نتایج جستجو برای: halogens
تعداد نتایج: 2719 فیلتر نتایج به سال:
The newly measured ionization potential of atomic astatine is discussed and compared with that the recently determined value for polonium other halogens. Regularities in these values are applied to understanding energetics diatomic Some surprises remain.
Various aldoximes and ketoximes were selectively reduced to the corresponding amines by catalytic transfer hydrogenation employing low cost magnesium powder and ammonium formate at room temperature. Many other functionalities such as halogens, –OH, –OCH3, –COOH and –CH3 remained unaffected. The hydrogenation is fast, mild, clean, cost effective and high yielding.
The two most common halogenation reactions are chlorination and bromination. The addition of these halogens to alkenes yields 1,2-dihalides. Chlorinations reactions are used to synthesize over 6 million tons per year of ethylene dichloride (1,2-dichloroethane) for use as a solvent and for subsequent polymerization to produce poly(vinylchloride) known more commonly as PVC which is used for plumb...
Halides were used as the precursors to prepare various kinds of materials by stripped off the halogens. Metals, metal silicides and carbon related materials could be prepared by using metal halides, silicon halides and carbon halides as the precursors. Some active metals and active meta stable species were used as stripping reagents.
We consider the roles of heteroatoms (mainly nitrogen, the halogens and the chalcogens) in dictating the conformation of linear conjugated molecules and polymers through non-covalent intramolecular interactions. Whilst hydrogen bonding is a competitive and sometimes more influential interaction, we provide unambiguous evidence that heteroatoms are able to determine the conformation of such mate...
Addition of Grignard reagents to pyridine N-oxides in THF at low temperature (-78 to -20 degrees C) and treatment with TFAA provides an efficient general procedure for synthesis of substituted pyridines. The method is compatible with a range of functional groups such as esters, halogens and nitriles.
[1] Although there is no evidence of active volcanism on Mars today, ‘‘localized’’ outgassing sources, the hot spots, may not be ruled out. If outgassing does occur somewhere on Mars, water, carbon dioxide, sulfur species, methane, and to a lesser extent, halogens would be the likely molecules of outgassing, based on terrestrial analogs. The sulfur species, methane, and halogens have not been d...
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