Question

The following 1H NMR absorptions were obtained on a spectrometer operating at 200 MHz and are given in Hz downfield from TMS. Convert the absorptions to δ units. a) 416 Hz = δ b) 1.97×103 Hz = δ c) 1.50×103 Hz = δ

Answer 1

Answer:

For (a): The chemical shift is $2.08\delta$

For (b): The chemical shift is $9.85\delta$

For (c): The chemical shift is $7.5\delta$

Explanation:

To calculate the chemical shift, we use the equation:

$\text{Chemical shift in ppm}=\frac{\text{Peak position (in Hz)}}{\text{Spectrometer frequency (in MHz)}}$

Given value of spectrometer frequency = 200 MHz

• For (a):

Given peak position = 416 Hz

Putting values in above equation, we get:

$\text{Chemical shift in ppm}=\frac{416Hz}{200MHz}\\\\\text{Chemical shift in ppm}=2.08\delta$

• For (b):

Given peak position = $1.97\times 10^3 Hz$

Putting values in above equation, we get:

$\text{Chemical shift in ppm}=\frac{1.97\times 10^3Hz}{200MHz}\\\\\text{Chemical shift in ppm}=9.85\delta$

• For (c):

Given peak position = $1.50\times 10^3 Hz$

Putting values in above equation, we get:

$\text{Chemical shift in ppm}=\frac{1.50\times 10^3Hz}{200MHz}\\\\\text{Chemical shift in ppm}=7.5\delta$