A method for synthesizing a monocarbanion sodium salt or potassium salt

Abstract

The application discloses a method for synthesizing monocarba-sodium borate or potassium salt, and belongs to the technical field of inorganic boron chemistry. 11 H 14 and KB 11 H 14 as raw materials, reacting in the presence of strong alkali, (trifluoromethyl)trimethylsilane and ether solvent, monocarba-sodium borate or potassium salt can be obtained in one step. The method has the advantages of simple operation, high yield, good product quality and easy scale production, and solvent-free coordination NaCB 11 H 12 and KCB 11 H 12 can be obtained by using the method.

Description

Technical Field

[0001] This invention belongs to the field of inorganic boron chemistry, and relates to a method for synthesizing single-carbon boranes, specifically a method for synthesizing solvent-free coordination [closo-CB] 11 H 12 Methods involving sodium or potassium salts. Background Technology

[0002] Due to their unique three-dimensional structure, low toxicity, and excellent thermal and chemical stability, monoboranes have been applied in numerous fields, such as biomedicine, photochemistry, supramolecular and coordination chemistry, and materials chemistry. In recent years, the development of monoboranes in nuclear medicine has shown a diversified trend, not only having a wide range of applications in the traditional BNCT field but also playing an important role in areas such as radioactive molecular imaging and therapy. In August 2020, my country's first boron neutron capture therapy experimental device was successfully developed at the Dongguan branch of the Institute of High Energy Physics, Chinese Academy of Sciences. There is an urgent need for boron-containing drugs to complement this device, fully utilizing this targeted radiotherapy approach to benefit cancer patients. As a high-boron-content compound, monoborane is a potential BNCT drug.

[0003] Traditionally, the synthesis of single-carbon boranes is divided into several stages, starting with decborane (B... 10 H 14 ) and [nido-B 11 H 14 ] - Two methods are used as raw materials, but due to the presence of decborane (B 10 H 14 Highly toxic, decylborane is unsuitable for industrial synthesis. To avoid using toxic decylborane (B... 10 H 14 ), then [nido-B 11 H 14 ] - Introduced to [closo-CB] 11 H 12 ] - In the synthesis of [the substance], the reaction equation is as follows:

[0004]

[0005] Recent research has mainly focused on [closo-CB] 11 H 12 ] - Me3NH + In salt synthesis, [closo-CB 11 H 12 ] - The synthesis methods for anionic alkali metal (M = Na, K) salts remain very limited, directly affecting [closo-CB] 11 H12 ] - The widespread use of anionic alkali metal (M=Na,K) salts. Summary of the Invention

[0006] To address the aforementioned technical problems, this application adopts [nido-B] 11 H 14 ] - Using anionic alkali metal (M = Na, K) salts as raw materials, alkali metal salts (M = Na, K) [closo-CB] are synthesized. 11 H 12 ] - The reaction equation is as follows:

[0007]

[0008] This invention provides a simple method for synthesizing sodium or potassium monoborane salts. Under inert gas protection, monoboranes can be synthesized in one step simply by adding a strong base and (trifluoromethyl)trimethylsilane. This method avoids the drawbacks of traditional preparation methods, such as harsh reaction conditions, cumbersome operation steps, and severe environmental pollution. This method allows for the one-step production of monoboranes. Furthermore, it avoids cation exchange, greatly simplifying the reaction apparatus, and is easy to synthesize in large quantities using NaCB. 11 H 12 and KCB 11 H 12 This will support further applications in the field of all-solid-state batteries.

[0009] The method for synthesizing sodium or potassium monoborane salts according to the present invention includes the following steps: using [nido-B 11 H 14 Sodium or potassium salts are used as raw materials, and in the presence of a strong base and (trifluoromethyl)trimethylsilane and an organic solvent, a reaction is carried out to obtain sodium or potassium monoborane salts.

[0010] The reaction equation is as follows:

[0011]

[0012] In this context, 1 represents a carbon atom, and M is selected from Na or K.

