Sodium tetraphenylborate and preparation method thereof

Abstract

The invention provides sodium tetraphenylborate and a preparation method thereof. The preparation method comprises the following steps: (1) in the presence of polyvinylpyrrolidone, reacting activated magnesium powder with chlorobenzene in dry tetrahydrofuran to obtain a Grignard reagent; (2) dropwise adding a tetrahydrofuran solution containing trimethyl borate into the Grignard reagent, and keeping the temperature to obtain a reaction solution; (3) adding the reaction liquid into an aqueous solution containing cerous nitrate and sodium carbonate, and hydrolyzing to obtain hydrolysate; and (4) adding an ionic liquid into the hydrolysate, carrying out gradient cooling, and filtering to obtain the cubic crystal system sodium tetraphenylborate. The sodium tetraphenylborate with high purity and high cubic crystal system rate is prepared through process optimization, the specific surface area of the sodium tetraphenylborate is remarkably increased, the dissolution rate of the sodium tetraphenylborate in an organic solvent is increased, meanwhile, the potassium ion residue of the prepared sodium tetraphenylborate is smaller than 2 ppm, and the standard of an electronic-grade reagent is met.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical reagents, in particular to sodium tetraphenylborate and a preparation method thereof. Background Art

[0002] As an important analytical reagent, sodium tetraphenylborate plays an irreplaceable role in potassium ion detection, organic amine titration, and fluorescence sensing. The traditional synthesis process is usually achieved through the Grignard reaction, where chlorobenzene and magnesium are used to prepare the phenyl Grignard reagent, which is then reacted with trimethyl borate to form a triphenylborane intermediate. Finally, it is hydrolyzed with sodium carbonate to obtain a crude product. However, due to the difficulty in separating the Grignard reaction byproducts (biphenyl and triphenylborane), this process generally results in a crude product with a purity of less than 90%. In addition, the crude product is mostly amorphous or needle-shaped mixed crystals, with a slow dissolution rate and the easy inclusion of impurities during the crystallization process, which restricts the industrial production of high-purity products.

[0003] Current purification technology mainly relies on recrystallization. Although purification is possible, it lacks the problem of directional control of crystal form. The crystal form of the purified product is random and the batch stability is poor. At the same time, the amorphous crude product dissolves slowly, making it difficult to meet the standards of electronic-grade reagents.

[0004] In recent years, cubic sodium tetraphenylborate has been studied for its uniform (100) crystal face exposure, which increases its specific surface area by 50% compared with needle-shaped crystals. It can significantly accelerate the dissolution process and shorten the corresponding time to 30s in blood potassium test strips. Therefore, it is of great significance to develop a type of sodium tetraphenylborate that can directionally induce cubic crystals. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In view of the deficiencies in the prior art, the present invention provides sodium tetraphenylborate and a preparation method thereof, which solve the problems raised in the above background technology.

[0007] (2) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] According to a first aspect of the present invention, there is provided a method for preparing sodium tetraphenylborate, comprising the following steps:

[0010] (1) In the presence of polyvinylpyrrolidone, activated magnesium powder is reacted with chlorobenzene in dry tetrahydrofuran to obtain a Grignard reagent;

[0011] (2) adding a tetrahydrofuran solution containing trimethyl borate dropwise to the Grignard reagent and keeping the mixture warm to obtain a reaction solution;

[0012] (3) adding the reaction solution to an aqueous solution containing cerium nitrate and sodium carbonate for hydrolysis to obtain a hydrolyzed solution;

[0013] (4) adding an ionic liquid to the hydrolyzate, gradually cooling the solution, and filtering the solution to obtain cubic sodium tetraphenylborate.

[0014] The present invention uses polyvinyl pyrrolidone to pre-absorb the active site of trimethyl borate, inhibits the generation of by-products such as triphenylborane, and improves the purity of the crude product. + Vacancies stabilize the cubic phase lattice, and coupling with ionic liquids makes the cubic crystal selectivity ≥98%, avoiding the problem of mixing amorphous and needle-shaped crystals. Finally, a gradient cooling program is used to match crystal growth, avoid impurity entrapment, and reduce potassium ion residue in the product.

[0015] Preferably, in step (1), the activated magnesium powder is magnesium powder pretreated with acetic acid, the particle size of the magnesium powder is 50 to 100 μm, and the concentration of the acetic acid is 3 to 8%.

