CN115850279A - Theophylline derived from combustible ion salt and preparation method - Google Patents

Abstract

The invention discloses a theophylline derived spontaneous combustion ionic salt and a preparation method thereof, and the theophylline belongs to fused ring aromatic hydrocarbon, and specifically comprises an imidazole five-membered ring and a hydropyrimidine six-membered ring, wherein a quaternary ammonium nitrogen atom is positioned on the imidazole five-membered ring, so that the theophylline derived spontaneous combustion ionic salt has better thermal stability. In addition, because the theophylline contains four nitrogen atoms, the content of nitrogen is higher, the energy density is higher, and the density specific impulse is higher. The anion is selected from dicyanamide, nitrocyanamide, dicyano dihydroborate and the like with excellent ignition performance, and the ignition performance of the theophylline derived spontaneous combustion ion salt is further improved while the high stability of the theophylline derived spontaneous combustion ion salt is maintained.

Description

Theophylline derived autogenous ion salt and preparation method

Technical Field

The invention relates to the field of self-igniting ion salts, and in particular to a self-igniting ion salt derived from theophylline and a preparation method thereof. The self-igniting ion salt derived from theophylline is an energetic compound, and is mainly used for aerospace propellants and energetic materials.

Background Art

At present, hydrazine and its derivatives (such as iso-dimethylhydrazine, unsymmetrical dimethylhydrazine, etc.) are commonly used bicomponent self-igniting rocket propellant fuels. As liquid fuels, hydrazine compounds have advantages such as high specific impulse and short ignition delay time, but hydrazine compounds also have the characteristics of high volatility, high toxicity, and strong carcinogenicity. In order to meet the ever-increasing environmental protection requirements today, the development of green, low-toxic, and low-pollution new fuels to replace hydrazine compounds has received great attention from the scientific community and has become one of the research frontiers in the field of rocket propellants.

Hypergolic ionic salt (including ionic liquid) rocket propellant has been a research hotspot in recent years due to its good combustion characteristics and other properties. Ionic salts are composed of anions and cations and have the characteristics of designable structure. However, most traditional ionic salts have low decomposition temperature and poor thermal stability. In addition, due to the low energy density of current ionic salts, there are limitations in terms of loading amount. Therefore, the stability and energy density of hypergolic ionic salts in the prior art need to be improved.

Therefore, the prior art still needs to be improved and developed.

Summary of the invention

The technical problem to be solved by the present invention is to provide a theophylline-derived spontaneous ignition ion salt and a preparation method thereof in view of the above-mentioned defects of the prior art, aiming to solve the problem that the stability and energy density of the spontaneous ignition ion salt in the prior art need to be improved.

The technical solution adopted by the present invention to solve the technical problem is as follows:

A theophylline-derived self-ignition ion salt, wherein the theophylline-derived self-ignition ion salt has a general structural formula of:

Wherein, R is selected from one of the alkyl groups with 1 to 8 carbon atoms, and ^Y- is selected from one or more of (CN) ₂ ^N- , (NO ₂ )(CN) ^N- , and H ₂ (CN) ₂ ^B- .

The theophylline is derived from a pyrolytic ion salt, wherein R is selected from one of methyl, ethyl, allyl, butyl and butylene.

The theophylline is derived from a flammable ion salt, wherein the decomposition temperature of the theophylline derived from a flammable ion salt is greater than 200° C., and the density specific impulse of the theophylline derived from a flammable ion salt is greater than 330 s·g·cm ^-3 .

A method for preparing theophylline-derived autogenous ion salt as described in any one of the above, comprising the steps of:

Under an inert atmosphere and preheating and stirring, theophylline and a strong base are dissolved in a first solvent, and a halogenated hydrocarbon is added to react to obtain an alkyl theophylline solution; wherein the alkyl group in the halogenated hydrocarbon is selected from one of alkyl groups with 1 to 8 carbon atoms, and the halogen is selected from one of Cl, Br, and I, and the preheating and stirring temperature is 50 to 120° C.;

The alkyl theophylline solution is filtered to remove insoluble inorganic matter, the filtrate is concentrated to precipitate, and then filtered again, the filtrate is collected, and dried to obtain alkyl theophylline.

Adding a mixed solution of DMF and methyl iodide to the alkyl theophylline, reacting for 2 to 3 days, adding a second solvent, filtering and drying to obtain alkyl methyl theophylline iodide;

The alkylmethyltheophylline iodide and cyanide are dissolved in distilled water, heated for reaction, filtered and dried to obtain theophylline-derived autogenous ion salt; wherein the anion in the cyanide is selected from one or more of (CN) ₂ N ^- , (NO ₂ )(CN)N ^- , H ₂ (CN)B ^- , the cation in the cyanide is silver, the temperature of the heating reaction is 25-80° C., and the time of the heating reaction is 3-10 hours.

The method for preparing theophylline-derived self-ignition ion salt comprises the following steps: the molar ratio of theophylline to the strong base is 1:1-1.2, the molar ratio of theophylline to the halogenated hydrocarbon is 1:3-10, and the molar ratio of DMF to methyl iodide is 1:2-10.

The method for preparing theophylline derived from a flammable ion salt, wherein the molar ratio of theophylline to the halogenated hydrocarbon is 1:5-8.

The method for preparing theophylline-derived autogenous ion salt, wherein the inert atmosphere is at least one of nitrogen, argon and helium;

The strong base includes: one or more of sodium hydroxide, potassium hydroxide, cesium carbonate, potassium carbonate, barium hydroxide, and calcium hydroxide.

The method for preparing theophylline-derived spontaneous combustion ion salt, wherein the first solvent comprises one or more of N,N-dimethylformamide, chloroform, ethyl acetate, acetone, dichloromethane, N-methylpyrrolidone, tetrahydrofuran, dioxane, dimethyl sulfoxide, methyl ethyl ketone, and acetonitrile;

The second solvent includes: one or more of ethyl acetate and diethyl ether.

The method for preparing theophylline-derived autogenous ion salt comprises the following steps: the temperature of the heating reaction is 35-60° C.; and the time of the heating reaction is 5-6 hours.

