Title:Comparison Between Solid Catalysis and Electrochemical Catalysis in the Synthesis of Methyl Carbamate via Hofmann Rearrangement
Volume: 22
Issue: 8
Author(s): Seba Nassif*, Rasha Alabbas, Ahmade Alassaf and Omar Alkhuder
Affiliation:
- Department of Chemistry, Faculty of Sciences, Al Baath University, Homs, Syria
Keywords:
Hoffman rearrangement, benzamide, niacinamide, solid catalysis, electrochemical catalysis, sodium halide.
Abstract:
Introduction: Hofmann rearrangement reactions are important organic reactions used
to obtain carbamates, which are formed via isocyanate as an intermediate compound. Since carbamates
have applications in various fields, such as pharmaceuticals, agricultural chemistry, and
herbicides, this research focuses on synthesizing carbamates using environmentally friendly
methods like solid catalysts and electrical techniques due to their unique characteristics in enhancing
selectivity and minimizing solvents. Additionally, a comparison between the two methods
was made.
Materials and Methods: In this study, two methods were employed to obtain carbamate. The
first method utilized heterogeneous catalysis with sodium halide-modified aluminum oxide to
achieve a high basic surface area alongside sodium hypochlorite as a safe and inexpensive oxidant.
The second method employs electrochemical catalysis using a carbon anode and a zinc
cathode, with sodium halides serving as intermediates.
Results: Sodium chloride modified with aluminum oxide demonstrated better results than sodium
bromide and iodide. A higher yield of carbamates was obtained in a shorter time and at
moderate temperatures. In contrast, in the electrochemical method, sodium bromide demonstrated
the best performance, achieving 75% conversion under ambient conditions.
Conclusion: The comparison between the two methods revealed that the electrochemical method
significantly outperformed, as it managed to avoid side products and directed the reaction
towards the target compound under mild conditions. Whereas the solid catalytic method
(Al2O3/NaCl) obtained lower yields and produced side products in a shorter reaction time.
