Question

In: Chemistry

a 1h nmr signal is observed at 149.0 hz (downfield of TMS) on a 135-Mhz instrument....

a 1h nmr signal is observed at 149.0 hz (downfield of TMS) on a 135-Mhz instrument. What is the observed chemical shift in parts per million? What is the chemical shift, in parts per million, if the sample is analyzed with a 200.0-MHz instrument? Where will the proton signal appear, in hertz, if the sample is analyzed with a 200..0-MHz instrument?

Solutions

Expert Solution

Explanation:

1)Chemical shift calculated as,

Given that Shift in Hz =149 ppm, Spectrometer frequency =135 Mhz. with this observed chemical shift can be calculated as ,

2) Chemical shift value in ppm is constant irrespective of spectrometer machine used. Also we can use relation,\

                                                                       =      220 Hz (apprx.)

On 200 Mhz instrument Signal will appear at 220 Hz.But Chemical shift value on the spectra remains 1.10 ppm. On 200 MHz machine also.


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