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.

EntryCatalystPhysical stateTime (hr)Yield % (3a)

1Conc. sulfuric acid (H2SO4)Viscous liquid1.55
2Paratoluenesulfonic acid (PTSA)White solid5.563
3Sulfamic acid (SA)White crystals4.567
4Bentonite-H2SO4Grey solid2.571
5Bentonite-PTSAGrey solid5.555
6Bentonite-SAGrey solid5.560
7Silica-H2SO4 (Si-H+)Grey powder2.586
8Silica-PTSAGrey powder5.556
9Silica-SAWhite powder4.554

Reagents and conditions: 4-hydroxybenzoic acid (1 mmole), menthol (3 mmole), 0.3 mole % catalyst, and temp 80°C.