FTO, performance explosive, synthesis routes

[Anders Hoveland]

Furoxanyltriazole oxide (FTO), with the formula C2N5HO3, could potentially exceed HMX in performance, while being a safer explosive, being more resistant to impact. Unlike molecules of HMX, the smaller molecules of FTO would be expected to pack together more densely due to intermolecular hydrogen bonding. FTO would also probably be more thermally stable than HMX. For a high performance explosive, the molecular structure of FTO is somewhat unique in that there are no nitro groups. Not only is FTO expected to be more stable than nitramine explosives, but FTO might also be more stable than some of the nitroaromatic compounds.

There are several possible routes for production of FTO. An ideal one would utilize regents that are inexpensive in bulk, and would involve as few steps as possible. Unlike many other "performance explosives" that surpass HMX in explosive performance, the preparation of FTO could be less complicated and thus viable for industrial production.

These are only prelimary ideas, please correct any mistakes, or provide your ideas for modifications of the procedures. I do not know if FeSO4, which under alkaline conditions is known to reduce picric acid to picramic acid, could reduce dinitro-1,2,3-triazole to 4-amino,5-nitro-1,2,3-triazole. The NH group in the ring, which serves as an electron donor to both nitro groups, might make the dinitrotriazole incapable of oxidizing the ferrous ion.

from the rules: "Discussions on synthesizing explosives...are forbiden. Although intellectual discussions on the chemical physical properties of... explosives... are allowed." (quote by billnotgatez )

Unfortunately, all attempts to nitrate unsubstituted 1,2,3-triazole using mixed acids have failed, even under rigorous conditions. (there does exist a clever way to directly nitrate it, however, but the procedure utilizes obscure regents)


Further details of the synthesis:

Apparently nitroacetone can be used to make nitrogenous rings, supporting my idea that nitroacetone should be able to condense with sodium azide to form 4-methyl,5-nitro-1,2,3-triazole.
"One-pot synthesis of 5-nitropyridines by the cyclocondensation of nitroacetone, triethyl orthoformate and enamine" Galina P. Sagitullina, Anna K. Garkushenko, Evgeny G. Atavin, and Reva S. Sagitullin
Department of Organic Chemistry, F. M. Dostoevsky Omsk State University, 644077 Omsk, Russian Federation

Could one perhaps condense CH2O and excess nitromethane (using the nitroaldol condensation reaction, simply heat with NaOH) to make nitroethanol (which is poisonous and easily absorbs through skin)? Then oxidize nitroethanol with a selective oxidizer such as 2-Iodoxybenzoic acid (no water can be present or the nitro group will disproportionate off from the acidity in a Meyer reaction) or pyridinium chlorochromate. This would then form 2-nitroacetaldehyde O2NCH2CH=O.
This could then potentially cyclize with sodium azide to form plain 4-nitro-1,2,3-triazole, without the methyl group that would have resulted if nitroacetone had been used. Possibly heating in concentrated nitric acid (100degC) could simultaneously oxidize the methyl group to a carboxyl, then decarboxylate the molecule, and finally add a nitro group in. While plain 1,2,3-triazole cannot be directly nitrated, 4-nitro-1,2,3-triazole is more susceptible.

At least for benzoic acid, decarboxylation proceeds readily by heating (only 100degC) if there is another electron withdrawing group (such as a chlorine atom) on the ring. (this would result in chlorobenzene and carbon dioxide).

Some information about 2-Iodoxybenzoic acid: it can oxidize methanol to formaldehyde in 94% yield, and can similarly oxidize ethylene glycol (vehicle anti-freeze) to glyoxal. However, dimethyl sulfoxide (DMSO) can not be used as a solvent for the latter, as its pressence will cause the ethylene glycol to be oxidized to formaldehyde instead. The 2-Iodoxybenzoic acid can then be re-oxidized and recycled after completion of the reaction.
2-Iodoxybenzoic acid can be prepared by the slow addition, over a half hour, of potassium bromate (76.0 g, 0.45 mol) to a vigorously stirred sulfuric acid mixture (0.73 M, 730 mL) containing 2-iodobenzoic acid (85.2 g, 0.34 mol).

