An environmentally friendly approach to the green synthesis of azo dyes in the presence of magnetic solid acid catalysts

Abstract

Fe3O4@SiO2-SO3H as a highly active catalyst for the rapid diazotization reaction and synthesis of azo-dyes under solvent-free conditions by a grinding method at room temperature is described.

Tungstic acid-functionalized Fe3O4@TiO2: preparation, characterization and its application for the synthesis of pyrano[2,3-c]pyrazole derivatives as a reusable magnetic nanocatalyst

“…Furthermore, these systems possess highly potential active sites for loading of other functional groups to prepare novel heterogeneous catalysts. [6][7][8][9][10][11] To prevent Fe 3 O 4 nanoparticles from oxidation in an air atmosphere and in order to increase the surface area and simplify the surface functionalization, a protective shell can be formed on their surface. 12 TiO 2 have been successfully applied as a nontoxic, low cost and highly effective catalyst that has good mechanical resistance and stability in acidic and oxidative environments.…”

A Sustainable Synthesis of Functionalized Pyrrole Fused Coumarins under Solvent‐Free Conditions Using Magnetic Nanocatalyst and a New Route to Polyaromatic Indolocoumarins

“…Fe 3 O 4 @SiO 2 ‐SO 3 H MNPs were prepared from silica‐coated magnetic nanoparticles Fe 3 O 4 @SiO 2 through doping with chlorosulfonic acid (Supporting Information). The SEM image recognized the formation of nearly spherical and uniform sized Fe 3 O 4 @SiO 2 ‐SO 3 H MNPs (Figure a).…”

Substituent and Solvent Polarity on the Spectroscopic Properties in Azo Derivatives of 2-Hydroxynaphthalene and Their Difluoroboranes Complexes

“…1-(4-Ethoxy)phenylazonaphthalen-2-ol ( 2 ) Red solid, yield 82%, m.p. 132–134 °C (133–134 °C [ 36 , 37 ]). 1 H NMR (CDCl 3 from TMS) δ (ppm): 15.66 (s, 1H), 8.64 (d, 1H, 3 J H,H = 8.40 Hz), 7.75 (m, 2H), 7.69 (d, 1H, 3 J H,H = 9.16 Hz), 7,62 (d, 1H, 3 J H,H = 7.88 Hz), 7.50 (m, 1H), 7.33 (m, 1H), 6.98 (s, 1H), 6.94 (m, 2H), 4.06 (q, 2H), 1.39 (t, 3H).…”