Effect of slow pyrolysis conditions on biocarbon yield and properties: Characterization of the volatiles

Slow pyrolysis of spruce and birch was performed at various heating programs and conditions in a horizontal quartz tube reactor heated by an electric furnace. The effects of feedstock and carbonization conditions on the yield of biocarbon, liquid and gaseous products were studied. The thermal properties, volatile matter (VM) content and the evolution profiles of volatiles from the biocarbons were characterized by thermogravimetry/mass spectrometry. The composition of volatiles was analyzed in detail by pyrolysis-gas chromatography/mass spectrometry. Increased char yield was observed when staged pyrolysis program, low purging flow rate or covered sample holder were applied. Spruce produced more charcoal than birch due to the higher lignin content of softwood. The amount and the evolution profiles of the main gaseous products were similar from spruce and birch biocarbons prepared under the same conditions. The relative amount of aromatic and polyaromatic compounds in VM drastically decreased with increasing carbonization temperature.

Understanding and Exploitation of Neighboring Heteroatom Effect for the Mild N-Arylation of Heterocycles with Diaryliodonium Salts under Aqueous Conditions: A Theoretical and Experimental Mechanistic Study

The mechanism of arylation of N-heterocycles with unsymmetric diaryliodonium salts is elucidated. The fast and efficient N-arylation reaction is interpreted in terms of the bifunctionality of the substrate: The consecutive actions of properly oriented Lewis base and Brønsted acid centers in sufficient proximity result in the fast and efficient N-arylation. The mechanistic picture points to a promising synthetic strategy where suitably positioned nucleophilic and acidic centers enable functionalization, and it is tested experimentally.