A method for electrochemically synthesizing fullerene monoaddition derivatives under constant current

Abstract

The present invention discloses a method for the constant current electrolytic synthesis of fullerene monoaddition derivatives, which relates to the technical field of the synthesis of fullerene derivatives. In the present invention, C 60 is mixed with an amino acid and glacial acetic acid in an electrolyte solution, and constant current electrolysis is carried out using an RVC electrode to obtain a fullerene monoaddition derivative. For the first time, the present invention successfully synthesizes the expected fullerene derivative by means of constant current electrolysis without adding aldehyde compounds, and has the characteristics of high yield and simple operation, and has a great technical breakthrough.

Description

Technical Field

[0001] The present invention relates to the technical field of fullerene derivative synthesis, and particularly to a method for synthesizing fullerene monoaddition derivatives by constant current electrolysis. Background Art

[0002] Functionalized fullerene (C 60 ) derivatives are an important type of substance, which play important roles in chemistry, medicine, pharmacy, biology, etc., and have attracted much attention from chemists. Chemists have been dedicated to their synthesis research for the past 30 years and have reported numerous synthesis methods for functionalized fullerene monoaddition and polyaddition derivatives. Most of these methods are chemical synthesis methods mainly based on thermochemistry.

[0003] The chemical modification of monoaddition fullerene derivatives generally falls into two categories. One is to attach some groups on the outer layer of the fullerene sphere surface, and the other is to modify the spherical framework by destroying the fullerene sphere: outer body modification and skeleton modification. The modification methods on the fullerene sphere surface include cycloaddition, radical addition, nucleophilic addition, dimerization reaction, transition metal catalyzed / promoted reaction, aldehyde / amine participation reaction, asymmetric synthesis, retro-cycloaddition reaction, mechanochemical reaction, halogenation, hydrogenation, hydroxylation, addition of organocopper reagents, addition of peroxides, addition of amines, etc. The fullerene cycloaddition reaction is one of the most studied fullerene reactions because such reactions can obtain monoaddition fullerene products that are easy to separate and have relatively high yields, and most functional groups can be used to modify fullerenes by cycloaddition methods. The most representative fullerene cycloaddition reactions include [2+1], [2+2], [3+2] and [4+2] cycloaddition reactions.

[0004] The [2+1] cycloaddition reaction of fullerenes forms a three-membered ring fullerene derivative by attaching carbon atoms or other atoms to the [5,6] or [6,6] bonds of fullerenes. Generally, this reaction occurs on the [6,6] bond. The most commonly used atom for forming the three-membered ring is the carbon atom, and the corresponding reaction is the Bingel reaction. In addition, there are other less commonly used methods, namely carbene addition and thermal addition of diazo compounds. The [2+2] cycloaddition compounds are generally formed by photochemical irradiation or thermal reaction with cycloalkenones, acyclic alkenones, ketenes, alkynes, benzene, alkenes, and cumulenes, resulting in a cycloaddition reaction between fullerenes and cyclobutane or cyclobutene fragments. The [2+2] cycloaddition reaction is also used to prepare fullerene dimers, i.e., two or more fullerene cages are connected by two C-C bonds. The [3+2] cycloaddition reaction is another most commonly used method for preparing fullerene monoaddition five-membered ring derivatives, namely the Prato reaction. This method can produce various fullerene five-membered heterocycles, such as fullerene triazoles, fullerene pyrazoles, fullerene pyridines, fullerene pyridines, fullerene dihydrofurans, fullerene pyrazoles, fullerene isoxazoles, fullerene tetrahydrofurans, fullerene tetrahydrothiophenes, fullerene oxazolidines, fullerene 2-imino-1,3-thiazolidines, etc. The [4+2] cycloaddition Diels-Alder reaction is one of the earliest studied fullerene reactions. It usually prepares six-membered carbon rings or heterocyclic compounds fused with fullerenes through [4+2] cycloaddition. Many [4+2] cycloaddition products are usually formed by the reaction of fullerenes with in-situ generated dienes.

