Irina A. Vatsadze

Novel Highly Energetic Pyrazoles: N-Trinitromethyl-Substituted Nitropyrazoles.

A new family of energetic compounds, nitropyrazoles bearing a trinitromethyl moiety at the nitrogen atom of the heterocycle, was designed. The desirable high-energy dense oxidizers 3,4-dinitro- and 3,5-dinitro-1-(trinitromethyl)pyrazoles were synthesized in good yields by destructive nitration of the corresponding 1-acetonylpyrazoles. All of the prepared compounds were fully characterized by multinuclear NMR and IR spectroscopy, as well as by elemental analysis. Single-crystal X-ray diffraction studies show remarkably high density. Impact sensitivity tests and thermal stability measurements were also performed. All of the pyrazoles possess positive calculated heats of formation and exhibit promising energetic performance that is the range of 1,3,5-trinitroperhydro-1,3,5-triazine and pentaerythritol tetranitrate. The new pyrazoles exhibit positive oxygen balance and are promising candidates for new environmentally benign energetic materials.

New aryloxy-substituted condensation polymers

Abstract Large family of new aromatic diamines containing aryloxy side groups was developed. All the diamines were obtained on the basis of 2,4,6-trinitrotoluene (TNT) — very cheap and available explosive material. TNT was converted into 1,3,5-trinitrobenzene (TNB); subsequent aromatic nucleophilic nitro-displacement reactions led to mono- and diaryloxy-substituted mono- and dinitrobenzenes which were converted into the final aryloxy-substituted diamines. Interaction of the diamines obtained with aromatic dicarboxylic acids chlorides and aromatic tetracarboxylic acids dianhydrides led to the formation of new aryloxy-substituted polyimides and polyimides combining high thermal properties with solubility in organic solvents.

1,3-Disubstituted and 1,3,3-trisubstituted adamantyl-ureas with isoxazole as soluble epoxide hydrolase inhibitors

Adamantyl ureas are good soluble epoxide hydrolase (sEH) inhibitors; however they have limited solubility and rapid metabolism, thus limiting their usefulness in some therapeutic indications. Herein, we test the hypothesis that nodal substitution on the adamantane will help solubilize and stabilize the compounds. A series of compounds containing adamantane derivatives and isoxazole functional groups were developed. Overall, the presence of methyl on the nodal positions of adamantane yields higher water solubility than previously reported urea-based sEH inhibitors while maintaining high inhibition potency. However, it did not improve microsomal stability.

Adamantyl-containing fluorinated 1,3-diketones

A convenient one-step procedure has been developed for the synthesis of fluorine-containing 2-(adamant-l-yl)-1,3-diketones by reaction of fluorinated 1,3-diketones with 1,3-dehydroadamantane. The products can be used as starting compounds for the preparation of new fluorinated adamantyl-containing heterocyclic compounds.

Synthesis and investigation of isomeric mono- and dinitro derivatives of 3-methyl-4-(pyrazol-3-yl)furazan

The regioselective introduction of nitro groups in pyrazoles, containing a furazanyl substituent at position 3(5) was investigated. All synthetically accessible isomeric mono- and dinitropyrazole derivatives were obtained. X-ray structural investigation was performed for all mononitroisomers and a dinitro derivative.

Synthesis of 1- and 5-(pyrazolyl)tetrazole amino and nitro derivatives

Regioselective introduction of nitro groups was studied in the case of pyrazoles containing a 1- or 5-tetrazole substituent at position 3(5). All the possible isomeric C-mononitropyrazoles were synthesized. The reduction of these compounds gave the respective 3(5)-amino-5(3)-tetrazolylpyrazoles, which were nitrated to 3(5)-nitramino-4-nitro-5(3)-tetrazolylpyrazoles. The reaction of 1-(nitropyrazol-3(5)-yl)tetrazoles with hydroxylamine-O-sulfonic acid produced the respective N-amino derivatives.

Synthesis and Study of 1,3- and 1,3,3-Substituted Ureas Containing Isoxazole and Adamantane Fragments

A series of 1,3-disubstituted and 1,3,3-trisubstituted isoxazolyl- and adamantyl-functionalized ureas was synthesized. The resulting compounds are potent inhibitors of soluble epoxide hydrolase. The compounds were obtained in high yields under mild conditions. Water solubility of the synthesized ureas was found to exceed significantly that of known analogs.

Kinetics and mechanism of thermal decomposition of nitropyrazoles

The decomposition of mono-, di-, and trinitropyrazole derivatives in the condensed state was studied by the manometric method. The reaction rate depends on the number and position of nitro groups in the pyrazole cycle and on the polarity of the medium and aggregate state of the substance. The activation energy of the initial non-catalytic stage of decomposition Е1 decreases on going from monoto trinitropyrazoles from 142 to 132 kJ mol−1, and the preexponential factor is 109±0.5 s−1. In a diphenyl solution the decomposition rate is lower than that in the melt, and this difference decreases with increasing in the number of nitro groups in the molecule. For the decomposition of trinitropyrazole in the solid state, Е1 decreases by 10 kJ mol−1. All these facts are explained in terms of the mechanism, according to which the reaction occurs as the oxidation of the adjacent carbon atom by the nitro group and proceeds via a strongly polar cyclic transition state.

Synthesis of 1-(N-nitropyrazolyl)-1Н-tetrazoles – a new type of heteronuclear N-nitropyrazole derivatives

A general method has been developed for the synthesis of 1-pyrazolyl-1Н-tetrazoles, and N-nitration of these compounds was studied. The structural features affecting the direction of nitration were identified. A series of 1-(N-nitropyrazolyl)-1Н-tetrazoles was obtained, representing a new type of heteronuclear N-nitropyrazole derivatives.

N-Alkylation and N-amination of isomeric nitro derivatives of 3-methyl-4-(1H-pyrazol-3(5)-yl)furazan

The reaction of bromoacetone and hydroxylamine-О-sulfonic acid with isomeric mono- and dinitropyrazoles containing a furazanyl moiety at position 3(5) gave pairs of regioisomeric products from pyrazole ring N-acetonylation and N-amination, respectively, that were characterized in detail by multinuclear NMR spectroscopy. X-ray structural study of the four synthesized N-amino derivatives indicated a non-planar structure, while the conformational analysis pointed to conformational lability of such molecules, and the role of intermolecular interactions in determining the crystal structure.