RU2804394C1 - Salts of 3-amino-4-(1h-tetrazol-5-yl-nno-azoxy)furazan and methods for their production - Google Patents

Abstract

FIELD: chemical industry.

SUBSTANCE: invention relates to new, not described in the literature salts of 3-amino-(1H-tetrazol-5-yl-NNO-azoxy)furazan of the general formula:

where X=NH₄ (Iа) or N₂H₅ (Ib), and to methods for their preparation, consisting in the fact that 3-amino-4-(cyano-NNO-azoxy) furazan (IV) is subjected to interaction with sodium azide in water or in a mixture of water with an aprotic organic solvent at an elevated temperature, followed by acidification of the reaction mixture with 10% hydrochloric acid, the obtained monohydrate of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (V) isolated and treated with a saturated aqueous solution of ammonia in a protic organic solvent, followed by isolation of the ammonium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ia) or, if necessary, obtaining the hydrazinium salt of 3-amino -4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ib), compound V is treated with hydrazine hydrate in a protic organic solvent, followed by isolation of the target product Ib. A one-stage method for obtaining ammonium salt Ia is also proposed, which consists in reacting 3-amino-4-(cyano-NNO-azoxy)furazan (IV) with trimethylsilyl azide and ammonium fluoride in an aprotic organic solvent, followed by isolation of ammonium salt Ia.

EFFECT: obtained a new type of salts of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazans, which have high enthalpies of formation (531 and 623 kcal/kg, respectively), good density (1.70 and 1.75 g/cm³, respectively), optimal values of the oxidizer excess coefficient (α ) (0.22 and 0.21), and high values of volumetric heat of combustion (19.0-20.1 MJ/L), which can be used as dispersants of solid fuels for direct-flow air-jet engines (DFAs).

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Description

The present invention relates to the field of organic chemistry, namely, to the chemistry of energy-intensive heterocyclic compounds, specifically, to new, not described in the literature, salts of 3-amino-(1H-tetrazol-5-yl-NNO-azoxy)furazan of the general formula:

where X=NH ₄ (Ia) or N ₂ H ₅ (Ib), and methods for their preparation. Compounds of general formula I can find use as solid fuel dispersants for ramjet engines (ramjet engines).

The literature describes structurally similar 3-methyl-4-(tetrazol-5-yl-NNO-azoxy)furazans (according to the SciFinder CAS American Chemical Society database) with the general formula:

where R=1-H (IIa), 1-Me (IIb) or 2-Me (IIc)

(S.G. Zlotin, A.I. Podgursky, N.V. Airapetova, O.A. Lukyanov, "Chemical properties of N'-cyanodiazene N-oxides. Reactions involving the nitrile group", Izv. AN. Ser. chem. ., 1991, 7, 1647-1653).

Compounds of general formula II are characterized by low values of enthalpy of formation, which makes the use of these compounds as dispersants of solid fuels for ramjet engines ineffective.

Also described in the literature are structurally similar 3-amino-4-(1H-tetrazol-5-yl)furazans (according to the SciFinder CAS American Chemical Society database), with the general formula:

where X=H (IIIa), NH ₄ (IIIb) or N ₂ H ₅ (IIIc)

(R. Wang, Y. Guo, Z. Zeng, W. Twamley, J.M. Sheeve. "Furazan-Functionalized Tetrazolate-Based Salts: A New Family of Insensitive Energetic Materials", Chem. Eur. J., 2009, 15, 2625 -2634).

Compounds of general formula III are characterized by low values of enthalpy of formation and density, as well as oxidizer excess coefficients (α) below the optimal value α=0.2-0.4, which makes the use of these compounds ineffective as solid fuel dispersants for ramjet engines.

The technical objective of the proposed invention is to find new, not described in the literature, compounds of the series (1H-tetrazol-5-yl-NNO-azoxy)furazans, characterized by a combination of high enthalpy of formation (ΔH _f °>500 kcal/kg), high density (d≥ 1.70 g/cm ³ ), the optimal coefficient of excess oxidizer (α=0.2-0.4), the melting point and the temperature of the onset of intensive decomposition above 150°C, which will ensure the effectiveness of their use as solid fuel dispersants for ramjet engines, as well as the development of methods for their production .

