- Hydrogen bonding. Part 66. Further studies of the fluoride ion assisted dissolution of 1-methyl-4,5-dicarboxyimidazole: Absence of cation participation and stoichiometric considerations
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Excess 1-methyl-4,5-dicarboxyimidazole (H2MDCI) dissolves into saturated solution in the presence of sodium fluoride, and precisely four F are required for each H2MDCI solubilized. To account for the apparent removal of two acidic hydrogens from H2MDCI in the presence of undissociated diacid we postulated strong complexation of Na+ by MDCI2-. We now find that the dissolution behavior of H2MDCI in the presence of either cesium or tetramethylammonium fluoride is identical to that with sodium fluoride. As cesium ion should bind weakly if at all to MDCI2-, and tetramethylammonium ion should not be bound, we conclude that the cation present plays no role in the fluoride ion assisted dissolution of H2MDCI. Analysis of dissolution stoichiometry and titration data suggests the possibility that two F- react with H2MDCI to form HMDCI+ and HF2/- and that two more F are required but do not act to abstract acid hydrogen.
- Harmon, Kenneth M.,LaFave, Natalie J.
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- Convenient synthesis of aliphatic (CF3)2N-compounds
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Convenient syntheses of organic compounds bearing the (CF3)2N group by means of nucleophilic substitution reactions with the [N(CF3)2]? anion were developed. The syntheses and properties of previously
- Breitenstein, Christoph,Ignat'ev, Nikolai,Frank, Walter
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Read Online
- Tetramethylammonium Fluoride Alcohol Adducts for SNAr Fluorination
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Nucleophilic aromatic fluorination (SNAr) is among the most common methods for the formation of C(sp2)-F bonds. Despite many recent advances, a long-standing limitation of these transformations is the requirement for rigorously dry, aprotic conditions to maintain the nucleophilicity of fluoride and suppress the generation of side products. This report addresses this challenge by leveraging tetramethylammonium fluoride alcohol adducts (Me4NF·ROH) as fluoride sources for SNAr fluorination. Through systematic tuning of the alcohol substituent (R), tetramethylammonium fluoride tert-amyl alcohol (Me4NF·t-AmylOH) was identified as an inexpensive, practical, and bench-stable reagent for SNAr fluorination under mild and convenient conditions (80 °C in DMSO, without the requirement for drying of reagents or solvent). A substrate scope of more than 50 (hetero) aryl halides and nitroarene electrophiles is demonstrated.
- Bland, Douglas C.,Lee, So Jeong,Morales-Colón, Mariá T.,Sanford, Melanie S.,Scott, Peter J. H.,See, Yi Yang
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supporting information
p. 4493 - 4498
(2021/06/28)
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- METHOD FOR PREPARING TETRAMETHYLAMMONIUM FLUORIDE
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A method for the preparation of anhydrous, alcohol-free tetramethylammonium fluoride is described. The method includes fluorination of tetramethylammonium chloride with potassium fluoride in an alcohol solvent, removal of insoluble potassium salts, and finally, removal of the alcohol solvent and replacement of it with an aprotic solvent.
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Page/Page column 7
(2018/03/09)
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- A fluoride salt ion liquid synthetic method of the
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The invention relates to the field of organic chemical synthesis, particularly a synthesis method of a fluoride salt ionic liquid. The method comprises the following steps: adding excessive hydrofluoric acid, ammonium fluoride or ammonium bifluoride into halogenated imidazole and other raw materials, stirring in a closed environment, heating to 50-70 DEG C, and sufficiently reacting for at least 3 hours to obtain a non-dewatered fluoride salt ionic liquid; detecting, purifying and dewatering to obtain a thick liquid; and detecting the thick liquid to obtain the qualified fluoride salt ionic liquid. The method has the advantages of simple technique, no organic solvent, no waste and high end product purity.