[0013] Furthermore, in the above technical solution, the strong alkali is potassium hydride or sodium hydride / bis(trimethylsilyl)aminosodium hydride.

[0014] Furthermore, in the above technical solution, the organic solvent is selected from tetrahydrofuran or ethylene glycol dimethyl ether.

[0015] Furthermore, in the above technical solution, the heating reaction temperature is 50-80℃, preferably 60℃.

[0016] Furthermore, in the above technical solution, the [clso-B] 11 H 14 The molar ratio of M (compound 1), strong base and (trifluoromethyl)trimethylsilane is 1:2-3:2-3.

[0017] Furthermore, in the above technical solution, the reaction is carried out under the protection of an inert gas.

[0018] Beneficial effects of the invention

[0019] 1. This invention is simple to operate, requiring only the addition of the substrate [nido-B] to the solvent. 11 H 14 ] - The synthesis of this compound involves strong bases and (trifluoromethyl)trimethylsilane, requiring no additional reagents or complex reaction processes, making the process simple.

[0020] 2. The raw materials required for the reaction process of this invention are inexpensive and readily available, and the reaction process generates little waste and causes little environmental pollution, thus having great potential for large-scale synthesis. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific implementation examples. These implementation examples are carried out under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following implementation examples.

[0022] Example 1

[0023] With NaB 11 H 14 (1a) NaCB was generated by conditional screening reaction with different proportions of alkali. 11 H 12 (2a) The reaction conditions are optimized as follows:

[0024]

[0025]

[0026] After screening, the optimal conditions for synthesizing 2a were determined to be as indicated by number 5: using 1.0 eq of sodium bis(trimethylsilylamino)amino and 3.0 eq of sodium hydride, reacting at 60°C for 3 days in ethylene glycol dimethyl ether solvent. The typical operating steps are as follows:

[0027] NaB 11 H 14(1.58 g, 10 mmol), sodium hydride (0.72 g, 30 mmol), and sodium bis(trimethylsilyl)aminocyanate (1.84 g, 10 mmol) were added to a 100 mL Shrek flask, connected to a double-row tube, and the system was filled with nitrogen gas through three evacuations. 40 mL of ethylene glycol dimethyl ether was injected using a syringe. The reaction mixture was stirred at 0 °C for 15 minutes, and (trifluoromethyl)trimethylsilane (4 mL, 30 mmol) was added, followed by condensation. The mixture was then stirred at 60 °C for 3 days, producing a large amount of yellow precipitate. After cooling to room temperature, the precipitate was quenched with water (1 mL). The residue was extracted with ether (4 x 60 mL) and water (4 x 60 mL). The organic phases were combined and evaporated under vacuum to obtain a yellow oily liquid. 1,4-dioxane was then added until a large amount of white solid precipitate formed. The precipitate was filtered and dried under dynamic vacuum to obtain 1,4-dioxane-coordinated NaCB. 11 H 12 The precipitate was dissolved in 20 mL of water, dried by rotary evaporation, and then dried under dynamic vacuum at 100 °C for 2 h to obtain solvent-free coordinated NaCB. 11 H 12 White powder (1.14 g, yield 68%). 1 H NMR (400MHz, DMSO-d6) δ2.36 (s, 1H), 2.24–0.70 (m, 11H). 13 C NMR(101MHz,DMSO-d6)δ50.69(s). 11 B NMR (128MHz, DMSO-d6) δ -6.95 (d, J = 140.0Hz, 1B), -13.27 (d, J = 136.3Hz, 5B), -16.15 (d, J = 150.6Hz, 5B).

[0028] NMR data analysis: Chemical shift δ2.36, singlet, assigned to one hydrogen atom on a single-carbon borane; chemical shift δ2.24–0.70, multiplet, assigned to 11 hydrogen atom on a single-carbon borane; chemical shift δ50.69, singlet, assigned to one carbon atom on a single-carbon borane cage; chemical shift δ-6.95, assigned to boron at position 12; chemical shift δ-13.27, assigned to boron at positions 7, 8, 9, 10, and 11; chemical shift δ-16.15, assigned to boron at positions 1, 2, 3, 4, and 5. Based on the above NMR results, the product is identified as NaCB. 11 H 12 .

