Preparation method of 1,3-adamantanediol

Abstract

The present invention discloses a method for preparing 1,3-adamantanediol. The method uses adamantane as a starting material and prepares 1,3-adamantanediol under the action of an oxidant. The oxidants used in the present invention are chromium trioxide and concentrated sulfuric acid, and the reaction temperature is 55° C. to 80° C. The present invention eliminates the process of halogenation of adamantane, eliminates the need for halogen, organic solvents, and metal catalysts in the production process, and has a maximum reaction temperature of only 80° C., thereby reducing production costs in multiple aspects and greatly improving the practical application value of the present invention.

Description

Technical Field

[0001] The present invention relates to the technical field of battery electrolyte additives, and in particular to a method for preparing 1,3-adamantanediol. Background Art

[0002] 1,3-Adamantanediol, also known as 1,3-dihydroxyadamantane, is an important organic synthesis intermediate and is widely used in pharmaceuticals, pesticides, daily chemicals, functional polymer materials and other fields.

[0003] The most common routes for synthesizing 1,3-adamantanediol use 1,3-dibromoadamantane as the starting material, either hydrolyzing it in a silver sulfate-sulfuric acid system to produce 1,3-adamantanediol, or heating and hydrolyzing it in a formic acid-sodium formate system to obtain the target product. However, 1,3-dibromoadamantane generally uses adamantane as the raw material and requires a halogenation reaction in the presence of a catalyst. This halogenation process not only consumes a large amount of bromine, resulting in high production costs, but the market price of 1,3-dibromoadamantane is more than twice that of 1,3-adamantanediol. Therefore, whether purchasing 1,3-dibromoadamantane or using adamantane as the starting material to prepare 1,3-dibromoadamantane and then produce 1,3-adamantanediol, the practical application value is low.

[0004] Therefore, researchers have further developed new synthetic routes, directly oxidizing adamantane to obtain the target product, 1,3-adamantanediol. For example, Chinese invention patent application number 202011594934.4, "A Method for Preparing 1,3-Dihydroxyadamantane," involves dissolving adamantane in an organic solvent, adding a nitroxide catalyst and cocatalysts such as cobalt acetate, nickel acetate, and copper acetate. Oxidation is then carried out with hypochlorite under alkaline conditions, followed by further purification to yield 1,3-adamantanediol. This reaction route is simple, but the reported yields are not high, with the highest molar yield reaching only 83.4%. Published data indicate that the molar yield is affected by the type of cocatalyst, with the highest yield achieved using the expensive cobalt acetate as a cocatalyst. However, this route also presents a difficult technical challenge: the inevitable formation of byproducts, adamantanemonool and adamantanetriol, during the oxidation of adamantane. This complicates the purification of the target product, resulting in low product purity. This may also explain the lack of detailed information on the product purity in the aforementioned literature.

[0005] Therefore, the synthetic route of directly oxidizing adamantane to obtain the target product 1,3-adamantanediol needs to be further optimized and improved to increase the yield while reducing the formation of reaction by-products to ensure the purity of 1,3-adamantanediol. Summary of the Invention

[0006] The purpose of the present invention is to optimize and improve the synthetic route for preparing 1,3-adamantanediol by direct oxidation of adamantane, thereby increasing the yield of the route and reducing the generation of by-products, thereby obtaining a method for preparing 1,3-adamantanediol with high yield and easy purification of the crude product.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing 1,3-adamantanediol, using adamantane as a starting material and preparing 1,3-adamantanediol under the action of an oxidant. The key lies in that the above-mentioned oxidant is chromium trioxide and concentrated sulfuric acid, and the reaction temperature is 55°C to 80°C.

[0008] Specifically, the mass ratio of adamantane to chromium trioxide is 136:300-350, and the mass ratio of adamantane to concentrated sulfuric acid is 136:45-800.

[0009] Preferably, the concentration of the concentrated sulfuric acid is 60% to 80%.