Here is the nitroaldol condensation procedure between nitroethane and CH2O. A lesser ammount of nitromethane could very easily substitute for the nitroethane:
75.1g Nitroethane, 0.3g calcium hydroxide and 80g 40% formaldehyde solution was dissolved in 75ml ethanol with stirring and was allowed to stand for 48h at room temperature. Distillation at 100-105°C/13 mmHg (85-86°C/6 mmHg, 99°C/10 mmHg) gave 48g 2-nitropropanol (46%) and 14.3g of 2-nitro-2-methyl- 1,3-propanediol, the latter remained as a crystalline residue in the distillation flask after distillation of the 2-nitropropanol.


nitroacetone

Nitromethane and acetaldehyde react in the presence of sodium carbonate to form 1-nitro-2-propanol. This can then be oxidized into nitroacetone. Nitroacetone may be extracted with ether, and has a normal boiling point of 152 degC, or 105 degC at 25mmHg (reduced pressure).

25g nitropropanol and 37.5g sodium dichromate are mixed in 25mL water. 35mL of 60% sulfuric acid are then slowly and periodically added to the solution over a period of 4 hours, keeping the temperature below 14 degC at all times.
A dark green crystalline substance was then extracted from the solution using ether. Crystals of nitroacetone form after the ether evaporates. The crystals are then recrystallized from methanol (to give a purer product). The resulting nitroacetone from this procedure melts at 46 degC. Solid nitroacetone is unstable in air, but it is stable as an ether solution away from prolonged exposure to sunlight. Nitroacetone slowly hydrolyzes with water.

Nitro acetone has a melting point between 46-50 degC. When care is taken to obtain the pure product, the melting point tends to be close to 49 degC.

Nitroacetone might be useful for preparing 4-methyl-5-nitro-triazole, by condensing it with sodium azide in the presence of concentrated NaOH. This would be a Michael addition reaction.


Something else that I found:
The nitrate salt of 1-amino,3-methyl-1,2,3-triazole melts at only 86-88degC. (where both the amino and methyl groups are on nitrogen atoms in the triazole ring)

Also to add, The reaction of dinitrotriazole with sodium azide to form compound (B) requires heating to 120C, nitrogen is evolved and NaNO2 byproduct results.
Compound (B) can also be oxidized with ammonium persulfate to form FTO (compound C).

Attachments:

[Anders Hoveland]

I should also add that the condensation of chlorobenzene with plain triazole would be extremely slow (months) without a catalyst. Using dinitrochlorobenzene or bromobenzene as the starting regent would be much more rapid.
Paradichlorobenzene (some types of mothballs) that has gone through a nitration could also be used.

The importance of hydrogen bonding influencing the density of energetic compounds should not be underestimated.
3-nitro-1,2,4-triazol-5-oxide (C2N4H2O3), despite having only a single nitro group, with the third oxygen not being "functional" (since it is double bonded to a carbon), nevertheless has a high detonation velocity approaching 8.6 km/sec because of its unusually high density for such a small molecule, 1.93 g/cm3, which is slightly higher than the density of HMX (1.91 g/cm3).

Another comparison could be made with 3-amino,5-nitro-1,2,4-triazole (ANTA), formula C2N5H3O2, which has a density of 1.82 g/cm3 and a velocity approaching 8.5 km/sec. These velocities are not quite as high as RDX
(8.75 km/sec), but nonetheless demonstrate that hydrogen bonding leads to high densities, even for smaller molecules.

Another name for furoxanyltriazine oxide (FTO) could be oxytriazolofuroxan. Looking at the molecular structure of FTO (C2N5HO3), it seems that this compound would probably be slightly more energetic than 1,1-diamino,2,2-dinitro ethylene (DADNE) (C2N4H4O4), which has a detonation velocity as high as 8870 m/sec. DADNE is another example where hydrogen bonding lends high density to a small molecule (1.63 g/cm3). The velocity of DADNE is greater than that of RDX, but less that for HMX, which has a velocity of 9.1 km/sec.

As for oxidizing furazans to furoxans, you are correct, furazans are very resistant to oxidation. I am sure that I read somewhere that it is possible, involving concentrated H2O2 and H2SO4, but I cannot find the reference so this could be incorrect. In the same paragraph of the source as I remember, it mentioned that oxidizing furoxans to two vicinal nitro groups is nearly impossible.

