3 research outputs found
Anhydrous Tetramethylammonium Fluoride for Room-Temperature S<sub>N</sub>Ar Fluorination
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
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