[0010] More specifically, the preparation method comprises the following steps: adding adamantane to a three-necked flask, adding concentrated sulfuric acid, controlling the reaction temperature to 55°C to 60°C, adding chromium trioxide in 2 to 3 batches, raising the temperature to 70°C to 80°C for reflux reaction, detecting the raw material content during the reaction, terminating the reaction when no raw material is detected, concentrating the reaction solution to obtain a black oil, adjusting the pH to neutral, extracting, cooling and crystallizing, filtering, obtaining a crude 1,3-adamantanediol product, and then recrystallizing to obtain a 1,3-adamantanediol product.

[0011] Furthermore, the above preparation method requires concentrated nitric acid as a solvent.

[0012] Furthermore, the mass concentration of the concentrated nitric acid is 65% to 70%, and the mass ratio of adamantane to concentrated nitric acid is 136:850 to 1230.

[0013] Preferably, the solvent used in the above-mentioned recrystallization is a mixed solvent of ethanol and n-hexane.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The reaction synthesis route of the present invention is simple. With adamantane as a starting material, the target product 1,3-adamantanediol is directly prepared through the oxidation of concentrated sulfuric acid and chromium trioxide. The present invention omits the process of halogenation reaction of adamantane. The production process does not require the use of halogen, organic solvents, and metal catalysts. The entire synthesis process does not involve ultra-high temperatures, and the maximum reaction temperature is 80°C. The present invention reduces production costs in many aspects and greatly improves the practical application value of the present invention.

[0016] The present invention uses concentrated nitric acid as a solvent, does not need to use an organic solvent, or does not need to use an acidic solvent such as concentrated nitric acid. Only by selecting concentrated sulfuric acid of appropriate concentration, controlling the amount of concentrated sulfuric acid, and appropriately increasing the amount of chromium trioxide, the purity of the product prepared by the above process can reach above 99.3%, and the yield can also be stably maintained at above 92%.

[0017] The product prepared by the present invention has a small number of impurities. The impurities detected by high-performance gas chromatography are only adamantane monool and adamantane triol. In addition, the present invention can reduce the proportion of adamantane triol in the impurities, which is beneficial to the purification of the product. The purity of the obtained crude product can be increased by up to 0.51% after recrystallization, thereby further improving the purity of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The figure is the nuclear magnetic spectrum of the 1,3-adamantanediol product prepared by the present invention.

[0019] Figure 2 It is the mass spectrometer of the 1,3-adamantanediol product prepared by the present invention.

[0020] Figure 3 It is the gas phase spectrum of the 1,3-adamantanediol product prepared by the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] For the convenience of description, the amounts of test materials used in the embodiments and comparative examples are all pure amounts.

[0023] Example 1

[0024] Add 1.36 g of adamantane to a three-necked flask, add 7 g of 70% concentrated nitric acid and 0.5 g of 70% concentrated sulfuric acid, control the reaction temperature to 55°C, add chromium trioxide in two batches, add 1 g of chromium trioxide in the first batch and 2 g of chromium trioxide in the second batch, raise the temperature to 75°C for reflux reaction, use a high-performance gas chromatograph to detect the raw material content during the reaction, terminate the reaction when no raw material is detected, and record the reaction time as 1.5 h.

[0025] The reaction solution was concentrated to remove nitric acid to obtain a black viscous oil. The pH was adjusted to neutral using sodium carbonate solution. After extraction with ethyl acetate, cooling and crystallization, and filtration, a crude 1,3-adamantanediol sample 1 was obtained. The purity of the crude product was tested, and the crude product was recrystallized from an ethanol / n-hexane mixed solvent to obtain a 1,3-adamantanediol product sample 1. The purity of the product was tested.

