Use of Isonicotinic Acid Hydrazide (INH) as Reagent for Determination of Certain Flavonoids

Synthesis of novel heterocycles using 1,2,3‐triazole‐4‐carbohydrazides as precursors

“…The 1 H NMR spectrum of 6 showed exchangeable singlets at 5.92 (2H) and 14.07 ppm (1H) due to the NH 2 and SH protons, respectively. Reactions of 6 and α-bromoketones 7a-c in boiling ethanol in the presence of triethylamine as a base for 2 hours gave the corresponding 7H- [1,2,4]triazolo [3,4-…”

“…In summary, simple methods have been developed for the synthesis of novel heterocycles. For example, reaction F I G U R E 1 ORTEP representation of the molecular structure of 3a, 3b, and 3f with 50% probability ellipsoids obtained by X-ray diffraction S C H E M E 2 Suggested mechanism for formation of 3 of acid hydrazides containing the 1,2,3-triazole moiety and α-bromoketones gave the corresponding hydrazones rather than the expected 1,2,4-triazines, while reaction of acid hydrazides and carbon disulfide followed by hydrazine hydrate gave the corresponding 1,2,4-triazole-3-thiol which on reaction with α-bromoketones gave the corresponding 7H- [1,2,4]triazolo [3,4-b] [1,3,4]thiadiazines. In addition, reaction of acid hydrazides and ethyl 2-cyano-3,3-bis (methylthio)acrylate gave the corresponding (1,2,3-triazole-4-carbonyl)-1,2,3-triazole-4-carbohydrazides rather than the expected 1H-pyrazole-4-carboxylates.…”

“…Acid hydrazides are widely used as preservatives and as reagents for determining certain flavonoids and also for the production of pharmaceuticals and polymers. [3,4] Indeed, acid hydrazides are efficient and common precursors in the production of various heterocycles [5][6][7][8] that have enormous potential as antimicrobials, [9][10][11][12][13][14][15][16] anticancer agents, [17] pharmaceuticals, [18] anticonvulsant, [19] antidepressant, [20] and anti-inflammatory agents. [21] In addition, these heterocycles act as herbicides [22] and dyes.…”

“…[21] In addition, these heterocycles act as herbicides [22] and dyes. [23,24] Acid hydrazides are generally produced from reaction of hydrazine and esters, cyclic anhydrides, acyl halides, and aldehydes, [25] while [1,2,4]triazolo [3,4-b] [1,3,4]thiadiazines can be produced through a two-step reaction that involves hydrazides, carbon disulfide, hydrazine hydrate, and phenacyl bromides. [26][27][28] Heterocycles such as 1,2,3-triazoles have potentially important applications, and various processes have been developed for their synthesis.…”

“…The hydrazones could also be synthesized in 85-90% yield via an alternative pathway that involved the reaction of 1,2,3-triazole-4-carbohydrazides and 4-acetyl-1,-2,3-triazoles in boiling ethanol containing glacial acetic acid. Reaction of one of the 4-carbohydrazides with carbon disulfide, followed by the reaction with hydrazine hydrate, gave 4H-1,2,4-triazole-3-thiol in 73% yield, which further reacted with other α-bromoketones in boiling ethanol to afford 7H- [1,2,4] triazolo [3,4-b] [1,3,4]thiadiazines in 82-84% yields. Additionally, reactions of certain carbohydrazides with ethyl 2-cyano-3,3-bis(methylthio)acrylate gave 1-aryl-1H-1,2,3-triazole-4-carbohydrazides rather than the expected 1H-pyrazole-4-carboxylates.…”