[0005] Among the reported chemical synthesis methods for fullerene multi-addition derivatives, there are mainly synthetic methods such as the site-directed method, template method, blocking method, and coordination chemistry method. The site-directed method reserves one or more extra reaction sites when modifying the side chains of fullerene derivatives, so that certain specific addition mode fullerene multi-addition derivatives can be synthesized by controlling the chain length. The template method is a synthetic method that uses certain special reactions for fixed-site addition to generate addition products with fixed sites. The blocking method generally first modifies two bulky groups on the fullerene carbon cage and uses the steric effect of the groups to synthesize multi-addition derivatives. The coordination chemistry method realizes the masking of certain regions on the fullerene carbon cage through the host-guest supramolecular interaction, thereby improving the regioselectivity of the multi-addition reaction.

[0006] The above chemical methods for synthesizing fullerene mono-addition or multi-addition derivatives have advantages but also have some limitations, such as single products, difficult control of reaction sites of multi-addition products, and harsh reaction conditions. Therefore, it is necessary to further develop synthetic methods for fullerene multi-addition derivatives that are easy to operate, have novel addition modes, and flexible and controllable numbers of addition groups.

[0007] Electrochemical synthesis is considered a novel and efficient strategy for preparing various fullerene derivatives due to its mild reaction conditions, good regioselectivity, and relatively high yields. In 1993, the Kadish research group first obtained C 60 2- by constant voltage electrolysis of fullerenes, and then methyl iodide was added to the C 60 2- solution, and two fullerene derivatives were successfully synthesized and isolated. In 2007, the Gao Xiang research group reported a method for synthesizing fullerene derivatives based on constant voltage electrolysis, namely the reaction of fullerenes with benzyl bromide. They successfully prepared and isolated four fullerene derivatives by electrochemical methods, and their work provided valuable experience for subsequent people to use electrochemical synthesis of fullerene derivatives.

[0008] In 2008, the Gao Xiang research group reported the reaction of electrochemically generated C 60 2- with benzyl bromide. When reducing C 60 and reacting with benzyl bromide in benzonitrile, a five-membered heterocycle was attached to the [5,6] bond of C 60 . Subsequently, in another electrochemical study of benzyl bromide and fullerene derivatives, they synthesized a variety of fused heterocyclic multi-addition derivatives. Since then, people have delved deeper into the exploration of electrochemical synthesis of fullerene derivatives. In 2014, the Wang Guanwu research group reported a protonation reaction of C 60 fused indoline dianion obtained by constant voltage electrolysis, and finally synthesized four tri-addition C 60 fused indoline fullerene derivatives in high yield. Subsequently, they reported a variety of methods for multi-addition synthesis of constant voltage electrolysis of fullerene derivatives. In 2015, after electrochemically reducing the C 60 fused oxazoline or imidazoline mono-addition fullerene derivative 17, they found that this reduction product would dissociate into fullerene derivative 18 and 19. Fullerene derivative 18 would then react with PhCH2Br to obtain fullerene derivative 19 and fullerene derivative 20, and both of these products are products that are difficult to obtain by thermal chemical reactions. In 2017, the Wang Guanwu research group reported a highly regioselective carbonylation electrochemical method that can directly obtain mono-carbonylated C 60 fused indoline derivatives. In the same year, the research group also reported the electrochemical benzylation reaction of C 60 fused benzofuran. In the following years, they reported a variety of electrochemical synthesis methods for fullerene derivatives, and these products are difficult to synthesize using thermal chemical methods. It can be seen that the electrochemical method can play an irreplaceable role in synthesizing fullerene products with some special addition sites.

[0009] There are two ways of electrochemical synthesis, one is constant voltage electrolysis and the other is constant current electrolysis. The methods reported so far for synthesizing fullerene derivatives by electrochemical synthesis are all constant voltage electrolysis, which is a more mature strategy than constant current electrolysis. There is basically no relevant report on the method of constant current electrolysis of fullerenes. The reason is that it is difficult to control a suitable current to enable precise addition of fullerenes to obtain the expected addition products. Therefore, it is necessary to propose a method for synthesizing fullerene monoaddition derivatives by constant current electrolysis to obtain monoaddition fullerene derivatives on the basis of higher yield. Summary of the Invention

[0010] The object of the present invention is to provide a method for synthesizing fullerene monoaddition derivatives by constant current electrolysis to solve the problems existing in the above-mentioned prior art.

