The
increase of alumina calcination temperature from 800 °C
to 1300 °C results in the transformation of γ-Al2O3 to α-Al2O3 phase accompanying
a decrease of specific surface area and the amount of tetrahedral
Al3+ sites. Over Ru–Ba/alumina catalysts, an increase
in alumina calcination temperature would broaden the size distribution
of Ru particles, enlarge the metal-to-oxide ratio of Ru, decrease
the amount of surface hydroxyl groups, as well as lower the temperature
for N2 desorption. As a result, the increase of alumina
calcination temperature lessens the effect of hydrogen poisoning and
decreases the activation energy for ammonia synthesis. The Ru–Ba/Al2O3 catalyst with alumina calcined at 980 °C
having both θ-Al2O3 and α-Al2O3 shows ammonia synthesis rate three times higher
than that with alumina calcined at 800 °C having a γ-Al2O3 phase.
Diaryl thioethers and S-cycles were obtained on the basis of the copper-catalyzed reaction of carbon disulfide and aryl iodides in the presence of DBU. This reaction enables the one-pot synthesis of diaryl thioethers by employing cheap, available, and easy-to-handle carbon disulfide with aryl iodides. The reaction was successfully employed in the construction of sulfur-containing cyclic molecules.
The reaction of arylisothiocyanate, alkyltriflate, and alkynes leads to variously substituted quinolines in high yields. The reaction undergoes alkyltriflate-triggered domino electrophilic activation and avoids the use of a transition-metal catalyst. A variety of functional groups are tolerated in the quinoline ring.
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