CH.COCH Methyl ethanoate has 2 types of hydrogen atoms,so we see two peaks in the spectrum at about 2.1 and 3.7 ppm. The peak at 3.7 ppm is due to the-OCH3 group since the electronegative-0-deshields the methyl group. The integrations are 1:1 since there are 3H of each type. Integral 1 11 10 9 6 4 ppm
H H一O一C-H H less shielded more shielded lower field (downfield) higher field(upfield) increasing magnetic field strength (Bo)
Chemical Shift The variations in the positions of NMR absorptions,arising from electronic shielding and deshielding,are called chemical shifts. shift downfield from TMS (Hz) chemical shift(ppm)= total spectrometer frequency (MHz) The chemical shift (in ppm)is independent of the spectrometer used. Most common scale is the 8(delta)scale
Chemical Shift • The variations in the positions of NMR absorptions, arising from electronic shielding and deshielding, are called chemical shifts. • The chemical shift (in ppm) is independent of the spectrometer used. • Most common scale is the d (delta) scale
Typical 1H NMR Scale is 0-10 ppm Deshield Shield Downfield Upfield 10 9 8 5 ppm
Typical 1H NMR Scale is 0-10 ppm
TheδScale chemical shift.ppmshif downfield from TMS (in Hz) spectrometer frequency (in MHz) 600Hz 480Hz 360Hz240Hz 120Hz 0Hz 1098765432 1 0 Ppm8 ↑TMS 60 MHz 3000Hz 2400Hz1800Hz1200Hz 600Hz 0Hz 109 87 6543 2 1 0 Ppm 8 ↑TMS 300 MHz
The d Scale