Ion-exchange Resin Catalysis of the Knoevenagel Condensation of Ketones¹

Silica grafted polyethylenimine as heterogeneous catalyst for condensation reactions

“…As expected for steric reasons, the Knoveanagel condensation with ketones is much slower [27,35]. With ASCPEI catalyst no reaction was observed after 24 h under conditions of Table 2.…”

“…The Knoevenagel condensation [15] and the nitroalkene synthesis from nitroaldol condensation [16] are carbon-carbon forming reactions that originate valuable compounds with biological activity [17][18][19][20][21]. Both reactions can be catalyzed by homogeneous catalysts [22][23][24][25][26][27][28][29][30][31] but heterogeneous catalysts have been also successfully used [32][33][34][35][36][37][38][39].…”

Magnetically Separable Base Catalysts: Heterogeneous Catalysis vs. Quasi-Homogeneous Catalysis

“…Usually, these condensations are catalyzed under homogeneous conditions by bases such as primary, secondary and tertiary amines. During the last decades, different solid base catalysts have been utilized to perform the Knoevenagel and nitroaldol condensations [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54]. In addition, recent investigations show that magnetic nanoparticles functionalized with amine groups are effective catalysts in Knoevenagel condensation [55][56][57].…”

Preparation and catalytic property of the solid base supported on the mixed zirconium phosphate phosphonate for Knoevenagel condensation

“…When the reaction of ZrOCl 2 ·8H 2 O and NaH 2 PO 4 with 1 a was for 1, 2, 3.5, 5,9,12,15,18,20,22 h at 60-70 • C, the basic number with H − = 9.3 for 3a was 1.75, 1.72, 1.59, 1.67,1.80, 2.00, 1.68, 1.34, 1.55, 1.71 mmol/g, respectively, the results showed that the reaction time had a profound effect on the basic number. The reaction of ZrOCl 2 ·8H 2 O and NaH 2 PO 4 with 1b or 1c was for 12 h at 60-70 • C, the basic number with H − = 9.3 for 3b, 3c was 2.26, 1.80 mmol/g, respectively.…”

“…Heterogeneous acid catalysis has received much attention due to its importance in petroleum refining and petrochemical processes, in comparison, heterogeneous base catalysis, although it play a decisive role in a number of organic reactions [1,2], is much less numerous. The Knoevenagel condensation has wide application in the organic synthesis [3][4][5], and it is usually catalysed by homogeneous bases or acids [6,7], however, the use of heterogeneous catalysts (i.e., zeolite molecular sieves and inorganic mesoporous material MCM-41 [8][9][10][11]; anionic resin [12,13]; hydrotalcite [14,15]; fluorapatite, hydroxyapatite, Aluminophosphate, phosphate, diphosphate (Na 2 CaP 2 O 7 ) and K + exchanged layered zirconium phosphate [16][17][18][19][20][21]; organic-silicate hybrid material and basic microporous titanosilicate ETS-10 [22,23]) has been reported in recent year, in addition, ultrasound, microwave irradiation and imidazolium ionic liquids [24][25][26] have also been applied. Zirconium phosphates and phosphonates have been extensively researched, their characteristics make them very interesting both from a fundamental point of view and in many application fields, they are easily obtained as multifunctional materials, used as ion exchanger, catalyst or cat- Scheme 1. alyst support, adsorbent [27][28][29][30].…”