Electroreductive synthesis of polyfunctionalized pyridin-2-ones from acetoacetanilides and carbon disulfide with oxygen evolution

A chemical reductant or a sacrificial electron donor is required in any reduction reaction, generally resulting in undesired chemical wastes. Herein, we report a reductant-free reductive [3+2+1] annulation of β-keto...

Synthesis of Alicyclic 2-Methylenethiazolo[2,3-b]quinazolinone Derivatives via Base-Promoted Cascade Reactions

The synthesis of alicyclic 2-methylenethiazolo[2,3-b]quinazo­l­inones is performed via base-promoted cascade reactions, starting from either alicyclic β-amino propargylamides using carbon disulfide, or from alicyclic ethyl 2-isothiocyanatocarboxylates by addition of propargylamine. In both cases the cascade reaction proceeds by way of a favoured 5-exo-dig process during the second ring closure, as confirmed by full NMR spectroscopic assignments. Moreover, a high-yielding retro­-Diels–Alder (RDA) reaction is performed on the norbornene derivatives leading to 2-methylene-2H-thiazolo[3,2-a]pyrimidin-5(3H)-ones. The obtained compounds exert modest antiproliferative activities against a panel of human gynaecological cancer cell lines.

Pyrolysis kinetic analysis of sequential extract residues from Hefeng sub-bituminous coal based on Coats-Redfern method

Sequential extract residues (Ri, i=1, 2, 3, 4, 5) were obtained from Hefeng acid-washing coal (HFAC) by petroleum ether, carbon disulfide, methanol, acetone and isometric carbon disulfide/acetone mixture, sequentially. Pyrolysis behavior of the samples was carried out using thermogravimetry analysis. Coats-Redfern method with different reaction order was used to analyze the pyrolysis kinetic of each sample, and the kinetic parameters, including correlation coefficient (R2), activation energy (E), pre-exponential factor (A), were calculated. Results showed that the weight loss of extract residues was higher than HFAC, and pyrolysis behavior varies greatly for residues, which may be due to unstable structure after extraction. From conversion-temperature (α-T) curves, pyrolysis process was divided into three stages: low-temperature stage (150-350 oC), medium temperature stage (350-550 oC) and high temperature stage (550-950 oC). And the medium temperature stage made great contribution to the process of pyrolysis, which was dominated by depolymerization and decomposition reaction, and the effect of kinetic fitting to this stage is better, with R2 higher than 0.95. Relationship between kinetic parameters and reaction order showed that swelling effect might be an important reason for the discrepancy of E for each sample in the process of pyrolysis. And Ln(A)-E relationship has a great significance to predict E and the A under higher reaction order.

Warm Plasma Application in Tar Conversion and Syngas Valorization: The Fate of Hydrogen Sulfide

Warm plasma techniques are considered a promising method of tar removal in biomass-derived syngas. The fate of another problematic syngas impurity—hydrogen sulfide—is studied in this work. It is revealed that processing simulated syngas with a microwave plasma results in hydrogen sulfide conversion. For different gas flow rates (20–40 NLPM) and hydrogen sulfide concentrations ranging from 250 ppm to 750 ppm, the conversion rate varies from ca. 26% to 45%. The main sulfur-containing products are carbon disulfide (ca. 30% of total sulfur) and carbonyl sulfide (ca. 8% of total sulfur). Besides them, significantly smaller quantities of sulfates and benzothiophene are also detected. The main components of syngas have a tremendous impact on the fate of hydrogen sulfide. While the presence of carbon monoxide, methane, carbon dioxide, and tar surrogate (toluene) leads to the formation of carbonyl sulfide, carbon disulfide, sulfur dioxide, and benzothiophene, respectively, the abundance of hydrogen results in the recreation of hydrogen sulfide. Consequently, the presence of hydrogen in the simulated syngas is the main factor that determines the low conversion rate of hydrogen sulfide. Conversion of hydrogen sulfide into various sulfur compounds might be problematic in the context of syngas purification and the application of the right technique for sulfur removal.