[0011] To achieve the above object, the present invention provides the following scheme:

[0012] The present invention provides a method for synthesizing fullerene monoaddition derivatives by constant current electrolysis, including the following steps:

[0013] In an inert gas atmosphere, C 60 is mixed with an amino acid and glacial acetic acid in an electrolyte solution, and constant current electrolysis is carried out using an RVC electrode (reticulated vitreous carbon electrode) to obtain the fullerene monoaddition derivative.

[0014] Further, the current of the constant current electrolysis is 8 - 12 mA, and more preferably 10 mA.

[0015] Further, the amino acid includes sarcosine, N-(2-cyanoethyl)glycine, N-ethylglycine, N-benzylglycine or iminodiacetic acid.

[0016] Further, the molar ratio of C 60 to the amino acid and glacial acetic acid is 1:5 - 30:5 - 30.

[0017] Still further, the molar ratio of C 60 to the amino acid and glacial acetic acid is 1:20:20.

[0018] Further, the electrolyte solution uses tetrabutylammonium acetate as the solute and a mixed solution of o-dichlorobenzene and acetonitrile with a volume ratio of 1:1 - 4:1 as the solvent. More preferably, the volume ratio of o-dichlorobenzene to acetonitrile is 4:1.

[0019] Further, the concentration of the electrolyte solution is 0.1 - 0.4 M, and more preferably 0.1 M.

[0020] Further, the time of the constant current electrolysis is 0.5 - 4 h.

[0021] Furthermore, the temperature of the constant current electrolysis is 80 - 140 °C, more preferably 120 °C.

[0022] The present invention also provides a fullerene mono - addition derivative prepared by the above - mentioned method.

[0023] The present invention discloses the following technical effects:

[0024] The present invention provides a method for synthesizing a fullerene mono - addition derivative by constant current electrolysis, which has the characteristics of high yield and simple operation. For the first time, the present invention successfully synthesizes the expected fullerene derivative by the method of constant current electrolysis without adding aldehyde compounds, which has a great technological breakthrough. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 It is the ultraviolet - visible spectrum of the fullerene derivative prepared in Example 1 of the present invention (at about 430 nm, there is an obvious characteristic absorption of the fullerene mono - addition derivative);

[0027] Figure 2 It is the nuclear magnetic resonance hydrogen spectrum ( 1 1H NMR) of the fullerene derivative prepared in Example 1 of the present invention;

[0028] Figure 3 It is the nuclear magnetic resonance carbon spectrum ( 13 13C NMR) of the fullerene derivative prepared in Example 1 of the present invention;

[0029] Figure 4 It is the mass spectrum (APCI - MS) of the fullerene derivative prepared in Example 1 of the present invention;

[0030] Figure 5 It is the ultraviolet - visible spectrum of the fullerene derivative prepared in Example 2 of the present invention (at about 430 nm, there is an obvious characteristic absorption of the fullerene mono - addition derivative);

[0031] Figure 6 It is the nuclear magnetic resonance hydrogen spectrum ( 1 1H NMR) of the fullerene derivative prepared in Example 2 of the present invention;

[0032] Figure 7 It is the nuclear magnetic resonance carbon spectrum ( 13 13C NMR) of the fullerene derivative prepared in Example 2 of the present invention;

[0033] Figure 8 Mass spectrum (APCI-MS) of the fullerene derivative prepared in Example 2 of the present invention;

[0034] Figure 9 Ultraviolet-visible spectrum of the fullerene derivative prepared in Example 3 of the present invention (at about 430 nm, there is an obvious characteristic absorption of the fullerene mono-adduct derivative);

[0035] Figure 10 1H nuclear magnetic resonance spectrum of the fullerene derivative prepared in Example 3 of the present invention ( 1 1H NMR) spectrum;

[0036] Figure 11 13C nuclear magnetic resonance spectrum of the fullerene derivative prepared in Example 3 of the present invention ( 13 13C NMR) spectrum;

[0037] Figure 12 Mass spectrum (APCI-MS) of the fullerene derivative prepared in Example 3 of the present invention;