A use of the theophylline-derived self-igniting ion salt as described in any one of the above items in aerospace propellants.

Beneficial effects: Since theophylline belongs to a condensed-ring aromatic hydrocarbon, specifically, it has an imidazole five-membered ring and a hydrogenated pyrimidine six-membered ring, and the quaternary ammonium nitrogen atom is located on the imidazole five-membered ring, it has good thermal stability. In addition, since theophylline has four nitrogen atoms, the nitrogen content is high, it has a high energy density, and the density specific impulse is also high. The anion is selected from dicyanamide, nitrocyanamide, dicyanodihydroborate, etc. with excellent ignition performance, while maintaining the high stability of theophylline-derived self-igniting ion salt, the ignition performance of theophylline-derived self-igniting ion salt is further improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isomeric reaction diagram for calculating the enthalpy of formation in the present invention.

FIG. 2 a is a photograph of the ionic salt of the present invention before ignition.

FIG. 2 b is a photograph of the ionic salt after ignition in the present invention.

FIG. 3 is a crystal molecular structure diagram of the spontaneous combustion ion salt of methylallyltheophylline dicyanamide salt in the present invention.

FIG. 4 is a crystal molecular structure diagram of the spontaneous combustion ion salt of methylbutyltheophylline dicyanamide salt in the present invention.

FIG. 5 is a hydrogen nuclear magnetic spectrum of the spontaneous combustion ion salt of 7,9-dimethyltheophylline dicyanamide salt in the present invention.

FIG. 6 is a carbon NMR spectrum of the spontaneous combustion ion salt of 7,9-dimethyltheophylline dicyanamide salt in the present invention.

FIG. 7 is a hydrogen nuclear magnetic spectrum of the spontaneous combustion ion salt of methylethyltheophylline dicyanamide salt in the present invention.

FIG8 is a carbon NMR spectrum of the spontaneous combustion ion salt of methylethyltheophylline dicyanamide salt in the present invention.

FIG. 9 is a hydrogen nuclear magnetic spectrum of the spontaneous combustion ion salt of methylallyl theophylline dicyanamide salt in the present invention.

FIG. 10 is a carbon NMR spectrum of the spontaneous ignition ion salt of methylallyltheophylline dicyanamide salt in the present invention.

FIG. 11 is a hydrogen nuclear magnetic spectrum of the spontaneous combustion ion salt of methylbutyltheophylline dicyanamide salt in the present invention.

FIG. 12 is a carbon NMR spectrum of the spontaneous ignition ion salt of methylbutyltheophylline dicyanamide salt in the present invention.

FIG. 13 is a hydrogen nuclear magnetic spectrum of the spontaneous ignition ion salt of methyl butyltheophylline dicyanamide salt in the present invention.

FIG. 14 is a carbon NMR spectrum of the spontaneous ignition ion salt of methyl butyltheophylline dicyanamide salt in the present invention.

FIG. 15 is a first structural formula of theophylline-derived ion salt of the present invention.

FIG. 16 is a second structural formula of theophylline derived from theophylline ion salt of the present invention.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

Please refer to FIG. 1 to FIG. 16 simultaneously. The present invention provides some embodiments of theophylline-derived ion salts.

As shown in FIG. 15 and FIG. 16 , the theophylline of the present invention is derived from a pyrolysis ion salt, and its general structural formula is:

Wherein, R is selected from one of the alkyl groups with 1 to 8 carbon atoms, and ^Y- is selected from one or more of (CN) ₂ ^N- , (NO ₂ )(CN) ^N- , and H ₂ (CN) ₂ ^B- .

Specifically, in the self-igniting ionic salt of the present application, the cation is a 7-alkyl-9-methyltheophylline quaternary ammonium ion or a 7-methyl-9-alkyltheophylline quaternary ammonium ion, and the anion is a cyanamide ion or a cyanoborohydride ion. The cyanamide ion can be (CN) ₂ ^N- , (NO ₂ )(CN) N- ^, and the cyanoborohydride ion can be H ₂ (CN) ₂ ^B- . Since theophylline belongs to a condensed-ring aromatic hydrocarbon, specifically, there is an imidazole five-membered ring and a hydrogenated pyrimidine six-membered ring, and the quaternary ammonium nitrogen atom is located on the imidazole five-membered ring, it has good thermal stability. In addition, since there are four nitrogen atoms in theophylline, the nitrogen content is high, it has a high energy density, and the density specific impulse is also high. The anion is selected from dicyanamide, nitrocyanamide, dicyanodihydroborate, etc. with excellent ignition performance, while maintaining the high stability of theophylline-derived self-igniting ionic salt, the ignition performance of theophylline-derived self-igniting ionic salt is further improved.

According to the different anions, theophylline derived from anionic salts can be expressed as:

In a preferred implementation of the embodiment of the present invention, R is selected from one of methyl, ethyl, allyl, butyl, and butylene.

Specifically, the alkyl group R is selected from methyl, ethyl, allyl, butyl, and butylene. The alkyl group is used to replace the hydrogen proton on the nitrogen atom at position 7 (or position 9) of theophylline as needed.

In a preferred implementation of the embodiment of the present invention, the decomposition temperature of the theophylline-derived ion salt is greater than 200° C., and the density specific impulse of the theophylline-derived ion salt is greater than 330 s·g·cm ⁻³ .

Specifically, the decomposition temperature of traditional ionic salts (ionic liquids) is lower than 180°C, while the decomposition temperature of the theophylline-derived self-igniting ionic salt of the present application is greater than 200°C, which shows that it has high thermal stability. And the density specific impulse is greater than 330s·g·cm ^-3 . Since the decomposition temperature of theophylline-derived self-igniting ionic salt is relatively high, theophylline-derived self-igniting ionic salt has high thermal stability, is more stable in use, and has higher safety. And because of the high density specific impulse, it can provide more energy for the propulsion process of rockets and other spacecraft.

