Resin: Volatile Components and Impact on Plant Pathogenic and Foodborne Bacteria.

() produces a white, sticky, latex-like resin with antimicrobial properties. The aims of this research were to evaluate the effects of this resin ( resin) on bacterial populations and to determine the impact of its primary volatile components on bioactivity. The impact of sample treatment on chemical composition of resin was analyzed using Fourier transform infrared spectroscopy (FTIR) coupled with principal component analysis.

Improving Processing and Performance of Pure Lignin Carbon Fibers through Hardwood and Herbaceous Lignin Blends.

Lignin/lignin blends were used to improve fiber spinning, stabilization rates, and properties of lignin-based carbon fibers. Organosolv lignin from Alamo switchgrass () and yellow poplar () were used as blends for making lignin-based carbon fibers. Different ratios of yellow poplar:switchgrass lignin blends were prepared (50:50, 75:25, and 85:15 ).

Enantioselective Syntheses of Lignin Models: An Efficient Synthesis of β-O-4 Dimers and Trimers by Using the Evans Chiral Auxiliary.

We describe an efficient five-step, enantioselective synthesis of (R,R)- and (S,S)-lignin dimer models possessing a β-O-4 linkage, by using the Evans chiral aldol reaction as a key step. Mitsunobu inversion of the (R,R)- or (S,S)-isomers generates the corresponding (R,S)- and (S,R)-diastereomers. We further extend this approach to the enantioselective synthesis of a lignin trimer model.

The effect of solvent composition on grafting gallic acid onto chitosan via carbodiimide.

The primary antioxidant (AOX) activity of chitosan can be introduced by grafting of phenolic compound - gallic acid (GA) to its amino and/or hydroxyl groups. The objective of this study was to investigate the effect of ethanol (EtOH) concentration (0%, 25%, 50%, and 75% in water) on efficiency of grafting GA onto chitosan in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/N-hydroxysuccinimide (NHS). The grafting was confirmed by FTIR and the efficiency was quantified as Folin's total phenolics.

Synthesis of enantiomerically pure lignin dimer models for catalytic selectivity studies.

A series of highly enantioselective transformations, such as the Sharpless asymmetric epoxidation and Jacobsen hydrolytic kinetic resolution, were utilized to achieve the complete stereoselective synthesis of β-O-4 lignin dimer models containing the S, G, and H subunits with excellent ee (>99%) and moderate to high yields. This unprecedented synthetic method can be exploited for enzymatic, microbial, and chemical investigations into lignin's degradation and depolymerization as related to its stereochemical constitution. Preliminary degradation studies using enantiopure Co(salen) catalysts are also reported.

Predicting enzyme adsorption to lignin films by calculating enzyme surface hydrophobicity.

The inhibitory action of lignin on cellulase cocktails is a major challenge to the biological saccharification of plant cell wall polysaccharides. Although the mechanism remains unclear, hydrophobic interactions between enzymes and lignin are hypothesized to drive adsorption. Here we evaluate the role of hydrophobic interactions in enzyme-lignin binding.

Approaches to the selective catalytic conversion of lignin: a grand challenge for biorefinery development.

Lignin comprises 15-25% of terrestrial biomass and is the second most abundant source of renewable carbon after cellulose. However, its structural heterogeneity frustrates efforts for its selective conversion into biobased chemicals. Catalyst design for lignin transformation offers an opportunity to improve selectivity, and, hence, improve lignin's utility as a raw material in chemical production.

Efficient cobalt-catalyzed oxidative conversion of lignin models to benzoquinones.

Phenolic lignin model monomers and dimers representing the primary substructural units of lignin were successfully oxidized to benzoquinones in high yield with molecular oxygen using new Co-Schiff base catalysts bearing a bulky heterocyclic nitrogen base as a substituent. This is the first example of a catalytic system able to convert both S and G lignin model phenols in high yield, a process necessary for effective use of lignin as a chemical feedstock.

The effect of axial ligand on the oxidation of syringyl alcohol by Co(salen) adducts.

Experimental work on the oxidation of the lignin model, syringyl alcohol, using oxygen and a Co(salen) catalyst has revealed variations in yield with different imidazole-based axial ligands. A reasonable linear relationship was found between product yield and pKa of the axial ligand. The current work, using density functional calculations, examined geometric, electronic, and energetic parameters to determine if additional quantitative relationships can be identified and used in subsequent catalyst design.

High-performance liquid chromatography/high-resolution multiple stage tandem mass spectrometry using negative-ion-mode hydroxide-doped electrospray ionization for the characterization of lignin degradation products.

In the search for a replacement for fossil fuel and the valuable chemicals currently obtained from crude oil, lignocellulosic biomass has become a promising candidate as an alternative biorenewable source for crude oil. Hence, many research efforts focus on the extraction, degradation, and catalytic transformation of lignin, hemicellulose, and cellulose. Unfortunately, these processes result in the production of very complex mixtures.

A comparative review of petroleum-based and bio-based acrolein production.

Acrolein is an important chemical intermediate for many common industrial chemicals, leading to an array of useful end products. This paper reviews all the synthetic methods, including the former (aldol condensation) and contemporary (partial oxidation of propylene) manufacturing methods, the partial oxidation of propane, and most importantly, the bio-based glycerol-dehydration route. Emphasis is placed on the petroleum-based route from propylene and the bio-based route from glycerol, an abundantly available and relatively inexpensive raw material available from biodiesel production.

Biomass fractionation for the biorefinery: heteronuclear multiple quantum coherence-nuclear magnetic resonance investigation of lignin isolated from solvent fractionation of switchgrass.

Two-dimensional heteronuclear multiple quantum coherence and quantitative (13)C nuclear magnetic resonance spectroscopy are used to identify the structural features of lignin isolated from solvent fractionation of switchgrass at several different severities. The spectra are consistent with a progressive deconstruction of the lignin as the fractionation severity increases, with structural units involved in cross-linking and capping of the bulk lignin polymer removed first, followed by increasing levels of acid-catalyzed, solvolytic cleavage of the bulk lignin. The results show that solvent fractionation conditions between about 120 °C and 0.

Comparative genome analysis of lignin biosynthesis gene families across the plant kingdom.

Background: As a major component of plant cell wall, lignin plays important roles in mechanical support, water transport, and stress responses. As the main cause for the recalcitrance of plant cell wall, lignin modification has been a major task for bioenergy feedstock improvement. The study of the evolution and function of lignin biosynthesis genes thus has two-fold implications.

Synthesis and self-assembly of glycal-based bolaforms.

Glycal-based bolaforms serve as synthetically flexible components of molecular self-assembly. The compounds are prepared in good yield by a Ferrier reaction between triacetylglucal or -galactal or diacetylxylal and a long chain alpha,omega-diol, followed by deacetylation under Zemplen conditions. The reactions are stereoselective and preferentially afford the alpha-diastereomer.

Molecular structures of glycal-based bolaamphiphiles: analysis of crystal packing and hydrogen-bond networks.

The crystal structures for the glycal bolaamphiphiles, 1,12-bis-(2,3-alpha-D-erythro-hex-2-enopyranosyloxy)-dodecane (1) and 1,12-bis-(2,3-alpha-D-threo-hex-2-enopyranosyloxy)-dodecane (2), were determined by single-crystal X-ray analysis. The structure for 1 showed that the alpha:alpha and alpha:beta diastereomers co-crystallized, with occupancy factors determining an isomeric ratio of 69:31. The pyranose rings for both structures are oriented away from each other and adopt a conventional glycal geometry.