scholarly journals A TEMPO-catalyzed oxidation–reduction method to probe surface and anhydrous crystalline-core domains of cellulose microfibril bundles

Cellulose ◽  
2021 ◽  
Author(s):  
Tânia M. Shiga ◽  
Haibing Yang ◽  
Bryan W. Penning ◽  
Anna T. Olek ◽  
Maureen C. McCann ◽  
...  
Keyword(s):  
Cellulose Microfibril ◽  
Reduction Method ◽  
Probe Surface ◽  
Oxidation Reduction ◽  
Crystalline Core ◽  
Catalyzed Oxidation

A TEMPO-catalyzed oxidation-reduction method to probe surface and anhydrous crystalline-core domains of cellulose microfibril bundles

2021 ◽  
Author(s):  
Tanîa M. Shiga ◽  
Haibing Yang ◽  
Bryan W. Penning ◽  
Anna T. Olek ◽  
Maureen C. McCann ◽  
...  
Keyword(s):  
Secondary Wall ◽  
Cellulose Microfibril ◽  
Reduction Method ◽  
Cellulose Microfibrils ◽  
Cotton Fibers ◽  
Uronic Acids ◽  
Oxidation Reduction ◽  
Crystalline Core ◽  
Secondary Wall Formation ◽  
Catalyzed Oxidation

Abstract A modified TEMPO-catalyzed oxidation of the solvent-exposed glucosyl units of cellulose to uronic acids, followed by carboxyl reduction with NaBD 4 to 6-deutero- and 6,6-dideuteroglucosyl units, provided a robust method for determining relative proportions of disordered amorphous, ordered surface chains, and anhydrous core-crystalline residues of cellulose microfibrils inaccessible to TEMPO. Both glucosyl residues of cellobiose units, digested from amorphous chains of cellulose with a combination of cellulase and cellobiohydrolase, were deuterated, whereas those from anhydrous chains were undeuterated. By contrast, solvent-exposed and anhydrous residues alternate in surface chains, so only one of the two residues of cellobiosyl units was labeled. Although current estimates indicate that each cellulose microfibril comprises only 18 to 24 (1 , 4)- b eta-D-glucan chains, we show here that microfibrils of walls of Arabidopsis leaves and maize coleoptiles, and those of secondary wall cellulose of cotton fibers and poplar wood, bundle into much larger macrofibrils, with 67 to 86% of the glucan chains in the anhydrous domain. These results indicate extensive bundling of microfibrils into macrofibrils occurs during both primary and secondary wall formation. We discuss how, beyond lignin, the degree of bundling into macrofibrils contributes an additional recalcitrance factor to lignocellulosic biomass for enzymatic or chemical catalytic conversion to biofuel substrates.

Bis(trifluoroacetylacetonato)cobalt(II) Catalyzed Oxidation-Reduction Hydration of Olefins Selective Formation of Alcohols from Olefins

1989 ◽  
Vol 18 (3) ◽  
pp. 515-518 ◽  
Author(s):  
Satoshi Inoki ◽  
Koji Kato ◽  
Toshihiro Takai ◽  
Shigeru Isayama ◽  
Tohru Yamada ◽  
...  
Keyword(s):  
Oxidation Reduction ◽  
Selective Formation ◽  
Catalyzed Oxidation

Preparation of Pd@Gr Composite Materials and Research on Catalytic Performance

2019 ◽  
Vol 944 ◽  
pp. 671-677
Author(s):  
Jin Feng Leng ◽  
Kang Wang ◽  
Chang Peng Xia
Keyword(s):  
Reduction Method ◽  
Chemical Reduction ◽  
Great Influence ◽  
Pd Nanoparticles ◽  
Catalytic Performance ◽  
Chemical Oxidation ◽  
Chemical Reduction Method ◽  
Graphene Surface ◽  
Oxidation Reduction

In this work, the preparation of graphene by chemical oxidation reduction method and a series of chemical reactions to get graphene oxide, with the preparation of graphene composites by simply chemical reduction method for the preparation of palladium/graphene composites. Through the chemical reduction method, the small size of Pd nanoparticles is acquired by controlling the content of reducing agent. The Pd nanoparticles on graphene surface is 10nm size and evenly distributed. Pd2+ adsorption on graphene surface and in situ were partially reduced to Pd to Pd2+ nanoparticles by the reducibility of graphene. In the process, the graphene was reduced to graphene and the final compound was thinner and more transparent than the pre-experiment oxide. The oxygen-containing functional groups on the surface of the graphene have influence to the nucleation and growth of metal nanoparticles and KI can control the morphology and size of nanoparticles. The particle size and dispersion uniformity have great influence on the catalytic performance of composites, the smaller particles have better catalytic performance. Keywords:palladium, graphene composites, nanoparticles

The acid-catalyzed oxido-reduction of spiroketals. Evidence for stereoelectronic control in hydride transfer to cyclic oxenium ions

1981 ◽  
Vol 59 (18) ◽  
pp. 2787-2802 ◽  
Author(s):  
Pierre Deslongchamps ◽  
Daryl D. Rowan ◽  
Normand Pothier
Keyword(s):  
Hydride Transfer ◽  
Reduction Reaction ◽  
Sodium Cyanoborohydride ◽  
Oxidation Reduction ◽  
Oxidation Reduction Reaction ◽  
Stereoelectronic Control ◽  
Acidic Conditions ◽  
Acid Catalyzed ◽  
Ether Ketone ◽  
Catalyzed Oxidation

Tricyclic spiroketal 1 undergoes an acid-catalyzed oxidation–reduction reaction which yields equatorial bicyclic ether aldehyde 5 specifically. Similarly, spiroketals 2, 3, and 4 give equatorial bicyclic ether ketone 12. These results are interpreted by invoking an internal hydride transfer from an alcohol function to a cyclic oxenium ion which takes place with stereoelectronic control. The reduction of tricyclic ketals 1 and 22 with sodium cyanoborohydride under acidic conditions is also reported.

Sign in / Sign up

Export Citation Format

Share Document