Today, biodiesel, a renewable, non-toxic and environmentally friendly fuel, is attracting increasing attention worldwide as an alternative to fossil fuel.

Owing to the depletion of resources coupled with increasing waste generation, the conversion of waste biomass to value-added materials has gained interest.

The ubiquitousness of esters and amide functionalities makes their coupling reaction one of the most sought-after organic transformations.

Protection (and deprotection) of hydroxyl groups via tetrahydropyranylation was carried out effectively using a catalytic amount of Fe3O4 supported silica sulphuric acid nanoparticles (Fe3O4@SiO2@SO3H) under solvent-free conditions.

Polymer supported catalysts are regarded as a borderline class of catalysts, which retains the advantages of homogeneous catalysts while securing the ease of recovery by simple filtration and workup of heterogeneous systems.