A polymethyl-substituted cage alkane compound, a preparation method and application thereof, and an aerospace fuel

Abstract

The application provides a kind of multi-methyl-substituted cage alkane compound and its preparation method and application, aerospace fuel, belong to organic synthesis and fuel technical field.The multi-methyl-substituted cage alkane compound provided by the application is 8, 11-dimethyl pentacyclo [5.4.0.0 2,6 .0 3,10 .0 5,9 ] Undecane (formula I) and 4, 8, 11-trimethyl pentacyclo [5.4.0.0 2,6 .0 3,10 .0 5,9 ] Undecane (formula II).The multi-methyl-substituted cage alkane compound provided by the application is used for cage hydrocarbon fuel, has high density, high calorific value and excellent low temperature performance.Moreover, formula II compound is liquid at room temperature, has good flowability, solves the long-term problem that PCU type fuel cannot be directly used as liquid fuel and used as high-energy additive due to high symmetry, high melting point and strong volatility. Formula I, formula II.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis and fuel technology, specifically relating to a polymethyl substituted cage-like alkane compound, its preparation method and application, and aerospace fuel. Background Technology

[0002] High-energy-density fuels are crucial for increasing the range and payload of rockets, missiles, and hypersonic vehicles. Hydrocarbons with a cage-like structure, containing highly strained multi-ring compounds within their molecules, can store additional strain energy, thus possessing both high density and high volumetric calorific value. Among them, pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane (PCU, C 11 H 14 With a theoretical volumetric calorific value as high as 54.7 MJ / L, it is a representative molecule in the field of high energy density fuels.

[0003] However, PCU and its simple derivatives face serious bottlenecks in practical applications: First, PCU itself has a melting point of over 200°C and is solid at room temperature, making it unsuitable for direct use as liquid aviation fuel; second, PCU is highly volatile and easily sublimates during storage and use; furthermore, when used as a fuel additive, it is prone to crystallization in low-temperature environments (high altitude, polar regions) and has poor miscibility with conventional hydrocarbon fuels (such as kerosene and diesel), requiring the use of additional co-solvents.

[0004] Alkylation modification of cage-like molecules can improve their low-temperature performance. For example, a prior art yields 3,8-dimethylpentane[5.3.0.0] via an intramolecular [2+2] cycloaddition reaction of methylcyclopentadiene dimer. 2,5 .0 3,9 .0 4,8 Decane, although its freezing point drops to around -30°C, has a low density (only 0.964 g / cm³). 3 ).

[0005] Therefore, developing a cage-like hydrocarbon fuel that maintains high density while having a low freezing point and good fluidity is a technical challenge that urgently needs to be solved in the current fuel industry. Summary of the Invention

[0006] The purpose of this invention is to provide polymethyl-substituted cage-like alkane compounds, their preparation methods and applications, and aerospace fuels. The polymethyl-substituted cage-like alkane compounds provided by this invention are used in cage-like hydrocarbon fuels, possessing both high density and excellent low-temperature performance; furthermore, the compound of formula II is liquid at room temperature and can be used in liquid cage-like hydrocarbon fuels or directly as liquid cage-like hydrocarbon fuels, exhibiting good fluidity.

[0007] To achieve the objectives of this invention, the following technical solutions are provided: A polymethyl-substituted cage-like alkane compound having the chemical structure shown in Formula I or Formula II: Formula I, Formula II.

[0008] The present invention also provides a method for preparing the polymethyl-substituted cage-like alkane compound described above, comprising the following steps: Cyclopentadiene and its derivatives were mixed with p-benzoquinone and subjected to a Diels-Alder reaction to obtain a bicyclic [2.2.1]hept-5-en-2,3-dione intermediate; the cyclopentadiene derivative was methylcyclopentadiene; The bicyclic [2.2.1]hept-5-en-2,3-dione intermediate was subjected to a cycloaddition reaction under photosensitizer and ultraviolet light to obtain a pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-dione intermediate; The five rings [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-dione intermediate, alkyltriphenylphosphonium bromide, and a polar organic solvent were mixed; a Wittig reaction was carried out with the addition of potassium tert-butoxide solution to obtain a pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-diene intermediate; the mixing and Wittig reaction are carried out at temperatures independently of -10 to 20°C; The five rings [5.4.0.0] 2,6 .0 3,10 .0 5,9 The undecane-8,11-diene intermediate was hydrogenated under hydrogen and a hydrogenation catalyst to obtain the polymethyl substituted cage-like alkane compound.