The 1-methyl-4-amino-4H-1,2,4-triazolium dicyanamide salt ionic liquid in the prior art is a monocyclic cation ionic liquid, and the monocyclic cation has four nitrogen atoms, and the thermal decomposition temperature is 143°C. The theophylline derived from the self-igniting ion salt of the present application is an ionic liquid with a condensed ring cation, and the condensed ring cation has four nitrogen atoms, and the thermal decomposition temperature is greater than 200°C. By comparing the two, it can be seen that the binary condensed ring structure in the condensed ring cation of the present application is conducive to increasing the thermal decomposition temperature of the ionic liquid, ensuring that the thermal stability of the ionic liquid is high.

The structural formula of 1-methyl-4-amino-4H-1,2,4-triazolium dicyanamide salt ionic liquid can be expressed as:

In a preferred implementation of the embodiment of the present invention, the density of the theophylline-derived ion salt is greater than or equal to 1.30 g·cm ^-3 .

Specifically, the density of theophylline-derived ion salt is relatively high, with a density greater than or equal to 1.30 g·cm ^-3 . A higher density allows for a higher loading capacity.

In summary, the theophylline derived from the ion salt of the present invention has the following effects:

First, theophylline has a binary fused ring structure, which can improve the stability of the compound and can be used as a skeleton to synthesize a series of self-igniting ion salts with high heat resistance and excellent comprehensive performance. The decomposition temperature of theophylline-derived self-igniting ion salts obtained in the present application is greater than 200°C, and has good thermal stability;

Secondly, theophylline-derived ionic salts have a higher density, and a higher density means a higher loading capacity. The density of theophylline-derived ionic salts obtained in the present application is ≥1.30 g·cm ^-3 , which can have a higher loading capacity in application. At the same time, a higher density also means a higher density specific impulse, thereby providing more energy for the propulsion process.

Thirdly, theophylline with a binary fused ring structure can be extracted from tea leaves. Using theophylline as a cationic precursor, the obtained ion salt has the advantages of being renewable and low in toxicity. The combustion products are green and environmentally friendly, and have little harm to the environment.

Based on the theophylline-derived self-igniting ion salt described in any of the above embodiments, the present invention also provides a preferred embodiment of a method for preparing theophylline-derived self-igniting ion salt:

The method for preparing theophylline-derived autogenous ion salt according to the embodiment of the present invention comprises the following steps:

Step S100, in an inert atmosphere and under preheating and stirring, dissolving theophylline and a strong base with a first solvent, and adding a halogenated hydrocarbon to react to obtain an alkyl theophylline solution; wherein the alkyl group in the halogenated hydrocarbon is selected from one of alkyl groups with 1 to 8 carbon atoms, and the halogen is selected from one of Cl, Br, and I, and the preheating and stirring temperature is 50 to 120°C.

Specifically, the molar ratio of theophylline to the strong base is 1:1 to 1.2, and the molar ratio of theophylline to the halogenated hydrocarbon is 1:3 to 10. Preferably, the molar ratio of theophylline to the halogenated hydrocarbon is 1:5 to 8.

The inert atmosphere is at least one of nitrogen, argon and helium.

The strong base includes one or more of sodium hydroxide, potassium hydroxide, cesium carbonate, potassium carbonate, barium hydroxide, and calcium hydroxide. The strong base is added to capture the hydrogen protons on the nitrogen atom in theophylline, so that the hydrocarbon carbon cations are more likely to attack the nitrogen anions. Among them, sodium hydroxide, potassium hydroxide, cesium carbonate, potassium carbonate, barium hydroxide, calcium hydroxide, etc. can well promote the reaction, while some strong bases and weak acid salts such as sodium carbonate and sodium bicarbonate have no effect. Therefore, adding a strong base in S100 can promote the reaction and make the halogenated hydrocarbon replace the hydrogen on the nitrogen atom at position 7 of theophylline.

The first solvent includes: one or more of N,N-dimethylformamide, chloroform, ethyl acetate, acetone, dichloromethane, N-methylpyrrolidone, tetrahydrofuran, dioxane, dimethyl sulfoxide, methyl ethyl ketone, and acetonitrile.

Step S200, filtering the alkyl theophylline solution to remove insoluble inorganic matter, concentrating the filtrate to precipitate, filtering again, collecting the filtrate, and drying to obtain alkyl theophylline.

Specifically, the alkyltheophylline solution is filtered to remove insoluble matter, and then concentrated, precipitated and dried to obtain alkyltheophylline.

Step S300, adding a mixed solution of DMF and methyl iodide to the alkyl theophylline, reacting for 2 to 3 days, adding a second solvent, filtering and drying to obtain alkyl methyl theophylline iodide salt.

Specifically, the molar ratio of DMF to methyl iodide is 1:2-10, and the second solvent includes one or more of ethyl acetate and ether. Methyl iodide is added to further cause a quaternization reaction. Alkyl methyl theophylline iodide salt is insoluble in the second solvent, and the second solvent is added after 2-3 days of reaction to precipitate the alkyl methyl theophylline iodide salt.

Step S400, dissolving the alkylmethyltheophylline iodide and cyanide in distilled water, heating for reaction, filtering and drying to obtain theophylline-derived autogenous ion salt; wherein the anion in the cyanide is selected from one or more of (CN) ₂ N ^- , (NO ₂ )(CN) N ^- , H ₂ (CN) ₂ B ^- , the cation in the cyanide is silver, the heating reaction temperature is 25 to 80° C., and the heating reaction time is 3 to 10 hours.

Preferably, the temperature of the heating reaction is 35-60° C.; the time of the heating reaction is 5-6 hours.

Specifically, inorganic salt precipitates such as iodide are removed by a vacuum filtration device to obtain a solution containing theophylline-derived self-igniting ion salt, and then the solvent is removed by a vacuum rotary evaporator to obtain theophylline-derived self-igniting ion salt with high purity.

The present application uses theophylline as a cationic precursor to prepare theophylline quaternary ammonium salt, and then prepares theophylline-derived self-igniting ion salt containing dicyanamide anion and other excellent ignition properties through anion exchange reaction. Moreover, the preparation method is simple, the experimental conditions are safe and easy to obtain, and there are no cumbersome post-processing steps. The specific reaction process is as follows:

It should be noted that theophylline has tautomers, and the final product is a mixture of the two products.

