5. (15 pts) Given the gyromagnetic ratio values for the following types of nucle

Question

5. (15 pts) Given the gyromagnetic ratio values for the following types of nuclei (in unit of 10 (1) (5 pts) What are the resonance frequencies for C and "P on a 300 MHz NMR (2) (5 pts) If a 2.2 ppm 'H chemical shift corresponds to a frequency difference of 1100 Hz rad Ts: H, 26.7522;13C, 6.7283; 3P, 10.841. spectrometer? from the reference point (i.e. 0 ppm) on a particular NMR spectrometer. What are the (3) (5 pts) If the water H peak shows up at 4.7 ppm on a 400 MHz spectrometer, what will resonance frequencies for Hand 3C on this spectrometer? be the chemical shift value (in ppm) for the water 'H peak on a 600 MHz spectrometer?

Explanation / Answer

1. Resonance frequency r = ( / 2) * B0

Larmor frequency L (MHz )= (MHz/T) * B0(T) =300

For, 13C,   = 6.7283 x 107 rad T-1S-1 =10.7 MHZT-1,

Then B0 = 28 T

So, r = 47.68 MHz

Similarly, for 31P = 10.841 x 107 rad T-1S-1 =17.2 MHZT-1,

Then B0 = 17.44 T

So, r = 47.74 MHz

2. Chemical shift =(e - r) / 0 (MHz)

So for H, 2.2 = 1100/0 (MHz)

Then  0 = 500 MHz

So, r for H is 1100Hz

So, r for for 13C =(10.7/2)*(500/10.7)=79.5 Hz

3. Chemical shift (in ppm) will be constant for a particular proton for all the spectrometer.

Hence,chemical shift value of the water peak is 4.7 ppm on a 600 MHz spctrometer.

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