Hydrolytic hydrogenation of chitin to amino sugar alcohol

Abstract

Chitin is the second most abundant biomass and characteristically contains nitrogen atoms in its monomer units. These favourable features promote chitin to be a potential resource for renewable organonitrogen compounds. 2-Acetamido-2-deoxysorbitol (ADS) is an attractive target in derivatives of chitin, but the conversion of chitin to ADS has not been reported so far.In this work, we demonstrate the catalytic conversion of chitin to ADS using mechanocatalysis in the presence of H 2 SO 4 and subsequent hydrolytic hydrogenation by H 2 SO 4 and Ru/TiO 2 without purification process. Our study clarified that the yield of ADS is strongly influenced by the reaction temperature and pH. The hydrolysis favourably proceeds at high temperature and low pH (2.0), but hydrogenation needs low temperature and specific pH of 34 to achieve high selectivity. Specifically, in the hydrogenation step, acid causes various side-reactions of amide and hemiacetal groups especially in the presence of Ru catalyst, whereas even a small amount of base drastically accelerates the retro-aldol reaction to form erythritol and N-acetylethanolamine.Therefore, a one-pot but two-step reaction is necessary to optimise both hydrolysis and hydrogenation steps and maximises the overall yield of ADS up to 52%.

Towards Shell Biorefinery: Advances in Chemical‐Catalytic Conversion of Chitin Biomass to Organonitrogen Chemicals

“…Direct production of 2acetamido-2-deoxysorbitol (ADS) from chitin is highly desirable, as reported by Kobayashi et al. [20] Chitin was hydrolyzed to NAG (19 %) and oligomers (64 %) over H 2 SO 4 employing mechanochemistry firstly, and the hydrolyzed mixture could be directly converted to ADS by hydrolytic hydrogenation over Ru/TiO 2 in the presence of 4 MPa H 2 , giving a low yield of 25 % based on NAG units in chitin. To enhance ADS yield, an additional hydrolysis step was conducted, giving a product solution containing 61 % NAG.…”

“…As mentioned earlier, the hydrogenation of NAG gave ADS. [20] Fukuoka's group [50] demonstrated the catalytic conversion of ADS to 2-acetamide-2-deoxyisosorbide (ADI), a promising precursor to N-containing polymers. Although the structures of ADS and sorbitol were similar, it was more difficult for ADS to undergo dehydration reaction.…”

Valorization of Oceanic Waste Biomass: A Catalytic Perspective

“…Addition of Ru/TiO 2 (5 wt% of chitin) to the depolymerized reaction mixture yielded Acetamido‐2‐deoxysorbitol in good yields (52 mol%) under 4 MPa H 2 pressure and pH=5. This was an excellent approach to facilitate one pot cascade catalysis for such rigid reactants, contributing significantly towards waste valorisation . When NAG was used as a reactant over transition metal catalyst in water still higher yields of polyols were achieved.…”

“…This was an excellent approach to facilitate one pot cascade catalysis for such rigid reactants, contributing significantly towards waste valorisation. [127] When NAG was used as a reactant over transition metal catalyst in water still higher yields of polyols were achieved. Under 180 8C, 40 bar H 2 with 1 mol% loading of Ru/C, 71.9 % of C6 Ncontaining polyols, 6.1 % C4 polyols and 8.7 % N-acetylmonoethanolamine (NMEA) were produced.…”

Efficient Conversion of Aqueous-Waste-Carbon Compounds Into Electrons, Hydrogen, and Chemicals via Separations and Microbial Electrocatalysis

“…Therefore, most of the attention is focused on hydrogen and other products, which add greater value to the biorefinery. Hydrogen is needed for upgrading of intermediates produced in biorefinery (Kamm et al, 2008;Borole, 2011;Ferrini and Rinaldi, 2014;Abdullah et al, 2015;Heracleous et al, 2017), production of fuel additives (Gawade et al, 2016) as well as for conversion of non-lignocellulosic biopolymers such as chitin to chemicals (Kobayashi et al, 2017). Current methods of hydrogen production include those from fossil as well as renewable resources Nikolaidis and Poullikkas, 2017).…”