Example 1

S1. Weigh 3.60g (0.02mol) of theophylline and 0.88g (0.022mol) of sodium hydroxide, add to a three-necked flask, add acetonitrile, and introduce _N2 gas to completely replace the air in the reactor with nitrogen. Place in a thermostatic oil bath preheated to 70°C, stir for 50min to completely dissolve theophylline, then drop 17.04g (0.12mol) of iodomethane into the system, continue the reaction, monitor the reaction endpoint by a silica gel plate, and obtain a methyltheophylline solution (7-methyltheophylline and 9-methyltheophylline are present in the solution).

S2, filtering the system, filtering out insoluble inorganic matter, concentrating the filtrate to precipitate, filtering again, collecting the filtrate, and drying to obtain methyltheophylline (7-methyltheophylline and 9-methyltheophylline).

S3. A mixed solution of 17.04 g (0.12 mol) of methyl iodine and 2.92 g (0.04 mol) of DMF was added dropwise to methyl theophylline (7-methyl theophylline and 9-methyl theophylline), and the reaction was continued for 2 days. After the reaction was completed, ethyl acetate was added for precipitation, and the solid was filtered and dried to obtain 5.44 g of 7,9-dimethyl theophylline iodide, with a yield of 80.95%.

S4. Weigh 3.36 g (0.01 mol) of 7,9-dimethyltheophylline iodide and 2.09 g (0.012 mol) of silver dicyanamide, add appropriate amount of distilled water, place in a 40°C oil bath, and continue the reaction for 4 hours.

S5. After the reaction is completed, the mixture is filtered, the filtrate is collected, and the mixture is dried to obtain 2.58 g of 7,9-dimethyltheophylline dicyanamide pyrophoric ion salt, with a yield of 93.82%.

As shown in Figures 5 and 6, the nuclear magnetic hydrogen spectrum of the spontaneous combustion ion salt of 7,9-dimethyltheophylline dicyanamide salt prepared in this embodiment is δ4.22ppm (s, 3H), 4.16ppm (s, 3H), 3.84ppm (s, 3H), 3.38ppm (s, 3H); the nuclear magnetic carbon spectrum is δ153.34ppm, 150.23ppm, 139.68ppm, 139.30ppm, 119.06ppm, 107.79ppm, 36.81ppm, 35.64ppm, 31.31ppm, 28.43ppm; the Fourier transform infrared spectrum is 3480cm ^-1 , 3060cm ^- 1, 2220cm ^- 1, 2128cm- ¹ , 1660cm ^-1 , 1544cm ^-1 , 1300cm ^-1 , 1056cm ^-1 , 880cm ^-1 , 774cm ^-1 ; elemental analysis calculated values (%): C 48.00, H 4.76, N 35.62; experimental values (%): C 47.85, H 4.89, N 35.69. The specific structure of the spontaneous ignition ion salt of 7,9-dimethyltheophylline dicyanamide salt is shown below:

The physicochemical properties of the 7,9-dimethyltheophylline dicyanamide self-igniting ion salt prepared in this example were measured. Its phase transition temperature (T _g /T _m ) was 180°C and its thermal decomposition temperature (T _d ) was 220°C, indicating that the 7,9-dimethyltheophylline dicyanamide self-igniting ion salt had a wide liquid range and excellent thermal stability. Its density was 1.38 g·cm ^-3 , which had a higher loading capacity compared with the traditional dimethylhydrazine fuel (0.79 g·cm ^-3 ).

Example 2

S1. Weigh 3.60g (0.02mol) of theophylline and 0.88g (0.022mol) of sodium hydroxide, add to a three-necked flask, add tetrahydrofuran, pass argon gas, and completely replace the air in the reactor with argon. Place in a thermostatic oil bath preheated to 50°C, stir for 80min, dissolve theophylline completely, then drop 11.39g (0.12mol) of ethyl bromide into the system, continue the reaction, monitor the reaction end point by a silica gel plate, and obtain an ethyl theophylline solution (7-ethyl theophylline and 9-ethyl theophylline are present in the solution).

S2. Filter the system to remove insoluble inorganic matter, concentrate the filtrate to precipitate, filter again, collect the filtrate, and dry to obtain ethyl theophylline (7-ethyl theophylline and 9-ethyl theophylline).

S3. A mixed solution of 17.04 g (0.12 mol) of methyl iodide and 2.92 g (0.04 mol) of DMF was added dropwise to ethyl theophylline (7-ethyl theophylline and 9-ethyl theophylline), and the reaction was continued for 3 days. After the reaction was completed, ether was added to precipitate, filtered, and the solid was dried to obtain 4.49 g of methylethyl theophylline iodide (i.e. 7-ethyl-9-methyl theophylline iodide and 7-methyl-9-ethyl theophylline iodide), in a yield of 64.14%.

S4. Weigh 3.50 g (0.01 mol) of methylethyltheophylline iodide and 2.09 g (0.012 mol) of silver dicyanamide, add appropriate amount of distilled water, place in a 35°C oil bath, and continue the reaction for 10 hours.

S5. After the reaction is completed, the reaction is filtered, the filtrate is collected, and the filtrate is dried to obtain 2.68 g of methylethyltheophylline dicyanamide spontaneous ignition ion salt (i.e., 7-ethyl-9-methyltheophylline dicyanamide spontaneous ignition ion salt and 7-methyl-9-ethyltheophylline dicyanamide spontaneous ignition ion salt), with a yield of 92.73%.