[0009] Preferably, the molar ratio of cyclopentadiene and its derivatives to p-benzoquinone is 1:0.9~1.2; The Diels-Alder reaction was carried out at a temperature of 0–25 °C for 2–6 h.

[0010] Preferably, the photosensitizer is a ketone photosensitizer; The ultraviolet light has a wavelength of 365 nm and an incident light intensity of 70~170 mW / cm². 2 ; The cycloaddition reaction is carried out at a temperature of 10~30℃ for 1~12h.

[0011] Preferably, the methyltriphenylphosphonium bromide and pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 The molar ratio of undecane-8,11-dione intermediate is 2~3.3:1; The molar ratio of methyltriphenylphosphonium bromide to potassium tert-butoxide is 1:1 to 1.2.

[0012] Preferably, the polar organic solvent includes one or more of tetrahydrofuran, ethyl acetate, acetonitrile, acetone, dichloromethane, and cyclohexane.

[0013] Preferably, the mixing and Wittig reaction are carried out in a protective atmosphere; the Wittig reaction time is 0.5 to 3 hours.

[0014] Preferably, the pressure of the hydrogen gas is 3~4 MPa; the temperature of the hydrogenation reaction is 120~150℃, and the holding time is 6~12h.

[0015] The present invention also provides the application of the polymethyl substituted cage-like alkane compounds described in the above technical solutions or the polymethyl substituted cage-like alkane compounds prepared by the preparation methods described in the above technical solutions in hydrocarbon fuels.

[0016] The present invention also provides an aerospace fuel comprising the polymethyl substituted cage-like alkane compound described in the above technical solution or the polymethyl substituted cage-like alkane compound prepared by the preparation method described in the above technical solution.

[0017] This invention provides a polymethyl-substituted cage-like alkane compound having the chemical structure shown in Formula I or Formula II, wherein Formula I is 8,11-dimethylpentane [5.4.0.0]. 2,6 .0 3,10 .0 5,9 Undecane (DMPCU), Formula II: 4,8,11-trimethylpentane [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane (TMPCU).

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1) The 4,8,11-trimethylpentane [5.4.0.0] provided by this invention 2,6 .0 3,10 .0 5,9 Undecane, a compound that is liquid at room temperature, solves the long-standing problem that PCU-type fuels, due to their high symmetry, have high melting points and high volatility, making them unsuitable for direct use as liquid fuels and high-energy additives.

[0019] 2) This invention disrupts the molecule's crystallization tendency by introducing methyl groups at positions 4, 8, and 11 of the cage-like framework, thus lowering its freezing point; DMPCU has a freezing point of 54°C, while TMPCU has a freezing point as low as -34°C, far lower than PCU (200°C). Simultaneously, the densities of DMPCU and TMPCU are 1.106 g / cm³, respectively. 3 and 1.00 g / cm 3 The volumetric calorific values ​​are 44.5 MJ / L and 41.51 MJ / L, respectively, exhibiting high density and high volumetric calorific value. Their overall energy density performance surpasses that of existing JP-10 fuels (density 0.94 g / cm³). 3 (Volume calorific value 39.37 MJ / L).

[0020] 3) This invention also provides a method for preparing the polymethyl-substituted cage-like alkane compound described in the above technical solution, wherein the Wittig reaction, by optimizing the feeding sequence, overcomes the limitation of the traditional Wittig reaction requiring strictly low temperatures (usually -78~-20℃), and can be achieved at -10~20℃ [5.4.0.0]. 2,6 .0 3,10 .0 5,9 The near-complete conversion of undecane-8,11-dione (PCUD) (conversion >99%, yield >97%) is achieved. Furthermore, the preparation method of this invention is simple to operate, operates under mild conditions, and is suitable for large-scale industrial production.

