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Noble gas compounds are chemical compounds that include an element from the noble gases, group 18 of the periodic table. Although the noble gases are generally unreactive elements, many such compounds have been observed, particularly involving the element xenon. From the standpoint of chemistry, the noble gases may be divided into two groups: the relatively reactive krypton, xenon (12.1 eV), and radon (10.7 eV) on one side, and the very unreactive argon (15.8 eV), neon (21.6 eV), and helium (24.6 eV) on the other. Consistent with this classification, Kr, Xe, and Rn form compounds that can be isolated in bulk at or near standard temperature and pressure, whereas He, Ne, Ar have been observed to form true chemical bonds using spectroscopic techniques, but only when frozen into a noble gas matrix at temperatures of 40 K or lower, in supersonic jets of noble gas, or under extremely high pressures with metals.
The Heck reaction is the chemical reaction of an unsaturated halide with an alkene in the presence of a base and a palladium catalyst to form a substituted alkene. It is named after Tsutomu Mizoroki and Richard F. Heck. Heck was awarded the 2010 Nobel Prize in Chemistry, which he shared with Ei-ichi Negishi and Akira Suzuki, for the discovery and development of this reaction. This reaction was the first example of a carbon-carbon bond-forming reaction that followed a Pd(0)/Pd(II) catalytic cycle, the same catalytic cycle that is seen in other Pd(0)-catalyzed cross-coupling reactions. The Heck reaction is a way to substitute alkenes.
The Suzuki reaction is an organic reaction, classified as a cross-coupling reaction, where the coupling partners are a boronic acid and an organohalide and the catalyst is a palladium(0) complex. It was first published in 1979 by Akira Suzuki, and he shared the 2010 Nobel Prize in Chemistry with Richard F. Heck and Ei-ichi Negishi for their contribution to the discovery and development of palladium-catalyzed cross-couplings in organic synthesis. This reaction is also known as the Suzuki–Miyaura reaction or simply as the Suzuki coupling. It is widely used to synthesize polyolefins, styrenes, and substituted biphenyls. Several reviews have been published describing advancements and the development of the Suzuki reaction. The general scheme for the Suzuki reaction is shown below, where a carbon-carbon single bond is formed by coupling an organoboron species (R1-BY2) with a halide (R2-X) using a palladium catalyst and a base.
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Xenon hexafluoride is a noble gas compound with the formula XeF6. It is one of the three binary fluorides of xenon, the other two being XeF2 and XeF4. All known are exergonic and stable at normal temperatures. XeF6 is the strongest fluorinating agent of the series. It is a colorless solid that readily sublimes into intensely yellow vapors.
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The Buchwald–Hartwig amination is a chemical reaction used in organic chemistry for the synthesis of carbon–nitrogen bonds via the palladium-catalyzed coupling reactions of amines with aryl halides. Although Pd-catalyzed C-N couplings were reported as early as 1983, Stephen L. Buchwald and John F. Hartwig have been credited, whose publications between 1994 and the late 2000s established the scope of the transformation. The reaction's synthetic utility stems primarily from the shortcomings of typical methods for the synthesis of aromatic C–N bonds, with most methods suffering from limited substrate scope and functional group tolerance. The development of the Buchwald–Hartwig reaction allowed for the facile synthesis of aryl amines, replacing to an extent harsher methods while significantly expanding the repertoire of possible C–N bond formation.
The Schiemann reaction is a chemical reaction in which a primary aromatic amine is transformed to an aryl fluoride via a diazonium tetrafluoroborate intermediate. This reaction is a traditional route to fluorobenzene and some related derivatives, including 4-fluorobenzoic acid.
A hexafluoride is a chemical compound with the general formula QXnF6, QXnF6m−, or QXnF6m+. Many molecules fit this formula. An important hexafluoride is hexafluorosilicic acid (H2SiF6), which is a byproduct of the mining of phosphate rock. In the nuclear industry, uranium hexafluoride (UF6) is an important intermediate in the purification of this element.
Palladium(II) fluoride, also known as palladium difluoride, is the chemical compound of palladium and fluorine with the formula PdF2.
Palladium(II,IV) fluoride, also known as palladium trifluoride, is a chemical compound of palladium and fluorine. It has the empirical formula PdF3, but is better described as the mixed-valence compound palladium(II) hexafluoropalladate(IV), PdII[PdIVF6], and is often written as Pd[PdF6] or Pd2F6.
Palladium(IV) fluoride, also known as palladium tetrafluoride, is the chemical compound of palladium and fluorine with the chemical formula PdF4. The palladium atoms in PdF4 are in the +4 oxidation state.
Neptunium(VI) fluoride (NpF6) is the highest fluoride of neptunium, it is also one of seventeen known binary hexafluorides. It is an orange volatile crystalline solid. It is relatively hard to handle, being very corrosive, volatile and radioactive. Neptunium hexafluoride is stable in dry air but reacts vigorously with water.
In organic and organometallic chemistry, dialkylbiaryl phosphine (or dialkylbiarylphosphine) ligands are phosphorus-containing supporting ligands that are used to modulate the chemical reactivity of palladium and other transition metal based catalysts. They were first described by Stephen L. Buchwald in 1998 for applications in palladium-catalyzed coupling reactions to form carbon-nitrogen and carbon-carbon bonds. Before their development, use of first- or second-generation phosphine ligands for palladium-catalyzed C-N bond-forming cross-coupling (e.g., tris(o-tolyl)phosphine and BINAP, respectively) necessitated harsh conditions, and the scope of the transformation was severely limited. The Suzuki-Miyaura and Negishi cross-coupling reactions were typically performed with Pd(PPh3)4 as catalyst and were mostly limited to aryl bromides and iodides at elevated temperatures, while the widely available aryl chlorides were unreactive. The development of new classes of ligands was needed to address these limitations.
References
- ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 1152–1153. ISBN 978-0-08-037941-8.
- ↑ Aullón, G.; Alvarez, S. (2007). "On the Existence of Molecular Palladium(VI) Compounds: Palladium Hexafluoride". Inorg. Chem. 46 (7): 2700–2703. doi:10.1021/ic0623819. PMID 17326630.
- ↑ Grushin, V. V. (2002). "Palladium Fluoride Complexes: One More Step toward Metal-Mediated C-F Bond Formation". Chem. Eur. J. 8 (5): 1006–1014. doi:10.1002/1521-3765(20020301)8:5<1006::AID-CHEM1006>3.0.CO;2-M. PMID 11891886.
- ↑ Watson, D. A.; Su, M.; Teverovskiy, G.; Zhang, Y.; García-Fortanet, J.; Kinzel, T.; Buchwald, S. L. (2009). "Formation of ArF from LPdAr(F): Catalytic Conversion of Aryl Triflates to Aryl Fluorides". Science . 325 (5948): 1661–1664. Bibcode:2009Sci...325.1661W. doi:10.1126/science.1178239. PMC 3038120 . PMID 19679769.
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