Greener and facile synthesis of 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s through a conventional heating procedure

Insights into 4,4′‐Arylmethylene‐Bis‐1H‐Pyrazol‐5‐Ols Scaffolds: Various Synthetic Routes and Their Applications

“…Catalyst recovery is with small catalyst loading, reducing the generation of harmful wastes (Scheme 14). [59] Zhou et al developed an effective one-pot synthesis for (3) using condensation reaction of (1) and phenyl hydrazine/ hydrazine hydrate ( 6) with ( 5) catalyzed by 2-hydroxy ethyl ammonium propionate in neat condition. Among the striking characteristics of this new approach are a shorter response time, high yield, cheap ionic liquid reusability, easy workup, and environmental friendliness (Scheme 14).…”

“…Catalyst recovery is with small catalyst loading, reducing the generation of harmful wastes (Scheme 14). [59] Zhou et al. developed an effective one‐pot synthesis for (3) using condensation reaction of (1) and phenyl hydrazine/hydrazine hydrate (6) with (5) catalyzed by 2‐hydroxy ethyl ammonium propionate in neat condition.…”

Recent Developments on Five-Component Reactions

“…A common method for the synthesis of 4,4′-(arylmethylene)bis(1 H -pyrazol-5-ol) derivatives is to conduct a pseudo-5CR of two equiv each of phenylhydrazines and ethyl acetoacetate with one equiv of aromatic aldehydes through a cycloaddition-Knoevenagel-Michael reaction sequence. In recent years, the synthesis of bis(1 H -pyrazol-5-ols) has been accomplished using different catalysts, such as nanocatalyst Pd(0)-guanidine@MCM-41 [ 34 ], guanidine hydrochloride [ 35 ], α -Casein [ 36 ], ZnAl 2 O 4 nanoparticle [ 37 ], La(OTf) 2 -grafted-GO (graphene oxide) [ 38 ], amino acid-based ionic liquids (AAILs) [ 39 ], and CuCr 2 O 4 nanoparticle [ 40 ]. Catalyst-free conditions have also been reported [ 41 ].…”

Mixed Ni2+Co2+ Transition Metal Nitroprusside: Determination of Its Electrochemical Behavior and Electrocatalytic Activity towards the Oxidation of Phenylhydrazine

“…[1][2][3] Phenylhydrazine is widely used as a chemical compound to induce anemia in animal studies. [4] Moreover, phenylhydrazine and its derivates have been utilized in organic synthesis for the diamination of alkenes, [5] the reaction of cyclization of chalcones, [6] the synthesis of heterocyclic molecules and cyclocondensations, [7,8] as well as building block for different reactions. [9] Therefore, as long as phenylhydrazine is not replaced by other green molecules, its presence in the environment by the anthropogenic activity is highly disturbing.…”