This study presents the first synthesis and characterization of a new high energy compound [1,2,3,4]tetrazino[5,6-e][1,2,3,4]tetrazine 1,3,6,8-tetraoxide (TTTO). It was synthesized in ten steps from 2,2-bis(tert-butyl-NNO-azoxy)acetonitrile. The synthetic strategy was based on the sequential closure of two 1,2,3,4-tetrazine 1,3-dioxide rings by the generation of oxodiazonium ions and their intramolecular coupling with tert-butyl-NNO-azoxy groups. The TTTO structure was confirmed by single-crystal X-ray.
Kinetic parameters of the unusual [2π + 2σ + 2σ]-cycloaddition reactions of quadricyclane (1) with tetracyanoethylene (2), 4-phenyl-1,2,4-triazoline-3,5-dione (3), N-phenylmaleimide (4), and diethyl azodicarboxylate (5) are determined experimentally. Additionally, the enthalpies of 1 + 2 reaction in 1,4-dioxane solution (−236.6 ± 1.0 kJ mol −1 ) and 1 + 3 reaction in toluene (−255.0 ± 2.8 kJ mol −1 ) are determined calorimetrically and shown to be the largest in absolute magnitude among all known cycloaddition reactions involving these dienophiles. Solvent effect on the rate of 1 + 3 reaction in 11 solvents is studied and found to be moderate and similar to that of the conventional Diels-Alder and ene reactions. The difference in the reaction rate constants of 1 with different dienophiles can be up to 9 orders of magnitude and is mainly caused by the difference in activation enthalpies. This difference is not correlated with the standard enthalpies of reactions and is likely the result of high sensitivity of the [2π + 2σ + 2σ] reaction rates to the energy of donor-acceptor interactions between the reactants.
A novel approach for the synthesis of 6‐(tert‐butyl‐NNO‐azoxy)‐5‐methylthio‐1,2,3,4‐tetrazine 1,3‐dioxide (1) was developed. This compound is likely to be a precursor of tetrazino‐tetrazine 1,3,6,8‐tetraoxide. The synthetic strategy consists of four steps: a synthesis of bis(tert‐butyl‐NNO‐azoxy)methane, coupling of the latter with dimethyl nitrodithioimidocarbonate to give N‐nitroimine 3, O‐alkylation of the latter to O‐alkylated nitroenamine and its reaction with BF3·Et2O to afford tetrazine 1,3‐dioxide 1. An X‐ray diffraction study of 1 was accomplished.
This study presents the first synthesis and characterization of anew high energy compound [1,2,3,4]tetrazino[5,6e][1,2,3,4]tetrazine 1,3,6,8-tetraoxide (TTTO). It was synthesized in ten steps from 2,2-bis(tert-butyl-NNO-azoxy)acetonitrile.The synthetic strategy was based on the sequential closure of two 1,2,3,4-tetrazine 1,3-dioxide rings by the generation of oxodiazonium ions and their intramolecular coupling with tertbutyl-NNO-azoxy groups.The TTTOstructure was confirmed by single-crystal X-ray.Supportinginformation for this article can be found under: http://dx.
Energetic compounds 1-6, consisting of one or two furazan rings linked by azo or azoxy bridges and one or two nitro-NNOazoxy substituents, were synthesized by nitration of the corresponding tert-butyl-NNO-azoxy precursors with NO 2 BF 4. Novel methods for the synthesis of 3,4-bis(tert-butyl-NNOazoxy)furazan (7) and bis-4,4'-(tert-butyl-NNO-azoxy)-3,3'-azoxyfurazan (21) were elaborated. The nitro-NNO-azoxy compounds obtained display high calculated detonation performance (v D = 8.07-9.40 km s À 1 and P C-J = 27.4-43.4 GPa) that is superior to the corresponding nitrofurazans (DNF, DNAzF, DNAF). The replacement of nitrofurazans with the corresponding (nitro-NNO-azoxy)furazans increases the specific impulse of the model solid composite propellant formulations by 2-10 s, which is due to high calculated heats of formation (600-892 kcal kg À 1) and positive oxygen balance (0-20 %) of the latter compounds.
7‐Nitro‐3‐(nitro‐NNO‐azoxy)[1,2,4]triazolo[5,1‐c][1,2,4]‐triazin‐4‐amine (4) is the first high‐melting compound bearing adjacent nitro‐NNO‐azoxy and amino groups. It was synthesized by nitration of 7‐nitro‐3‐(tert‐butyl‐NNO‐azoxy)[1,2,4]triazolo[5,1‐c][1,2,4]triazin‐4‐amine (3) with NO2BF4. Compound 4 is a rather thermally stable (decomposition onset temperature 154 °C), highly energetic (calculated heat of formation 580 kcal·kg–1), and highly dense (1.875 g cm–3) material with a CO‐level oxygen balance.
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