[0021] 4) As can be seen from the results of the embodiments of the present invention, the minimum ignition temperature of the polymethyl substituted cage-like alkane structure fuel provided by the present invention is as low as 282°C, which is significantly lower than JP-10 (404°C) and ordinary aviation kerosene. It is easy to ignite and burn, and has good thermal stability (initial oxidation temperature >187°C). It is suitable for scenarios with high ignition performance requirements such as scramjet engines and rocket engines. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The 8,11-dimethylpentane [5.4.0.0] prepared in Example 1 of this invention. 2,6 .0 3,10 .0 5,9 Mass spectrum of undecane (DMPCU); Figure 2 The DMPCU prepared in Example 1 of this invention13 C NMR spectrum; Figure 3 The DMPCU prepared in Example 1 of this invention 1 H NMR spectrum; Figure 4 The 4,8,11-trimethylpentane [5.4.0.0] prepared in Example 2 of this invention. 2,6 .0 3,10 .0 5,9 Mass spectrum of undecane (TMPCU); Figure 5 The TMPCU prepared in Example 2 of this invention 13 CNMR spectrum; Figure 6 The TMPCU prepared in Example 2 of this invention 1 H NMR spectrum. Detailed Implementation

[0024] This invention provides a polymethyl-substituted cage-like alkane compound having the chemical structure shown in Formula I or Formula II: Formula I, Formula II.

[0025] The present invention also provides a method for preparing the polymethyl-substituted cage-like alkane compound described above, comprising the following steps: Cyclopentadiene and its derivatives were mixed with p-benzoquinone and subjected to a Diels-Alder reaction to obtain a bicyclic [2.2.1]hept-5-en-2,3-dione intermediate; the cyclopentadiene derivative was methylcyclopentadiene; The bicyclic [2.2.1]hept-5-en-2,3-dione intermediate was subjected to a cycloaddition reaction under photosensitizer and ultraviolet light to obtain a pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-dione intermediate; The five rings [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-dione intermediate, alkyltriphenylphosphonium bromide, and a polar organic solvent were mixed; a Wittig reaction was carried out with the addition of potassium tert-butoxide solution to obtain a pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-diene intermediate; the mixing and Wittig reaction are carried out at temperatures independently of -10 to 20°C; The five rings [5.4.0.0] 2,6 .03,10 .0 5,9 The undecane-8,11-diene intermediate was hydrogenated under hydrogen and a hydrogenation catalyst to obtain the polymethyl substituted cage-like alkane compound.

[0026] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art or prepared using methods well known to those skilled in the art.

[0027] In this invention, cyclopentadiene and its derivatives are mixed with p-benzoquinone and subjected to a Diels-Alder reaction to obtain a bicyclic [2.2.1]hept-5-ene-2,3-dione intermediate.

[0028] In this invention, the cyclopentadiene and its derivatives are selected from cyclopentadiene or methylcyclopentadiene; the cyclopentadiene or methylcyclopentadiene is obtained by pyrolysis of the corresponding dimer; the pyrolysis temperature is 150~180℃.

[0029] In this invention, the cyclopentadiene or methylcyclopentadiene and p-benzoquinone are mixed in a first polar organic solvent to carry out a Diels-Alder reaction; the first organic solvent is selected from one or more of ethyl acetate, tetrahydrofuran, acetonitrile and acetone.

[0030] In this invention, the molar ratio of cyclopentadiene and its derivatives to p-benzoquinone is 1:0.9~1.2, and in specific embodiments it can be 1:1 or 1:1.1; the temperature of the Diels-Alder reaction is 0~25℃, and in specific embodiments it can be 5℃, 10℃ or 15℃, and the time is 2~6h, and in specific embodiments it can be 3, 4 or 5h.

[0031] In this invention, after the Diels-Alder reaction is completed, the resulting reaction system is further subjected to rotary evaporation, concentration, and recrystallization. This invention removes the solvent from the product obtained from the reaction by rotary evaporation, and removes volatile impurities and residual solvent by concentration. This invention does not impose any particular limitation on the specific operation methods of rotary evaporation and concentration; conventional rotary evaporation and concentration methods can be used.

[0032] After obtaining the bicyclic [2.2.1]hept-5-en-2,3-dione intermediate, the present invention subjectes the bicyclic [2.2.1]hept-5-en-2,3-dione intermediate to a cycloaddition reaction under photosensitizer and ultraviolet light conditions to obtain a pentacyclic [5.4.0.0] 2,6 .0 3 ,10 .0 5,9 Undecane-8,11-dione intermediate.