[0026] Example 2

[0027] Add 1.36 g of adamantane to a three-necked flask, add 8 g of concentrated nitric acid with a mass concentration of 65% and 0.45 g of concentrated sulfuric acid with a mass concentration of 75%, control the reaction temperature to 60°C, add chromium trioxide in two batches, add 1.6 g of chromium trioxide in the first batch and 1.6 g of chromium trioxide in the second batch, raise the temperature to 80°C for reflux reaction, use a high-performance gas chromatograph to detect the raw material content during the reaction, terminate the reaction when no raw material is detected, and record the reaction time as 1 h.

[0028] The reaction solution was concentrated to remove nitric acid to obtain a black viscous oil. The pH was adjusted to neutral using sodium carbonate solution. After extraction with ethyl acetate, cooling and crystallization, and filtration, a crude 1,3-adamantanediol sample 2 was obtained. The purity of the crude product was tested, and the crude product was recrystallized from an ethanol / n-hexane mixed solvent to obtain a 1,3-adamantanediol product sample 2, and the purity of the product was tested.

[0029] Example 3

[0030] Add 1.36 g of adamantane to a three-necked flask, add 6 g of concentrated nitric acid with a mass concentration of 68% and 0.55 g of concentrated sulfuric acid with a mass concentration of 80%, control the reaction temperature to 58°C, add chromium trioxide in three batches, add 1.0 g of chromium trioxide in the first batch, 1.0 g of chromium trioxide in the second batch, and 1.0 g of chromium trioxide in the third batch, and raise the temperature to 70°C for reflux reaction. During the reaction, use a high-performance gas chromatograph to detect the raw material content. The reaction is terminated when no raw material is detected. The reaction time is recorded as 1 hour and 40 minutes.

[0031] The reaction solution was concentrated to remove nitric acid to obtain a black viscous oil. The pH was adjusted to neutral using sodium carbonate solution. After extraction with ethyl acetate, cooling and crystallization, and filtration, a crude 1,3-adamantanediol sample 3 was obtained. The purity of the crude product was tested, and the crude product was recrystallized from an ethanol / n-hexane mixed solvent to obtain a 1,3-adamantanediol product sample 3, and the purity of the product was tested.

[0032] Example 4

[0033] Add 1.36 g of adamantane to a three-necked flask, add 8 g of concentrated sulfuric acid with a mass concentration of 60%, control the reaction temperature to 60°C, add chromium trioxide in three batches, add 1 g of chromium trioxide in the first batch, add 1 g of chromium trioxide in the second batch, and add 1.5 g of chromium trioxide in the third batch. Raise the temperature to 80°C for reflux reaction. Use a high-performance gas chromatograph to detect the raw material content during the reaction. Stop the reaction when no raw material is detected. Record the reaction time as 2.5 h.

[0034] The reaction solution was concentrated to obtain a black viscous oil, and the pH was adjusted to neutral using sodium carbonate solution. After extraction with ethyl acetate, cooling and crystallization, and filtration, a crude 1,3-adamantanediol sample 4 was obtained. The purity of the crude product was tested, and the crude product was recrystallized from an ethanol / n-hexane mixed solvent to obtain a 1,3-adamantanediol product sample 4, and the purity of the product was tested.

[0035] Comparative Example

[0036] Comparative Example 1

[0037] The implementation process is the same as that of Example 1, except that concentrated nitric acid is not used as a solvent, but 13.2 g of anhydrous acetic acid is used as a solvent, and the subsequent steps are the same as in Example 1 to prepare a crude reference substance 1-1 and a product reference substance 1-1; similarly, concentrated nitric acid is not used as a solvent, but 13.2 g of anhydrous acetic acid is used as a solvent, the amount of chromium trioxide is increased, and 4 g of chromium trioxide is used. The subsequent steps are the same as in Example 1 to prepare a crude reference substance 1-2 and a product reference substance 1-2.

[0038] Comparative Example 2

[0039] The implementation process is the same as that of Example 1, except that chromium trioxide is added at one time. The subsequent steps are the same as those of Example 1 to prepare crude reference substance 2 and product reference substance 2.

