Search results for "Halogen"
showing 10 items of 434 documents
Halogen‐Imparted Reactivity in Lithium Carbenoid Mediated Homologations of Imine Surrogates: Direct Assembly of bis‐Trifluoromethyl‐β‐Diketiminates a…
2020
The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamidoyl chlorides (TFAICs) units is reported. The tactic is levered on a highly chemoselective homologation-metalation-acyl nucleophilic substitution sequence which precisely enables to assemble novel trifluoromethylated β-diketiminates within a single synthetic operation. Unlike previous homologations conducted with LiCH2Cl furnishing aziridines, herein we exploit the unique capability of iodomethyllithium to act contemporaneously as a C1 source (homologating effect) and metalating agent. The mechanistic rationale grounded on experimental evidences supports the hypothesized proposal and, the struct…
The preparation of (14C) and [3H] labelled benzene oxide
1977
Benzene oxide -[U-14C] was prepared from benzene -(U-14C) by modifications of methods described for the inactive compound. Benzene oxide-[3.6–3H] was prepared by decomposition of 3.6-bis-trimethylsilyl-1,4-cyclohexadiene with tritiated water. bromination of the 1,4-cyclohexadiene-[3,6-3H] so obtained. epoxidation and dehydrobromination. With the latter method benzene oxide-[3,6–3H] can be prepared at a much lower cost and higher specific activity than benzene oxide-[U-14C].
Metal-Free and User-Friendly Regioselective Hydroxyfluorination of Olefins
2018
A simple, user-friendly, metal-free protocol for the regioselective anti-Markovnikov hydrofluorination of olefins using readily available and inexpensive reagents has been developed. This new approach displays a broader scope than previously reported methodologies and has been applied to the late-stage fluorination of a complex molecule, giving rise to a fluorosteroid derivative. The stereochemistry of the process has also been studied in some detail.
Halogen bonding interactions with the [Mo3S7Cl6]2-cluster anion in the mixed valence salt [EDT-TTFI2]4[Mo3S7Cl6]oCH3CN
2008
Electrocrystallization of iodinated TTF molecules in presence of trinuclear [Mo3S7Cl6]2- cluster anions provides the first example of radical salts with halogen bonding interactions at the organic/inorganic interface
When Does Gold Behave as a Halogen? Predicted Uranium Tetraauride and Other MAu4 Tetrahedral Species, (M = Ti, Zr, Hf, Th)
2003
Quantum chemical calculations suggest that a series of molecules with the general formula MAu4 are stable, where M = U, Th, and a group-4 atom. They correspond to Au in the formal valence state -1 and indicate that gold can act as a ligand similar to the halogen series. Of the MAu4 species studied, UAu4, the first predicted mixed gold uranium compound, has a short M-Au bond distance, 2.71 A, which would locate Au between Br and I from the bond length point of view in the U-tetrahalide series. Energetically, the U-Au bond is weaker than the corresponding U-Br and U-I bonds.
A tight-binding potential for the simulation of solid and liquid iodine
2003
In this work, we suggest an interatomic potential for iodine applicable to the simulation of the condensed phases of the halogen within the temperature and density range accessible to experiments. The potential includes an attractive term that is partitioned into directional chemical bonding with a many-particle character and a pairwise interaction. Despite its simplicity, the potential reproduces the crystal structure of solid iodine, the presence of atomic phases with increasing pressure, and the metallic or insulating character of the solid phases. Finally, we present preliminary simulation results for fluid iodine.
Global sea-to-air flux climatology for bromoform, dibromomethane and methyl iodide
2013
Volatile halogenated organic compounds containing bromine and iodine, which are naturally produced in the ocean, are involved in ozone depletion in both the troposphere and stratosphere. Three prominent compounds transporting large amounts of marine halogens into the atmosphere are bromoform (CHBr3), dibromomethane (CH2Br2) and methyl iodide (CH3I). The input of marine halogens to the stratosphere has been estimated from observations and modelling studies using low-resolution oceanic emission scenarios derived from top-down approaches. In order to improve emission inventory estimates, we calculate data-based high resolution global sea-to-air flux estimates of these compounds from surface ob…
Effect of cropping cycles and repeated herbicide applications on the degradation of diclofop-methyl, bentazone, diuron, isoproturon and pendimethalin…
2002
A greenhouse study was conducted to investigate the ability of four crops (wheat, corn, oilseed rape and soybean) to influence the degradation of bentazone, diclofop-methyl, diuron, isoproturon and pendimethalin in soil. The present study showed that microbial biomass-carbon was significantly higher in planted soils than in bulk soil, especially with wheat and corn, after several cropping cycles. The biomass in corn and soybean planted soils was adversely affected by bentazone but recovered after three cropping cycles. In wheat-planted soils, diclofop-methyl application resulted in persistent increase of the amount of microbial biomass. Bentazone did not show accelerated degradation even af…
Reactive and organic halogen species in three different European coastal environments
2005
We present results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy) for the study of reactive halogen species (RHS) BrO, IO, OIO and I2. Two recent field campaigns took place in Spring 2002 in Dagebüll at the German North Sea Coast and in Spring 2003 in Lilia at the French Atlantic Coast of Brittany. In addition, data from a campaign in Mace Head, Ireland in 1998 was partly re-evaluated. During the recent field campaigns volatile halogenated organic compounds (VHOCs) were determined by a capillary gas chromatograph coupled with an electron capture detector and an inductively coupled plasma mass spectrometer (GC/ECD-ICPMS) in air and wat…
Breakthrough in the α-Perchlorination of Acyl Chlorides
2012
The preparation of -perchloroacyl chlorides, from reaction of the corresponding unfunctionalized acyl halides with chlorine, was efficiently achieved under base-catalysis, using a tetraalkylammonium chloride as catalyst. The process is solvent-free and the procedure is easy, inexpensive, and suitable for scale-up.