Synthesis and Properties of Energetic 1,2,4‐Oxadiazoles

Abstract

The synthesis and characterization of a series of 3,5‐di‐aryl‐1,2,4‐oxadiazoles are reported and the effects of nitro groups in the aromatic rings on the experimental heats of decomposition (ΔHd) and heats of combustion (ΔHc) are evaluated. Heats of formation (ΔHf) and densities (ρ) were calculated and correlations between ΔHd and ΔHf were assessed for these compounds. Experimental determination of ρ (by gas pycnometry) on a selection of the compounds led to the calculation of detonation velocity (VD), detonation pressure (PD) and specific impulse (ISP) parameters by the Explo 5 program. An X‐ray analysis of compound (4i) confirmed the structure and showed a crystal density (at 120 K) close to that determined by gas pycnometry.

A Mild and Efficient One‐Pot Preparation of 1,2,4‐Oxadiazoles from Nitriles and Carboxylic Acids Using Vilsmeier Reagent

“…Preparation of amidoximes 3 a–h was very straightforward using a reported method . Reaction between nitriles 2 a‐h and hydroxylamine hydrochloride in the presence of sodium carbonate (at reflux for 2 h or at room temperature for 6 h) leads to the corresponding 3 a–h in excellent yields (Scheme ).…”

“…Also, some drugs have a 1,2,4‐oxadiazole ring shown in Figure . In addition, 1,2,4‐oxadiazoles have been utilized as building blocks for example in the synthesis of explosive and energetic compounds …”

Development of 1,2,4-Oxadiazoles as Potent and Selective Inhibitors of the Human Deacetylase Sirtuin 2: Structure–Activity Relationship, X-ray Crystal Structure, and Anticancer Activity

“…The synthetic route for the preparation of the 3-aryl-1,2,4-oxadiazole derivatives 4 – 46 is outlined in Scheme . The reaction between the known N ′-hydroxyaryl­imidamides 47a – m − and the appropriate acyl halides in dry dichloromethane and in the presence of triethylamine at room temperature gave the crude N ′-acyloxyaryl­imidamide intermediates that without further purification were heated in toluene or o -xylene at reflux to obtain the 1,2,4-oxadiazole compounds 9 , 24 – 43 (Scheme A). Compounds 4 – 8 , 10 – 23 were synthesized by treating the selected 5-(bromoalkyl)-3-(substituted)­phenyl-1,2,4-oxadiazoles 24 (for 4 , 10 – 18 ), 25 (for 5 ), 26 (for 6 ), 27 (for 7 ), 28 (for 8 ), 29 (for 19 - 21 ), 30 (for 22 ), and 33 (for 23 ) with different commercially available amines, sodium iodide, and potassium carbonate in dry DMF at 60 °C for 1–2 h (Scheme B).…”

3-(3,5-Dinitrophenyl)-5-amino-1,2,4-oxadiazole: synthesis, structure and properties of a novel insensitive energetic material

“…Compound 1 was synthesized using literature reported methods. 31 3,5-Dinitrobenzonitrile (8.0 g, 41.4 mmol) and hydroxylamine hydrochloride (11.3 g, 8.8 mmol) were dissolved in 80 mL ethanol. Then sodium carbonate (8.6 g, 81.1 mmol) and 50 mL deionized water were added sequentially under stirring conditions.…”

“…Compound 1 was synthesized using literature reported methods. 31 Comp. 2 (0.50 g, 1.4 mmol) was dispersed in 30 mL of methanol at room temperature, and then the mixture was cooled to 5 °C and stirred for 3 h. In a separate flask, 40 mL aqueous ammonia was slowly added dropwise to 40 g sodium hydroxide solid to produce an excess of NH 3 gas, which was bubbled through the methanol suspension.…”