[0040] Analysis and testing

[0041] The samples prepared in the examples were analyzed by high performance gas chromatography-mass spectrometry and nuclear magnetic resonance analysis, and their structures were consistent with the structural characteristics of 1,3-adamantanediol (see Appendix Figure 1 and 2 ); The crude product, sample and reference substance prepared in Example 1 were detected by high-efficiency gas chromatograph (internal standard method) to determine the purity of the test samples. The results are shown in Tables 1 and 2.

[0042] The yields in each embodiment and control example were calculated according to formula 1. The results are shown in Table 2.

[0043] Formula 1: Yield (%) = actual weight of the sample obtained (g) / theoretical amount calculated based on the amount of adamantane used (g) × 100%.

[0044] Table 1: Gas chromatogram peak list of crude 1,3-adamantanediol 4

[0045]

[0046] Table 2: Summary of sample and reference yield, purity and moisture test results

[0047] sample Corresponding crude product yield (%) Product yield (%) Corresponding crude product purity (%) Product purity (%) Sample 1 93.2 92.8 99.06 99.41 Sample 2 93.0 92.1 99.10 99.52 Sample 3 92.9 92.0 99.12 99.63 Sample 4 92.8 91.8 98.86 99.36 Reference substance 1-1 83.2 80.6 97.83 97.96 Reference 1-2 85.6 82.8 98.02 98.13 Reference substance 2 86.3 84.1 95.60 97.30

[0048] Table 3: Summary of impurity content of crude products to be tested

[0049]

[0050]

[0051] As can be seen from the results in Tables 1 and 2, the crude product purity of each embodiment of the present invention can reach over 98.86%, and the main by-products are adamantane monool and adamantane triol. After further purification by recrystallization, a 1,3-adamantanediol product with a purity of over 99.41% can be obtained. At the same time, the yield of the present invention is high, and the final product yield can reach over 92.0%.

[0052] As shown in Table 3, the crude reference products 1-1 and 1-2 showed increased adamantantriol content, but the product purity increased by only 0.1% compared to the crude product. However, the purity of the example product increased by up to 0.51% compared to the crude product. This is because adamantantriol is more difficult to separate from the product than adamantane monool, and a high adamantantriol content can make purification difficult. Therefore, to improve product purity, it is necessary to control the production of adamantantriol and reduce the proportion of adamantantriol in the crude product.

Claims

1. A method for preparing 1,3-adamantanediol, using adamantane as a starting material and preparing 1,3-adamantanediol under the action of an oxidant, wherein: The oxidizing agents are chromium trioxide and concentrated sulfuric acid, and the reaction temperature is 55°C to 80°C; The mass ratio of adamantane to chromium trioxide is 136:300-350, and the mass ratio of adamantane to concentrated sulfuric acid is 136:45-800; The preparation method requires concentrated nitric acid as a solvent; The mass concentration of the concentrated nitric acid is 65% to 70%, and the mass ratio of adamantane to concentrated nitric acid is 136:850 to 1230; The concentration of the concentrated sulfuric acid is 60% to 80%.

2. The method for preparing 1,3-adamantanediol according to claim 1, wherein The preparation method specifically comprises the following steps: adding adamantane into a three-necked flask, adding concentrated sulfuric acid, controlling the reaction temperature at 55°C to 60°C, adding chromium trioxide in 2 to 3 batches, heating to 70°C to 80°C for reflux reaction, detecting the raw material content during the reaction, terminating the reaction when no raw material is detected, concentrating the reaction solution to obtain a black oily substance, adjusting the pH to neutral, extracting, cooling, crystallizing, and filtering to obtain a crude 1,3-adamantanediol product, and then recrystallizing to obtain a 1,3-adamantanediol product.

3. The method for preparing 1,3-adamantanediol according to claim 2, wherein The solvent used for the recrystallization is a mixed solvent of ethanol and n-hexane.

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