Can someone please help with these proton NMR problems? Thanks (1) Explain brief
ID: 941450 • Letter: C
Question
Can someone please help with these proton NMR problems? Thanks (1) Explain briefly what is an advantage of using delta (8) scale for the chemical shift rather than hertz scale. (2) Define in your own words the following terms and acronyms: multiplet upfield TMS FID deshielded (3) (a) Predict the chemical shift and multiplicity for each group of protons in the following compound. (b) Predict approximate chemical shift of signals in proton-decoupled sC NMR spectrum for each group of carbons in the following compound? CH3 CH CH3Explanation / Answer
Solution.
1) Hertz scale is field dependent, so the chemical shifts in hertzes would depend on the spectrometer frequency. As a result, the chemical shifts would not be comparable between two different labs.
2) Multiplet is if the signal is split, but too difficult for interpretation. It may be a reult of two or more signals overlapping.
Upfield is a nucleus decreased chemical shift. It is shielded and "feels" magnetic field weaker.
TMS is tetramethylsilane - the standard molecule which has a chemical shift 0 ppm (by definition).
FID is the NMR signal resulting from a nuclear spin magnetization.
Deshielded atom shows increased chemical shift resulting from low electron density.