As shown in Figures 7 and 8, the nuclear magnetic hydrogen spectrum of the spontaneous combustion ion salt of methylethyltheophylline dicyanamide salt prepared in this embodiment is δ4.56ppm (q, J = 7.1Hz, 2H), 4.20ppm (s, 3H), 3.82ppm (s, 3H), 3.37ppm (s, 3H), 1.54ppm (t, J = 7.2Hz, 3H); its nuclear magnetic carbon spectrum is δ154.25ppm, 151.47ppm, 139.88ppm, 119.55ppm, 108.22ppm, 45.28ppm, 36.99ppm, 31.64ppm, 28.63ppm, 14.34ppm; the Fourier transform infrared spectrum is 3476cm ^-1 , 3072cm ^-1 , 2220cm ^-1 , 2120cm ^-1 , 1668cm ^-1 , 1540cm ^-1 , 1306cm ^-1 , 1008cm ^-1 , 882cm ^-1 , 760cm ^-1 ; elemental analysis calculated values (%): C 49.82, H 5.23, N 33.89; experimental values (%): C 49.90, H5.01, N 33.85. The specific structure of the pyrophoric ion salt of methylethyltheophylline dicyanamide salt is shown below:

The physicochemical properties of the methylethyltheophylline dicyanamide salt self-igniting ion salt prepared in this example were measured. The thermal decomposition temperature (T _d ) of the methylethyltheophylline dicyanamide salt self-igniting ion salt was 204° C., and the density was 1.37 g·cm ^-3 . The higher the density of the fuel, the more fuel can be filled in a given space. At the same time, a higher density also represents a higher density specific impulse, which can provide more energy for the propulsion process.

Example 3

S1. Weigh 3.60g (0.02mol) of theophylline and 0.88g (0.022mol) of sodium hydroxide, add them to a three-necked flask, add acetonitrile, and introduce _N2 gas to completely replace the air in the reactor with nitrogen. Place in a thermostatic oil bath preheated to 120°C, stir for 30min to completely dissolve theophylline, then drop 14.52g (0.12mol) of propylene bromide into the system, continue the reaction, monitor the reaction endpoint by a silica gel plate, and obtain an allyl theophylline solution (the solution contains 7-allyl theophylline and 9-allyl theophylline).

S2, filtering the system, filtering out insoluble inorganic matter, concentrating the filtrate to precipitate, filtering again, collecting the filtrate, and drying to obtain allyltheophylline (7-allyltheophylline and 9-allyltheophylline).

S3, to allyl theophylline (7-allyl theophylline and 9-allyl theophylline) was added dropwise a mixed solution of 17.04 g (0.12 mol) of methyl iodide and 2.92 g (0.04 mol) of DMF, and the reaction was continued for 2 days. After the reaction was completed, ethyl acetate was added to precipitate, filtered, and the solid was dried to obtain 4.36 g of methyl allyl theophylline iodide (i.e. 7-allyl-9-methyl theophylline iodide and 7-methyl-9-allyl theophylline iodide), in a yield of 60.22%.

S4. Weigh 3.62 g (0.01 mol) of methylallyl theophylline iodide and 2.09 g (0.012 mol) of silver dicyanamide, add appropriate amount of distilled water, place in a heated oil bath at 60°C, and continue the reaction for 3 h.

S5. After the reaction is completed, the reaction is filtered, the filtrate is collected, and the filtrate is dried to obtain 2.76 g of methylallyl theophylline dicyanamide spontaneous ignition ion salt (i.e., 7-allyl-9-methyltheophylline dicyanamide spontaneous ignition ion salt and 7-methyl-9-allyl theophylline dicyanamide spontaneous ignition ion salt), with a yield of 91.69%.

As shown in Figures 9 and 10, the nuclear magnetic hydrogen spectrum of the spontaneous combustion ion salt of methylallyl theophylline dicyanamide salt prepared in this embodiment is δ6.05ppm (ddt, J=16.3, 10.5, 5.9Hz, 1H), 5.37ppm (dd, J=39.5, 13.7Hz, 2H), 5.11ppm (d, J=5.9Hz, 2H), 4.17ppm (s, 3H), 3.79ppm (s, 3H), 3.33ppm (s, 3H); its nuclear magnetic carbon spectrum is δ154.19ppm, 151.40ppm, 139.89ppm, 129.51ppm, 121.43ppm, 119.50ppm, 108.15ppm, 51.16ppm, 37.13ppm, 31.64ppm, 28.63ppm; the Fourier transform infrared spectrum is 3424cm ^-1 , 3020cm ^-1 , 2228cm ^-1 , 2132cm ^-1 , 1672cm ^-1 , 1540cm ^-1 , 1308cm ^-1 , 1000cm ^-1 , 876cm ^-1 , 760cm ^-1 ; elemental analysis calculated values (%): C 52.82, H 5.02, N 32.54; experimental values (%): C 52.71, H 5.22, N 32.49. The specific structure of the pyrophoric ion salt of methylallyl theophylline dicyanamide salt is shown below:

α＝90°，β＝119.095(16)°，γ＝90°，Z＝4，晶胞体积为

The crystal molecular structure of the pyrophoric ion salt of methylallyltheophylline dicyanamide prepared in this embodiment is shown in FIG3 . The molecular formula is C ₁₃ H ₁₅ N ₇ O ₂ , the crystal structure is monoclinic, the space group is P2 _1/c , and the unit cell parameters are

α＝90°，β＝119.095(16)°，γ＝90°，Z＝4，the unit cell volume is

Table 1 Crystal data of pyrophoric ion salt of methylallyl theophylline dicyanamide salt

分析数据如表2所示，其中，U(eq)定义为正交U_ij张量的痕量的三分之一。Atomic coordinates (×10 ⁴ ) and isotropic atomic displacement parameters of the pyrophoric ion salt of methylallyltheophylline dicyanamide prepared in this example

The analytical data are shown in Table 2, where U(eq) is defined as one third of the trace of the orthogonal U _ij tensor.

Table 2 Atomic coordinates and isotropic atomic displacement parameters of the spontaneous ion salt of methylallyltheophylline dicyanamide salt

分析数据如表3所示，其中，各向异性原子位移因子幂呈式：-2π²[h²a*²U₁₁+2hka*b*U₁₂+…]。Anisotropic atomic displacement parameters of the spontaneous ignition ion salt of methylallyltheophylline dicyanamide prepared in this example

The analysis data are shown in Table 3, where the anisotropic atomic displacement factor power is expressed as: -2π ² [h ² a* ² U ₁₁ +2hka*b*U ₁₂ +…].

