306776-12-5

Upstream product

• 41564-97-0 1,2-bis(3,4-dimethoxyphenyl)-1,3-propanediol 
• 120-14-9 3,4-dimethoxy-benzaldehyde 
• 18066-68-7 ethyl 3,4-dimethoxyphenylacetate 
• 1131-62-0 1-(3,4-dimethoxyphenyl)ethanone 
• 1268612-72-1 1,2-bis-(3,4-dimethoxyphenyl)-3-(tert-butyldiphenylsiloxy)-1-propanone 

Relevant academic research and scientific papers

Nature and kinetic analysis of carbon-carbon bond fragmentation reactions of cation radicals derived from SET-oxidation of lignin model compounds

Features of the oxidative cleavage reactions of diastereomers of dimeric lignin model compounds, which are models of the major types of structural units found in the lignin backbone, were examined. Cation radicals of these substances were generated by using SET-sensitized photochemical and Ce(IV) and lignin peroxidase promoted oxidative processes, and the nature and kinetics of their C- bond cleavage reactions were determined. The results show that significant differences exist between the rates of cation radical C1-2 bond cleavage reactions of 1,2-diaryl-(β-1) and 1-aryl-2-aryloxy-(β-O-4) propan-1,3-diol structural units found in lignins. Specifically, under all conditions C1-2 bond cleavage reactions of cation radicals of the β-1 models take place more rapidly than those of the β-O-4 counterparts. The results of DFT calculations on cation radicals of the model compounds show that the C1-2 bond dissociation energies of the β-1 lignin model compounds are significantly lower than those of the β-O-4 models, providing clear evidence for the source of the rate differences.

Toward the oxidative deconstruction of lignin: Oxidation of β-1 and β-5 linkages

There have been numerous reports on methods for the oxidative cleavage of β-O-4 linkages in lignin model compounds, but relatively few reports of how those methods affect other linkages that are present in lignin. We have investigated the effect of several of these oxidation methods on the β-1 and the β-5 lignin linkages, using four β-1 and β-5 model compounds. We observed that direct oxidative cleavage of C-C bonds occurs in metal-catalyzed TEMPO oxidation systems and with iron porphyrin oxidations, neither of which had we observed in similar oxidations on β-O-4 models. The β-5 linkage proved to be largely resistant to all of these oxidative systems, but the dihydrofuran ring in the β-5 model 3 was opened when treated with KMnO4 at elevated temperature. Most promising was the oxidation of 2 with DDQ, which produced the benzylic ketone in high yield (84%), as it does in reactions with β-O-4 models. This reaction exhibits selectivity for the benzylic position as well as compatibility with phenols, characteristics that are highly desirable for a two-step, benzylic oxidation/Baeyer-Villiger route for cleavage of lignin.

Chemical conversion of β-O-4 lignin linkage models through Cu-catalyzed aerobic amide bond formation

Methods for conversion of the lignin β-O-4 models into amide derivatives and phenols have been developed, which is achieved via chemo-selective oxidation of the secondary benzylic alcohol and subsequent Cu-catalyzed aerobic amide bond formation.