Typical Values of Chemical Shifts and Coupling Constants

3 TYPICAL VALUES OF CHEMICAL SHIFTS AND COUPLING CONSTANTS 

If we saw a resonance at 3.7 ppm, our first guess would be a proton on a singly oxygenated carbon, -CH2-O- (part d below), but it is dangerous to get locked into that idea because the possibility exists of smaller effects adding together, as shown in the example above. 

electron-rich carbon (e.g., ortho or para to O or N of phenol, aniline, phenolic ether, or in an electron-rich heteroaromatic pyrrole, furan) 6-7 ppm  

Note that there are other types of protons not listed here that can fall into the same chemical shift ranges listed above. The above categories are simply the most common ones. Also, through-space ( anisotropic ) effects of unsaturated groups (C=C, 0=0, and aromatic rings) can change chemical shifts from the above categories in ways that depend on conformation. 

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