Coincidentaly, there exists a method to turn furoxans into 1,2,3-triazoles. When heated,
CH3C(=O)NH{C2N2O2}N=N(C6H5) can rearrange into CH3C(=O)NH{C2N3}(NO2)(C6H5), where the phenyl group is on the nitrogen atom in the triazole ring which is not bonded to either carbon. A solution of the furoxan (10mmol in 10mL DMSO was heated at 110C for 3 hours. The DMSO was evaporated and the oily residue separated using chloroform. "Synthesis and cascade rearrangement of 3-arylazo-4-(3-ethoxycarbonylureido)furoxans" S.I. Molotov, A.S Kulikov

Here is the procedure for turning an adjacent amino and nitro group into a furoxan ring:
A mixture of 21 g. (0.32 mole) KOH and 250 ml of 95% ethanol in a 1L flask is heated on a steam bath until the solid dissolves. 40 g. (0.29 mole) of o-nitroanaline (where the amino and nitro groups are beside eachother on the benzene ring) is dissolved in the warm alkali solution. The resulting deep red solution is then cooled to 0°C, and sodium hypochlorite solution (made with 50g NaOH, 200mL water, which has absorbed 0.58 moles of chlorine gas) added slowly with good stirring over the course of 10 minutes. The yellow precipitate is collected on a large funnel, washed with 200 ml of water, and air-dried. The crude product weighs 36.0–36.5 g. and melts at 66–71°C. The product is purified by recrystallization from a solution made up from 45 ml. of 95% ethanol and 15 ml of water. the material is that is insoluble in the hot solvent is removed by filtration, and the hot filtrate is allowed to cool to room temperature. The yield of yellow benzofuroxan is 31.6–32.5 g. (80–82%), m.p. 72–73°.


There is yet another route to preparing furazans.
Ethyl diazoacetate can react with N2O4 giving a dicarboxyl furoxan ethyl ether, with the structure
(O2N2C2)(C[=O]OCH2CH3)2 in 75-85% yield. This ester can then be reacted with anhydrous ammonia gas to form
(O2N2C2)(C[=O]NH2)2. This could be reduced with SnCl2 in HCl solution to the furazan. The yields of such a reduction for
(O2N2C2)(NH2)(C[=O]NH2) to the furazan derivitive is only 11%. Finally the furazan derivitive can react with hypohlorite in a Hoffman rearrangement (in yields that would probably be about 50%) to give diamino furazan
(ON2C2)(NH2)2, which is a useful precursor for many other energetic compounds. The reduction is necessary as diaminofuroxan would be chemically unstable and has never been successfully prepared. However, if the Hoffman rearrangement was limited only puting on one amino group, it is potentially possible that this amino could be first oxidized to a nitro group, then more hypochlorite added to react the other --C(=O)NH2 group into an amine, since amino-nitro-furazan does exist. Ethyl diazoacetate can be prepared by reacting
CH3CH2OC(=O)CH2NH2 with NaNO2 and a solution of sodium acetate.

3,4-Diaminofurazan (DAF) in yield of 56.4% with purity of 98.4% was prepared from glyoxal under atmospheric pressure. 3,4-dinitrofurazan (DNF) in yield of 62.5% with purity of 99.8% was synthesized from DAF by an one-step oxidation using 50% H2O2 as a oxidant in the presence of H2SO4 with initial concentration of 56.9% at 35C for 3.5 hours.

Dinitrotriazole derivitives can be reduced with either Zn/HCl or SnCl2 to aminonitrotriazole, with yields of 50-75%. H.H. Licht and H. Ritter, J. Energetic Materials, volume 12, p223 (1004)

FTO should be nearly as powerful, if not slightly more so than HMX. 1,3-dioxytetrazolofuroxan, a compound with a similar structure except a tetrazine ring instead of a triazine ring, which has already been synthesized, was initially calculated to have a detonation pressure of 618 kbar. Later theoretic researchers greatly downward revised such calculations for tetrazines, so while this value still indicates excellent potential for this class of compounds, the experimental value will probably be much lower*. The formula of 1,3-dioxytetrazolofuroxan is C2N6O4, only one more N atom than a molecule of FTO. Consider that HMX generates only 390kbar of pressure.

*DTTO was initially over-optimistically calculated to generate 1318 kbar, but a later revision reduced it to a more plausible 558 kbar, which is still much higher than any other chemical compound yet observed. This means that the original theoretic value for the DTTO, which has two adjoining triazine rings, was reduced by 42%. It is somewhat of a long stretch of imagination, but I believe all this can indirectly give at least some credible indication about how powerful FTO would be.

[Anders Hoveland]

Attached to this post is some more information about furazano-1,2,3,4-tetrazine-1,3-dioxide.

"Oxadiazolo[3.4-c][1,2,3,4]tetrazine 4.6-di-N-oxide (35) is obtained as a yellow crystalline compound (melting point 110-123degC with decomposition) by reaction of the amine derivitive (44) with excess nitronium tetrafluroborate in acetonitrile at (minus) -20degC. Compound 35 is very sensitive to shock and, although it can be stored for long periods at 0degC, it should be handled with care." NO2BF4 must be used, not N2O5, because the inermediate appears to be reactive toward the nitrate anion, which then results only in oxidizing the amino group to a nitro group, rather than formation of a new dioxytetrazine ring.