[0033] In this invention, the photosensitizer is a ketone photosensitizer, preferably one or more of acetophenone, benzophenone, benzophenone, 2-isopropylthioxanthraphenone, and 2-naphthylacetone; the wavelength of the ultraviolet light is 365 nm, and the incident light intensity is 70~170 mW / cm². 2 In specific embodiments, the value can be 100, 130, or 150 mW / cm. 2 The cycloaddition reaction is carried out at a temperature of 10~30℃ and for a holding time of 1~12h. Specifically, the cycloaddition reaction is an intramolecular [2+2] cycloaddition reaction.

[0034] In this invention, the organic solvent used in the cycloaddition reaction is tetrahydrofuran. In a specific embodiment of this invention, the specific steps of the cycloaddition reaction are as follows: the bicyclic [2.2.1]hept-5-ene-2,3-dione intermediate is dissolved in tetrahydrofuran and cycloaddition reaction is carried out with p-benzoquinone.

[0035] The five rings were obtained [5.4.0.0]. 2,6 .0 3,10 .0 5,9 Following the undecane-8,11-dione intermediate, this invention will incorporate the pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-dione intermediate, methyltriphenylphosphonium bromide, and a polar organic solvent were mixed; potassium tert-butoxide solution was added, and the mixture was subjected to a Wittig reaction to obtain a pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-diene intermediate.

[0036] In this invention, the polar organic solvent includes one or more of tetrahydrofuran, ethyl acetate, acetonitrile, acetone, dichloromethane, and cyclohexane; the protective atmosphere is nitrogen; the potassium tert-butoxide solution is a tetrahydrofuran solution of potassium tert-butoxide; and the potassium tert-butoxide solution is added dropwise.

[0037] In this invention, the methyltriphenylphosphonium bromide and pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 The molar ratio of undecane-8,11-dione intermediate is 2~3.3:1, and in a specific embodiment it can be 2.6:1; the molar ratio of methyltriphenylphosphonium bromide and potassium tert-butoxide is 1:1~1.2, and in a specific embodiment it can be 1:1.

[0038] In a specific embodiment of the present invention, the Wittig reaction specifically involves the following steps: The five rings [5.4.0.0] 2,6 .0 3,10.0 5,9 Undecane-8,11-dione intermediate and methyltriphenylphosphonium bromide (0.24 mol) were dissolved in tetrahydrofuran, transferred to a reactor, purged with nitrogen, and cooled to -10 to 20 °C. A tetrahydrofuran solution of potassium tert-butoxide was slowly added dropwise, and the reaction was continued at -10 to 20 °C. The temperature was then raised to room temperature to continue the reaction, yielding a pentacyclic [5.4.0.0] 2, 6 .0 3,10 .0 5,9 Undecane-8,11-diene intermediate.

[0039] The specific feeding sequence of this invention allows the in-situ generated active Wittig reagent to react immediately with the substrate, thus eliminating the need for strict low temperatures (it can be carried out at room temperature) and achieving a yield higher than 95%. In the Wittig reaction process of this invention, the carbonyl group at the 8,11-position of the diketone intermediate is converted to a gem-dimethylmethylene group (i.e., C=CH2), yielding the corresponding pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-diene intermediate.

[0040] In this invention, after the Wittig reaction is completed, the reaction system is allowed to stand and separate into layers; the upper layer solution is then dried, filtered, rotary evaporated, and extracted sequentially; the drying reagent is calcium bromide; and the extraction reagent is cyclohexane.

[0041] The five rings were obtained [5.4.0.0]. 2,6 .0 3,10 .0 5,9 Following the undecane-8,11-diene intermediate, the present invention will incorporate the pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 The undecane-8,11-diene intermediate was hydrogenated under hydrogen and a hydrogenation catalyst to obtain the polymethyl substituted cage-like alkane compound.

