Background: Quinoline is a type of N-based organic heterocyclic biologically active compound. Quinolines have fetched the interest of scientists because of their wide scope of applications. Several methods have been developed for the synthesis of quinoline and its derivatives. In this study a new, efficient, simple, one-pot synthesis of the substituted quinolines was developed by using of palladium nanoparticles as a catalyst.
Methods: Catalyst synthesized by algal extract of green alga Botryococcus braunii and palladium acetate solution, and characterized by different instrumental techniques like FTIR, SEM and XRD. The synthesized palladium nanoparticles explored for the catalytic activity in the synthesis of quinoline derivatives by the use of 2-aminobenzyl alcohol in toluene with acetyl derivatives followed by addition of potassium hydroxide. Formation of product was confirm by 1HNMR, 13C NMR, IR and electron ionization mass spectra.
Results: The formation of palladium nanoparticles characterized by visual observation means color change from light pale yellow to dark brown indicates the reduction of palladium ions into palladium nanoparticles. Synthesized palladium nanoparticles characterized by FTIR spectrum of algal extract of green algae B. braunii for presence of proteins, lipids, carbohydrates, carotenoids, vitamins and other secondary metabolites in algal extract, which functions as active components for bioreduction. Morphology of catalyst confirmed by SEM and X-ray diffraction measurements for shape, crystalline nature and size. The synthesized palladium nanoparticles explored for the catalytic activity in synthesis of quinoline derivatives by the use of 2-aminobenzyl alcohol in toluene and added acetyl derivatives followed by addition of potassium hydroxide. In order to establish the optimum heating method a comparative study between conventional and microwave heating method carried out in the presence of palladium nanoparticles as a biocatalyst.
Conclusion: This protocol provides a convenient and practical procedure to the preparation of quinoline derivatives from 2-aminobenzyl alcohol, acetyl derivatives, potassium hydroxide and palladium nanoparticles as catalyst. This protocol would be helpful for synthesizing other quinoline derivatives and several organic heterocycles which are using in different fields such as biological, industrial, pharmaceutical, chemical, medical etc.