Search results for "Halogen"
showing 10 items of 434 documents
Cross-Metathesis Reactions as an Efficient Tool in the Synthesis of Fluorinated Cyclic β-Amino Acids
2009
The synthesis of enantiomerically pure, cyclic, gamma,gamma-difluorinated beta-amino acids with various ring sizes has been carried out with a cross-metathesis (CM) reaction being one of the key steps, followed by a Dieckmann-type condensation to bring about the cyclization. Subsequent catalytic hydrogenation under microwave irradiation with (-)-8-phenylmenthol as a chiral auxiliary led to the successful chemo- and diastereoselective chemical reduction of the resulting cyclic beta-enamino esters. The efficiency and scope of the CM reaction with different types of fluorinated imidoyl chlorides and unsaturated esters has also been studied in order to determine the optimal reaction conditions …
Halogen-bonded solvates of tetrahaloethynyl cavitands
2017
The formation and structures of halogen-bonded solvates of three different tetrahaloethynyl cavitands with acetone, chloroform, acetonitrile, DMF and DMSO were prepared and investigated. The inclusion and host–guest behaviour of the resorcinarene cavitands was found to be highly dependent on the flexibility of the ethylene-bridging unit.
Ab initio study of halogenated diphenyl ethers. NMR chemical shift prediction
2000
Analyses of known and new types of polyhalogenated aromatic substances in oven ash from recycled aluminium production
2003
Abstract Persistent aromatic bromine, chlorine and mixed chlorine-bromine compounds were analysed from recycled aluminium smelter (ALS) ashes to explore the impact of brominated flame retardants (BFR) on their formation. Polybrominated diphenyl ethers (PBDE) were the most abundant original BFRs found. Induction furnace ash contained tetra- to octa-BDEs about 2000 ng g −1 in similar congener ratios as the original scrap, but contents of nona- and deca-BDEs were only 25 and 5 ng g −1 indicating their significant degradation in ALS process. In the most non-polar fraction, PCB levels and profiles were similar as earlier ALS ash samples in 1990s. The highest PCB level measured was that of deca-C…
Structure and Sensory Analyses of Tainting Substances in Finnish Freshwater Environments
1988
GC/MS/SNIFF/TASTE methods have been used in Finland to identify the causes of three tainting problems in water and one in fish nets. Structure determination was often verified by comparison with authentic compounds. Algal growth was implicated to be the source of geosmin and MIB in river water in Northern Finland and was associated with the appearance of tainting problems in raw water and reservoir water in Åland county. Terpenoids (e.g. camphor), degradation products of natural lipids (e.g. aldehydes, ketones and unsaturated aliphatic compounds) and volatile organohalogen compounds were frequently found in contaminated water but showed minor tainting effects compared to geosmin and MIB. Di…
Formation and distortion of iodidoantimonates(III): the first isolated [SbI6]3- octahedron
2017
The ability to intentionally construct, through different types of interactions, inorganic–organic hybrid materials with desired properties is the main goal of inorganic crystal engineering. The primary deformation, related to intrinsic interactions within inorganic substructure, and the secondary deformation, mainly caused by the hydrogen bond interactions, are both responsible for polyhedral distortions of halogenidoantimonates(III) with organic cations. The evolution of structural parameters, in particular the Sb—I secondary- and O/N/C—H...I hydrogen bonds, as a function of temperature assists in understanding the contribution of those two distortion factors to the irregularity of [SbI6]…
ChemInform Abstract: Enantioselective Palladium-Catalyzed Oxidative β,β-Fluoroarylation of α,β-Unsaturated Carbonyl Derivatives.
2016
The site-selective palladium-catalyzed three-component coupling of deactivated alkenes, arylboronic acids, and N-fluorobenzenesulfonimide is disclosed herein. The developed methodology establishes a general, modular, and step-economical approach to the stereoselective β-fluorination of α,β-unsaturated systems.
Relativistic DFT Calculation of (119)Sn Chemical Shifts and Coupling Constants in Tin Compounds.
2006
The nuclear shielding and spin-spin coupling constants of (119)Sn in stannane, tetramethylstannane, methyltin halides Me4-nSnXn (X = Cl, Br, I; n = 1-3), tin halides, and some stannyl cations have been investigated computationally by DFT methods and Slater all-electron basis sets, including relativistic effects by means of the zeroth order regular approximation (ZORA) method up to spin-orbit coupling. Calculated (119)Sn chemical shifts generally correlate well with experimental values, except when several heavy halogen atoms, especially iodine, are bound to tin. In such cases, calculated chemical shifts are almost constant at the scalar (spin-free) ZORA level; only at the spin-orbit level i…
ChemInform Abstract: Halogen-Bonded Supramolecular Complexes and Networks
2009
In spite of some controversy of the true nature of the interaction between polarized halogen atoms and neutral or charged Lewis bases, termed “halogen bonding”, as a primary interaction, it is a very useful new tool/way to construct supramolecular complexes and networks. This is especially true in solid state supramolecular chemistry where utilization of weak intermolecular interactions such as halogen bonding opens up new insights to materials design and supramolecular synthesis.