کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1314766 | 975985 | 2011 | 7 صفحه PDF | دانلود رایگان |
Four studies of the 1H NMR spectrum for the aromatic protons of 4-fluoroaniline between 1958 and 1974 give three very different solutions to the second-order, AA′BB′X, spectrum. A re-evaluation of the second-order spectrum was done at 300 MHz. Simultaneous simulations of the 1H NMR spectrum and 19F NMR spectrum for 4-fluoroaniline were done using WINDNMR-Pro, and a new set of parameters for the six coupling constants was obtained from the optimized simulations. This new set of parameters was used as a basis to evaluate the AA′BB′X spectrum for the aromatic protons in N4-(4′-fluorophenyl)succinamic acid and in N4-(4′-fluorophenyl)-3,3-difluorosuccinamic acid by simultaneous simulations of the 1H NMR spectrum and 19F NMR spectrum for each using WINDNMR-Pro. Formation of the amide bond results in small, but significant, changes in the values for the set of parameters in both molecules. These results confirm that second-order analyses as an AA′BB′X system are required for derivatives of 4-fluoroaniline, rather than first-order analyses that have been used in previous reports.
Optimized simulation of a 1H NMR second-order, AA′BB′X, spectrum for the aromatic protons in a para-fluoroanilide using WINDNMR-Pro.Figure optionsDownload as PowerPoint slideResearch highlights
► Re-evaluation of the second-order, AA′BB′X, 1H NMR spectrum for 4-fluoroaniline.
► Simultaneous simulations of the 1H and 19F NMR spectra using WINDNMR-Pro.
► New set of NMR parameters for 4-fluoroaniline.
► Second-order, AA′BB′X, NMR parameters obtained for succinamic acid 4′-fluoroanilide.
Journal: Journal of Fluorine Chemistry - Volume 132, Issue 4, April 2011, Pages 269–275