Quick action, quicker reaction
doi:10.1038/nindia.2008.135 Published online 7 March 2008
Researchers in Mumbai have designed a reusable nano-sized catalyst from copper that wraps up an important chemical reaction within minutes as opposed to the earlier long hours. Known as 'click' reaction, it produces nitrogen containing organic compounds triazoles with wide ranging industrial applications in corrosion inhibitors, agrochemicals, optical brighteners, and photographic materials.
Nano-sized catalysts are known to accelerate reaction rate by increasing the catalyst surface area and reducing its consumption. Copper nano-catalysts have been useful in modifying the 'click' reaction. But all the catalysts took long reaction time and were not reusable. To overcome these shortcomings, the researchers used two chemical agents (hydrazine hydrate and ascorbic acid), which converted copper salts into copper nanoparticles in the presence of solvents like dimethyl formamide (DMF) and formamide (FM), and coated them with PVP (poly N-vinyl-2-pyrrolidone).
Hydrazine hydrate in DMF and FM produced copper nanostructures of varying shapes and sizes and ascorbic acid in FM spawned mostly spherical nanostructures. Both the copper nanostructures were separately used in click reaction (between two organic compounds – benzyl azide and phenyl propargyl ether) that produced triazoles (1,2,3 triazoles), a white crystalline solid, within 15 minutes. Normally, it takes two to 24 hours to achieve this.
"The operational simplicity of this method and the purity of the recovered products make it attractive not only for large scale synthesis of these biologically active molecules but also for synthesis of screening libraries for drug discovery," says lead researcher Sudhir Kapoor from the Radiation and Photochemistry Division of Bhabha Atomic Research Centre, Mumbai.
- Sarkar, A. et al. PVP-Stabilized Copper Nanoparticles: A Reusable Catalyst for "Click" Reaction between Terminal Alkynes and Azides in Nonaqueous Solvents. J. Phys. Chem. C. 112, 3334-3340 (2008)