Functionalized Metal-Free Carbon Nanosphere Catalyst for the Selective C-N Bond Formation under Open-Air Conditions

Area of Science:

• Materials Science
• Catalysis
• Organic Chemistry

Background:

• Developing efficient, metal-free catalysts is crucial for sustainable organic synthesis.
• Carbon nanomaterials offer tunable properties for catalytic applications.
• Selective C-N coupling reactions are vital for synthesizing pharmaceuticals and fine chemicals.

Purpose of the Study:

• To develop a versatile, shape-controlled, nitrogen-doped carbon nanomaterial for metal-free C-N coupling.
• To investigate the synergistic effects of N-doping and KOH activation on catalytic performance.
• To demonstrate the catalyst's utility in synthesizing imines and benzimidazoles.

Main Methods:

• Synthesis of nitrogen-doped carbon nanomaterials from candle soot via N-doping and KOH activation.
• Characterization using Transmission Electron Microscopy (TEM) and elemental mapping.
• Evaluation of catalytic activity in selective C-N coupling reactions, including o-phenylenediamine (OPD) conversion.

Main Results:

• Sphere-shaped N-doped carbon nanomaterials (ANCS) with enhanced surface area and electron-deficient properties were successfully synthesized.
• The ANCS catalyst achieved 96% conversion and 97% selectivity for 2-phenylbenzimidazole from OPD.
• Pristine carbon showed significantly lower activity (48% conversion, 36% selectivity).
• The catalyst facilitated mild C-N coupling for various aromatic amines and diamines.

Conclusions:

• The developed ANCS nanomaterial is a highly efficient, metal-free catalyst for selective C-N coupling reactions.
• Synergistic N-doping and KOH activation are key to the catalyst's superior performance.
• This work presents a promising approach for synthesizing valuable drug motifs using sustainable carbon-based catalysts.