Theoretical exploration of the reactivity of cellulose models under non‐thermal plasma conditions—mechanistic and NBO studies

Walid Lamine (1, 2) , Frédéric Guégan (2) , François Jerome (2) , Gilles Frapper (2)

1 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
2 IC2MP [Poitiers] - Institut de chimie des milieux et matériaux de Poitiers [UMR 7285]

Mechanistic details of cellulose depolymerization by non-thermal (atmospheric) plasma (NTAP) remains under-explored given the complexity of the medium. In this study, we have investigated the reaction mechanism of glycosidic-bond degradation triggered by reaction with hydroxyl radicals, considered as the principal reactive species in NTAP medium. In the first step of reaction sequence, H-abstraction reactions by HO.. radical on different C H sites of the pyranose ring were found to be nonselective and markedly exergonic giving rise to a set of cellobiosyl carboradicals likely to undergo further reactions. We then showed that cellobiosyl carboradicals are protected against direct hydrolysis, no activation of the (1-4)-beta-glycosidic bond being characterized. Interestingly, a simple homolytic bond cleavage allowed to obtain desired monomer. Among the 18 possible fragmentations, involving C-C and C-O bond breaking from cellobiosyl carboradicals, 14 transition states were successfully identified, and only three reaction pathways proved kinetically and thermodynamically feasible. Natural bond orbital (NBO) analysis was performed to shed light on electronic structures of different compounds.

Mots clés: depolymerization; hydrolysis; conversion; radicals; biomass; bond

Domaines: Autre

Walid Lamine, Frédéric Guégan, François Jerome, Gilles Frapper. Theoretical exploration of the reactivity of cellulose models under non‐thermal plasma conditions—mechanistic and NBO studies. Journal of Computational Chemistry, 2022, 43 (20), pp.1334-1341. ⟨10.1002/jcc.26934⟩. ⟨hal-03844787⟩