Acid-Catalyzed Condensation of Benzamide with Glyoxal, and Reaction Features

Scholars from around the world have been attempting to simplify and cheapen the synthetic method for the promising high-energy compound CL-20 for decades. The lack of understanding of the formation mechanisms of hexaazaisowurtzitane derivatives-CL-20 precursors-is a barrier to solving the said problems. Here, we report the results from an in-depth study into the acid-catalyzed condensation between benzamide and glyoxal in a molar ratio of 2:1 in polar protic and aprotic solvents. Sixteen compounds were isolated and identified, of which eight were synthesized for the first time. A geminal diol, N,N'-(2,2-dihydroxyethane-1,1-diyl)dibenzamide, was synthesized. Two isomers of 1,2-bis(benzoylamino)-1,2-ethanediol were isolated and identified. N,N'-(1-oxoethane-1,2-diyl)dibenzamide and 2-oxo-2-[(phenylcarbonyl)amino]ethyl benzoate were produced that were likely formed due to the 1,2-hydride shift. N-polysubstituted 1,4-dioxane-2,3,5,6-tetramine was synthesized for the first time, whose structure may be of interest as a scaffold for new explosives. DMSO, THF and HCOOH were found to be able to engage in a reaction with benzamide, or condensation products thereof, and glyoxal under acid-catalyzed conditions.

Synthesis of Diaminoacetic Acid Derivatives as a Promising Scaffold for the Synthesis of Polyheterocyclic Cage Compounds

Here, we explored in detail an acid-catalyzed condensation of glyoxylic acid or its ethyl ester with several carboxamides of different basicity, or with mesyl amide, to furnish diaminoacetic acid derivatives. The most suitable synthesis conditions and the reaction catalysts were identified. Properties such as structure and basicity of the starting amides were demonstrated to influence the condensation process. Elemental iodine was used for the first time herein as an acid catalyst for the condensation of glyoxylic acid or its ester, which gave access to diaminoacetic acid derivatives in higher yields in most cases, as opposed to p-toluenesulfonic acid (PTSA). An abnormally high activity of mesyl amide when condensed with ethyl glyoxylate was noticed, which may evidence a special impact of the sulfonyl moiety in the amide molecule on the condensation.

Design and exploration of 5-nitro-3-trinitromethyl-1H-1,2,4-triazole and its derivatives as energetic materials

According to the fact that 5-nitro-3-trinitromethyl-1H-1,2,4 triazole (NTNMT) is a successful, good explosive, energetic groups such as -CH3, -NH2, -NHNO2, -NO2, -ONO2, -NF2, -CN, -NC, -N3 groups were introduced into NTNMT and their oxygen balance was at about zero. The energetic properties, detonation performance, and sensitivity were studied at the B3LYP/6-31G** level of density functional theory to seek for possible high energy density compounds. The effects of substituent groups on heat of formation (HOF), density ρ, detonation velocity D, detonation pressure P, detonation energy Q, and sensitivity (evaluated using oxygen balance OB, the nitro group charges -QNO2, and bond dissociation energies BDE were studied and discussed. The order of contribution of the substituent groups to ρ, D, and P was -NF2 > -ONO2 > -NO2 > -NHNO2 > -N3 > -NH2 > -NC > -CN > -CH3; while to HOF is -N3 > -NC > -CN > -NO2 > -NF2 > -ONO2 > -NH2 > -NHNO2 > -CH3. The trigger bonds in the pyrolysis process for NTNMT derivatives may be N-NO2, N-NH2, N-NHNO2, C-NO2, or O-NO2 varying with the attachment of different substituents. Results show that NTNMT-NHNO2, -NH2, -CN, and -NC derivatives have high detonation performance and good stability. In a word, the oxygen balance at about zero strategy in this work offers new routes for the improvement in properties and stabilities of energetic materials. In the present paper, several 5-nitro-3-trinitromethyl-1H-1,2,4 triazole (NTNMT) derivatives were designed. Their energetic properties, detonation performance, and sensitivity were studied at the B3LYP/6-31G** level of density functional theory (DFT) to seek for possible high energy density compounds (HEDCs). The different substituents have some changes in the influence on heat of formation (HOF), density ρ, detonation velocity D, detonation pressure P, detonation energy Q, and sensitivity. In a word, the oxygen balance at about zero strategy in this work offers new routes for the improvement in properties and stabilities of energetic materials.

Theoretical research on cage-like furazan-based energetic compounds and its derivatives

In this manuscript, we reported the design and prediction of two furazan-based cage-like molecules and their derivatives using density function theory (DFT). The heat formation and detonation properties were calculated using Hess's law and Kamlet-Jacobs equations with the B3PW91 method. The molecular stability and geometry were analyzed using the M06-2X method, and molecular crystal structures were predicted based on Monte Carlo simulation, while chemical reactive sites were judged using the PBE0 method based on Fukui function. The theoretical calculation result proved that the designed molecules exhibit ideal symmetric cage-like geometry and show superior physicochemical and detonation properties. Compared with traditional energetic materials, the designed molecules display more positive solid heat formation and lower sensitivity. The designed molecules could be considered promising high energy density material candidates with potential synthesis and application value. Two designed molecules display superior detonation performance and ideal completely symmetric cage-like geometry, which were proved theoretically as a promising HEDM candidate. A series of derivatives also exhibited excellent crystal density and physicochemical properties, while with more stable structure.

Theoretical design of bis-azole derivatives for energetic compounds

Bis-azole derivatives are a new class of energetic materials with features that include high nitrogen content, high heat of formation (HOF), high detonation performance and insensitivity to external stimuli. In this paper, 599 new bis-azole compounds were designed in a high-throughput fashion using bis-azole molecules of high density and high thermal decomposition temperature as the basic structure, and high energy groups such as nitro (–NO₂) and amino groups (–NH₂) as substituents. The molecular geometry optimization and vibration frequency analysis were performed using the DFT-B3LYP/6-311++G(d,p) method. The calculation results show that none of bis-azole derivatives exhibit a virtual frequency. Additionally, the density, heat of formation and characteristic height (h₅₀) of the above compounds were obtained. Detonation performances were predicted by the Kamlet–Jacobs equations, and their structures and performances were studied. Furthermore, correlations between the performance parameters and the parent structure of the molecule, the number of substituting group and configuration were summarized, revealing promising potential candidates for high-energy density materials (HEDMs).

Bis-azole derivatives are a new class of energetic materials with features that include high nitrogen content, high heat of formation (HOF), high detonation performance and insensitivity to external stimuli.

Energetic N-azidomethyl derivatives of polynitro hexaazaisowurtzitanes series: CL-20 analogues having the highest enthalpy

Novel energetic components for rocket propellants, based on polynitro hexaazaisowurtzitanes, have been prepared with high enthalpies of formation that significantly exceed that of CL-20.

Bottom-up design of high-energy-density molecules (N2CO)n (n = 2–8)

A bottom-up strategy from an HEDM seed (i.e., cyc-N₂CO) to novel oligomeric HEDMs was propsed.