[0042] In this invention, the hydrogen pressure is 3-4 MPa, the hydrogenation reaction temperature is 120-150°C, and the holding time is 6-12 h; the hydrogenation catalyst is Pd / C or Pt / C, and the mass of the hydrogenation catalyst is pentacyclic [5.4.0.0]. 2,6 .0 3, 10 .0 5,9 The mass of the undecane-8,11-diene intermediate is 1-5%, which can be 2.5 or 3.0% in specific embodiments.

[0043] In this invention, the organic solvent used in the hydrogenation reaction is tetrahydrofuran; specifically, in a particular embodiment of this invention, it is a pentacyclic [5.4.0.0]. 2,6 .0 3,10 .0 5,9 Undecane-8,11-diene dissolves in tetrahydrofuran and undergoes a cycloaddition reaction.

[0044] The hydrogenation reaction described in this invention further includes sequentially filtering, rotary evaporating, and sublimating the resulting system. This invention removes the solvent from the product obtained from the reaction by rotary evaporation and removes volatile impurities and residual solvent by sublimation under reduced pressure. This invention does not impose any particular limitation on the specific operation methods of rotary evaporation and sublimation under reduced pressure; conventional rotary evaporation and sublimation methods can be used.

[0045] The present invention also provides the application of the polymethyl substituted cage-like alkane compounds described in the above technical solutions or the polymethyl substituted cage-like alkane compounds prepared by the preparation methods described in the above technical solutions in hydrocarbon fuels.

[0046] The present invention also provides an aerospace fuel comprising the polymethyl-substituted cage-like alkane compound described in the above technical solution.

[0047] In this invention, the aerospace fuel can also be a mixture of polymethyl-substituted cage-like alkane compounds and high-density aerospace fuel; the high-density aerospace fuel can be kerosene-based aviation fuel JP-10 and / or synthetic hydrocarbon aviation fuel RP-3. In this invention, when the aerospace fuel is a mixed fuel, the volume percentage of the polymethyl-substituted cage-like alkane compound is 10-30%; the polymethyl-substituted cage-like alkane compound of this invention can be directly mixed with high-density aerospace fuel without the need for a co-solvent.

[0048] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, describes the polymethyl substituted cage-like alkane compounds, their preparation methods, applications, and aerospace fuels provided by the present invention, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0049] Example 1 1) Five Rings [5.4.0.0] 2,6 .0 3,10 .0 5,9 The synthesis of undecane-8,11-dione (PCUD) involves the following steps: The cyclopentadiene dimer was cleaved at 170 °C to obtain cyclopentadiene; Cyclopentadiene (0.2 mol) was added dropwise to an ethyl acetate solution of p-benzoquinone (0.2 mol) at 0–5 °C, and the mixture was stirred for 2 h. The reaction was then carried out at room temperature (25 °C) for 2 h. After the reaction was completed, the resulting system was concentrated by rotary evaporation and recrystallized to obtain yellow-green needle-like crystals, which is a bicyclic [2.2.1]hept-5-en-2,3-dione intermediate.

[0050] Weigh out 3.5 g (0.02 mol) of the above-mentioned bicyclic [2.2.1]hept-5-en-2,3-dione intermediate and dissolve it in tetrahydrofuran (20 mL). Place the solution in a quartz reaction tube and expose it to a 365 nm LED ultraviolet lamp (130 mW / cm²). 2 The mixture was stirred under irradiation for 3 hours; the resulting reaction solution was recrystallized to obtain a white powder, containing pentacyclic [5.4.0.0]. 2,6 .0 3,10 .0 5,9 Undecane-8,11-dione (PCUD) was obtained, with a calculated yield of approximately 85%.

[0051] 2) Wittig reaction, pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Synthesis of undecane-8,11-diene (PCUDE): Weigh out 0.1 mol of PCUD and 0.24 mol of methyltriphenylphosphonium bromide, dissolve them in anhydrous tetrahydrofuran (400 mL), transfer to a reactor, purge with nitrogen for 30 min, and cool to -10 °C. Slowly add 150 mL of a tetrahydrofuran solution containing 0.24 mol of potassium tert-butoxide under stirring; the solution changes from light yellow to brown during the addition. After the addition is complete, continue the reaction at -10 °C with stirring for 1 h, then raise the temperature to room temperature and react for 3 h. Allow to stand and separate into layers; take the upper reddish-brown solution, dry with calcium bromide, filter, rotary evaporate, and then thermally extract with cyclohexane to obtain a yellow powder PCUDDE with a conversion >99% and a calculated yield >98%.