The stated technical problem is achieved by new, not described in the literature, salts of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan of the general formula:

where X=NH ₄ (Ia) or N ₂ H ₅ (Ib), and methods for their preparation. The proposed compounds of general formula I contain in their molecule furazan and tetrazole rings linked by an azoxy bridge, which ensures a high enthalpy of formation, good density and optimal oxygen balance of these compounds. Compounds of general formula I may be of interest as dispersants for solid fuels for ramjet engines.

Known (tetrazol-5-yl-NNO-azoxy)furazans of general formula II also contain furazan and tetrazole rings linked by an azoxy bridge, but are characterized by a low enthalpy of formation and low density due to the presence of methyl substituents in the furazan and tetrazole rings. Known 3-amino-4-(1H-tetrazol-5-yl)furazans of general formula III do not contain an azoxy group in their molecule and are characterized by a low enthalpy of formation and low oxidant excess coefficients (α = 0.11-0.13), which makes the use of compounds of general ineffective formula III as solid fuel dispersants for ramjet engines. A method has also been proposed for the preparation of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan salts of general formula I, where X=NH ₄ (Ia) or N ₂ H ₅ (Ib), which consists in: that 3-amino-4-(cyano-NNO-azoxy)furazan (IV) is reacted with sodium azide in water or in a mixture of water with an aprotic organic solvent at elevated temperature, followed by acidification of the reaction mixture with 10% hydrochloric acid, which is formed at In this case, a new monohydrate of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (V) is isolated and reacted with a saturated aqueous solution of ammonia in a protic organic solvent, followed by the release of ammonium salt 3-amino-4 -(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ia) or, if necessary, to obtain the hydrazinium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ib), compound V is treated with hydrazine hydrate in a protic organic solvent, followed by isolation of the target product Ib.

A one-step method has also been proposed for the preparation of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan salt of general formula I, where X=NH ₄ (Ia), which consists in the fact that 3-amino-4- (cyano-NNO-azoxy)furazan (IV) is reacted with trimethylsilyl azide and ammonium fluoride in an aprotic organic solvent, followed by the release of ammonium salt 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ia ). The processes for obtaining target products Ia and Ib proceed according to the following scheme:

For example, dioxane is used as an aprotic organic solvent at the stage of obtaining new 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan monohydrate (V). The volume ratio of water: aprotic organic solvent is preferably 1:1. The process is carried out at a temperature predominantly of 50-60°C.

As a protic organic solvent at the stage of obtaining the ammonium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ia) or the hydrazinium salt of 3-amino-4-(1H-tetrazol-5-yl) -NNO-azoxy)furazan (Ib) is used, for example, methanol, ethanol. The process is carried out at a temperature preferably from 0 to 25°C.

As an aprotic organic solvent in the preparation of the ammonium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ia) in one step directly from 3-amino-4-(cyano-NNO-azoxy) furazan (IV) when reacting with trimethylsilyl azide and ammonium fluoride, for example, acetonitrile is used. The process is carried out at temperatures from 0 to 25°C.

A measure of the effectiveness of solid fuel dispersants for ramjet engines (ramjet engines) is the lower volumetric calorific value (Q _v(low) , MJ/l). The higher this value, the more effective the compound is as a solid fuel dispersant for ramjet engines. The value of the lower volumetric heat of combustion of a dispersant is directly influenced by its enthalpy of formation, density and oxidizer excess coefficient (α) (M.E. Reznikov, “Aviation fuels and lubricants (aviation chemmotology)”, Military Publishing House, Moscow, 2004, p. 323; D.B. Lempert, V.V. Raznoschikov, L.S. Yanovsky, “Assessment of the influence of the elemental composition, density and enthalpy of formation of solid fuel dispersants on the flight range of an atmospheric aircraft,” Journal of Applied Chemistry, 2019, 92, 1578 -1583). The technical result of the present invention is the creation of compounds of a new type of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan salts of general formula I, where X=NH ₄ (Ia) or N ₂ H ₅ (Ib) and development of methods for their production. Compounds Ia and Ib have high experimental values of the enthalpy of formation (531 and 623 kcal/kg, respectively), good density (1.70 and 1.75 g/ ^cm3 , respectively) and optimal values of the oxidant excess coefficient (α) (0.22 and 0.21, respectively) . Thanks to this combination of characteristics, the ammonium and hydrazinium salts of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan Ia and Ib in terms of lower volumetric heat of combustion (Q _v(low) ) are significantly superior to octogen (HMX) - the most effective solid fuel dispersant for ramjet engines among standard components.

