The 1 H and 13 C NMR chemical shifts of 48 industrially preferred solvents in six commonly used deuterated NMR solvents (CDCl 3 , acetone-d 6 , DMSO-d 6 , acetonitrile-d 3 , methanol-d 4 , and D 2 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, n-heptane, and iso-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.
A highly selective NHC-catalyzed synthesis of γ-butyrolactones from the fusion of enals and α-ketophosphonates has been developed. Computational modeling of competing transition states was employed to guide a rational design strategy and achieve enhanced levels of enantioselectivity with a new tailored C1-symmetric biaryl saturated imidazolium-derived NHC catalyst. This new annulation is compatible with a wide range of acyl phosphonates and α,β-unsaturated aldehydes.
The potential safety hazards associated
with the Suzuki–Miyaura
cross-coupling of aryl bromides with vinylboron species were evaluated.
In the Suzuki–Miyaura cross-coupling of 1-bromo-3-(trifluoromethyl)benzene
with potassium vinyltrifluoroborate in the presence of potassium carbonate
(K2CO3) in 9:1 dimethyl sulfoxide (DMSO)/water
at 80 °C, the thermal profile revealed a significant exotherm
upon the addition of catalytic 1,1′-bis(diphenylphosphino)ferrocene
palladium(II) dichloride [Pd(dppf)Cl2]. Further investigations
indicated that the exotherm was consistently higher and the reactions
were faster in the studied aqueous systems compared to anhydrous conditions.
Although under anhydrous conditions the exotherms were comparable
among the studied cases, the rate of the exotherm was highly dependent
on the choice of aryl electrophile, solvent, base, catalyst, as well
as vinylboron species. In many of the studied cases the maximum temperature
of a synthesis reaction (MTSR) was considerably higher than the boiling
point of the solvent and/or the onset temperature of the DMSO decomposition,
indicating that in the absence of active cooling the system could
quickly exceed the boiling point of the solvent or trigger the decomposition
of the reaction mixture to result in a runaway reaction.
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