Hydrolysis of Biological Material
Timm Lankau and Chin-Hui Yu
Department of Chemistry, National Tsing Hua University 101 KuangFu Road Sec.2, HsinChu 30013, Taiwan
Vendredi 26 Janvier 2018, 14h00
bibliothèque LCT, tour 12 - 13, 4ème étage
S-Adenosyl-L-methionine (SAM) decays into homoserine-γ-lactone (HSL) and methyl-thioadenosine (MTA) in acidic and neutral solutions (Equation 1).[1] MD Simulation with an AM1 Hamiltonian for the solute and the flexible AMBER force field for the bulk of the H2O molecules show that the high barrier and the low energy gain of this reaction can be linked to interactions among the carboxylate group of the SAM molecule and solvent H2O molecules, which are not observed on the product side. Hence, the H2O molecules effectively slow down the reaction that otherwise would be much faster.
![[Picture]](chyu-image1.jpg)
The base catalyzed depolymerisation (BCD) of lignin could become a green, sustainable feedstock for small aromatic molecules. The computational [M06/6 31+G(d,p)//M06/6 31G(d,p)] analysis of the hydrolysis of β-phenoxy-α-phenylethanol as a model for the βO4' link in lignin shows that the depolymerisation proceeds via a resonance-stabilised carbanion, while intermediate oxiranes and formaldehyde, which originate from a second reaction path, are the key compounds in the yield-limiting repolymerisation.[2]
![[Picture]](chyu-image2.jpg)
Additional MD simulations with a PM7 Hamiltonian for the lignin model show that the mechanism for the formation of the oxiranes changes from SN2 at standard conditions to E1 at 300 °C and 250 bar in a real-life BCD reactor.
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References :
[1] T. Lankau and C. H. Yu J. Phys. Chem. A 2017, 121, 505.
[2] T. Lankau and C. H. Yu Green Chem. 2016, 18, 1590.