Thus, compounds of general formula I, having high values of volumetric heat of combustion (19.0-20.1 MJ/l), may be of interest as effective dispersants of solid fuels for ramjet engines.

The starting 3-amino-4-(cyano-NNO-azoxy)furazan (IV) was obtained from N-(4-nitrosofurazan-3-yl)-2,2,2-trifluoroacetamide according to a published method (N.E. Leonov, F " Synthesis and properties of novel energetic (cyano-NNO-azoxy)furazans", Mendeleev Commun., 2021, 31, 792-794). The starting trimethylsilyl azide was obtained from trimethylsilyl chloride and sodium azide according to a published method (A.Y. Sukhorokov, I.V. Bliznets, A.V. Lesiv, Y.A. Khomutova, Y.A. Strelenko, S.L. Ioffe, “The chemistry of N,N-bis(siloxy)enamines. Part 8. A general method for the preparation of α-azido oximes from aliphatic nitro compounds", Synthesis, 2005, 7, 1077-1082). The invention is illustrated by the following examples, which do not limit its scope.

Example 1.

Step 1. Preparation of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan monohydrate (V).

Sodium azide (234 mg, 3.6 mmol) was added in one portion to a suspension of 3-amino-4-(cyano-NNO-azoxy)furazan (IV) (462 mg, 3.0 mmol) in water (8 ml) at 25°C and stirring. . The reaction mixture was heated to 50°C and stirred at this temperature for 4.5 hours. Then the reaction mixture was cooled to 25°C, water (12 ml) was added and acidified with 10% hydrochloric acid to pH ≈1. The precipitate was filtered, washed with ice water (4×10 ml), and dried in vacuum. 433 mg (67%) of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan monohydrate (V) was obtained in the form of yellow crystals. The combined filtrates were extracted with ethyl acetate (5×50 ml). The combined organic extracts were washed with water (25 ml), saturated aqueous sodium chloride (25 ml), dried over magnesium sulfate and concentrated in vacuo at 35°C. The residue was dissolved in ethyl acetate (6 ml) and petroleum ether (6 ml) was added. The precipitate was filtered, washed with petroleum ether (2×5 ml), and dried in vacuum. An additional 136 mg (21%) of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan monohydrate (V) was obtained in the form of yellow crystals. The total yield of compound V was 88%. DSC (5°C⋅min ^-1 ): Temp _. =183°C. Elemental analysis for C ₃ H ₃ N ₉ O ₂ ⋅H ₂ O: Found: H, 2.36; C, 16.80; N, 58.47. Calculated: N, 2.34; S, 16.75; N, 58.60. High resolution mass spectrum (ESI): Found: m/z: 196.0333 [M-H] ^- . C ₃ H ₃ N ₉ O ₂ . Calculated: m/z: 196.0337 [M-N] ^- . IR spectrum (KBr), ν/cm ^-1 : 3626 s, 3524 s, 3418 s, 3322 s, 3258 s, 3212 s, 3173 s, 1850 s, 1634 s, 1603 sr, 1521 sr, 1493 sr, 1466 s, 1411 words, 1372 words, 1325 words, 1236 words, 1201 words, 1117 words. ^1H NMR spectrum (acetone- _d6 , δ, ppm, 600.13 MHz): 5.57 (br.s, 1H, NH), 6.62 (br.s, 2H, _NH2 ). ¹³ C NMR spectrum (acetone-d ₆ , δ, ppm, 150.90 MHz): 152.0 (C(3)), 152.5 (br. s, C(4)), 155.0 (C(5')). NMR spectrum ¹⁴ N (acetone-d ₆ , δ, ppm, 43.37 MHz): -67 ( N (O)=N, =90 Hz), -341 (NH ₂ , =790 Hz). ^1H NMR spectrum (DMSO- _d6 , δ, ppm, 600.13 MHz): 6.91 (br. s, 2 H, NH ₂ ), 8.39 (br. s, 1 H, NH). ¹³ C NMR spectrum (DMSO-d ₆ , δ, ppm, 150.90 MHz): 151.2 (C(3)), 151.8 (br.s, C(4)), 154.6 (br.s, C(5) ')). NMR spectrum ¹⁴ N (DMSO-d ₆ , δ, ppm, 43.37 MHz): -68 ( N (O)=N, =380 Hz). ¹⁵ N NMR spectrum (DMSO-d ₆ , δ, ppm, 60.83 MHz): 29.0 (N(5)), -2.8 (N(2)), -8.0 (N(2') and N(3 ')), -67.9 ( N (O)=N), -77.4 (N(1') and N(4')), -333.1 (NH ₂ ).