[0038] Figure 13 Ultraviolet-visible spectrum of the fullerene derivative prepared in Example 4 of the present invention (at about 430 nm, there is an obvious characteristic absorption of the fullerene mono-adduct derivative);

[0039] Figure 14 1H nuclear magnetic resonance spectrum of the fullerene derivative prepared in Example 4 of the present invention ( 1 1H NMR) spectrum;

[0040] Figure 15 13C nuclear magnetic resonance spectrum of the fullerene derivative prepared in Example 4 of the present invention ( 13 13C NMR) spectrum;

[0041] Figure 16 Mass spectrum (APCI-MS) of the fullerene derivative prepared in Example 4 of the present invention;

[0042] Figure 17 Ultraviolet-visible spectrum of the fullerene derivative prepared in Example 5 of the present invention (at about 430 nm, there is an obvious characteristic absorption of the fullerene mono-adduct derivative);

[0043] Figure 18 1H nuclear magnetic resonance spectrum of the fullerene derivative prepared in Example 5 of the present invention ( 1 1H NMR) spectrum;

[0044] Figure 19 13C nuclear magnetic resonance spectrum of the fullerene derivative prepared in Example 5 of the present invention ( 13 13C NMR) spectrum;

[0045] Figure 20 This is the mass spectrum (APCI-MS) of the fullerene derivative prepared in Example 5 of the present invention. Detailed implementation manners

[0046] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0047] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0048] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0049] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are only exemplary.

[0050] Regarding "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0051] The raw materials and reagents used in the experiments of the present invention are shown in Table 1.

[0052] Table 1

[0053]

[0054]

[0055] o-Dichlorobenzene, toluene, and chlorobenzene were all treated with anhydrous calcium chloride for water removal before use.

[0056] TBAA was used as the supporting electrolyte for the electrochemically constant-current electrolytic synthesis of fullerene derivatives. The concentration of the TBAA electrolytic solution used was 0.1 M, and the solvent composition was o-DCB(V):acetonitrile(V)=4:1. After preparation, clean and anhydrous molecular sieve was added to the solution, and the solution was deoxygenated by bubbling.

[0057] The method for the constant-current electrolytic synthesis of fullerene monoaddition derivatives in the present invention comprises the following steps:

[0058] Two RVC electrodes with exposed carbon rods were used as the positive and negative electrodes for constant-current electrolysis respectively. In the C 60 solution, cyanoethyl amino acid (20 eq.) and glacial acetic acid (20 eq.) were added. 0.1 M TBAA (tetrabutylammonium acetate) was selected as the supporting electrolyte, and the solvent was o-DCB:MeCN = 4:1 (volume ratio). Under the condition of an inert gas at 120 °C, the current was 10 mA, and constant-current electrolysis was carried out. During the electrolysis process, thin-layer chromatography columns were used to monitor the reaction results. It was found that when the reaction proceeded to 30 min, in addition to the unreacted C 60 in the reaction, obvious reaction product spots appeared. Then, the reaction time was extended. When the reaction proceeded to 3.5 h, it was found that the product spots were the densest. After the reaction was stopped, it was separated and characterized. Through ultraviolet monitoring, it was found that there was a very obvious characteristic peak of fullerene derivative monoaddition at 431 nm, as Figure 1 shown. The obtained product was tested by mass spectrometry, and the results were as Figure 2 shown.

[0059] Based on the above experiments (standard conditions) of the present invention, the condition screening shown in Table 2 was carried out.

[0060] Table 2 Condition Screening

[0061]

[0062]

[0063] Note: "n.d." in the table indicates that no product was found.

