Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Session: 1
Room: Exhibit Hall
Mary Eweama - Fayetteville State University
Co-Author(s): Lacey A. Picinich, Fayetteville State University, Fayetteville, NCHanna M. Paige, Fayetteville State University, Fayetteville, NCAli R. Siamaki, Fayetteville State University, Fayetteville, NC
Buchwald-Hartwig amination is a cross coupling reaction between aryl halides or pseudohalides and primary or secondary amines to produce aryl amines. The reaction has become a fundamental tool in organic synthesis for the formation of carbon-nitrogen (sp2) bonds in variety of biologically active molecules, natural products, pharmaceuticals, and material science. These reactions usually employ a Pd complex in homogeneous form along with a ligand to stabilize the metal center. In this regard, there are many disadvantages for using homogeneous catalysis including the potential contamination of the metal in the final product and lack of recyclability of the catalyst. Heterogeneous catalysis is an alternative attractive approach to construct C-N (sp2) bonds in which the metal is fixed on variety of solid support such as zeolites, polymers, mesoporous silica, and carbon materials. This would allow for ease of separation of the catalyst from the reaction and reusability for the subsequent runs. In this presentation, we will introduce the synthesis of amine-functionalized carbon nanotubes (CNTs) supported Pd nanoparticles (Pd/MWCNTs-NH2) via simple dry mixing of the corresponding palladium salts and amine-functionalized CNTs using a a mechanical energy of a ball-mill mixer. The method is very straightforward and rapid and does not require any solvent or reducing agents, a feature that allows for large-scale preparation of these materials. The as-prepared catalyst demonstrated excellent catalytic activity for the Buchwald-Hartwig carbon–carbon cross coupling reactions of variety of aryl halides and functionalized primary and secondary amines under microwave irradiation conditions and short reaction time of twenty minutes. The product of the reactions was analyzed by Gas Chromatography-Mass Spectroscopy technique (GC-MS) as well as 1H and 13C NMR spectroscopy. The Pd/MWCNTs-NH2 nanoparticles prepared by this simple, solventless, and inexpensive preparation provide a more direct, cost-efficient, and streamlined means to accomplish often-challenging Buchwald-Hartwig amination reactions. Future research involves the large-scale application of this method for the synthesis of target substituted aryl amines utilizing continuous flow manufacturing process.
Funder Acknowledgement(s): National Science Foundation (NSF) HBCU-UP RIA Grant 2101126
Faculty Advisor: Ali R. Siamaki, asiamaki@uncfsu.edu
Role: I have prepared the amine-functionalized carbon nanotubes using ball-mill method. I have used the as-prepared catalyst for Buchwald-Hartwig amination reaction and analyze the reaction mixtures using GC-MS spectroscopy.