Reaction of azines with 5-pyrazolones

The synthesis of 4,4′-arylmethylene-bis(3-(trifluoromethyl)-1-phenyl-1H-pyrazol-5-ol) in aqueous media without catalyst

“…So this protocol is more economical, safe and environmentally benign than the known results [23][24][25]28,29].…”

“…The compounds that contain two pyrazolone ring can be used as extractant for some metal ions [20] and ligands [21,22]. In 1971, Buzykin and Lonshchakova performed the synthesis of aryl-bis(1-phenyl-3-methyl-5-pyrazolon-4-yl)methane using benzene as solvents [23]. Later, Li and co-worker reported the solid-state synthesis of these compounds [24] and Bai et al employed the microwave irradiation to promote the solventfree synthesis of these compounds [25].…”

Synthesis of 4,4’-(Arylmethylene)bis(1H-pyrazol-5-ols) Using Silica-bonded Ionic Liquid as Recyclable Catalyst

“…In recent years, different reagents were applied for the synthesis of 4,4'-(arylmethylene)bis(3-methyl -1-phenyl-pyrazol-5-ols) derivatives, some of them including condensation reaction between arylaldehydes and two equivalents of 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one (Li et al, 1998;Singh & Singh, 1984;Pavlov et al, 1998;Buzykin & Lonshchakova, 1971;Wang et al, 2005;Elinson et al, 2008;Sujatha et al, 2009;Niknam & Mirzaee, 2011;Mosaddegh et al, 2010;Zang et al, 2011;Tayebi et al, 2011). 1) and used as heterogeneous solid acid catalyst for the synthesis of 4,4'-alkylmethylene-bis(3-methyl-5-pyrazolones).…”

Melamine Trisulfunic Acid: An Efficient and Recyclable Solid Acid Catalyst for the Synthesis of 4,4′‐(Arylmethylene)‐bis‐(1H‐pyrazol‐5‐ols)

“…18,19 The first set of procedures utilizes the catalysis of the components with piperidine in ethanolic solution. 20,21 The second set of methods involve the non-catalyzed tandem Knoevenagel-Michael reaction under neutral conditions in either ethanol 22 or benzene 23 solutions. Although it affords the corresponding 4,4¢-(arylmethylene)-bis-(1H-pyrazol-5-ols) in reliable 70-90% yields, the reaction requires 3-12 h of ini-tial reflux with a further 24 h under ambient temperature to go to completion.Wang et al, 24 reported its synthesis in water using sodium dodecyl sulfate as the surfactant catalyst over a one-hour period, but the process needs a temperature of 100 o C. Finally, Elinson et al utilized electrocatalytic procedure for its synthesis.…”