[0016] Preferably, in step (1), the concentration of polyvinyl pyrrolidone in the Grignard reagent is 0.2-0.5%;

[0017] The molar ratio of the activated magnesium powder to chlorobenzene is 1:1.05-1.3.

[0018] Preferably, in step (1), the reaction temperature is 45-55° C. and the reaction time is 1-1.5 h.

[0019] Preferably, in step (2), the molar ratio of the trimethyl borate to the Grignard reagent is 1:3.05-3.15, the trimethyl borate is calculated as boron atom, and the Grignard reagent is calculated as phenyl group.

[0020] Preferably, in step (3), the concentration of cerium nitrate in the aqueous solution containing cerium nitrate and sodium carbonate is 100-200 ppm, and the concentration of sodium carbonate is 10-15%.

[0021] Preferably, in step (3), the hydrolysis temperature is 70-80° C. and the time is 1-1.5 h.

[0022] Preferably, in step (4), the ionic liquid is selected from at least one of 1-butyl-3-methylimidazolium tetrafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, and tributylmethylamine tetrafluoroborate;

[0023] The concentration of the ionic liquid is 0.5-0.8 wt%.

[0024] Preferably, the gradient cooling in step (4) includes one-stage cooling, two-stage cooling and three-stage cooling;

[0025] The first stage of cooling is reduced to 60°C at a cooling rate of 1°C / min;

[0026] The second stage of cooling is reduced to 40°C at a cooling rate of 0.5°C / min;

[0027] The temperature was lowered to 25° C. in three stages at a cooling rate of 0.2° C. / min.

[0028] According to a second aspect of the present invention, there is provided sodium tetraphenylborate obtained according to the above preparation method, wherein the sodium tetraphenylborate is a cubic crystal system.

[0029] Beneficial effects

[0030] The present invention provides sodium tetraphenylborate and a preparation method thereof. It has the following beneficial effects:

[0031] (1) This scheme provides a method for preparing sodium tetraphenylborate. Polyvinyl pyrrolidone is used to inhibit the byproducts of the Grignard reaction, so that the purity of the crude product is greater than 96%. Cerium nitrate is used to fill lattice vacancies and cooperate with the ionic liquid template effect to achieve directional growth of the cubic crystal system. Finally, combined with a gradient cooling program, the dissolution rate of sodium triphenylborate is increased to more than 12 minutes, and the potassium ion residue is less than 2 ppm. When used in blood potassium test strips, the corresponding time is shortened to 30 seconds.

[0032] (2) The sodium tetraphenylborate provided in this scheme has a uniform cubic crystal system, which significantly improves the specific surface area of ​​sodium tetraphenylborate and the dissolution rate of sodium tetraphenylborate in organic solvents. At the same time, the potassium ion residue of the prepared sodium tetraphenylborate is less than 2ppm, meeting the standards of electronic grade reagents. DETAILED DESCRIPTION

[0033] To facilitate understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different ways and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments or examples and are not intended to limit the present invention. In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise known, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0035] The preparation method of sodium tetraphenylborate of the present invention will be further described below by means of specific examples. However, it will be understood by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific conditions are not specified in the examples, the conventional conditions or manufacturer's specifications were used. Reagents used where the manufacturer is not specified are all commercially available conventional products.

[0036] Example 1

[0037] A method for preparing cubic sodium tetraphenylborate comprises the following steps:

[0038] Step 1. In the presence of 0.3 wt % polyvinylpyrrolidone, activated magnesium powder with a particle size of 80 μm treated with 5% acetic acid and chlorobenzene were added to dry tetrahydrofuran and reacted at 50° C. for 1.2 h to obtain a Grignard reagent, wherein the mass ratio of the activated magnesium powder to the chlorobenzene is 1:1.05;

[0039] Step 2: adding a tetrahydrofuran solution containing trimethyl borate to the Grignard reagent and keeping the temperature at 50° C. to obtain a reaction solution, wherein the molar ratio of the Grignard reagent to trimethyl borate is 3.10:1;

[0040] Step 3: Add an aqueous solution containing 150 ppm of cerium nitrate and 12% of sodium carbonate to the reaction solution, and hydrolyze at 75° C. for 1.2 hours to obtain a hydrolyzed solution;

[0041] Step 4: Add 0.6% 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid to the hydrolyzate, first cool the temperature to 60°C at a cooling rate of 1°C / min, then cool it to 40°C at a cooling rate of 0.5°C / min, and finally cool it to 25°C at a cooling rate of 0.2°C / min. Filter, wash with a mixed solvent of ethanol and toluene, and vacuum dry at 60°C to obtain a cubic crude product.

