The Chemical Shift of Connected to sp 3 Hybridized Carbons Let’s start with the chemical shift of protons of alkyl C-H groups. Upfield means lower energy – right side of the spectrum (lower ppm) This might be a confusing terminology and we talked about its origin in earlier, so read that post if you need to know more but you definitely need to remember that:ĭownfield means higher energy – left side of the spectrum (higher ppm) The right side of the spectrum is the low energy region ( upfield) and the left side is the high energy region ( downfield). ![]() Most often the signal area for organic compounds ranges from 0-12 ppm. The energy axis is called a δ (delta) axis and the units are given in part per million (ppm). ![]() Today, the focus will be on specific regions of chemical shift characteristic for the most common functional groups in organic chemistry.īelow are the main regions in the 1H NMR spectrum and the ppm values for protons in specific functional groups: ![]() In the previous post, we talked about the principles behind the chemical shift addressing questions like how the ppm values are calculated, why they are independent of the magnetic field strength, and what is the benefit of using a more powerful instrument.
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