Content area
Full Text
Abstract:
Selection of solvent and pH of the reaction mixture are important for the formation of desired products. Ethanol and DMF as reaction medium, pH was kept either basic (pH 10) or acidic (pH 4). Hydrazine hydrate and hydrazine hydrochloride in ethanol gave different product with dibenzoylmethane. Flavones with hydrazine hydrate in ethanol gave a product similar to that obtained by the action of hydrazine hydrate on dibenzoylmethane in ethanol. Flavones with hydrazine hydrochloride in DMF only to give flavone hydrazones. Dibenzoylmethane with hydrazine hydrate in ethanol gave pyrazole, but with hydrazine hydrochloride in ethanol gave flavone hydrazones . Flavones with hydrazine hydrochloride in DMF gave flavone hydrazones.
With hydrazine hydrate (pH 10) dibenzoylmethane and flavone gave pyrazole while dibenzoylmethne with hydrazine hydrochloride (pH 4) gave flavone hydrazone.
Key Words: Dibenzoylmethane, flavone, pyrazole, hydrazine hydrochloride, hydrazine hydrate, pH.
Introduction:
Analysis of literature survey for the reactions of hydrazine hydrate and hydrazine hydrochloride with dibenzoylmethane and flavones reveals that the various products formed are dependent on the reaction condition. In the recent years, organic reactions carried out in aqueous media have received attention from chemists because of the concerns about the environment [1-3]. Several pyranopyrazoles are synthesized by iodine catalysed four component reactions in aqueous medium[4]. Pyrazole, pyrazole carboxamide and pyrazole carbothimide were synthesized by the reactions of substituted prop-2-en-1-one with hydrazine hydrate, semicarbazide hydrochloride and thiosemicarbazide hydrochloride respectively[5]. Many pyrazole derivatives shows pharmacological properties and are widely used as pharmaceuticals, anesthetics, analgesics [6], antiaggregative agent [7], agrochemicals [8, 9].
Flavonoids [10] are ubiquitous group of polyphenolic substances which are present in most of the plants. Flavonoids have been shown to have antimicrobial, antiinflammatory, antiallergic, antimatagenic, antiviral, antineoplastic, antithrombotic and vasodilatory activity. The potent antioxidant activity of flavonoids, their ability to scavenge hydroxy radicals, superoxide anion and lipid peroxy radicals may be the most important function of flavonoids. Substituted pyrazoles have been synthesized by refluxing with nucleophile such as isonicotinic acid / hydrazide/semicarbazide/ thiosemicarbazide in DMF solvent [11]. Substituted Chalcone on treatment with hydrazine hydrate in DMSO and catalytic iodine result in the formation of pyrazole[12]. Pyrazoles can also be synthesized from flavones [13] with hydrazine.
Herein author has tried...