Stage 2.

Preparation of ammonium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ia) from 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan monohydrate (V ).

A saturated solution was added dropwise to a suspension of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (V) monohydrate (495 mg, 2.30 mmol) in methanol (4 ml) at 0°C and stirring. aqueous ammonia (25%) (0.2 ml, 188 mg, 2.76 mmol) in methanol (1 ml). The reaction mixture was stirred at 0°C for 1 hour. The precipitate was filtered, washed with cold methanol (2×2 ml), and dried in vacuum. We obtained 168 mg (34%) of the ammonium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO)-azoxy)furazan (Ia) in the form of yellow crystals. The combined filtrate was evaporated to dryness, the residue was dissolved in boiling methanol (5 ml), then acetonitrile (25 ml) was added and the solution was cooled to -20°C. The precipitate was filtered, washed with cold acetonitrile (5 ml), and dried in vacuum. An additional 197 mg (40%) of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan ammonium salt (Ia) was obtained in the form of yellow crystals. The total yield of compound Ia was 74%. DSC (5°С⋅min ^-1 ): T _{decomposition.} =199°C. Elemental analysis for C ₃ H ₆ N ₁₀ O ₂ : Found: H, 2.82; S, 16.84; N, 65.32. _{C3H6N10O2 . _ _} Calculated: N, 2.82; S, 16.83; N, 65.41. High resolution mass spectrum (ESI): Found: m/z: 196.0339 [M-NH ₄ ] ^- . _{C3H6N10O2 . _ _} Calculated: m/z: 196.0337 [M-NH ₄ ] ^- . IR spectrum (KBr), ν/cm ^-1 : 3401 sr, 3240 sr, 3181 sr, 3050 sl, 2765 sr, 1678 sr, 1637 s, 1625 s, 1514 s, 1484 sr, 1451 s, 1429 s, 1404 s, 1337 words, 1208 words, 1178 words, 1122 words. ^1H NMR spectrum (DMSO- _d6 , δ, ppm, 500.13 MHz): 6.82 (br.s, 2H, _NH2 ), 7.46 (br.s, 4H, _NH4 ⁺ ). ¹³ C NMR spectrum (DMSO-d ₆ , δ, ppm, 125.76 MHz): 151.1 (C(3)), 151.6 (br.s, C(4)), 162.4 (br.s, C(5) ')). NMR spectrum ¹⁴ N (DMSO-d ₆ , δ, ppm, 36.14 MHz): -81 ( N (O)=N, =300 Hz), -358 (NH ₄ ⁺ , =10 Hz). ¹⁵ N NMR spectrum (DMSO-d ₆ , δ, ppm, 60.83 MHz): 23.9 (N(5)), 14.6 (N(2') and N(3')), -6.0 (N(2 )), -58.1 (N(O)= N or N(1') and N(4')), -63.5 (N(O)= N or N(1') and N(4')), - 82.0 ( N (O)=N), -334.3 (NH ₂ ), -357.7 (NH ₄ ⁺ ).

Example 2.

Step 1. Preparation of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan monohydrate (V).

The process of obtaining 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan monohydrate (V) is carried out similarly to example 1.

Stage 2.

Preparation of hydrazinium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ib) from 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan monohydrate (V ).

