Research Article
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 |
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