3 research outputs found

    Anhydrous Tetramethylammonium Fluoride for Room-Temperature S<sub>N</sub>Ar Fluorination

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    This paper describes the room-temperature S<sub>N</sub>Ar fluorination of aryl halides and nitroarenes using anhydrous tetramethylammonium fluoride (NMe<sub>4</sub>F). This reagent effectively converts aryl-X (X = Cl, Br, I, NO<sub>2</sub>, OTf) to aryl-F under mild conditions (often room temperature). Substrates for this reaction include electron-deficient heteroaromatics (22 examples) and arenes (5 examples). The relative rates of the reactions vary with X as well as with the structure of the substrate. However, in general, substrates bearing X = NO<sub>2</sub> or Br react fastest. In all cases examined, the yields of these reactions are comparable to or better than those obtained with CsF at elevated temperatures (i.e., more traditional halex fluorination conditions). The reactions also afford comparable yields on scales ranging from 100 mg to 10 g. A cost analysis is presented, which shows that fluorination with NMe<sub>4</sub>F is generally more cost-effective than fluorination with CsF

    NMR Chemical Shifts of Trace Impurities: Industrially Preferred Solvents Used in Process and Green Chemistry

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    The <sup>1</sup>H and <sup>13</sup>C NMR chemical shifts of 48 industrially preferred solvents in six commonly used deuterated NMR solvents (CDCl<sub>3</sub>, acetone-<i>d</i><sub>6</sub>, DMSO-<i>d</i><sub>6</sub>, acetonitrile-<i>d</i><sub>3</sub>, methanol-<i>d</i><sub>4</sub>, and D<sub>2</sub>O) are reported. This work supplements the compilation of NMR data published by Gottlieb, Kotlyar, and Nudelman (J. Org. Chem. 1997, 62, 7512) by providing spectral parameters for solvents that were not commonly utilized at the time of their original report. Data are specifically included for solvents, such as 2-Me-THF, <i>n</i>-heptane, and <i>iso</i>-propyl acetate, which are being used more frequently as the chemical industry aims to adopt greener, safer, and more sustainable solvents. These spectral tables simplify the identification of these solvents as impurities in NMR spectra following their use in synthesis and workup protocols
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