Bu(t) (with a little "t") means a tert-butyl group, with the structure --C(CH3)3

Attachments:

[Anders Hoveland]

DTTO has a calculated density of 1.97 g/cm3 and a detonation velocity of 10.27 km/sec
iso-DTTO (which does not have a molecular structure with bilateral symetry) has calculated
values of 1.99 g/cm3, 10.37 km/sec.

attachments relating to synthesis of DTTO


I am unsure how stable non-N-substituted 1,2,3,4-tetrazines are, whether they are merely very thermally unstable or if the unstable ring only has a transient existence in solution. The available information is sparse.

The researchers that would have prepared such a compound would be from Russia or Japan. However, one paper suggests such non-oxidized tetrazine compounds have not been isolated, although it is several years old and it is not unlikely that the compound could have been prepared since that time.
"The unknown unsubstituted tetrazines: 1,2,3,4-tetrazine and 1,2,3,5-tetrazine"
J. Russell Thomas, Geoffrey E. Quelch, Henry F. Schaefer III
J. Org. Chem., 1991, 56 (2), pp 539–543

Apparently 6-Phenyl[1,2,3]triazolo[4,5-e]-1,2,3,4-tetrazine (where the phenyl group is not on the tetrazine ring) has been synthesized and exists long enough to be crystallized.
"First synthesis of a 1,2,3,4-tetrazine" Terumitsu Kaihoh, Takashi Itoh, Kentaro Yamaguchi and Akio Ohsawa
J. Chem. Soc., Chem. Commun., 1988.

If you have any information about such a compound or intermediate, please share.

Attachments:

[Anders Hoveland]

Since guanyl azide is known to cyclize to form tetrazoles when its solution is boiled for several hours,
perhaps 1-azido,2-nitroso furazan could similarly cyclize to 5,6-furazano-1,2,3,4-tetrazine-1-oxide, a compound that has already been prepared by other means. The cyclization would have to be performed without heat, however, since tetrazines that are only 1N-oxidized are not thermally stable. It may not be that easy, since several other straightforward routes (using other precursors) that were tried were not found it be successful.

(reacting nitrosyl chloride with furazan should form nitroso furazan. Further oxidation by chlorine in the absence of water should give 1-chloro-2-nitroso furazan, which could then react with a solution of sodium azide)

[sunil]

Mar 4, 2011 17:07:12 GMT -8 Anders Hoveland said:

Furoxanyltriazole oxide (FTO), with the formula C2N5HO3, could potentially exceed HMX in performance, while being a safer explosive, being more resistant to impact. Unlike molecules of HMX, the smaller molecules of FTO would be expected to pack together more densely due to intermolecular hydrogen bonding. FTO would also probably be more thermally stable than HMX. For a high performance explosive, the molecular structure of FTO is somewhat unique in that there are no nitro groups. Not only is FTO expected to be more stable than nitramine explosives, but FTO might also be more stable than some of the nitroaromatic compounds.

There are several possible routes for production of FTO. An ideal one would utilize regents that are inexpensive in bulk, and would involve as few steps as possible. Unlike many other "performance explosives" that surpass HMX in explosive performance, the preparation of FTO could be less complicated and thus viable for industrial production.

These are only prelimary ideas, please correct any mistakes, or provide your ideas for modifications of the procedures. I do not know if FeSO4, which under alkaline conditions is known to reduce picric acid to picramic acid, could reduce dinitro-1,2,3-triazole to 4-amino,5-nitro-1,2,3-triazole. The NH group in the ring, which serves as an electron donor to both nitro groups, might make the dinitrotriazole incapable of oxidizing the ferrous ion.

from the rules: "Discussions on synthesizing explosives...are forbiden. Although intellectual discussions on the chemical physical properties of... explosives... are allowed." (quote by billnotgatez )

Unfortunately, all attempts to nitrate unsubstituted 1,2,3-triazole using mixed acids have failed, even under rigorous conditions. (there does exist a clever way to directly nitrate it, however, but the procedure utilizes obscure regents)


Further details of the synthesis:

Apparently nitroacetone can be used to make nitrogenous rings, supporting my idea that nitroacetone should be able to condense with sodium azide to form 4-methyl,5-nitro-1,2,3-triazole.
"One-pot synthesis of 5-nitropyridines by the cyclocondensation of nitroacetone, triethyl orthoformate and enamine" Galina P. Sagitullina, Anna K. Garkushenko, Evgeny G. Atavin, and Reva S. Sagitullin
Department of Organic Chemistry, F. M. Dostoevsky Omsk State University, 644077 Omsk, Russian Federation

Could one perhaps condense CH2O and excess nitromethane (using the nitroaldol condensation reaction, simply heat with NaOH) to make nitroethanol (which is poisonous and easily absorbs through skin)? Then oxidize nitroethanol with a selective oxidizer such as 2-Iodoxybenzoic acid (no water can be present or the nitro group will disproportionate off from the acidity in a Meyer reaction) or pyridinium chlorochromate. This would then form 2-nitroacetaldehyde O2NCH2CH=O.
This could then potentially cyclize with sodium azide to form plain 4-nitro-1,2,3-triazole, without the methyl group that would have resulted if nitroacetone had been used. Possibly heating in concentrated nitric acid (100degC) could simultaneously oxidize the methyl group to a carboxyl, then decarboxylate the molecule, and finally add a nitro group in. While plain 1,2,3-triazole cannot be directly nitrated, 4-nitro-1,2,3-triazole is more susceptible.

At least for benzoic acid, decarboxylation proceeds readily by heating (only 100degC) if there is another electron withdrawing group (such as a chlorine atom) on the ring. (this would result in chlorobenzene and carbon dioxide).

Some information about 2-Iodoxybenzoic acid: it can oxidize methanol to formaldehyde in 94% yield, and can similarly oxidize ethylene glycol (vehicle anti-freeze) to glyoxal. However, dimethyl sulfoxide (DMSO) can not be used as a solvent for the latter, as its pressence will cause the ethylene glycol to be oxidized to formaldehyde instead. The 2-Iodoxybenzoic acid can then be re-oxidized and recycled after completion of the reaction.
2-Iodoxybenzoic acid can be prepared by the slow addition, over a half hour, of potassium bromate (76.0 g, 0.45 mol) to a vigorously stirred sulfuric acid mixture (0.73 M, 730 mL) containing 2-iodobenzoic acid (85.2 g, 0.34 mol).

Here is the nitroaldol condensation procedure between nitroethane and CH2O. A lesser ammount of nitromethane could very easily substitute for the nitroethane:
75.1g Nitroethane, 0.3g calcium hydroxide and 80g 40% formaldehyde solution was dissolved in 75ml ethanol with stirring and was allowed to stand for 48h at room temperature. Distillation at 100-105°C/13 mmHg (85-86°C/6 mmHg, 99°C/10 mmHg) gave 48g 2-nitropropanol (46%) and 14.3g of 2-nitro-2-methyl- 1,3-propanediol, the latter remained as a crystalline residue in the distillation flask after distillation of the 2-nitropropanol.


nitroacetone

Nitromethane and acetaldehyde react in the presence of sodium carbonate to form 1-nitro-2-propanol. This can then be oxidized into nitroacetone. Nitroacetone may be extracted with ether, and has a normal boiling point of 152 degC, or 105 degC at 25mmHg (reduced pressure).

25g nitropropanol and 37.5g sodium dichromate are mixed in 25mL water. 35mL of 60% sulfuric acid are then slowly and periodically added to the solution over a period of 4 hours, keeping the temperature below 14 degC at all times.
A dark green crystalline substance was then extracted from the solution using ether. Crystals of nitroacetone form after the ether evaporates. The crystals are then recrystallized from methanol (to give a purer product). The resulting nitroacetone from this procedure melts at 46 degC. Solid nitroacetone is unstable in air, but it is stable as an ether solution away from prolonged exposure to sunlight. Nitroacetone slowly hydrolyzes with water.

Nitro acetone has a melting point between 46-50 degC. When care is taken to obtain the pure product, the melting point tends to be close to 49 degC.

Nitroacetone might be useful for preparing 4-methyl-5-nitro-triazole, by condensing it with sodium azide in the presence of concentrated NaOH. This would be a Michael addition reaction.


Something else that I found:
The nitrate salt of 1-amino,3-methyl-1,2,3-triazole melts at only 86-88degC. (where both the amino and methyl groups are on nitrogen atoms in the triazole ring)

Also to add, The reaction of dinitrotriazole with sodium azide to form compound (B) requires heating to 120C, nitrogen is evolved and NaNO2 byproduct results.
Compound (B) can also be oxidized with ammonium persulfate to form FTO (compound C).