[0052] 3) Hydrogenation reaction: The above PCUDE (0.05 mol) was dissolved in cyclohexane (20 mL), and Pd / C catalyst (0.5 g) was added. The mixture was placed in a high-pressure reactor. After purging with nitrogen three times, hydrogen gas was introduced to 5 MPa, and the temperature was raised to 135 °C and maintained for 8 h. After the reaction was completed, the mixture was cooled, filtered, and rotary evaporated. The resulting product was then sublimated under reduced pressure to obtain a white powder of DMPCU with a purity >98%.

[0053] Its density was measured to be 1.106 g / cm³. 3 It has a melting point of 54℃ and a measured volumetric calorific value of 44.5 MJ / L.

[0054] Example 2 ; 1) 4-Methylpentane [5.4.0.0] 2,6 .0 3,10 .0 5,9 The synthesis of undecane-8,11-dione (MPCUD) involves the following steps: The methylcyclopentadiene dimer was cleaved at 170 °C to obtain methylcyclopentadiene; The methylcyclopentadiene (0.2 mol) was added dropwise to an ethyl acetate solution of p-benzoquinone (0.2 mol) at 0-5 °C, and the mixture was stirred (700 rpm) for 2 h. The mixture was then naturally heated to room temperature (25 °C) and subjected to a Diels-Alder reaction for 2 h. After the reaction was complete, the resulting system was concentrated by rotary evaporation until no solvent residue remained, and then recrystallized to obtain yellow-green needle-like crystals, representing a methyl-substituted bicyclic [2.2.1]hept-5-en-2,3-dione intermediate.

[0055] Weigh out 3.5 g (0.02 mol) of the above-mentioned methyl-substituted bicyclo[2.2.1]hept-5-en-2,3-dione intermediate, dissolve it in tetrahydrofuran (20 mL), place it in a quartz reaction tube, and incubate it under a 365 nm LED ultraviolet lamp (130 mW / cm²). 2 The reaction mixture was stirred under irradiation for 3 hours; the resulting reaction solution was recrystallized to obtain a white powder, 4-methylpentane [5.4.0.0]. 2,6 .0 3,10 .0 5,9 Undecane-8,11-dione (MPCUD) was obtained with a calculated yield of approximately 78%.

[0056] 2) Wittig reaction: Weigh out 0.1 mol of MPCUD and 0.26 mol of methyltriphenylphosphonium bromide and dissolve them in anhydrous tetrahydrofuran (400 mL). Transfer the solution to a reactor and purge with nitrogen for 30 min. Cool to 0 °C. Under stirring, slowly add 100 mL of a tetrahydrofuran solution containing 0.26 mol of potassium tert-butoxide over 3 min. During the addition, the reaction system changes from light yellow to brown. After the addition is complete, allow the mixture to rise naturally to room temperature (25 °C) and continue the reaction for 2 h. Allow the mixture to stand and separate into layers. Take the upper reddish-brown solution, dry it with calcium bromide, filter and rotary evaporate until no solvent remains, then extract with cyclohexane to obtain a yellow oily substance. The conversion rate is >99%, and the calculated yield is >98%.

[0057] 3) Hydrogenation reaction: The diene intermediate (0.05 mol) was dissolved in cyclohexane (20 mL), and a Pd / C catalyst (0.5 g) was added. The mixture was placed in a high-pressure reactor. After purging with nitrogen three times, hydrogen gas was introduced to 5 MPa, and the temperature was raised to 135 °C and maintained for 8 h. After the reaction was completed, the mixture was cooled, filtered, and rotary evaporated. The resulting product was then distilled under reduced pressure (120 °C, 0.5 mm Hg) to obtain a colorless and transparent liquid, TMPCU, with a purity >98%.

[0058] Its density (at 20℃) was tested to be 1.00 g / cm³. 3 The volumetric net calorific value is 41.51 MJ / L, the freezing point is -34℃, the minimum ignition temperature is 282℃ (flat plate ignition test), and the viscosity at 0℃ is 19.75 mPa·s.