Table 3 Anisotropic atomic displacement parameters of pyrophoric ionic salts of methylallyltheophylline dicyanamide salt

分析数据如表4所示。The chemical bond lengths of the pyrophoric ion salt of methylallyl theophylline dicyanamide prepared in this example are

The analysis data are shown in Table 4.

Table 4 Chemical bond lengths of methylallyl theophylline dicyanamide self-igniting ion salts

The analytical data of the chemical bond angles (°) of the pyrophoric ion salt of methylallyltheophylline dicyanamide salt prepared in this example are shown in Table 5.

Table 5 Chemical bond angles of methylallyl theophylline dicyanamide self-igniting ion salts

The torsion angle (°) analysis data of each chemical bond of the methallyltheophylline dicyanamide salt spontaneous ion salt prepared in this example are shown in Table 6.

Table 6 The torsion angles of the chemical bonds of the spontaneous ion salt of methylallyl theophylline dicyanamide salt

及各项同性原子位移参数

分析数据如表7所示。The hydrogen atomic coordinates of the spontaneous ignition ion salt of methylallyl theophylline dicyanamide prepared in this example

and the isotropic atomic displacement parameters

The analysis data are shown in Table 7.

Table 7 Hydrogen atom coordinates and isotropic atomic displacement parameters of methylallyl theophylline dicyanamide self-igniting ion salt

The physicochemical properties of the methallyl theophylline dicyanamide self-igniting ion salt prepared in this example were measured. The phase transition temperature (T _g /T _m ) of the methallyl theophylline dicyanamide self-igniting ion salt was 90° C., the thermal decomposition temperature (T _d ) was 212° C., and the density was 1.35 g·cm ^-3 .

Example 4

S1. Weigh 3.60g (0.02mol) of theophylline and 0.88g (0.022mol) of sodium hydroxide, add to a three-necked flask, add acetonitrile, pass into _N2 gas, and completely replace the air in the reactor with nitrogen. Place in a thermostatic oil bath preheated to 70°C, stir for 50min, dissolve theophylline completely, then drop 16.44g (0.12mol) of bromobutyl into the system, continue the reaction, monitor the reaction end point by a silica gel plate, and obtain a butyltheophylline solution (7-butyltheophylline and 9-butyltheophylline are present in the solution).

S2. Filter the system to remove insoluble inorganic matter, concentrate the filtrate to precipitate, filter again, collect the filtrate, and dry to obtain butyltheophylline (7-butyltheophylline and 9-butyltheophylline).

S3, to butyltheophylline (7-butyltheophylline and 9-butyltheophylline), a mixed solution of 17.04 g (0.12 mol) methyl iodide and 2.92 g (0.04 mol) DMF was added dropwise, and the reaction was continued for 2 days. After the reaction was completed, ethyl acetate was added to precipitate, filtered, and the solid was dried to obtain 5.33 g of methylbutyltheophylline iodide (i.e. 7-butyl-9-methyltheophylline iodide and 7-methyl-9-butyltheophylline iodide), and the yield was 70.50%.

S4. Weigh 3.79 g (0.01 mol) of methylbutyltheophylline iodide and 2.09 g (0.012 mol) of silver dicyanamide, add appropriate amount of distilled water, place in a 40°C oil bath, and continue the reaction for 4 hours.

S5. After the reaction is completed, the reaction is filtered, the filtrate is collected, and the filtrate is dried to obtain 2.92 g of methylbutyltheophylline dicyanamide spontaneous ignition ion salt (i.e., 7-butyl-9-methyltheophylline dicyanamide spontaneous ignition ion salt and 7-methyl-9-butyltheophylline dicyanamide spontaneous ignition ion salt), with a yield of 92.11%.

As shown in Figures 11 and 12, the nuclear magnetic hydrogen spectrum of the spontaneous combustion ion salt of methylbutyltheophylline dicyanamide prepared in this embodiment is δ4.53ppm (t, J = 7.2Hz, 2H), 4.20ppm (s, 3H), 3.83ppm (s, 3H), 3.38ppm (s, 3H), 1.95-1.84ppm (m, 2H), 1.42-1.30ppm (m, 2H), 0.94pp m (t, J = 7.4 Hz, 3H); its NMR carbon spectrum is δ 154.30 ppm, 151.48 ppm, 139.93 ppm, 119.70 ppm, 108.24 ppm, 49.44 ppm, 37.01 ppm, 31.64 ppm, 31.18 ppm, 28.64 ppm, 18.68 ppm, 12.64 ppm; Fourier transform infrared spectrum is 3488 cm ^-1 , 3044cm ^-1 , 2228cm ^-1 , 2144cm ^-1 , 1680cm ^-1 , 1544cm ^-1 , 1308cm ^-1 , 1004cm ^-1 , 896cm ^-1 , 760cm ^-1 ; elemental analysis calculated value (%): C 52.99, H 6.03, N 30.90; experimental value (%): C 53.01, H 5.92, N 30.97. The specific structure of the pyrophoric ion salt of methylbutyltheophylline dicyanamide salt is shown below:

α＝90°，β＝95.289(9)°，γ＝90°，Z＝4，晶胞体积为

The crystal molecular structure of the pyrophoric ion salt of methylbutyltheophylline dicyanamide salt is shown in FIG4 . The molecular formula is C ₁₄ H ₁₉ N ₇ O ₂ . The crystal structure is monoclinic, the space group is P2 _1/n , and the unit cell parameters are

α＝90°，β＝95.289(9)°，γ＝90°，Z＝4，the unit cell volume is

Table 8 Crystal data of pyrophoric ion salt of methylbutyltheophylline dicyanamide salt

分析数据如表9所示，其中，U(eq)定义为正交U_ij张量的痕量的三分之一。Atomic coordinates (×10 ⁴ ) and isotropic atomic displacement parameters of the pyrophoric ion salt of methylbutyltheophylline dicyanamide prepared in this example

The analytical data are shown in Table 9, where U(eq) is defined as one third of the trace of the orthogonal U _ij tensor.