[0042] Example 2

[0043] A method for preparing cubic sodium tetraphenylborate comprises the following steps:

[0044] Step 1. In the presence of 0.2 wt % polyvinylpyrrolidone, activated magnesium powder with a particle size of 50 μm treated with 5% acetic acid and chlorobenzene were added to dry tetrahydrofuran and reacted at 45° C. for 1.5 h to obtain a Grignard reagent, wherein the mass ratio of the activated magnesium powder to the chlorobenzene is 1:1.15;

[0045] Step 2: adding a tetrahydrofuran solution containing trimethyl borate to the Grignard reagent and keeping the temperature at 45° C. to obtain a reaction solution, wherein the molar ratio of the Grignard reagent to trimethyl borate is 3.05:1;

[0046] Step 3, adding an aqueous solution containing 100 ppm cerium nitrate and 12% sodium carbonate into the reaction solution, hydrolyzing at 70℃ for 1.5 h to obtain a hydrolysis solution;

[0047] Step 4, adding 1-butyl-3-methylimidazolium tetrafluorophosphate ionic liquid with a concentration of 0.5% into the hydrolysis solution, first reducing the temperature to 60℃ at a rate of 1℃ / min, then reducing the temperature to 40℃ at a rate of 0.5℃ / min, and finally reducing the temperature to 25℃ at a rate of 0.2℃ / min, filtering, washing with a mixed solvent of ethanol and toluene, and vacuum drying at 60℃ to obtain a crude product of cubic crystal system.

[0048] Example 3

[0049] A method for preparing cubic crystal sodium tetraphenylboron, comprising the following steps:

[0050] Step 1, in the presence of polyvinylpyrrolidone with a concentration of 0.5wt%, adding activated magnesium powder with a particle size of 100μm treated with acetic acid with a concentration of 5% and chlorobenzene into dry tetrahydrofuran to react at 55℃ for 1.0h to obtain Grignard reagent, wherein the mass ratio of activated magnesium powder to chlorobenzene is 1:1.3;

[0051] Step 2, adding a tetrahydrofuran solution containing trimethyl borate into the Grignard reagent, and keeping at 50℃ to obtain a reaction solution, wherein the molar ratio of Grignard reagent to trimethyl borate is 3.15:1;

[0052] Step 3, adding an aqueous solution containing 200 ppm cerium nitrate and 12% sodium carbonate into the reaction solution, hydrolyzing at 80℃ for 1.5 h to obtain a hydrolysis solution;

[0053] Step 4, adding 1-butyl-3-methylimidazolium tetrafluorophosphate ionic liquid with a concentration of 0.8% into the hydrolysis solution, first reducing the temperature to 60℃ at a rate of 1℃ / min, then reducing the temperature to 40℃ at a rate of 0.5℃ / min, and finally reducing the temperature to 25℃ at a rate of 0.2℃ / min, filtering, washing with a mixed solvent of ethanol and toluene, and vacuum drying at 60℃ to obtain a crude product of cubic crystal system.

[0054] Comparative Example 1

[0055] This comparative example has the same preparation method as Example 1, except that in Step 1, magnesium powder without activation treatment is used.

[0056] Comparative Example 2

[0057] This comparative example has the same preparation method as Example 1, except that in Step 1, the Grignard reagent is not prepared in the presence of polyvinylpyrrolidone.

[0058] Comparative Example 3

[0059] The preparation method of this comparative example is the same as that of Example 1, except that in step 2, the molar ratio of the Grignard reagent to trimethyl borate is 2.95:1.

[0060] Comparative Example 4

[0061] The preparation method of this comparative example is the same as that of Example 1, except that in step 3, cerium nitrate is not added.

[0062] Comparative Example 5

[0063] The preparation method of this comparative example is the same as that of Example 1, except that in step 4, no ionic liquid is added.

[0064] Comparative Example 6

[0065] The preparation method of this comparative example is the same as that of Example 1, except that in step 4, the temperature is directly lowered to 25° C. at a cooling rate of 0.5° C. / min.

[0066] Comparative Example 7

[0067] The preparation method of this comparative example is the same as that of Example 1, except that in step 4, the concentration of the ionic liquid added to the hydrolyzate is 0.1%.

[0068] The properties of the crude sodium tetraphenylborate prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were tested, as shown in Table 1.

