Amino group immobilized on polyacrylamide: An efficient heterogeneous catalyst for the Knoevenagel reaction in solvent-free and aqueous media

Polystyrene-Supported Pyridinium Chloroaluminate Ionic Liquid as a New Heterogeneous Lewis Acid Catalyst for Knoevenagel Condensation

“…This reaction produces several important key products that include nitriles used in anionic polymerisation and the α,β-unsaturated ester intermediates employed in the synthesis of several therapeutic drugs and pharmacological products. 10,11 Several types of catalysts were introduced previously for Knoevenagel condensation such as the weak bases ammonia, primary amine and secondary amines and their salts, 12,13 16 LaCl 3 , 17 non-cross-linked polystyrene-supported piperazine, 18 zeolite, 19 amino group immobilised on polyacrylamide, 20 SiO 2 -HClO 4 and SiO 2 -PPA, 21 amine functionalised MCM-41, 22 ionic liquids, 23−25 silica based substituted piperidine, 26 and amino functionalised mesoporous silica. 27 However, many of the reported catalysts suffer from drawbacks such as generation of environmentally perilous waste material, tedious work-up, long reaction times, complicated operations, and the use of * Correspondent.…”

Toward Exploiting the Behavior of Niobium-Containing Mesoporous Silicates vs. Polyoxometalates in Catalysis

“…In general, the Knoevenagel condensation is carried out in the presence of different catalysts, including carbonyl compounds, aldehydes or ketones, and active methylene compounds. Lewis acid catalysts such as LaCl 3 (Narsaiah and Nagaiah, 2003 ), piperidine and alkali metal supported catalysts (Leelavathi and Kumar, 2004 ; Martín-Aranda et al, 2005 ; Perozo-Rondon et al, 2006 ), ionic liquids (Moriel et al, 2010 ), or alkali modified metal oxides (Calvino-Casilda et al, 2009 ), zeolites (Wada and Suzuki, 2003 ) and mesoporous materials (Zienkiewicz et al, 2009 ) or polymer-supported catalysts (Tamami and Fadavi, 2005 ) were used as catalysts.…”

Malononitrile: A Versatile Active Methylene Group

“…(Scheme -09) Tamami B. and Fadavi A. [24] have synthesized the malononitrile derivatives 24 in presence of modified form of polyacrylamide catalyst heated under water by using equimolar mixture of aromatic aldehyde 22 and nitrile 23 analogs. Lin Q. et al [25] have designed a novel chemosensor of cyanide analogous 26 by the condensation between napthaldehyde 25 with mlononitrile 1 heated at 90°C fro 2 hrs in aqueous media via green synthesis.…”