[0064] By comparing Conditions 1, 2, and 3 in Table 2, it is found that the magnitude of the current has a certain impact on the final yield of the reaction. When the current magnitude is 8 mA, the yield of the expected product is only 34.10%, while when the current increases to 12 mA, the yield of the expected product is only 29.50%. Compared with Condition 1, changing the current magnitude in Conditions 2 and 3 will reduce the yield of the product. Adjusting the electrolyte solution, replacing acetonitrile with an equal amount of methanol, the result shows that the yield drops to 25.4% (Condition 4), and obvious insolubles can be observed in the solution during electrolysis. When glacial acetic acid is not added (Condition 5) or glacial acetic acid is replaced with another organic acid MSA (methanesulfonic acid) (Condition 6), the yield of the target product decreases more significantly. The yield is only 26.20% when glacial acetic acid is not added, and the yield is only 17.5% when glacial acetic acid is replaced with MSA. It can be seen that the presence of glacial acetic acid plays a very important role in the reaction process. The present invention further sets up experiments for Conditions 10, 11, and 12, and by comparing the differences among several groups of experiments, it is found that when the electrolyte TBAA (tetrabutylammonium acetate) is replaced with TBAP (tetrabutylammonium perchlorate) or replaced with TBAPF6 (tetrabutylhexafluorophosphate), TBACl (tetrabutylammonium chloride) under the condition of not adding glacial acetic acid, the production of the expected product is not monitored in the reaction. Thus, it can be seen that the presence of AcO - is particularly important in the reaction, and even related to whether the product can be produced. To verify whether the presence of AcO - promotes the progress of the reaction, the present invention also tried to add TBACl and glacial acetic acid under the condition of not adding TBAA (Condition 13), creating a condition where there is both the presence of AcO - and [(CH2)3CH3]4N + present. As a result, the target product was again monitored in the reaction. Although the yield of the target product is 7% under this artificially created condition approximating the presence of TBAA, it verifies a very crucial issue, that is, the presence of acetate ions does indeed promote the production of the target product.

[0065] In addition to screening the current and electrolyte solution, the temperature, electrode, and gas conditions were also screened. By comparing Conditions 8 and 9, it can be found that 120 °C is the optimal reaction temperature condition for this reaction. Replacing the RVC electrode with a platinum electrode will cause a significant decrease in the yield of the target product (Condition 7), and this reaction can only obtain the target product under the condition of inert gas protection (Condition 14). Under the condition of not passing current, the reaction proceeded for 5 h, but the yield of the target product was only 17% (Condition 15). It can be seen that the presence of current is also crucial.

[0066] As shown in Table 3, after condition screening, corresponding amino acid substrate expansion was carried out. The results showed that the corresponding fullerene mono-addition products were generated under conditions a - d within a relatively short time. In particular, under condition a, the corresponding fullerene derivative with a yield of 52% was obtained after only 2.5 h of electrolysis. Condition e might have generated CO2 due to the dropping of the carboxyl group during heating.

[0067] Table 3 Electrochemical reactions of fullerenes with different amino acids

[0068]

[0069]

[0070]

[0071] In the present invention, the embodiments of constant current electrolysis of fullerenes with different amino acids are specifically as follows:

[0072] Example 1 Electrochemical synthesis of fullerene derivative EP-Me

[0073]

[0074] After washing a 25 mL four-necked flask, magnetic stir bar, condenser, RVC electrode, and graphite electrode to be used, place them in an oven at 60 °C for drying for 1 h. Cut the RVC electrode into a cylindrical shape and the graphite electrode into a pencil shape. Then insert the graphite electrode into the RVC electrode, with a little of the graphite electrode exposed at the bottom of the RVC electrode. Finally, install the two connected electrodes on the four-necked flask and seal it well. Weigh C 60 (0.1 mmol, 1 eq), sarcosine (2 mmol, 20 eq) and add them to the four-necked flask equipped with the graphite electrode and RVC electrode. Set up a closed reaction device with a reflux condenser, and use a vacuum double manifold to evacuate - replace with argon three times. Finally, fill in an appropriate amount of argon as the reaction gas condition. Add 10 mL of the prepared 0.1 M TBAA solution, set the reaction temperature to 120 °C, connect a constant current electrolyzer, set the electrolysis current to 10 mA. When the temperature reaches the set value, add AcOH (2 mmol, 20 eq), and then start the constant current electrolyzer for electrolysis. Monitor the reaction progress by TLC spotting. When the reaction reaches the best state, stop the reaction. The crude product is concentrated in vacuo and then separated and purified on a chromatographic column using toluene as the eluent to obtain the desired product EP-Me. The product is dissolved in carbon disulfide, precipitated once with n-hexane, and then precipitated twice with methanol. Filter off the solution to obtain a solid product. Place the product in a vacuum drying oven at 100 °C for vacuum drying for 24 h to obtain a brown solid product, and the separation yield is 52.0%.

