Spectroscopic study of the phase transitions of copper(II) n-alkanoates
摘要:
FTIR spectra of copper nonanoate, decanoate, undecanoate and dodecanoate are recorded every 5 K from room temperature to 390 K. Changes detected in the infrared spectra when heating the sample allow the heat absorptions observed in some of these samples prior to the transition to the mesophase to be explained as due to conformational changes taking place in the alkyl chain next to the carboxylate group. Low frequency infrared and Raman spectra are consistent with a D-4h geometry for the ionic core where the copper ions are located. Moreover, the study of the low frequency region at the temperature of the mesophase permit the detection of rearrangements around the central core in the transition from the crystal to the mesophase.
General base-tuned unorthodox synthesis of amides and ketoesters with water
作者:Saikat Khamarui、Rituparna Maiti、Dilip K. Maiti
DOI:10.1039/c4cc07961b
日期:——
We discovered a highly reactive λ3-hypervalent iodane species using an inorganic/organic base for the unorthodox synthesis of amides and ketoesters through grafting terminal alkynes. In contrast to the metal-catalyzed dehydrative approaches the in situ generated nonmetallic reagent efficiently created C–N/C–O and CO bonds with amines/alkynes and water at rt.
Lead(<scp>ii</scp>) soaps: crystal structures, polymorphism, and solid and liquid mesophases
作者:F. J. Martínez-Casado、M. Ramos-Riesco、J. A. Rodríguez-Cheda、M. I. Redondo-Yélamos、L. Garrido、A. Fernández-Martínez、J. García-Barriocanal、I. da Silva、M. Durán-Olivencia、A. Poulain
DOI:10.1039/c7cp02351k
日期:——
phases and mesophases. The crystal structures at room temperature of all of the members of the series are now solved, showing the existence of two polymorphic forms in the room temperature crystal phase, different to short and long-chain members. Only nonanoate and decanoate present both forms, and this polymorphism is proven to be monotropic. At higher temperature, these compounds present a solid mesophase
This disclosure provides for new catalyst systems and new methods for preparing and using the catalyst systems for generating a trimerization product. In an aspect, the new catalyst systems comprise a chromium carboxylate that is prepared by anhydrous metathesis. In another aspect, the catalyst system comprise a chromium carboxylate that is prepared by anhydrous metathesis and a metal pyrrolide compound. The catalyst systems imparts improved performance and/or reduced catalyst system cost to an olefin trimerization process.
This disclosure provides a process for making transition metal carboxylate compositions by combining in an polar aprotic first solvent a transition metal precursor and a Group 1 or Group 2 metal carboxylate under substantially acid-free and substantially anhydrous conditions, to generate a mixture comprising the transition metal carboxylate composition. Optionally, the transition metal carboxylate composition can be purified, for example, by substantially removing the first solvent provide a residue comprising the transition metal carboxylate composition, and also optionally, further by extracting the transition metal carboxylate composition from the residue with a non-coordinating second solvent to provide an extract comprising the transition metal carboxylate composition.