RESUMEN
Triruthenium dodecacarbonyl (Ru3(CO)12) was applied to prepare the Ru-based ammonia synthesis catalysts. The catalyst obtained from this precursor exhibited higher activity than the other Ru salts owing to its unique atomic reorganization under mild temperatures. Herein, Ru3(CO)12 as a guest metal source incorporated into the pore of ZIF-8 formed the Ru@N-C catalysts. The results indicated that the Ru nanoparticle (1.7 nm) was dispersed in the confined N coordination environment, which can increase the electron density of the Ru nanoparticles to promote N[triple bond, length as m-dash]N bond cleavage. The promoters donate the basic sites for transferring the electrons to Ru nanoparticles, further enhancing ammonia synthesis activity. Ammonia synthesis investigations revealed that the obtained Ru@N-C catalysts exhibited obvious catalytic activity compared with the Ru/AC catalyst. After introducing the Ba promoter, the 2Ba-Ru@N-C(450) catalyst exhibited the highest ammonia synthesis activity among the catalysts. At 360 °C and 1 MPa, the activity of the 2Ba-Ru@N-C(450) is 16 817.3 µmol h-1 gRu-1, which is 1.1, 1.6, and 2 times higher than those of 2Cs-Ru@N-C(450) (14 925.4 µmol h-1 gRu-1), 2K-Ru@N-C(450) (10 736.7 µmol h-1 gRu-1), and Ru@N-C(450) (8604.2 µmol h-1 gRu-1), respectively. A series of characterizations were carried out to explore the 2Ba-Ru@N-C(450) catalysts, such as H2-TPR, XPS, and NH3-TPD. These results suggest that the Ba promoter played the role of an electronic and structural promoter; moreover, it can promote the NH3 desorption from the Ru nanoparticles.
RESUMEN
A palladium-catalyzed aryl C-H bonds activation/acetoxylation reaction utilizing a bidentate system has been explored. This transformation has been applied to a wide array of pyridine and 8-aminoquinoline derivatives and it exhibits excellent functional group tolerance.
RESUMEN
A novel and convenient Pd(0)-catalyzed carboannulation with propargylic compounds for the synthesis of highly substituted aromatic amine derivatives in a one-pot operation was developed. In this process, a significant breakthrough in aminobenzannulation is observed. Moreover, the reaction appears to be very general and suitable for a variety of amines.
RESUMEN
A new and efficient synthesis of indene and benzo[b]furan derivatives has been achieved via Pd-catalyzed carboannulation of propargyl carbonates with nucleophiles in good to excellent yields with high regio- and stereoselectivity. A novel sequence of nucleophilic attack is observed, and a possible mechanism is proposed.
RESUMEN
We have disclosed a very nice advance of nickel(II)-catalyzed carboannulation reactions. Highly substituted indene derivatives are readily prepared in moderate to excellent yields under very mild reaction conditions in air via a nickel(II)-catalyzed cyclization of propargylic compounds with soft nucleophiles.
Asunto(s)
Alquinos/química , Indenos/síntesis química , Níquel/química , Catálisis , Ciclización , Indenos/química , Estructura Molecular , EstereoisomerismoRESUMEN
Indene derivatives including an allene functional group are readily prepared in moderate to excellent yields with high regioselectivity under very mild reaction conditions by the Pd/C-catalyzed reaction of propargylic compounds. The resulting products can be further elaborated using Pd-catalyzed annulation reactions.
RESUMEN
[reaction: see text] Indene or naphthalene derivatives are readily prepared in moderate to excellent yields with high regio- and stereoselectivity under very mild reaction conditions by the reaction of acetylenic malonates and ketones with I2, ICl, or NIS. The resulting iodides can be further elaborated using palladium-catalyzed coupling reactions.