[0075] 1 1H NMR (600 MHz, CDCl3 / CS2 = 1 / 2): δ (ppm) 4.41 (s, 4H), 3.02 (s, 3H). 13 13C NMR (151 MHz, CDCl3 / CS2 = 1 / 2): δ 154.62, 147.12, 146.09, 145.91, 145.84, 145.52, 145.32, 145.13, 144.40, 142.97, 142.50, 142.08, 141.94, 141.76, 140.06, 136.13, 70.98, 69.87, 41.38. APCI-MS: m / z calcd for C 63 17H7N: 777.1 [M]-, found: 777.0.

[0076] Example 2 Electrochemical Synthesis of Fullerene Derivative EP-CN

[0077]

[0078] After washing the 25 mL four-necked flask, magnetic stir bar, condenser, RVC electrode, and graphite electrode to be used, place them in an oven at 60 °C for drying for 1 h. Cut the RVC electrode into a cylindrical shape and the graphite electrode into a pencil shape. Then insert the graphite electrode into the RVC electrode, with a little of the graphite electrode protruding from the bottom of the RVC electrode. Finally, install the two connected electrodes on the four-necked flask and seal it properly. Weigh C 60 (0.1 mmol, 1 eq), N-(2-cyanoethyl)glycine (2 mmol, 20 eq) and add them to the four-necked flask equipped with the graphite electrode and RVC electrode. Set up a closed reaction device with a reflux condenser, use a vacuum double manifold to evacuate - replace with argon three times, and finally fill with an appropriate amount of argon as the reaction gas condition. Add 10 mL of the prepared 0.1 M TBAA solution, set the reaction temperature to 120 °C, connect a constant current electrolyzer, set the electrolysis current to 10 mA. When the temperature reaches the set value, add AcOH (2 mmol, 20 eq), and then start the constant current electrolyzer for electrolysis. Monitor the reaction progress by thin layer chromatography spotting. When the reaction reaches the best state, stop the reaction. The crude product is concentrated in vacuo and then separated and purified on a chromatographic column using toluene as the eluent to obtain the desired product EP-CN. The product is dissolved in carbon disulfide, precipitated once with n-hexane, and then precipitated twice with methanol. Filter off the solution to obtain a solid product. Place the product in a vacuum drying oven at 100 °C for vacuum drying for 24 h to obtain a brown solid product, and the separation yield is 42.4%.

[0079] 11H NMR (600 MHz, CDCl3 / CS2 = 1 / 2): δ (ppm) 4.55 (s, 4H), 3.50 (t, J = 7.0 Hz, 2H), 3.00 (t, J = 7.0 Hz, 2H). 13 13C NMR (151 MHz, CDCl3 / CS2 = 1 / 2): δ 154.00, 147.16, 146.14, 145.94, 145.65, 145.46, 145.40, 145.16, 144.39, 142.99, 142.54, 142.01, 141.95, 141.79, 140.11, 136.14, 117.45, 70.21, 67.48, 50.22, 17.89. APCI-MS: m / z calcd for C 65 28H8N2: 816.1 [M] - , found: 816.0.

[0080] Example 3 Electrochemical Synthesis of Fullerene Derivative EP-Et

[0081]