A hydrazine solution was added dropwise to a suspension of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (V) monohydrate (215 mg, 1.0 mmol) in methanol (3 ml) at 0°C and stirring. -hydrate (64%) (0.06 ml, 60 mg, 1.2 mmol) in methanol (3 ml). The reaction mixture was stirred at 0°C for 1 hour. The precipitate was filtered, washed with cold methanol (2×2 ml), and dried in vacuum. We obtained 181 mg (79%) of hydrazinium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ib) in the form of yellow crystals. DSC (5°C⋅min ^-1 ): Tdec _. =177°C. Elemental analysis for C ₃ H ₇ N ₁₁ O ₂ : Found: H, 3.10, C, 15.73, N, 67.13. _{C3H7N11O2 . _ _} Calculated: H, 3.08, S, 15.72, N, 67.23. High resolution mass spectrum (ESI): Found: m/z: 196.0346 [M-N ₂ H ₅ ] ^- . _{C3H7N11O2 . _ _} Calculated: m/z: 196.0337 [M-N ₂ H ₅ ] ^- . IR spectrum (KBr), ν/cm ^-1 : 3422 s, 3310 sr, 3197 sr, 3141 sr, 3065 sr, 2801 s, 2695 s, 2615 s, 1663 s, 1633 s, 1528 s, 1511 s, 1468 s, 1433 s, 1393 s, 1206 s, 1173 s, 1130 s. ^1H NMR spectrum (DMSO- _d6 , δ, ppm, _600.13 MHz): 6.87 (br.s, 2H, _NH2 ), 7.30 (br.s, 5H, _N2H5 ⁺ ). ¹³ C NMR spectrum (DMSO-d ₆ , δ, ppm, 150.90 MHz): 151.2 (C(3)), 151.6 (br.s, C(4)), 162.5 (br.s, C(5) ')). NMR spectrum ¹⁴ N (DMSO-d ₆ , δ, ppm, 43.37 MHz): -81 ( N (O)=N, =400 Hz), -331 (NH ₂ and N ₂ H ₅ ⁺ , =1430 Hz). ¹⁵ N NMR spectrum (DMSO-d ₆ , δ, ppm, 60.83 MHz): 24.1 (N(5)), 13.9 (N(2') and N(3')), -5.9 (N(2 )), -59.5 (N(O)= N or N(1') and N(4')), -63.8 (N(O)= N or N(1') and N(4')), - 81.5 ( N (O)=N), -331.2 (N ₂ H ₅ ⁺ or NH ₂ ), -334.2 (N ₂ H ₅ ⁺ or NH ₂ ).

Example 3.

Preparation of the ammonium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ia) from 3-amino-4-(cyano-NNO-azoxy)furazan (IV) in one stage.

Trimethylsilyl azide (0.33 ml, 287 mg, 2.5 mmol), and then ammonium fluoride (37 mg, 1.0 mmol) was added in one portion. The reaction mixture was stirred at 25°C for 24 hours. The precipitate was filtered, washed with dry acetonitrile (3×5 ml), and dried in vacuum. We obtained 167 mg (78%) of the ammonium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ia) in the form of yellow crystals. The product is identical (by IR, ¹ H, ¹³ C NMR) to compound Ia obtained according to example 1.

Example 4.

The process for obtaining the ammonium salt of 3-amino-4-(1H/-tetrazol-5-yl-NNO-azoxy)furazan (Ia) is carried out similarly to example 1, but at stage 1 of obtaining 3-amino-4-(1H/-tetrazole) monohydrate -5-yl-NNO-azoxy)furazan (V) instead of water, a mixture of water and dioxane (1:1) is used, and at stage 2 of obtaining ammonium salt 3-amino-4-(1H-tetrazol-5-yl-NNO- azoxy)furazan (Ia), ethanol is used instead of methanol. We obtained 261 mg (53%) of the ammonium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ia) in the form of yellow crystals. The product is identical (by IR, ¹ H, ¹³ C NMR) to compound Ia obtained according to example 1.

Claims (5)

1. Salts of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan of the general formula: X=NH ₄ (Ia) or N ₂ H ₅ (Ib). 2. Salts of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan of general formula I according to claim 1 as solid fuel dispersants for ramjet engines (ramjet engines). 3. Method for producing 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan salts of general formula I according to claim 1, where X=NH ₄ (Ia) or N ₂ H ₅ (Ib), consisting in the fact that 3-amino-4-(cyano-NNO-azoxy)furazan (IV) is reacted with sodium azide in water or in a mixture of water with an aprotic organic solvent at a temperature of 50-60°C, followed by acidification of the reaction mixture 10 % hydrochloric acid, the resulting 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan monohydrate (V) is isolated and reacted with a saturated aqueous ammonia solution in a protic organic solvent, followed by isolation ammonium salt of 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan (Ia) or, if necessary, obtaining hydrazinium salt 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy )furazan (Ib), compound V is treated with hydrazine hydrate in a protic organic solvent, followed by isolation of the target product (Ib). 4. A method for producing 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy)furazan salt of general formula I according to claim 1, where X=NH ₄ (Ia), consisting in the fact that 3-amino -4-(cyano-NNO-azoxy)furazan (IV) is reacted with trimethylsilyl azide and ammonium fluoride in an aprotic organic solvent, followed by the release of ammonium salt 3-amino-4-(1H-tetrazol-5-yl-NNO-azoxy) furazan (Ia).