ACETYLATION AND RING CLOSURE IN REDUCTION OF NITRO- AND NITROAMINO-GUANIDINE¹

Abstract

Guanidine and 1-acetamidoguanidine have been isolated from the hydrogenation of nitroguanidine in acetic acid. Large ratios of catalyst to substrate are necessary for the successful hydrogenation of nitroaminoguanidine in this media. Nitroaminoguanidine undergoes acetylation in acetic acid under mild conditions and the l-acetamido-2-nitroguanidine hydrogenates with much greater ease than the parent substance.l-Aeetamido-2-aminoguanidine can be recovered as derivatives from the reduction products if mild conditions are employed; generally, however, this compound undergoes cyclization to 3-methyl-4,5-diamino-l,2,4-triazole under the conditions of recovery from acidic medium. Acetylation or formylation of diaminoguanidine salts also yields similarly substituted triazoles. Evidence is presented to support the structure assigned to these cyclized products. In basic medium benzal l-aeetamido-2-aminoguanidine undergoes ring closure to benzal 3-methyl-5-hydrazino-l, 2,4-triazole.Chicago, Illinois China Lake, Calif.

The Chemistry of 1,2,4-Triazoles.

“…closure occurs to yield 4,5-diamino-3methyl-1,2,4-477-triazole(224,307). The formation of the triazole arises from a prior acetylation of nitroaminoguanidine which immediately undergoes ring closure on reduction.…”

A Review on the Reactivity of 1-Amino-2-Nitroguanidine (ANQ)

“…Theoretically, the cyclization reaction of compound 16 may occur at N 1 , N 2 or N 3 and lead to the formation of the corresponding three products. However, the evidence suggested that this ring-closure reaction occurred mainly at N 2 , and 3-methyl-4,5-diamino-l, 2,4-triazole ( 17) was easily obtained, as seen in Scheme 6 [45]. Reaction with oxalic acid in aqueous solution at 92–94 °C for 8 h resulted in the corresponding mono- and di-hydrazides, compounds 18 and 19 .…”

Syntheses of Heterocyclic Compounds from Aminoguanidine

“…Benzylideneaminoguanidine (37) is methylated with methyl iodide, and the intermediate (38) hydrolysed to I-amino-I -methylguanidine (39) which, on treatment with benzoyl chloride, yields the cyclized product (40) as a benzoyl derivative in one step. Direct reaction of benzoyl chloride with (38) does not result in cyclization, but only gives 1 -benzylidineamino-3-benzoyl-lmethylguanidine (41).…”

“…Reductions of nitroguanidine carried out in acetic acid produce 3-amino-5-methyl-l,2,4-triazole as a by-product [37, 421. Nitroaminoguanidine similarly affords 3,4-diamino-5-methyl-l,2,4-triazole [37, 421 as a by-product, the structure of which is confirmed by diazotization in the presence of hypophosphorous acid, when removal of both amino groups yields the known compound 3-methyl-l,2,4-triazole [37] in 63 yield. The initial diazotization product can be coupled with P-naphthol to afford the azo dye, 1-(3-methyl-1,2,4triazol-5-yl)azo-2-naphthol, which is also obtainable by diazotization and coupling of 3-amino-5-methyl-l,2,4triazole [37].…”