مشخصات پژوهش

The preparation and the use of nanoparticles (NPs) in organic synthesis has become a subject of intense investigation. In particular, magnetic nanoparticles (MNPs) which offer advantages in clean and sustainable chemistry as they can be non-toxic, readily accessible, and retrievable.1 It has been demonstrated that catalytic systems that contain both Lewis and Bronsted acidity are more beneficial than Lewis or Bronsted acidic catalysts alone.2 Among the various transition metals as a Lewis acid, vanadium exists on the surface of the earth more abundantly and vanadium based oxidants are effectively used for various organic reactions.3 Therefore immobilization of the functionalized acid via covalent attachment to the supporting materials can combine the acid characteristics with the advantages of magnetic nanoparticles to facilitate catalyst recovery, recycling and to reduce effluent contamination. Herein, we wish to report the synthesis and application of novel nano magnetic Fe3O4 based vanadic acid [MNPs@ VO(OH)2] with dual ability both as Lewis and Bronsted acid sites. The described catalyst [MNPs@ VO(OH)2] was synthesized successfully and used for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol)s (Scheme 1).