Synthesis of 1,1-bis(methoxy-NNO-azoxy)-3,3,3-trinitropropane from 1,1-bis(methoxy-NNO-azoxy)ethene and nitroform

A reaction of 1,1-bis(methoxy-NNO-azoxy)ethene with nitroform at ∼20 °C gave 1,1-bis-(methoxy-NNO-azoxy)-3,3,3-trinitropropane.     

Synthesis of methoxy-NNO-azoxyethene

The first representative of the alkoxy-NNO-azoxy olefin series, viz., methoxy-NNO-azoxyethene, was synthesized by the pyrolysis of 1,1-bis(methoxy-NNO-azoxy)ethane.     

3-Ethoxy-2,2-bis(methoxy-<Emphasis Type="Italic">NNO</Emphasis>-azoxy)propan-1-ol. Synthesis and X-ray diffraction analysis

Reaction of bis(methoxy-NNO-azoxy)methane with formaldehyde in ethanol gives 3-ethoxy-2,2-bis(methoxy-NNO-azoxy)propan-1-ol as a minor product along with target 2,2-bis(methoxy-NNO-azoxy)ethanol. The structure of the former was confirmed by the counter synthesis and X-ray diffraction analysis.     

1,1-Bis(methoxy-<Emphasis Type="Italic">NNO</Emphasis>-azoxy)ethene. Synthesis and X-ray diffraction analysis

A reaction of 2,2-bis(methoxy-NNO-azoxy)ethyl methanesulfonate with ethyl(diisopropyl)amine afforded 1,1-bis(methoxy-NNO-azoxy)ethene (3). Compound 3 was examined by X-ray diffraction analysis. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 619–624, March, 2008.     

Reactivity of alkoxy-NNO-azoxy compounds toward hydrazine hydrate and inorganic reducing agents

The chemical stability of alkoxy-NNO-azoxy compounds to reduction with hydrazine hydrate has been studied. Methoxy-NNO-azoxymethane and bis(methyl-ONN-azoxy) formaldehyde acetal are more stable by orders of magnitude than bis(methoxy-NNO-azoxy)methane and 2,2-bis(methoxy-NNO-azoxy)propane. Methoxy-NNO-azoxymethane is also resistant to reduction with titanium(III) under acidic conditions and with iron(II) under basic conditions. Probable reaction mechanisms have been proposed on the basis of the substrate reactivity toward nucleophiles, acids, and alkalies.     

Chlorination of geminal bis(alkoxy-NNO-azoxy) compounds with sodium hypochlorite

Chlorination of geminal bis(alkoxy-NNO-azoxy) compounds with sodium hypochlorite involves the central carbon atom and gives 1,1-bis(alkoxy-NNO-azoxy)-1-chloroalkanes with high yield. Dichlorobis-(methoxy-NNO-azoxy)methane oxidizes sodium iodide to elemental iodine. The signal from the central carbon atom in the ¹³C NMR spectra of bis(alkoxy-NNO-azoxy)dichloromethanes is broadened and displaced downfield relative to those of the initial compounds.     

Synthesis of amino-substituted 1,3-bis(tert-butyl-NNO-azoxy)benzenes 2.* 2-amino and 2,4-diamino derivatives

Oxidation of one of the amino groups of 2-bromo-4,6-dichloro-1,3-phenylenediamine to the nitroso group followed by its conversion into thetert-butyl-NNO-azoxy group afforded a derivative ofm-(tert-butyl-NNO-azoxy)aniline,viz., 2-bromo-3-(tert-butyl-NNO-azoxyl)-4,6-dichloroaniline. Analogously, the second amino group was converted into thetert-butyl-NNO-azoxy group to form a derivative of 1,3-bis(tert-butyl-NNO-azoxy)benzene,viz., 3-bromo-2,4-bis(tert-butyl-NNO-azoxyl)-1,5-dichlorobenzene The reaction of the latter with ammonia yielded 2-amino- and 2,4-diamino-substituted 1,3-bis-(tert-butyl-NNO-azoxyl)benzenes. For Part 1, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2126–2130, November, 1999.     

