Magnetic Nanocatalyst due to their high surface to volume ratio has high activity and selectivity. Also, due to the magnetic properties of these compounds can be easily removed with a magnet from the reaction mixture. 1 Sulfonic acids and their derivatives are important groups of organic compounds. The wide ranges of applications are in the pharmaceutical industry, dyes, surfactants, pesticides. The synthetic methods for the preparation of sulfonic acids include: (1) Oxidation of compounds sulfur-containing functional group and (2) sulfonation of aromatic compounds. Thiol oxidation by oxidants is a classic method for preparation aromatic and aliphatic sulfonic acids. The methods that have been reported have one or more disadvantages including: long time, difficult separation, low efficiency, the use of strong oxidant, and the use of expensive and harmful materials to the environment. In this study, sulfonic acids were produced selectively from direct oxidation of thiols using hydrogen peroxide as the environmentally friendly oxidant and in the presence of catalytic amounts of Fe3O4 magnetic nanoparticles in EtOH under reflux conditions. Firstly magnetic nano catalyst was produced and characterized by different techniques, and then reaction conditions were optimized. With optimized condition in hand, the structurally divers thiols were converted to crossponding sulfonic acids in good to high yields. In summary, this procedure has several major advantages: (1) the preparation and separation of Fe3O4 MNPs is simple; (2) the use of green oxidant and solvent; (3) high efficient for the selective oxidation of structurally divers thiols in good to high yields; (4) reused of catalyst for several times.
