25778-04-5Relevant articles and documents
Transformation of one of two C≡N groups of o-dicyanobenzene in the presence of cyanoguanidine. Crystal and gas-phase structure of 2-(2′-cyanophenyl)-4,6-diamino-1,3,5-triazine
Janczak, Jan,Kubiak, Ryszard
, p. 60 - 69 (2005)
The transformation of one C≡N group in o-dicyanobenzene in the presence of cyanoguanidine yielding the melaminium derivative in crystalline form has been performed. In the final step of the closing of 1,3,5-triazined ring both hydrogen atoms of one amine
A Facile Synthesis of Pd–C3N4@Titanate Nanotube Catalyst: Highly Efficient in Mizoroki–Heck, Suzuki–Miyaura C–C Couplings
Velpula, Venkata Ramana Kumar,Ketike, Thirupathaiah,Paleti, Gidyonu,Kamaraju, Seetha Rama Rao,Burri, David Raju
, p. 95 - 105 (2019/11/03)
Abstract: A Pd–C3N4@titanate nanotube (Pd–C3N4@TNT) catalyst workable in water medium, robust against leaching and agglomeration was prepared in a facile synthetic procedure using quite common chemicals such as TiO2 powder, urea and palladium acetate. The Pd–C3N4@TNT catalyst has been characterized by BET surface area and pore size distribution, X-ray diffraction, solid-state 13C NMR spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The Pd–C3N4@TNT is a green catalyst for the Miziroki–Heck and Suzuki–Miyaura C–C coupling reactions in water medium with high efficiency (??99% product yields) due to atomic level immobilization of Pd in C3N4 networked titanate nanotubes. Pd–C3N4@TNT is robust against leaching and agglomeration due to stable and furthermore it is recyclable and usable at least for five repeated cycles. The use of water as solvent, absence of leaching and agglomeration, recyclability and reusability ascertains the greenness of Pd–C3N4@TNT) catalyst and process. Graphic Abstract: Novel Pd–C3N4@titanate nanotube catalyst prepared from bulk TiO2 and urea by simple hydrothermal and thermal pyrolysis followed by immobilization of Pd is active and selective for Mizoroki–Heck, Suzuki–Miyaura C–C couplings in water medium.[Figure not available: see fulltext.].
Prebiotic Origin of Pre-RNA Building Blocks in a Urea “Warm Little Pond” Scenario
Menor Salván,Bouza, Marcos,Fialho, David M.,Burcar, Bradley T.,Fernández, Facundo M.,Hud, Nicholas V.
, p. 3504 - 3510 (2020/10/02)
Urea appears to be a key intermediate of important prebiotic synthetic pathways. Concentrated pools of urea likely existed on the surface of the early Earth, as urea is synthesized in significant quantities from hydrogen cyanide or cyanamide (widely accepted prebiotic molecules), it has extremely high water solubility, and it can concentrate to form eutectics from aqueous solutions. We propose a model for the origin of a variety of canonical and non-canonical nucleobases, including some known to form supramolecular assemblies that contain Watson-Crick-like base pairs.The dual nucleophilic-electrophilic character of urea makes it an ideal precursor for the formation of nitrogenous heterocycles. We propose a model for the origin of a variety of canonical and noncanonical nucleobases, including some known to form supramolecular assemblies that contain Watson-Crick-like base pairs. These reactions involve urea condensation with other prebiotic molecules (e. g., malonic acid) that could be driven by environmental cycles (e. g., freezing/thawing, drying/wetting). The resulting heterocycle assemblies are compatible with the formation of nucleosides and, possibly, the chemical evolution of molecular precursors to RNA. We show that urea eutectics at moderate temperature represent a robust prebiotic source of nitrogenous heterocycles. The simplicity of these pathways, and their independence from specific or rare geological events, support the idea of urea being of fundamental importance to the prebiotic chemistry that gave rise to life on Earth.
