Basic catalyzed Knoevenagel condensation by FAU zeolites exchanged with alkylammonium cations

Hierarchical K/LTL zeolites: Synthesis by alkali treatment, characterization and catalytic performance in Knoevenagel condensation reaction

“…Considering the 13 emerging trend for the development of an environmental benign 14 processes or sustainable technologies for the chemical industry, 15 the adverse effects of homogeneous catalysts in particular liquid 16 bases such as the difficulties in the separation, recovery, and their 17 reusability can be overcome by the use of heterogeneous solid 18 bases [1,2]. The heterogeneous catalysis resulted in the improved 19 performance in terms of remarkable selectivity and product yield 20 by the suppression of the side reactions including self-condensa- 21 tion and oligomerization, and additionally beneficial economic 22…”

DBU Derived Ionic Liquids and Their Application in Organic Synthetic Reactions

“…Generally, Knoevenagel reactions are carried out by condensation of active methylene compounds with aldehydes using some organic bases with their salts as catalysts, including dimethylamino pyridine, piperidine, guanidine, ethylenediamine (Narsaiah et al, 2004;Han et al, 2008), and so on. Also, alternative protocols for Knoevenagel condensations catalyzed by Lewis acids such as ZnCl 2 (Shanthan Rao & Venkataratnam, 1991), CuCl 2 (Attanasi et al, 1983), TiCl 4 (Green et al, 1985), LaCl 3 (Narsaiah & Nagaiah, 2003), Mg(ClO 4 ) 2 (Bartoli et al, 2008) and various heterogeneous solid bases, including Zeolites (Saravanamurugan et al, 2006;Martns et al, 2008), sulfate-ion promoted Zirconia , clay (Bigi et al, 1999), and layered double hydroxides (LDHs) (Kantam et al, 2006) have been reported in literatures. However, many of those procedures required the use of large amount of organic solvents as reaction medium, long reaction time, harsh reaction conditions and had difficulties in the reuse of catalysts, which prompt chemical researchers for further development of more environmentally benign, efficient and operationally simple Knoevenagel protocols.…”

Zeolites as Catalysts for the Synthesis of Fine Chemicals

“…Recently, Martins et al [233,234] have prepared new basic zeolite catalysts, comprising ion-exchanged methylammonium cations in Y and X zeolite [235]. The authors found that the ion exchange of sodium by methylammonium cations reduces the micropore volume of the catalyst but enhances the strength of basic sites.…”