[0069] Table 1

[0070]

[0071]

[0072] According to the data in Table 1, by comparing Comparative Example 1 with Example 1, the reaction efficiency of unactivated magnesium powder is reduced, the by-product biphenyl increases, and impurities interfere with the crystal orientation, resulting in a 30% increase in needle-shaped crystals; by comparing Comparative Example 2 with Example 1, the lack of polyvinyl pyrrolidone has always caused side reactions, and the impurities of triphenylborane are increased, thereby destroying the growth of the cubic crystal system; by comparing Comparative Example 3 with Example 1, insufficient Grignard reagent will lead to an increase in triphenyl residues, thereby affecting the growth of the cubic crystal system; by comparing Comparative Example 4 with Example 1, not adding cerium nitrate will increase lattice vacancies, promote the dominant growth of needle-shaped crystals, and reduce detection sensitivity; by comparing Comparative Example 5 and Comparative Example 7 with Example 1, without adding an ion template machine or adding a small amount of ion milling machine, the crystal surface adsorption is incomplete and the amorphous phase increases; by comparing Comparative Example 6 with Example 1, direct cooling will lead to impurity embedding, affecting the generation rate of the cubic crystal system.

[0073] The present invention prepares high-purity and high-cubic sodium tetraphenylborate through the above-mentioned process optimization, significantly increases the specific surface area of ​​sodium tetraphenylborate, and improves the dissolution rate of sodium tetraphenylborate in organic solvents. At the same time, the potassium ion residue of the prepared sodium tetraphenylborate is less than 2 ppm, meeting the standards of electronic-grade reagents.

[0074] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing sodium tetraphenylborate, characterized in that: The following steps are involved: (1) In the presence of polyvinylpyrrolidone, activated magnesium powder is reacted with chlorobenzene in dry tetrahydrofuran to obtain a Grignard reagent; (2) adding a tetrahydrofuran solution containing trimethyl borate dropwise to the Grignard reagent and keeping the mixture warm to obtain a reaction solution; (3) adding the reaction solution to an aqueous solution containing cerium nitrate and sodium carbonate for hydrolysis to obtain a hydrolyzed solution; (4) adding an ionic liquid to the hydrolyzate, gradually cooling the solution, and filtering the solution to obtain cubic sodium tetraphenylborate.

2. The method for preparing sodium tetraphenylborate according to claim 1, wherein: In step (1), the activated magnesium powder is magnesium powder pretreated by acetic acid, the particle size of the magnesium powder is 50 to 100 μm, and the concentration of the acetic acid is 3 to 8%.

3. The method for preparing sodium tetraphenylborate according to claim 1, wherein: In step (1), the concentration of polyvinyl pyrrolidone in the Grignard reagent is 0.2-0.5%; The molar ratio of the activated magnesium powder to chlorobenzene is 1:1.05-1.

3.

4. The method for preparing sodium tetraphenylborate according to claim 1, wherein: In step (1), the reaction temperature is 45-55° C. and the reaction time is 1-1.5 h.

5. The method for preparing sodium tetraphenylborate according to claim 1, wherein: In step (2), the molar ratio of the trimethyl borate to the Grignard reagent is 1:3.05-3.15, the trimethyl borate is calculated as boron atom, and the Grignard reagent is calculated as phenyl group.

6. The method for preparing sodium tetraphenylborate according to claim 1, wherein: In step (3), the concentration of cerium nitrate in the aqueous solution containing cerium nitrate and sodium carbonate is 100-200 ppm, and the concentration of sodium carbonate is 10-15%.

7. The method for preparing sodium tetraphenylborate according to claim 1, wherein: In step (3), the hydrolysis temperature is 70-80° C. and the time is 1-1.5 h.

8. The method for preparing sodium tetraphenylborate according to claim 1, wherein: In step (4), the ionic liquid is selected from at least one of 1-butyl-3-methylimidazolium tetrafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, and tributylmethylamine tetrafluoroborate; The concentration of the ionic liquid is 0.5-0.8 wt%.

9. The method for preparing sodium tetraphenylborate according to claim 1, wherein: The gradient cooling in step (4) includes one-stage cooling, two-stage cooling and three-stage cooling; The first stage of cooling is reduced to 60°C at a cooling rate of 1°C / min; The second stage of cooling is reduced to 40°C at a cooling rate of 0.5°C / min; The temperature was lowered to 25° C. in three stages at a cooling rate of 0.2° C. / min.

10. Sodium tetraphenylborate obtained according to the preparation method according to any one of claims 1 to 9, characterized in that: The sodium tetraphenylborate is a cubic crystal system.

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