scholarly journals Isolation and X-ray characterization of palladium–N complexes in the guanylation of aromatic amines. Mechanistic implications

2013 ◽  
Vol 9 ◽  
pp. 1455-1462 ◽  
Author(s):  
Abdessamad Grirrane ◽  
Hermenegildo Garcia ◽  
Eleuterio Álvarez
Keyword(s):  
Aromatic Amines ◽  
Palladium Complexes ◽  
Reaction Conditions ◽  
X Ray ◽  
Palladium Catalyzed

In the context of palladium-catalyzed guanylation of anilines herein, we have been able to characterize and isolate bis(anilino) and bis(guanidino)Pd(II) complexes using reaction conditions under which stoichiometric amounts of palladium salts are used. Characterization of these palladium complexes strongly supports a mechanistic proposal for the catalytic guanylation of anilines using PdCl2(NCCH3)2 as catalyst that involves the intermediacy of these Pd(II) complexes.

Synthesis and Solid State and Solution Characterization of Mono- and Di-(η1-C) Carbamoyl−Palladium Complexes. New Efficient Palladium-Catalyzed Routes to Carbamoyl Chlorides:  Key Intermediates to Isocyanates, Carbamic Esters, and Ureas

2000 ◽  
Vol 19 (19) ◽  
pp. 3879-3889 ◽  
Author(s):  
Michele Aresta ◽  
Potenzo Giannoccaro ◽  
Immacolata Tommasi ◽  
Angela Dibenedetto ◽  
Anna Maria Manotti Lanfredi ◽  
...  
Keyword(s):  
Solid State ◽  
Palladium Complexes ◽  
Palladium Catalyzed ◽  
Carbamic Esters

Synthesis and characterization of the solid uranium(VI) dioxo-diacetohydroxamate complex

2007 ◽  
Vol 95 (8) ◽  
Author(s):  
Cynthia-May S. Gong ◽  
Frédéric Poineau ◽  
Kenneth R. Czerwinski
Keyword(s):  
Solid Phase ◽  
Uranyl Acetate ◽  
Proton Nuclear Magnetic Resonance ◽  
Acetohydroxamic Acid ◽  
Acetate Dihydrate ◽  
Reaction Conditions ◽  
X Ray ◽  
Ft Ir ◽  
X Ray Absorption

A novel dry synthesis for the uranium(VI) dioxo-diacetohydroxamate (UAHA) complex has been developed. The complex was generated in >80% yield by mechanically grinding solid uranyl acetate dihydrate (UAc) with solid acetohydroxamic acid in stoichiometric amounts. The resulting UOThe UAHA solid was extensively characterized by ultraviolet-visible (UV-vis), Fourier-transform infrared (FT-IR), and extended X-ray absorption fine structure (EXAFS) spectroscopies. The compound did not fluoresce after laser excitation. Proton nuclear magnetic resonance (NMR) spectra were obtained of the complex in DThe easy synthesis and purification of UAHA enables researchers to strictly control reaction conditions; to eliminate interfering salts and water; and to study the complex in the solid-phase.

scholarly journals Synthesis and Characterization of Various Amino Acid Derived Thiohydantoins

Proceedings ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 37
Author(s):  
Petar Stanić ◽  
Marija Živković ◽  
Biljana Šmit
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Allyl Isothiocyanate ◽  
Structural Diversity ◽  
Biologically Active ◽  
Reaction Conditions ◽  
X Ray ◽  
X Ray Crystallography ◽  
Sulfur Containing

Hydantoins and their sulfur containing analogues, thiohydantoins, are cyclic ureides that have attracted huge attention ever since their discovery. Most of them are biologically active compounds and several points of structural diversity have made them very synthetically attractive. Although substituents can be introduced to the hydantoin nucleus, most substituted hydantoins are synthesized from substrates already containing these groups, while forming the hydantoin nucleus. This is a common route to the synthesis of hydantoins and one of them is employed in this study. A series of 3-allyl-2-thiohydantoins is synthesized from various α-amino acids in a reaction with allyl isothiocyanate. The substitution of the acquired thiohydantoin depends on the structure of the starting α-amino acid. The residual group of the α-amino acid becomes the substituent at the C5-position, while N-monosubstituted amino acids give rise to a substituent in the N1-position. The reaction is carried out in a two-step process and the reaction conditions generally depend on the nature of the amino acid itself. All thiohydantoins are obtained in a good yield and fully characterized by NMR and IR spectroscopy, as well as X-ray crystallography.