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Paragraph 0244; 0245; 0246; 0247; 0248; 0249
(2016/10/10)
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- XeOF3-, an example of an AX3YE2 valence shell electron pair repulsion arrangement; Syntheses and structural characterizations of [M][XeOF3] (M = Cs, N(CH3) 4)
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The XeOF3- anion has been synthesized as its Cs + and N(CH3)4+ salts and structurally characterized in the solid state by low-temperature Raman spectroscopy and quantum-chemical calculations. Vibrational frequency assignments for [Cs][XeOF3] and [N(CH3) 4][XeOF3] were aided by 18O enrichment. The calculated anion geometry is based on a square planar AX3YE 2 valence-shell electron-pair repulsion arrangement with the longest Xe-F bond trans to the oxygen atom. The F-Xe-F angle is bent away from the oxygen atom to accommodate the greater spatial requirement of the oxygen double bond domain. The experimental vibrational frequencies and trends in their isotopic shifts are reproduced by the calculated gas-phase frequencies at several levels of theory. The XeOF3- anion of the Cs + salt is fluorine-bridged in the solid state, whereas the anion of the N(CH3)4+ salt has been shown to best approximate the gas-phase anion. Although [Cs][XeOF3] and [N(CH 3)4][XeOF3] are shock-sensitive explosives, the decomposition pathways for the anions have been inferred from their decomposition products at 20°C. The latter consist of XeF2, [Cs][XeO2F3], and [N(CH3)4][F]. Enthalpies and Gibbs free energies of reaction obtained from Born-Fajans-Haber thermochemical cycles support the proposed decomposition pathways and show that both disproportionation to XeF2, [Cs][XeO2F3], and CsF and reduction to XeF2, CsF, and O2 are favorable for [Cs][XeOF3], while only reduction to XeF2 accompanied by [N(CH3)4][F] and O2 formation are favorable for [N(CH3)4][XeOF3]. In all cases, the decomposition pathways are dominated by the lattice enthalpies of the products.
- Brock, David S.,Mercier, Helene P. A.,Schrobilgen, Gary J.
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p. 10935 - 10943
(2010/09/16)
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- The synthesis of quaternary ammonium salts from ammonium salts and dialkyl carbonate
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Quaternary ammonium salts were synthesized from ammonium salts and dialkyl carbonates over an ionic liquid catalyst 1-ethyl-3-methylimidazolium bromide. The Royal Society of Chemistry 2006.
- Zheng, Zhuoqun,Wu, Tinghua,Zhou, Xiaoping
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p. 1864 - 1865
(2008/03/14)
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- Anhydrous flouride salts and reagents and methods for their production
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Anhydrous organic fluoride salts and reagents prepared by a method comprising the nucleophilic substitution of a fluorinated aromatic or fluorinated unsaturated organic compound with a salt having the formula: [QnM]x+Ax?in an inert polar, aprotic solvent; wherein M is an atom capable of supporting a formal positive charge, the n groups Q are independently varied organic moieties, n is an integer such that the [QnM] carries at least one formal positive charge, x is an integer defining the number of formal positive charge(s), +, carried by the [QnM], A? is an anionic nucleophile capable of substituting for F in the fluorinated compound and F represents fluorine or a radioisotope thereof.
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Page/Page column 5
(2008/06/13)
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- Different fluoride anion sources and (trifluoromethyl)trimethylsilane: Molecular structure of tris(dimethylamino)sulfonium bis(trifluoromethyl)trimethylsiliconate, the first isolated pentacoordinate silicon species with five Si-C bonds
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(Trifluoromethyl)trimethylsilane, CF3SiMe3 reacts with [(Me2N)3S]+[Me3SiF2]-, Q+F- and Q+[HF2]-(Q+ = Me4N+, [(Me2N)3C]+, [(Me2N)4P]+) at -70 to 50°C to afford the first hypervalent silicon species, [(CF3)2SiMe3]- with five Si-C bonds (stable in monoglyme up to -10°C) as the main reactive species whose molecular structure was determined by X-ray crystallography.
- Kolomeitsev, Alexander,Bissky, German,Lork, Enno,Movchun, Valery,Rusanov, Eduard,Kirsch, Peer,Roeschenthaler, Gerd-Volker
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p. 1017 - 1018
(2007/10/03)
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- Synthesis of Quaternary Ammonium Fluoride Salts by a Solid-Liquid Halogen Exchange Process in Protic Solvents
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Both hydrophilic and lipophilic quaternary ammomium fluoride compounds are prepared by direct exchange of the corresponding halides with solid potasium fluoride containing an optimized amount of water (4.0 mol percent).The procedure is most effective when methanol is applied as a solvent.A variety of quaternary ammonium fluorides were prepared in 75-97percent yield.
- Dermeik, Salman,Sasson, Yoel
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p. 4827 - 4829
(2007/10/02)
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