Microwave versus ultrasound assisted synthesis of some new heterocycles based on pyrazolone moiety

Synthesis of selected azoles derivatives using the cross-combination of microwave and ultrasound factors

“…Pyrazole and isoxazole derivatives of 2,4-pentadione, ethyl l,3-oxobutanoate and curcumin in particular were obtained in time-and energy-saving manner consistent with the guidelines of Green Chemistry. All the compounds obtained confirmed the literature data [7,9,11].…”

“…In 2010 both ultrasounds and microwaves were employed separately to promote the synthesis of pyrazolones in the reaction of β-ketoesters with hydrazine derivatives in ethanol. The reaction reached completion in a short time (5-25 min) and produced main products with good yields [9]. A series of isoxazole derivatives were prepared by ultrasound-promoted cyclization in shorter times than the corresponding classical reaction [10].…”

A Combined Experimental and Theoretical Investigation on Pyrazolone Derivative as Corrosion Inhibitor for Mild Steel in 0.5 M Sulphuric Acid Media

“…It has been observed that there is a decrease in the loss in weight of MS plates with increasing the concentration of the inhibitor. This behaviour can be attributed to the increase in the number of adsorbed PYR molecules on MS surface via the lone pair of electrons on the hetero atoms (O, N & S), blocking the active sites of acid attack and thereby protecting the metal from corrosion [26]. Thus it has been concluded that the corrosion inhibition of these compounds is due to the presence of heteroatoms (O, N, S).…”

Microwave-assisted synthesis of nitrogen-containing heterocycles

“…Among other activities, pyrazolones act as appropriate precursors for the preparation of herbicides, liquid crystals, and dyes. They are traditionally synthesized by treatment of b-ketoesters with substituted hydrazines under acidic conditions at elevated temperature [62].…”

“…Mutairi et al [62] have irradiated the mixture of hydrazine derivatives 112 and b-keto esters 111 with MW (300 W) for 1-15 min under solvent-free condition which produced pyrazolones 113 (12 examples) in moderate to good yields (40-91%; Scheme 32). 113 are also produced under conventional condition (stirring in EtOH, at room temperature [RT] for 1-5 h).…”