Tetrazole and Azido Derivatives of Pyrimidine: Synthesis, Mechanism, Thermal Behaviour & Steering of Azido–Tetrazole Equilibrium

Abstract

A new family of pyrimidine modified tetrazole & azido derivatives (1-16) was developed using the conventional and nucleophilic substitution methods. The 1H-tetrazol-1-yl)pyrimidine (1-10) compounds were prepared via traditional cycloaddition and condensation method. The compounds tetrazolo [1,5-a]pyrimidine (11 a,12 a, and 13 a), azido-(1H-tetrazol-1-yl) pyrimidine (14 a and 15 a) and tetrazolo[1,5-c]pyrimidine (16 a) were synthesized by simultaneously introducing conventional and nucleophilic substitution approaches. The latter technique was easy to process and reduce the synthesis time. The factors (solvent, temperature, steric effect, electron-donating groups, and electron-withdrawing groups) were found responsible for steering the azido-tetrazole equilibrium in the compounds 11 a, 12 a, 13 a, and 16 a. All the prepared compounds were well characterized including single-crystal X-ray diffraction struc- tures of 1, 3, 4, 6, 8, 10, 11 a, 12 a, 13 a, 14 a, 15 a, and 16 a. Thermal behaviour was investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The current work is significant to the development of a new class of pyrimidine modified tetrazole and azido derivatives in sense of easy reaction approach, good to excellent yields, safe process, and simple work-ups.

Synthesis and Study of Steering of Azido-tetrazole Behavior in Tetrazolo[1,5-c]pyrimidin-5-amine-Based Energetic Materials

“…The synthesis technique was slightly modified from our group's recently reported method comparatively at low temperatures and less time. 15 The 4-chloropyrimidin-2-amine reacts with sodium azide (NaN 3 ) in a polar solvent (acetic acid) at 50 °C for 2 h to produce pure compound 1 in high yield as the completion of the reaction was confirmed by thin-layer chromatography (TLC) as a white solid. Moreover, the azido-tetrazole equilibrium was maintained due to the existence of −NH 2 (electron-donating group), polar solvent (acetic acid), and moderate temperature.…”

“…Researchers continuously work on factors such as nature of the substituents (electrondonating or electron-withdrawing groups), solvent (polar or nonpolar), temperature (low or high), and physical state of the compound (solid-state or solution) that have the most influence on the steering of azide−tetrazole equilibrium and is attracting attention over time by the development of vast knowledge as a result of new findings. 14,15 Energetic organic materials normally consisting of CHON tend to be nitrogen-rich which increases the energetic properties by releasing dinitrogen gas upon detonation and overcoming the drawback of environmental threats. 16 During the initiation of the energetic organic materials, the breakage of bonds among C−N, N−N, or N = N leads to the rapid release of energy, which results in high detonation and favorable thermal stability.…”

Synthesis and Energetic Properties of Trending Metal‐Free Potential Green Primary Explosives: A Review

“…Furazan and tetrazole rings are wellknown promising structures of this class of energetic compounds. [67] Compared to the other four kinds of oxadiazole rings, furazan rings exhibit the highest heat of formation 215 kJ ⋅ mol À 1 . Moreover, furazan ring-based compounds have better densities and good oxygen balance as compared to 1,2,4-triazole derivatives.…”

“…Bis‐heterocyclic compounds connected with the C−C bond are considered as most stable and studied intensely. Furazan and tetrazole rings are well‐known promising structures of this class of energetic compounds [67] . Compared to the other four kinds of oxadiazole rings, furazan rings exhibit the highest heat of formation 215 kJ ⋅ mol −1 .…”

Synthesis of Tetrakis-Tetrazole via a Repetitive MCR

“…There are several reported approaches for the synthesis of tetrazoles from nitriles, amides, thioamides, ketones, amines, and alkenes. One of the most common method of synthesis involves the [3+2] cycloaddition between hydrazoic acid and organic nitriles [4]. In this context is noteworthy that IMCR process via the Ugi-azide of 4CR allows to access to molecules that containing several tetrazole cores providing several advantages as atom economy, operational simplicity, convergency, diversity, and complexity [5].…”