Kinetics and possible mechanisms of alkaline hydrolysis of alkoxy-<Emphasis Type="Italic">NNO</Emphasis>-azoxy compounds

Hydrolysis rate of alkoxy-NNO-azoxy compounds like di(methoxy-NNO-azoxy)methane I, di-(methyl-NON-azoxy)formal II, di(methoxy-NNO-azoxy)methane III, and 2,2-di(methoxy-NNO-azoxy)propane IV in 5 M KOH solution was measured by manometric method at 80°C; rates relation is 1:40:540:10. Reversible deprotonation to form C-anions followed by their rapid decomposition is a presumable mechanism for compounds I–III. Nucleophilic attack of OH-anion on the carbon atom of CH₃ON=N(O) group is the most probable first stage of hydrolysis in the case of compound IV.     

Syntheis of amino-substituted 1,3-bis(tert-butyl-NNO-azoxy)benzenes

Oxidation of 4,6-dichloro-1,3-phenylenediamine with Caro's acid yields the corresponding dinitrosobenzene, which reacts withN,N-dibromo-tert-butylamine to give 1,5-bis(tert-butyl-NNO-azoxy)-2,4-dichlorobenzene. Treatment of the latter with ammonia yields 4-amino-and 4,6-diamino-1,3-bis(tert-butyl-NNO-azoxy)benzenes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 7, pp. 1307–1310, July, 1999.     

Alkylation of 1,1-bis(methoxy-NNO-azoxy)alkanes under phase-transfer catalysis

1,1-Bis(methoxy-NNO-azoxy)alkanes were alkylated in high yield at the central carbon atom under conditions of phase-transfer catalysis with selective formation of mono- and dialkyl derivatives.     

Electrophilic substitution of thetert-butyl-NNO-azoxy group by the bromine atom

The electrophilic substitution of thetert-butyl-NNO-azoxy group by the bromine atom was observed for the first time when 6-bromo-2,4-bis(tert-butyl-NNO-azoxy)-5-chloro-1,3-phenylenediamine was treated with bromine in AcOH. The structural factors promoting this reaction are discussed. The direction of the replacement was confirmed by PM3 calculations of the heats of formation of intermediate cationic σ-adducts. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2131–2134, November, 1999.     

Polyazoxyfurazans in reactions with ammonia

The reaction of 4,4"-bis(4-nitrofurazan-3-yl-NNO-azoxy)azoxyfurazan with ammonia affords a product of nucleophilic substitution for the furazanyldiazene oxide fragment, while the nitro groups remain intact.     

Synthesis of 5-amino-6-nitro-1,2,3,4-tetrazine 1,3-dioxide

5-Amino-(tert-butyl-NNO-azoxy)-1,2,3,4-tetrazine 1,3-dioxide reacts with nitronium tetra-fluoroborate to give 5-amino-6-nitro-1,2,3,4-tetrazine 1,3-dioxide. This compound is of interest as a new energetic material. A plausible reaction mechanism involves electrophilic substitution of the tert-butyl-NNO-azoxy group by the nitro group.

     

Selective reduction of the nitro group in the presence of the azoxy group. Synthesis of 2-(alkyl-NNO-azoxy)anilines

Tin(ii) chloride selectively reduces the aromatic nitro group to the amino group, the azoxy group remaining intact. This allows the preparation of 2-(R-NNO-azoxy)anilines from 2-(R-NNO-azoxy)nitrobenzenes bearing electron-donating or weak electron-withdrawing substituents (Me or Br) in the benzene ring and alkyl substituents at the distal N atom of the azoxy group. The presence of electron-withdrawing substituents at the azoxy group (for example, CO₂Et) leads to a change in the direction of the reaction resulting in selective reduction of the azoxy group to the hydrazo group.     

Novel energetic aminofurazans with a nitro-NNO-azoxy group

Novel energetic azoxy- and azofurazans bearing nitro-NNO- azoxy and amino groups were synthesized using the ammonolysis of some known (nitro-NNO-azoxy)furazans. 3-Amino-4-{[4′-(nitro-NNO-azoxy)f urazan-3′-yl]-NNO- azoxy}furazan displays the highest melting point (114 °C, decomp.) among the known (nitro-NNO-azoxy)furazans, optimal density (1.80 g cm⁻³), high experimental enthalpy of formation (639 kcal kg⁻¹) and mechanical sensitivity on the level of PETN. In terms of the specific impulse level, the model solid composite propellant formulations based on this compound outperform similar formulations based on RDX, HMX or CL-20 by 7–12 s.     

