Direct Conversion of N-acetyl-d-glucosamine to N-containing Heterocyclic Compounds 3-Acetamidofuran and 3-Acetamido-5-acetyl Furan.

Purpose Effectual waste utilization from plant as well as marine biomass has gained tremendous importance with reference to sustainability. The valorization of marine biomass produces value added compounds containing not only C, H, O but also renewable N atom in the skeleton which widens the scope for its exploration which may prove to be economically beneficial to the society. Heterogeneous catalytic transformation of marine biomass i.e. N-acetyl glucosamine (NAG) to N-substituted aromatic heterocyclic furan derivatives is reported for the very first time. Cost effective and stable metal oxide catalysts were deployed for the transformation. Catalyst screening study showed that La₂O₃ was found to be an excellent catalyst for N-acetyl glucosamine (NAG) dehydration which mainly produced 3-acetamidofuran (3AF). Methods The physicochemical properties of the metal oxide catalyst were investigated by various techniques such as XRD, FTIR, MeOH-FTIR, TPD, SEM, N₂ sorption studies and HR-TEM analysis for structure activity relationship. Results The effect of various reaction parameters such as catalyst concentration, reaction temperature, reaction time and solvent effect on dehydration of N-acetyl glucosamine has been studied in detail for higher yields. The results revealed that the presence of weak basic sites which are Brønsted in nature and nano pores present on the surface were responsible for improved dehydration of the chitin biomass to selectively yield 3-acetamidofuran (3AF). La₂O₃ catalyst showed optimum 50% 3AF yield from N-acetyl glucosamine at 180 °C in 3 h. Conclusion Efficacious exploitation of marine biomass to value added chemicals using heterogeneous catalysts can be extensively exploited. Separation of N-substituted heterocyclic aromatics is the most innovative aspect of the current study. Thus, utilization of heterogeneous catalyst and renewable biomass as a raw material indicates a transition towards more sustainable and greener approach. With reference to valorization of biomass waste towards sustainability. We report for the first time heterogeneous catalytic transformation of marine biomass i.e. N-acetyl glucosamine (NAG) over La₂O₃ catalyst to yield 50% 3-acetamido furan (3AF) and 20% 3-acetamido-5-acetylfuran with 100% NAG conversion. The superior performance of La₂O₃ catalyst was attributed to the presence of brønsted basicity and nanopores present at catalysts surface. [ABSTRACT FROM AUTHOR]