with a trialkyl borate. . The alkali metal is lithium;
The method for producing a boron-based alkali metal salt according to any one of claims 1 to 5, wherein a boron-based lithium salt is synthesized. The alkali metal tetraalkyl borate is lithium tetraalkyl borate,
The first raw material preparation step includes
A step of reacting an alkali metal alkoxide having an alkali metal other than lithium as a cation with a trialkyl borate to synthesize an alkali metal tetraalkyl borate having an alkali metal other than lithium as a cation;
An alkali metal tetraalkylborate having an alkali metal other than lithium as a cation reacts with a lithium salt having lithium as a cation to replace the alkali metal of the alkali metal tetraalkylborate with lithium in the lithium salt. A step of synthesizing the lithium tetraalkylborate.
The method for producing a boron-based alkali metal salt according to any one of claims 1 to 4, wherein a boron-based lithium salt is synthesized. The alkali metal tetraalkyl borate is an alkali metal tetraalkyl borate having an alkali metal other than lithium as a cation, and after the synthesis step, the boron-based alkali metal salt obtained in the synthesis step and lithium as a cation And a step of replacing the alkali metal of the boron-based alkali metal salt with lithium of the lithium salt,
The method for producing a boron-based alkali metal salt according to any one of claims 1 to 4, wherein a boron-based lithium salt is synthesized.