An efficient and environmentally adapted synthesis of xanthene derivatives by condensation of a wide range of aryl aldehydes and 1,3-cyclohexanediones in water using a catalytic amount of Fe₃O₄ nanoparticles is explained. The Fe₃O₄ nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and FT-IR spectroscopy.

Molybdate sulfuric acid (MSA) has been demonstrated to be an efficient and reusable catalyst for the synthesis of quinoxaline and phenazine derivatives based on the condensation of 1,2-diketones and o-pheneylenediamines in ethanol as solvent at room temperature. Also, some novel polycyclic phenazines and quinoxalines are reported. The practical and simple method adopted in the present study led to very high yields of the products under mild conditions within short time intervals.

A novel magnetically heterogeneous catalyst based on the immobilization of boron sulfonic acid onto Fe ₃ O ₄ @SiO ₂ nanoparticles (Fe ₃ O ₄ @SiO ₂ –BSA) is reported. It was characterized via FT-IR, XRD, SEM, EDS, and VSM analysis.

Urea-hydrogen peroxide (UHP) was used in the presence of maleic anhydride as mediator in a simple and convenient method for the oxidation in high yield of some thiols to the corresponding disulfides. Peroxymaleic acid formed in situ from the reaction of UHP with maleic anhydride has a key role in this oxidation. Performance of the reaction in various solvents showed that methanol was the solvent of choice at 0 oC. The products were isolated by simple filtration on silica gel.

Graphene oxide (GO) was employed as an efficient and powerful catalyst in one-pot, three-component synthesis of new pyranocoumarins.