The Effenberger´s synthesis of 3,3´-bipyrazole revisited

Abstract

When 1,4-bis-ethoxymethylen-2,3-butanedione 2 reacts with hydrazine, following a slightly modified Effenberger's procedure, other compounds than the expected 3,5'-bipyrazole 1 are obtained. This paper describes the isolation, besides 1, of two pyridazinones and one 6H-6,7-dihydropyrazolo[1,5-d]-1,2,4-triazine and the determination of their structure by mass spectrometry and by 1 H and 13 C NMR.

Synthetic Routes to Bioactive Bipyrazole Derivatives

“…In addition, the 2,2′,5,5′‐tetranitro‐2 H ,2′ H ‐3,3′‐bipyrazole ( 72 ), as a structural isomer of 71 , was synthesized from reaction of 68 with acetic anhydride and 100 % nitric acid (Scheme 13). [60,61] …”

“…In addition, the 2,2',5,5'-tetranitro-2H,2'H-3,3'bipyrazole (72), as a structural isomer of 71, was synthesized from reaction of 68 with acetic anhydride and 100 % nitric acid (Scheme 13). [60,61] 4 polynitrogen catenated chain in the fused ring as a fuel with nitro groups as an oxidizer (Scheme 15). [63] The The potassium salt 81 was found to have applications in the field of primary explosives.…”