Pyrolysis mechanism study of minimally damaged hemicellulose polymers isolated from agricultural waste straw samples.

The pyrolysis mechanism of hemicellulose has been investigated using two minimally damaged hemicellulose polymers isolated from two agricultural straw samples. The obtained hemicelluloses have been characterized by multiple methods, and the results showed that they were mainly composed of l-arabino-4-O-methyl-d-glucurono-d-xylan. Their O-acetyl groups and high degrees of polymerization and branching were well preserved.

Pyrolysis behaviors of four lignin polymers isolated from the same pine wood.

Four lignin polymers, alkali lignin (AL), klason lignin (KL), organosolv lignin (OL), and milled wood lignin (MWL), were isolated from the same pine wood. Structural characterization by FTIR and (13)C NMR indicated that the four lignins have different structural features. Their pyrolysis behaviors were analyzed by TG-FTIR and Py-GC/MS.

[Chemical constituents from Corydalis yanhusuo].

Objective: To investigate the chemical constituents of Corydalis yanhusuo.

Method: The compounds were isolated and purified by column chromatography over macroporous absorption resin, silica gel, and Sephadex LH-20. Their structures were elucidated on the basis of physicochemical properties and spectral data.

Two new compounds from Helichrysum arenarium (L.).

Two new compounds were isolated from the whole plant of Helichrysum arenarium (L.) Moench. By means of spectroscopic data (IR, UV, 1D and 2D NMR, HR-MS, ESI-MS, and NOESY) and chemical evidence, the structures were established as 6,7-dimethoxy-4-hydroxy-1-naphthoic acid (1) and (Z)-5-hydroxy-7-methoxy-4-[3-methyl-4-(O-beta-D-xylopyranosyl)but-2-enyl]isobenzofuran-1(3H)-one (2).