76788-37-9Relevant academic research and scientific papers
Selective C-O Bond Cleavage of Lignin Systems and Polymers Enabled by Sequential Palladium-Catalyzed Aerobic Oxidation and Visible-Light Photoredox Catalysis
Magallanes, Gabriel,K?rk?s, Markus D.,Bosque, Irene,Lee, Sudarat,Maldonado, Stephen,Stephenson, Corey R. J.
, p. 2252 - 2260 (2019/02/19)
Lignin, which is a highly cross-linked and irregular biopolymer, is nature's most abundant source of aromatic compounds and constitutes an attractive renewable resource for the production of aromatic commodity chemicals. Herein, we demonstrate a practical and operationally simple two-step degradation approach involving Pd-catalyzed aerobic oxidation and visible-light photoredox-catalyzed reductive fragmentation for the chemoselective cleavage of the β-O-4 linkage - the predominant linkage in lignin - for the generation of lower-molecular-weight aromatic building blocks. The developed strategy affords the β-O-4 bond cleaved products with high chemoselectivity and in high yields, is amenable to continuous flow processing, operates at ambient temperature and pressure, and is moisture- and oxygen-tolerant.
Investigate cleavage of β-O-4 linkage in lignin model compounds by aerobic oxidation of Cα and Cγ hydroxyl groups
Patil, Nikhil D.,Yan, Ning
supporting information, p. 3024 - 3028 (2016/07/06)
The selective cleavage of common linkages in lignin polymers is a promising approach to generate valuable aromatic hydrocarbons. Herein, we found that on oxidation of Cα and Cγ hydroxyl groups in β-O-4 lignin model compounds with TEMPO catalyst resulted in the formation of 1,3-dicarbonyl TEMPO adduct. These oxidized products readily underwent fragmentation at Cα-Cβ bond in the presence of a catalytic amount of acid to generate corresponding carboxylic acid and phenol monomers.
Facile and selective hydrogenolysis of β-O-4 linkages in lignin catalyzed by Pd-Ni bimetallic nanoparticles supported on ZrO2
Zhang, Jia-Wei,Cai, Yao,Lu, Guo-Ping,Cai, Chun
, p. 6229 - 6235 (2016/12/03)
The β-O-4 linkage in lignin can be selectively cleaved by Pd-Ni bimetallic nanoparticles supported on ZrO2 using hydrogen gas as the hydrogen donor under ambient pressure and neutral conditions. Conspicuous enhancement in activity is observed compared with single nickel and palladium catalysts based on the results of experiments and characterization. Moreover, hydrogenation of the produced phenols is tuned by adjusting the amount of NaBH4. The catalyst can be reused over ten times in the model reaction and over five times in the hydrogenolysis of lignin without an obvious change in activity and selectivity.
Reactions of Lignin-related Cinnamaldehydes and Cinnamyl Alcohols with Borane and Sodium Tetrahydridoborate
Li, Shiming,Lundquist, Knut
, p. 64 - 67 (2007/10/02)
Hydroboration/oxidation of 3-(3,4-dimethoxyphenyl)-2-propen-1-ol gives a mixture of 1-(3,4-dimethoxyphenyl)-1,3-propanediol, 3-(3,4-dimethoxyphenyl)-1,2-propanediol and 3-(3,4-dimethoxyphenyl)-1-propanol; the same compounds are obtained as by-products when the lignin model 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol is synthesized by hydroboration/oxidation of α-(2-methoxyphenoxy)-3,4-dimethoxycinnamic acid. (Z)-3-(3,4-dimethoxyphenyl)-2-propen-1-ol and (E0-α-(2-methoxy-phenoxy)-3,4-dimethoxycinnamic acid give compratively large amounts of 3-(3,4-dimethoxyphenyl)-1,3-propanediol.The results support the view that the by-products are formed via 3-(3,4-dimethoxyphenyl)-2-propen-1-ol.Small amounts of the same by-products are obtained on tetrahydridoborate reduction of (E)-3-(3,4-dimethoxyphenyl)propenal .Analogous results were obtained with (E)-3-phenylpropenal.Models representative of lignin units of the cinnamaldehyde and cinnamyl alcohol types have been prepared and precise 1H NMR spectral data (400 MHz, 300 K) for the compounds are reported.
Asymmetric catalysis. Production of chiral diols by enantioselective catalytic intramolecular hydrosilation of olefins
Bergens, Steven H.,Noheda, Pedro,Whelan, John,Bosnich
, p. 2121 - 2128 (2007/10/02)
Rhodium(I) chiral diphosphine complexes efficiently and rapidly catalyze the intramolecular hydrosilation of silyl ethers derived from allylic alcohols. The efficiency and rates of intramolecular hydrosilations were determined for a variety of silyl and olefin substituents. The catalysts were found to tolerate a wide variety of silyl substituents, although terminal alkyl olefin substituents were found to retard catalysis. Terminal aryl olefin substituents were found to be hydrosilated efficiently and at reasonable rates. One of the chiral catalysts is highly enantioselective for terminal aryl olefin substituents. Almost quantitative ee's are obtained. Moreover, the ee's are only slightly sensitive to aryl and olefin substituents, suggesting that this enantioselective catalysis can provide a wide range of chiral species. Oxidative cleavage of the hydrosilation products gives chiral diols.
