Theoretical studies on thermal decomposition mechanism of arabinofuranose

The thermal decomposition mechanism of arabinofuranose as hemicellulose model compound was investigated by using density functional theory methods M062X with the 6-31++G(d,p) basis set. Five possible pyrolytic reaction pathways were proposed and the standard kinetic parameters in all reaction pathways were calculated. In reaction pathway (1), arabinofuranose is transformed to acyclic containing-carbonyl isomer through a ring-opening reaction and the isomer further decomposes through five possible pyrolysis reaction pathways (1-1) ∼ (1-5). Reaction pathway (2) describes the evolutionary process of formic acid and reaction pathways (3)-(5) describe the formation process of furanones. The calculation results show that reaction pathways (1-2), (1-4) and (5) are the major reaction channels and reaction pathways (1-1), (1-5), and (2)-(4) are the competitive reaction channels in pyrolysis of arabinofuranose. The major pyrolysis products are low molecular products such as glycolaldehyde 4, acetaldehyde 12, 2-furaldehyde 20, 2-hydroxy-5-hydroxymethyl-furan-3-one 38 and CO. The main competitive products are formaldehyde, formic acid, ethanediol 5, acetol 9, 5-hydroxymethyl-furan-3-one 33, 5-hydroxymethyl-furan-2-one 36, CO2, H2, and so on.