Representative model compounds for understanding the pyrolytic behavior of pre-oxidized β-ether-type lignin

To achieve a better understanding of the pyrolysis behavior of pre-oxidized β-ether-type lignin, three Cα=O type dimers with different substituent groups on the aromatic ring were synthesized and analyzed by a simultaneous thermal analysis instrument (STA), in-situ Fourier transform infrared spectroscopy (in-situ FTIR), and pyrolysis-gas chromatography/ mass spectrometry (Py-GC/MS). The results showed that major primary pyrolysis reactions of Cα=O type models normally occurred at 200 to 400 °C, and connecting bridge structures of models were completely destroyed, causing the emission of abundant volatiles. Substituent groups of aromatic rings played direct roles in thermal stability of models, volatiles emission, product characteristics, and secondary reaction pathways of major primary products. Particularly, the aryl–OCH3 group clearly enhanced the reactivity of intramolecular linkages and was an important active functional group for secondary reactions. As major primary products and intermediates, guaiacol and 2-methoxy-benzaldehyde were formed via the cleavage of Cα–O and Cα–Cβ bonds and could also be converted into phenol, benzaldehyde, and 2-methylphenol via rearrangement of aryl–OCH3 into an aryl–CH3 group or –OCH3 group removal. Oxidization of benzylic alcohol to benzylic ketone not only simplified depolymerization pathways, but also resulted in better selectivity of phenolic monomers and a predictable product distribution.

Inclusion Complexation of Benzanilide and Fast Violet B with β-cyclodextrin-A Theoretical Approach

The theoretical investigation of inclusion complexation of amide-imidol tautomer of two guest molecules benzanilide (BA) and fast violet B (FVB) with β-cyclodextrin (β-CD) using DFT B3LYP 3-21G method in the gas phase. Benzanilide has no substitution in the basic skeleton and the other selected compound substituted with three groups such as –NH2, -CH3 and –OCH3 group in the same aromatic ring. The tautomer of two selected compounds was formed the stable inclusion complexes with the β-CD supramolecule. The theoretically calculated complexation energy was observed the negative value for all the inclusion complexes. This method was applicable to determine the structural assignment of the inclusion complexes between BA, FVB and β-CD.