Research Article
Green Synthesis Characterization and Thermotropic Behaviour of O-Linked Glycopyranosides of Phenolic Esters
Table 1
Optimization of the catalyst for the preparation of phenolic ester 3a using the direct condensation reaction.
| Entry | Catalyst | Physical state | Time (hr) | Yield % (3a) |
| 1 | Conc. sulfuric acid (H2SO4) | Viscous liquid | 1.5 | 5 | 2 | Paratoluenesulfonic acid (PTSA) | White solid | 5.5 | 63 | 3 | Sulfamic acid (SA) | White crystals | 4.5 | 67 | 4 | Bentonite-H2SO4 | Grey solid | 2.5 | 71 | 5 | Bentonite-PTSA | Grey solid | 5.5 | 55 | 6 | Bentonite-SA | Grey solid | 5.5 | 60 | 7 | Silica-H2SO4 (Si-H+) | Grey powder | 2.5 | 86 | 8 | Silica-PTSA | Grey powder | 5.5 | 56 | 9 | Silica-SA | White powder | 4.5 | 54 |
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Reagents and conditions: 4-hydroxybenzoic acid (1 mmole), menthol (3 mmole), 0.3 mole % catalyst, and temp 80°C.
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