Synthesis and Characterization of Superparamagnetic Fe3O4 Nanoparticles

2013 ◽  
Vol 750-752 ◽  
pp. 340-343 ◽  
Author(s):  
De Hui Sun ◽  
Jiao Wu ◽  
Ji Lin Zhang
Keyword(s):  
Room Temperature ◽  
Thermal Method ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
Xrd Pattern ◽  
X Ray ◽  
Magnetic Investigation ◽  
Average Size

We synthesized Fe3O4 nanoparticles using a solvent thermal method and characterized the morphologies, structures, surface properties, thermal stability and magnetism of the products by Field emission scanning electron microscopy (FE-SEM), Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA) and vibrating sample magnetometer (VSM). The experimental results showed that the Fe3O4 nanoparticles have a tunable average size range from 55 nm to 85 nm. Their diameters decreased with increase of precursor FeCl24H2O concentration or increase of the reaction time under other reaction conditions held constant. The XRD pattern confirmed that the Fe3O4 nanoparticles belong to cubic structure. Magnetic investigation reveals that the Fe3O4 nanoparticles have higher saturation magnetization and negligible coercivity at room temperature.

The synthesis of a hexameric expanded hemiporphyrazine

2020 ◽  
Vol 24 (01n03) ◽  
pp. 129-134
Author(s):  
Briana R. Schrage ◽  
Kullapa Chanawanno ◽  
Laura A. Crandall ◽  
Christopher J. Ziegler
Keyword(s):  
Structure Elucidation ◽  
Catalytic Amount ◽  
Protonated Form ◽  
Free Base ◽  
Reaction Conditions ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Third ◽  
Expanded Porphyrins

Although the chemistry of expanded porphyrins is well developed, there has been significantly less work on expanded isoindoline based macrocycles such as hemiporphyrazines. In this report we present the synthesis and characterization of a new hexameric expanded hemiporphyrazine which we refer to as hexahemiporphyrazine. The synthesis incorporated bis(6-amino-2-pyridyl)amine as a starting material, which could be produced from 2,6-diaminopyridine using melt reaction conditions. Bis(6-amino-2-pyridyl)amine can adopt a three different conformations, two of which are observed in the free base and protonated form, and the third in the backbone of hexahemiporphyrazine. Reaction of bis(6-amino-2-pyridyl)amine and diiminoisoindoline in the presence of a catalytic amount of BF3 produces the hexihemiporphyrazine macrocycle, which was characterized spectroscopically and by X-ray crystallography. Structure elucidation reveals two inverted pyridine rings in a configuration reminiscent of that seen in hexaphyrin, however hexahemiporphyrazine lacks cross conjugation across the macrocycle.

The Preparation and Characterization of Pt/Fe Electrocatalyst for Direct Methanol Oxidation

1994 ◽  
Vol 368 ◽  
Author(s):  
Chaoying Ma ◽  
A. D. Kowalak ◽  
Changmo Sung
Keyword(s):  
Methanol Oxidation ◽  
Chemical Method ◽  
Reaction System ◽  
Pt Catalyst ◽  
Reaction Conditions ◽  
X Ray ◽  
Transmission Electron ◽  
Scan Rate ◽  
Direct Methanol

ABSTRACTPt/Fe electrocatalysts (Pt/Fe) supported on Vulcan XC-72 carbon black were prepared by chemical method. The formation of Pt/Fe clusters was confirmed by transmission electron microscopy (TEM) and energy dispersive x-ray spectrometry (EDXS). The electrochemical efficiency and durability of the catalysts for direct methanol oxidation were compared with the catalyst containing Pt only (Pt) under the same reaction conditions of 1 M CH3OH in 0.1 M H2SO4 electrolyte solution. The current density for the Pt/Fe is three times of that of the Pt catalyst. Effects of various factors on the behavior of the catalysts, such as reaction time during preparation, order of the addition of the chemicals into the reaction system, methanol concentration, activation per unit Pt, scan rate for cyclic voltammograph, were examined.

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