32565-77-8Relevant articles and documents
Highly Selective Oxidation and Depolymerization of α,γ-Diol-Protected Lignin
Lan, Wu,de Bueren, Jean Behaghel,Luterbacher, Jeremy S.
, p. 2649 - 2654 (2019/02/01)
Lignin oxidation offers a potential sustainable pathway to oxygenated aromatic molecules. However, current methods that use real lignin tend to have low selectivity and a yield that is limited by lignin degradation during its extraction. We developed stoichiometric and catalytic oxidation methods using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as oxidant/catalyst to selectively deprotect the acetal and oxidize the α-OH into a ketone. The oxidized lignin was then depolymerized using a formic acid/sodium formate system to produce aromatic monomers with a 36 mol % (in the case of stoichiometric oxidation) and 31 mol % (in the case of catalytic oxidation) yield (based on the original Klason lignin). The selectivity to a single product reached 80 % (syringyl propane dione, and 10–13 % to guaiacyl propane dione). These high yields of monomers and unprecedented selectivity are attributed to the preservation of the lignin structure by the acetal.
19F Nuclear Magnetic Resonance Spectroscopy for the Elucidation of Carbonyl Groups in Lignins. 1. Model Compounds
Ahvazi, Behzad C.,Argyropoulos, Dimitris S.
, p. 2167 - 2175 (2007/10/03)
A new method for the detection of different classes of carbonyl groups in a series of carbonyl-containing lignin-like model compounds has been developed. The method is based on the selective fluoride-induced trifluoromethylation of carbonyl groups with (trifluoromethyl)trimethylsilane (TMS-CF3) in the presence of tetramethylammonium fluoride (TMAF), followed by hydrolysis with aqueous HF or TMAF in the case of quinones. In this study a series of ketones, aldehydes, quinones, and dimeric-lignin model compounds were quantitatively trifluoromethylated followed by 19F NMR spectral analyses of the resulting fluorine-containing derivatives, allowing for a thorough understanding of their structure/19F chemical shift relationships. These studies have shown that the 19F-NMR chemical shifts of the trifluoromethyl groups vary significantly and consistently for various classes of carbonyl groups which may be present in complex lignocellulosic materials. These studies are to form the basis for the development of a novel and sensitive method that can be used to obtain quantitative information on the various carbonyl groups present in such materials.