Table 9 Atomic coordinates and isotropic atomic displacement parameters of methylbutyltheophylline dicyanamide self-igniting ion salt

分析数据如表10所示，其中，各向异性原子位移因子幂呈式：-2π²[h²a*²U₁₁+2hka*b*U₁₂+…]。Anisotropic atomic displacement parameters of the spontaneous ignition ion salt of methylbutyltheophylline dicyanamide salt prepared in this example

The analysis data are shown in Table 10, wherein the anisotropic atomic displacement factor power is expressed as: -2π ² [h ² a* ² U ₁₁ +2hka*b*U ₁₂ +…].

Table 10 Anisotropic atomic displacement parameters of spontaneous ion salts of methylbutyltheophylline dicyanamide salt

分析数据如表11所示。The chemical bond lengths of the methylbutyltheophylline dicyanamide self-igniting ion salt prepared in this embodiment are

The analysis data are shown in Table 11.

Table 11 Chemical bond lengths of methylbutyltheophylline dicyanamide self-igniting ion salts

The analytical data of the chemical bond angles (°) of the methylbutyltheophylline dicyanamide salt spontaneous ion salt prepared in this example are shown in Table 12.

Table 12 Chemical bond angles of methylbutyltheophylline dicyanamide self-igniting ion salts

The torsion angle (°) analysis data of each chemical bond of the methylbutyltheophylline dicyanamide salt spontaneous ion salt prepared in this example is shown in Table 13.

Table 13 Torsion angles of chemical bonds of methylbutyltheophylline dicyanamide self-igniting ion salt

及各项同性原子位移参数

分析数据如表14所示。The hydrogen atomic coordinates of the spontaneous ignition ion salt of methylbutyltheophylline dicyanamide salt prepared in this example

and the isotropic atomic displacement parameters

The analysis data are shown in Table 14.

Table 14 Hydrogen atom coordinates and isotropic atomic displacement parameters of methylbutyltheophylline dicyanamide self-igniting ion salt

The physical and chemical properties of the methylbutyltheophylline dicyanamide self-igniting ion salt prepared in this example were measured, and it was found that the phase transition temperature (T _g /T _m ) of the methylbutyltheophylline dicyanamide self-igniting ion salt was 112° C., the thermal decomposition temperature (T _d ) was 221° C., and the density was 1.30 g·cm ^-3 .

Example 5

S1. Weigh 3.60g (0.02mol) of theophylline and 0.88g (0.022mol) of sodium hydroxide, add to a three-necked flask, add acetonitrile, pass _N2 gas, and completely replace the air in the reactor with nitrogen. Place in a thermostatic oil bath preheated to 70°C, stir for 50min, dissolve theophylline completely, then drop 16.20g (0.12mol) of bromobutylene to the system, continue the reaction, monitor the reaction end point by a silica gel plate, and obtain an olefin butyl theophylline solution (7-olefin butyl theophylline and 9-olefin butyl theophylline are present in the solution).

S2, filtering the system, filtering out insoluble inorganic matter, concentrating the filtrate to precipitate, filtering again, collecting the filtrate, and drying to obtain butyltheophylline (7-butyltheophylline and 9-butyltheophylline).

S3, to butyltheophylline (7-butyltheophylline and 9-butyltheophylline), a mixed solution of 17.04 g (0.12 mol) methyl iodide and 2.92 g (0.04 mol) DMF was added dropwise, and the reaction was continued for 2 days. After the reaction was completed, ethyl acetate was added to precipitate, filtered, and the solid was dried to obtain 4.62 g of methylbutyltheophylline iodide (i.e. 7-butyl-9-methyltheophylline iodide and 7-methyl-9-butyltheophylline iodide), and the yield was 61.44%.

S4. Weigh 3.77 g (0.01 mol) of methylbutyltheophylline iodide and 2.09 g (0.012 mol) of silver dicyanamide, add appropriate amount of distilled water, place in a 40°C oil bath, and continue the reaction for 4 hours.

S5. After the reaction is completed, the reaction is filtered, the filtrate is collected, and the filtrate is dried to obtain 2.89 g of methyl butyl theophylline dicyanamide salt spontaneous ignition ion salt (i.e., 7-butyl-9-methyl theophylline dicyanamide salt spontaneous ignition ion salt and 7-methyl-9-butyl theophylline dicyanamide salt spontaneous ignition ion salt), with a yield of 91.75%.

As shown in Figures 13 and 14, the nuclear magnetic hydrogen spectrum of the spontaneous combustion ion salt of methyl butyl theophylline dicyanamide salt prepared in this embodiment is δ5.83ppm (ddt, J = 17.3, 10.2, 7.1Hz, 1H), 5.16-5.00ppm (m, 2H), 4.63ppm (t, J = 6.6Hz, 2H), 4.21ppm (s, 3H), 3.83ppm (s, 3H), 3.38ppm (s, 3H) , 2.67ppm (q, J = 6.7Hz, 2H); its nuclear magnetic carbon spectrum is δ154.18ppm, 151.35ppm, 139.91ppm, 132.65ppm, 119.30ppm, 118.13ppm, 107.98ppm, 48.81ppm, 37.13ppm, 33.49ppm, 31.66ppm, 28.70ppm; Fourier transform infrared spectrum is 3400cm ^-1 , 2948cm ^-1 , 2140cm ^-1 , 1600cm ^-1 , 1448cm ^-1 , 1336cm ^-1 , 1060cm ^-1 , 932cm ^-1 , 732cm ^-1 ; elemental analysis calculated values (%): C 53.33, H 5.43, N 31.09; experimental values (%): C 53.03, H 5.63, N 31.18. The specific structure of the pyrophoric ion salt of methyl butyl theophylline dicyanamide salt is shown below:

The physicochemical properties of the methylbutyltheophylline dicyanamide self-igniting ion salt prepared in this example were measured. The phase transition temperature (T _g /T _m ) of the methylbutyltheophylline dicyanamide self-igniting ion salt was <-70°C, the thermal decomposition temperature (T _d ) was 215°C, and the density was 1.33 g·cm ^-3 .