[0082] After washing the 25 mL four-necked flask, magnetic stir bar, condenser, RVC electrode, and graphite electrode to be used, place them in an oven at 60 °C and dry for 1 h. Cut the RVC electrode into a cylindrical shape and the graphite electrode into a pencil shape. Then insert the graphite electrode into the RVC electrode, with a little of the graphite electrode protruding from the bottom of the RVC electrode. Finally, install the two connected electrodes on the four-necked flask and seal it well. Weigh C 60 (0.1 mmol, 1 eq), N-ethylglycine (2 mmol, 20 eq) and add them to the four-necked flask equipped with the graphite electrode and RVC electrode. Set up a closed reaction device with a reflux condenser, and use a vacuum double manifold to evacuate - replace with argon three times. Finally, fill with an appropriate amount of argon as the reaction gas condition. Add 10 mL of the prepared 0.1 M TBAA solution, set the reaction temperature to 120 °C, connect a constant current electrolyzer, set the electrolysis current to 10 mA. When the temperature reaches the set value, add AcOH (2 mmol, 20 eq), and then start the constant current electrolyzer for electrolysis. Monitor the reaction progress by TLC spotting on a plate. When the reaction reaches the best state, stop the reaction. The crude product is concentrated under vacuum and then separated and purified on a chromatographic column using toluene as the eluent to obtain the desired product EP-Et. The product is dissolved in carbon disulfide, precipitated once with n-hexane, and then precipitated twice with methanol. Filter off the solution to obtain a solid product. Place the product in a vacuum drying oven at 100 °C and dry it under vacuum for 24 h to obtain a brown solid product. The separation yield is 37.3%.

[0083] 1 1H NMR (600 MHz, CDCl3 / CS2 = 1 / 2): δ (ppm) 4.43 (s, 4H), 3.18 (q, J = 7.2 Hz, 2H), 1.59 (t, J = 7.2 Hz, 3H). 13 13C NMR (151 MHz, CDCl3 / CS2 = 1 / 2): δ 154.80, 147.09, 146.07, 145.88, 145.86, 145.50, 145.30, 145.10, 144.40, 142.95, 142.48, 142.07, 141.92, 141.74, 140.05, 136.15, 70.40, 67.64, 49.28, 14.27. APCI-MS: m / z calcd for C 64 H9N: 791.1 [M]-, found: 791.0.

[0084] Example 4 Electrochemical Synthesis of Fullerene Derivative EP-Ph

[0085]

[0086] After washing a 25 mL four-necked flask, magnetic stir bar, condenser, RVC electrode, and graphite electrode to be used, place them in an oven at 60 °C and dry for 1 h. Cut the RVC electrode into a cylindrical shape and the graphite electrode into a pencil shape. Then insert the graphite electrode into the RVC electrode, with a little of the graphite electrode protruding from the bottom of the RVC electrode. Finally, install the two connected electrodes onto the four-necked flask and seal it properly. Weigh C 60 (0.1 mmol, 1 eq), N-benzylglycine (2 mmol, 20 eq) and add them to the four-necked flask equipped with the graphite electrode and RVC electrode. Set up a closed reaction device with a reflux condenser, and use a vacuum double manifold to evacuate - fill with argon three times. Finally, fill in an appropriate amount of argon as the reaction gas condition. Add 10 mL of the prepared 0.1 M TBAA solution, set the reaction temperature to 120 °C, connect a constant current electrolyzer, set the electrolysis current to 10 mA. When the temperature reaches the set value, add AcOH (2 mmol, 20 eq), and then start the constant current electrolyzer for electrolysis. Monitor the reaction progress by TLC spotting. When the reaction reaches the best state, stop the reaction. The crude product is concentrated in vacuo and then separated and purified on a chromatographic column using toluene as the eluent to obtain the desired product EP-Ph. The product is dissolved in carbon disulfide, precipitated once with n-hexane, and then precipitated twice with methanol. Filter off the solution to obtain a solid product. Place the product in a vacuum drying oven at 100 °C and dry it in vacuo for 24 h to obtain a brown solid product. The separation yield is 32.7%.

[0087] 1 1H NMR (600 MHz, CDCl3 / CS2 = 1 / 2): δ (ppm) 7.68 (d, J = 7.6 Hz, 2H), 7.45 (t, J = 7.5, 2H), 7.36 (t, J = 7.4, 1H), 4.45 (s, 4H), 4.32 (s, 2H). 13 13C NMR (151 MHz, CDCl3 / CS2 = 1 / 2): δ 154.71, 147.13, 146.11, 145.92, 145.89, 145.53, 145.34, 145.14, 144.42, 142.97, 142.51, 142.11, 141.95, 141.77, 140.08, 137.75, 136.18, 128.70, 128.67, 127.61, 70.50, 67.49, 58.91. APCI-MS: m / z calcd for C 69 H 11 N: 853.1 [M]-, found: 853.1.