[0059] Application examples The DMPCU obtained in Example 1 was mixed with JP-10 at room temperature to obtain a mixed fuel.

[0060] When the blended fuel contained 30% DMPCU (by volume), the density of the blended fuel was measured to be 0.97 g / cm³. 3 It has a freezing point of -25℃, a volumetric calorific value of approximately 40.63 MJ / L, and a viscosity of 9.92 mPa·s at 0℃.

[0061] When the blended fuel contains 10% DMPCU (by volume), the density of the blended fuel is measured to be 0.95 g / cm³. 3 With a freezing point < -60℃, a volumetric calorific value of approximately 39.77 MJ / L, and a viscosity of 6.05 mPa·s at 0℃, DMPCU significantly improves energy density compared to pure JP-10 (freezing point -79℃, viscosity at 0℃ 5.14 mPa·s, but with lower density and calorific value) while maintaining acceptable low-temperature viscosity. This demonstrates that DMPCU is a high-energy additive with significant application potential.

[0062] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A polymethyl-substituted cage-like alkane compound, characterized in that, It has the chemical structure shown in Formula I or Formula II: Formula I, Formula II.

2. The method for preparing the polymethyl-substituted cage-like alkane compound according to claim 1, characterized in that, Includes the following steps: Cyclopentadiene and its derivatives were mixed with p-benzoquinone and subjected to a Diels-Alder reaction to obtain a bicyclic [2.2.1]hept-5-en-2,3-dione intermediate; the cyclopentadiene derivative was methylcyclopentadiene; The bicyclic [2.2.1]hept-5-en-2,3-dione intermediate was subjected to a cycloaddition reaction under photosensitizer and ultraviolet light to obtain a pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-dione intermediate; The five rings [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-dione intermediate, alkyltriphenylphosphonium bromide, and a polar organic solvent were mixed; a Wittig reaction was carried out with the addition of potassium tert-butoxide solution to obtain a pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 Undecane-8,11-diene intermediate; the mixing and Wittig reaction are carried out at temperatures independently of -10 to 20°C; The five rings [5.4.0.0] 2,6 .0 3,10 .0 5,9 The undecane-8,11-diene intermediate was hydrogenated under hydrogen and a hydrogenation catalyst to obtain the polymethyl substituted cage-like alkane compound.

3. The preparation method according to claim 2, characterized in that, The molar ratio of cyclopentadiene and its derivatives to p-benzoquinone is 1:0.9~1.2; The Diels-Alder reaction was carried out at a temperature of 0–25 °C for 2–6 h.

4. The preparation method according to claim 2, characterized in that, The photosensitizer is a ketone photosensitizer; The ultraviolet light has a wavelength of 365 nm and an incident light intensity of 70~170 mW / cm². 2 ; The cycloaddition reaction is carried out at a temperature of 10~30℃ for 1~12h.

5. The preparation method according to claim 2, characterized in that, The methyltriphenylphosphonium bromide and pentacyclic [5.4.0.0] 2,6 .0 3,10 .0 5,9 The molar ratio of undecane-8,11-dione intermediate is 2~3.3:1; The molar ratio of methyltriphenylphosphonium bromide to potassium tert-butoxide is 1:1 to 1.

2.

6. The preparation method according to claim 2, characterized in that, The polar organic solvent includes one or more of tetrahydrofuran, ethyl acetate, acetonitrile, acetone, dichloromethane, and cyclohexane.

7. The preparation method according to claim 2 or 6, characterized in that, The mixing and Wittig reaction are carried out in a protective atmosphere; the Wittig reaction time is 0.5 to 3 hours.

8. The preparation method according to claim 2, characterized in that, The pressure of the hydrogen gas is 3~4 MPa; the temperature of the hydrogenation reaction is 120~150℃, and the holding time is 6~12h.

9. The use of the polymethyl substituted cage-like alkane compound of claim 1 or the polymethyl substituted cage-like alkane compound prepared by any one of claims 2 to 8 in hydrocarbon fuels.

10. An aerospace fuel, characterized in that, Includes the polymethyl substituted cage-like alkane compound of claim 1 or the polymethyl substituted cage-like alkane compound prepared by the preparation method of any one of claims 2 to 8.

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