Table 3.

Comparative investigation of catalytic performance of Fe₃O₄@SiO₂@urea-riched ligand/Ch-Cl and its relative intermediates as well as some known catalysts upon model reaction for 1a^a.

Entry	Catalyst	The amount of catalyst	Yield (%)
1	Fe3O4	10 mg	40
2	Fe3O4@SiO2	10 mg	40
3	Fe3O4@SiO2@urea-riched ligand	10 mg	70
4	Fe3O4@SiO2@urea-riched ligand/Ch-Cl	10 mg	75
5	Ch-Cl	10 mol%	50
6	FeCl3	10 mol%	50
7	Al(HSO4)3	10 mol%	45
8	Ca(HSO4)2	10 mol%	35
9	Zn(HSO4)2	10 mol%	35
10	Fe(HSO4)3	10 mol%	40
11	NH2SO3H	10 mol%	45
12	H3BO3	10 mol%	40
13	Urea	10 mol%	75
14	Thiourea	10 mol%	60
15	K2CO3	10 mol%	70
16	NaOH	10 mol%	Trace
17	C5H5N	10 mol%	45

^aReaction conditions: 4-acetylphenyl 4-methylbenzenesulfonate (1 mmol, 0.290 g), malononitrile (1 mmol, 0.066 g), ammonium format (1.5 mmol, 0.094 g), benzaldehyde (1 mmol, 0.106 g), solvent-free, 110 °C, 30 min.