[0029] Example 2

[0030] With KB 11 H 14 (1b) KCB was generated by conditional screening reaction with different proportions of KH. 11 H 12(2b) The reaction conditions were optimized as follows:

[0031]

[0032]

[0033]

[0034] After screening, the optimal conditions for synthesizing 2b were determined to be as indicated by number 3: reacting 3.0 eq potassium hydride in tetrahydrofuran solvent at 60°C for 3 days; the typical operating steps are as follows:

[0035] KB 11 H 14 (1.74 g, 10 mmol) and KH (1.2 g, 30 mmol) were added to a 100 mL Shrek flask, connected to a double-row tube, and the system was filled with nitrogen gas through three evacuations. 40 mL of tetrahydrofuran was injected using a syringe. The reaction mixture was stirred at 0 °C for 15 minutes, and (trifluoromethyl)trimethylsilane (4 mL, 30 mmol) was added, followed by condensation. The mixture was then stirred at 60 °C for 3 days, producing a large amount of yellow precipitate. After cooling to room temperature, the precipitate was quenched with water (1 mL). The residue was extracted with ether (4 x 60 mL) and water (4 x 60 mL). The organic phases were combined and evaporated under vacuum to obtain a yellow oily liquid. 1,4-dioxane was then added until a large amount of white solid precipitate formed. The precipitate was filtered and dried under dynamic vacuum to obtain 1,4-dioxane-coordinated KCB. 11 H 12 White powder. The precipitate was washed with dichloromethane (3 x 30 mL) and n-hexane (3 x 30 mL), and then dried under dynamic vacuum to obtain unsolvated KCB. 11 H 12 (1.21g, yield 66%). 1 H NMR (400MHz, DMSO-d6) δ2.36 (s, 1H), 2.24–0.70 (m, 11H). 13 C NMR(101MHz,DMSO-d6)δ50.69(s). 11 B NMR (128MHz, DMSO-d6) δ -6.95 (d, J = 140.0Hz, 1B), -13.27 (d, J = 136.3Hz, 5B), -16.15 (d, J = 150.6Hz, 5B).

[0036] NMR data analysis: Chemical shift δ2.36, singlet, attributed to one hydrogen atom on a single-carbon borane; chemical shift δ2.24–0.70, multiplet, attributed to 11 hydrogen atom on a single-carbon borane; chemical shift δ50.69, singlet, attributed to one carbon atom on a single-carbon borane; chemical shift δ-6.95, attributed to boron at position 12; chemical shift δ-13.27, attributed to boron at positions 7, 8, 9, 10, and 11; chemical shift δ-16.15, attributed to boron at positions 1, 2, 3, 4, and 5. Based on the above NMR results, the product is identified as KCB. 11 H 12 .

[0037] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for synthesizing a sodium or potassium salt of monoborane, characterized in that, Includes the following steps: with [nido-B 11 H 14 Using sodium or potassium salt 1 as a raw material, in the presence of a strong base and (trifluoromethyl)trimethylsilane and an organic solvent, a reaction is carried out to obtain sodium or potassium monoborane salt 2; the reaction equation is as follows: ， Wherein, reference numeral 1 represents a carbon atom, and M is selected from Na or K; the strong base is selected from a mixture of sodium bis(trimethylsilylamino)amino and sodium hydride, or potassium hydride; the [nido-B 11 H 14 The molar ratio of M, strong base and (trifluoromethyl)trimethylsilane is 1:2-3:2-3; the organic solvent is selected from tetrahydrofuran or ethylene glycol dimethyl ether.

2. The synthesis method according to claim 1, characterized in that: The reaction temperature is 50-80℃.

3. The synthesis method according to claim 1 or 2, characterized in that: The reaction is carried out under the protection of an inert gas.

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