2-Alkyl-4-amino-5-(tert-butyl-NNO-azoxy)-2H-1,2,3-triazole 1-oxides: synthesis and reduction

A new approach to the synthesis of 4-amino-5-(tert-butyl-NNO-azoxy)-2-R-2H-1,2,3-triazole 1-oxides 1 was developed. Compounds 1 were obtained by reactions of 3-amino-4-(tert-butyl-NNO-azoxy)furoxan with aliphatic amines RNH₂ (R = Me, Et, Prⁱ, Bu, and Bu^t). 4-Amino-5-(tert-butyl-NNO-azoxy)-2-tert-butyl-2H-1,2,3-triazole 1-oxide was transformed under the action of acids into 4-amino-5-(tert-butyl-NNO-azoxy)-1-hydroxy-1H-1,2,3-triazole. Methylation of the latter with diazomethane mainly involves the O atom of the triazole oxide ring. Reduction of compounds 1 gave 4-amino-5-(tert-butyl-NNO-azoxy)-2-R-2H-1,2,3-triazoles and 4-amino-5-(tert-butyldiazenyl)-2-R-2H-1,2,3-triazoles (R = Me, Prⁱ, and Bu^t). The structures of the compounds obtained were confirmed by ¹H, ¹³C, and ¹⁴N NMR spectroscopy.     

Aliphatic α-nitroalkyl-<Emphasis Type="Italic">ONN</Emphasis>-azoxy compounds and their derivatives

Interaction of primary amines and 2,2-dimethyl-5-nitro-5-nitroso-1,3-dioxane in the presence of dibromoisocyanurate generates 2,2-dimethyl-5-nitro-1,3-dioxan-5-yl-ONN-azoxyalkanes. Based on the reaction of the latter with AcCl/MeOH followed by further transformations, the first representatives of mononitro- and polynitroalkyl-ONN-azoxyalkanes, i.e., (methyl-NNO-azoxy)nitromethane and dinitro(methyl-NNO-azoxy)methane, as well as some their derivatives, were prepared.     

Synthesis of brominated 2-(tert-butyl-NNO-azoxy)anilmes

2-(tert-Butyl-NNO-azoxy)aniline was prepared by selective reduction of 2-(tert-butyl-NNO-azoxy)nitrobenzene. Its bromination yielded the correspondingpara-bromo- andortho, para-dibromoanilines (3a,b).meta-Bromoanilines (6a,b) were synthesized by selective replacement of theortho-bromine atoms in ortho,para-bromo(tert-butylazoxy)benzenes (5a,b) by ammonia in toluene under pressure.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1620–1623, September, 1994.This work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 93-03-18461).     

Conformational analysis of 1,3,2-dioxathiane and its oxides

Computer simulation of the routes of conformational isomerization of 1,3,2-dioxathiane and its Soxides by nonempirical quantum-chemical method RHF/6-31G(d) revealed the main and local minima and transition states of this process. It was shown that the barrier of ring inversion is reduced in going from 1,3,2-dioxathiane to its oxides. The established ΔG ⁰ (300 K) value of S=O group in cyclic sulfite (−15.0 kJ mol⁻¹) is in good agreement with the experimental data.     

The tert-butyl-NNO-azoxy group in the synthesis of 1,2,4-benzotriazin-3(4H)-one 1-oxides

Treatment of 2-(tert-butyl-NNO-azoxy)anilines with phosgene at 20 °C was proposed as a novel route to 1,2,4-benzotriazin-3(4H )-one 1-oxides. This method involves a new reaction, viz., an intramolecular interaction of the tert-butyl-NNO-azoxy group with a C-electrophile (leading to the formation of the N(2)—C(3) bond of the triazine ring) followed by elimination of the tert-butyl group. Complete assignment of the signals in the ¹H and ¹³C NMR spectra of the compounds obtained was performed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1507–1509, August, 2007.