Test Example 1

The formation enthalpy and density specific impulse of the ionic salt are calculated by Gaussian 09 software and EXPLO (Version 6.02) software. The formation enthalpy of the ionic salt is calculated by isobond reaction and Born-Haber energy cycle method, as shown in Figure 1. Then, according to the molecular composition of the self-igniting ionic salt, the calculated formation enthalpy and the experimentally measured density, the specific impulse of the ionic salt is calculated using EXPLO (Version 6.02) software. The calculation results are shown in Table 15 below:

Table 15 Formation enthalpy and density specific impulse of theophylline derived from ion salts

The calculation results show that the density specific impulses of the five ion salts obtained in this application are much higher than that of the traditional propellant unsymmetrical dimethylhydrazine (215.7s·g·cm ^-3 ), showing excellent application potential.

Test Example 2

The ignition performance of theophylline-derived spontaneous ignition ion salt synthesized in the present application was studied using an ignition observation platform equipped with a microscopic high-speed camera, an online high-temperature infrared thermometer and a flame detector. The oxidant used in the test was 100% nitric acid. The test process is as follows: a drop of 100% nitric acid is dripped into a beaker containing about 3 mL of ion salt using a dropper, and whether the two burn after contact, that is, whether spontaneous ignition can occur.

1. Test equipment: Self-ignition test device, including microscopic high-speed camera, online high-temperature infrared thermometer and flame detector.

2. Test procedure: The ionic salts obtained in Examples 1 to 5 were reacted with 100% nitric acid, and the ignition ability was recorded by a self-ignition test device.

Table 16 Statistics of ion salt ignition delay time

As shown in the results of Table 16, the five ionic salts synthesized in the present application can all spontaneously ignite with 100% nitric acid, and the ignition diagrams are shown in Figures 2a and 2b.

Based on the theophylline-derived self-igniting ion salt described in any of the above embodiments, the present invention further provides an embodiment of the application of theophylline-derived self-igniting ion salt in aerospace propellant:

Specifically, theophylline-derived autogenous ion salts are used to prepare aerospace propellants, which have the following effects: first, they have good thermal stability and are safer; second, they have a higher loading capacity; and third, they provide more energy for the propulsion process.

It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims (10)

1. A theophylline-derived self-ignition ion salt, characterized in that the theophylline-derived self-ignition ion salt has the general structural formula:

Wherein, R is selected from one of the alkyl groups with 1 to 8 carbon atoms, and ^Y- is selected from one or more of (CN) ₂ ^N- , (NO ₂ )(CN) ^N- , and H ₂ (CN) ₂ ^B- . 2. The theophylline-derived spontaneous combustion ion salt according to claim 1, characterized in that R is selected from one of methyl, ethyl, allyl, butyl and butylene. 3. The theophylline-derived self-ignited ion salt according to claim 2, characterized in that the decomposition temperature of the theophylline-derived self-ignited ion salt is greater than 200°C, and the density specific impulse of the theophylline-derived self-ignited ion salt is greater than 330 s·g·cm ^-3 . 4. A method for preparing theophylline-derived autogenous ion salt according to any one of claims 1 to 3, characterized in that it comprises the steps of: Under an inert atmosphere and preheating and stirring, theophylline and a strong base are dissolved in a first solvent, and a halogenated hydrocarbon is added to react to obtain an alkyl theophylline solution; wherein the alkyl group in the halogenated hydrocarbon is selected from one of alkyl groups with 1 to 8 carbon atoms, and the halogen is selected from one of Cl, Br, and I, and the preheating and stirring temperature is 50 to 120° C.; The alkyl theophylline solution is filtered to remove insoluble inorganic matter, the filtrate is concentrated to precipitate, and then filtered again to collect the filtrate and dry it to obtain alkyl theophylline; Adding a mixed solution of DMF and methyl iodide to the alkyl theophylline, reacting for 2 to 3 days, adding a second solvent, filtering and drying to obtain alkyl methyl theophylline iodide; The alkylmethyltheophylline iodide and cyanide are dissolved in distilled water, heated for reaction, filtered and dried to obtain theophylline-derived autogenous ion salt; wherein the anion in the cyanide is selected from one or more of (CN) ₂ N ^- , (NO ₂ )(CN)N ^- , H ₂ (CN)B ^- , the cation in the cyanide is silver, the temperature of the heating reaction is 25-80° C., and the time of the heating reaction is 3-10 hours. 5. The method for preparing theophylline-derived spontaneous combustion ion salt according to claim 4, characterized in that the molar ratio of theophylline to the strong base is 1:1-1.2, the molar ratio of theophylline to the halogenated hydrocarbon is 1:3-10, and the molar ratio of DMF to methyl iodide is 1:2-10. 6. The method for preparing theophylline-derived autogenous ion salt according to claim 5, characterized in that the molar ratio of theophylline to the halogenated hydrocarbon is 1:5-8. 7. The method for preparing theophylline-derived spontaneous combustion ion salt according to claim 4, characterized in that the inert atmosphere is at least one of nitrogen, argon and helium; The strong base includes: one or more of sodium hydroxide, potassium hydroxide, cesium carbonate, potassium carbonate, barium hydroxide, and calcium hydroxide. 8. The method for preparing theophylline-derived spontaneous combustion ion salt according to claim 4, characterized in that the first solvent comprises: one or more of N,N-dimethylformamide, chloroform, ethyl acetate, acetone, dichloromethane, N-methylpyrrolidone, tetrahydrofuran, dioxane, dimethyl sulfoxide, methyl ethyl ketone, and acetonitrile; The second solvent includes: one or more of ethyl acetate and diethyl ether. 9. The method for preparing theophylline-derived self-ignition ion salt according to claim 4, characterized in that the temperature of the heating reaction is 35-60°C and the time of the heating reaction is 5-6h. 10. Use of the theophylline-derived autogenous ion salt according to any one of claims 1 to 3 in aerospace propellants.

Images