CES as an Efficient Natural Catalyst for Synthesis of Schiff Bases under Solvent-Free Conditions: An Innovative Green Approach

Table 2

Comparison of CES with different reported methods used for synthesis of Schiff bases.

Serial no.	Catalyst	Solvent	R (R–NH2)	R′ (R′–CHO)	Reaction condition	Time	Yield%
1	Montmorillonite [42]	Chloroform	H	H	RT grinding	10 min	95
2	CeCl3·7H2O [43]	Ethanol	H	2-OH	Reflux	2 hrs	68
3	P2O5/Al2O3 [44]	—	H	H	RT stirring	20 min	80
4	Mg(ClO4)2 [45]	DCE	4-NO2	4-OMe	RT	8 hrs	95
5	Acid catalysis [46]	Trimethyl orthoformate	—	—	Stirring	8 hrs	—
6	Alumina [47]	—	H	H	Stirring 20°C	2 hr	99
7	Acetic acid [48]	—	H	—	Grinding	—	89
8	Conc. H2SO4 [49]	Ethanol	—	—	Reflux	1 h.	70
9	Montmorillonite K-10 clay [50]	—	H	H	MW	3 min	98
10	CES	Solvent-free	4-OCH3	4-NO2	RT grinding	10–15 min	98