[0088] Example 5 Electrochemical Synthesis of Fullerene Derivative EP-COOH

[0089]

[0090] After washing the 25 mL four-necked flask, magnetic stir bar, condenser, RVC electrode, and graphite electrode to be used, place them in an oven at 60 °C and dry for 1 h. Cut the RVC electrode into a cylindrical shape and cut the graphite electrode into a pencil shape. Then insert the graphite electrode into the RVC electrode, with a little of the graphite electrode protruding from the bottom of the RVC electrode. Finally, install the two connected electrodes onto the four-necked flask and seal it properly. Weigh C 60(0.1 mmol, 1 eq), iminodiacetic acid (2 mmol, 20 eq) were added into a four-necked flask equipped with graphite electrodes and RVC electrodes. A closed reaction device with a reflux condenser was set up. The vacuum double manifold was used to evacuate and replace with argon three times, and finally an appropriate amount of argon was charged as the reaction gas condition. 10 mL of the prepared 0.1 M TBAA solution was added. The reaction temperature was set at 120 °C. The constant current electrolyzer was connected, and the electrolysis current was set at 10 mA. When the temperature reached the set value, AcOH (2 mmol, 20 eq) was added, and then the constant current electrolyzer was started for electrolysis. Thin layer chromatography was used to monitor the reaction progress by spotting the reaction plate. When the reaction reached the best condition, the reaction was stopped. The crude product was concentrated in vacuo and then separated and purified on a chromatographic column using toluene as the eluent to obtain the desired product EP-COOH. The product was dissolved in carbon disulfide, precipitated once with n-hexane, and then precipitated twice with methanol. The solution was removed by filtration to obtain a solid product. The product was placed in a vacuum drying oven at 100 °C and dried in vacuo for 24 h to obtain a brown solid product, and the separation yield was 17.1%.

[0091] 1 1H NMR (600 MHz, CDCl3 / CS2 = 1 / 2): δ (ppm) 4.41 (s, 4H), 3.02 (s, 3H). 13 13C NMR (151 MHz, CDCl3 / CS2 = 1 / 2): δ 154.66, 147.13, 146.11, 145.92, 145.86, 145.53, 145.33, 145.14, 144.42, 142.98, 142.51, 142.09, 141.95, 141.77, 140.07, 136.15, 71.01, 69.90, 41.37. APCI-MS: m / z calcd for C 63 H7N: 777.1 [M]-, found: 777.0.

[0092] The present invention adopts specific electrolysis conditions and selects different amino acid substrates to prepare fullerene monoaddition products. Although the fullerene monoaddition products of the present invention can all be synthesized in one step through the Prato reaction, for the first time, the present invention successfully synthesizes the expected fullerene derivatives by means of constant current electrolysis without adding aldehyde compounds, which has a great technical breakthrough.

[0093] The above-described embodiments are only descriptions of the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for the constant-current electrolytic synthesis of fullerene monoaddition derivatives, characterized in that, It includes the following steps: In an inert gas atmosphere, C 60 is mixed with an amino acid and glacial acetic acid in an electrolyte solution, and constant current electrolysis is carried out using an RVC electrode to obtain the fullerene monoaddition derivative; The electrolyte solution uses tetrabutylammonium acetate as the solute and a mixed solution of o-dichlorobenzene and acetonitrile with a volume ratio of 1:1 - 4:1 as the solvent.

2. The method according to claim 1, characterized in that The current of the constant current electrolysis is 8 - 12 mA.

3. The method according to claim 1, wherein The amino acids include sarcosine, N-(2-cyanoethyl)glycine, N-ethylglycine, N-benzylglycine, or iminodiacetic acid.

4. The method according to claim 1, wherein The C 60 has a molar ratio with amino acid and glacial acetic acid of 1:5 - 30:5 - 30.

5. The method according to claim 1, wherein The concentration of the electrolyte solution is 0.1 - 0.4 M.

6. The method according to claim 1, wherein The time of the constant current electrolysis is 0.5 - 4 h.

7. The method according to claim 1, characterized in that, The temperature of the constant current electrolysis is 80 - 140 °C.

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