Synthesis of Dinitro-Substituted Furans, Thiophenes, and Azoles

Abstract

Direct nitration of the corresponding mononitro furans with fuming nitric acid, thiophenes with acetyl nitrate, and thiazoles with trifluoroacetyl nitrate, gave dinitro-substituted furans, thiophenes, and thiazoles. The nitrations of 2-alkylthiophenes with 3 and 5 molar equivalents of acetyl nitrate, generated in situ, are discussed. Reactions of the mononitro furans with fuming nitric acid gave 1,1,5,5-tetrasubstituted dihydrofurans as by-products. Treatment of 5-methyl-4-nitroisoxazole with hydrazine or its methyl or phenyl derivative, followed by oxidation of the corresponding 4-amino-5-nitro-1H-pyrazoles with hydrogen peroxide (50%) gave 4,5-dinitro-1H-pyrazoles. A safe one-pot synthesis of 1-alkyl-3,5-dinitro-1H-[1,2,4]triazoles was developed from dicyandiamide.

Efficient and Safe Synthesis of 1‐Methyl‐3,5‐Dinitro‐1,2,4‐Triazole Using Continuous Flow Chemistry

“…MDNT has a relatively low melting point and mechanical sensitivity, making it a viable substitute for 2,4,6‐Trinitrotoluene (TNT) in the production of melt‐casting explosives . MDNT was first synthesized in the 1960s, and since then, various synthesis methods have been developed and reported by a number of researchers . The synthesis method recently developed by Price has been recognized for its low cost and simplicity, which make it ideal for application on an industrial scale .…”

“…5 MDNT was first synthesized in the 1960s, and since then, various synthesis methods have been developed and reported by a number of researchers. [6][7][8][9] The synthesis method recently developed by Price has been recognized for its low cost and simplicity, which make it ideal for application on an industrial scale. 10 However, despite these achievements, it is still difficult to induce scaled-up production of MDNT at an industrial level using traditional batch chemistry as these methods generate partially oxidized substances during their oxidation step, which uses H 2 O 2 and Na 2 WO 4 .…”

Five‐Membered Heterocycles: 1,3‐Azoles

“…Direct nitration of various imidazoles and thiazoles with nitric acid/trifluoroacetic anhydride, which involves N 2 O 5 , affords mononitro derivatives with an average yield of 60% [151]. Finally, dinitrothiazoles have been obtained by direct nitration of the corresponding mononitro derivative with acetyl nitrate [152].…”