Practice question

Proton NMR window spans approximately zero to twelve ppm because hydrogen experiences limited shielding variation: shielded alkanes resonate 0.8 to 1.5 ppm, electron-withdrawing alpha carbons 3 to 5 ppm, aromatic and amide protons 6 to 10 ppm, aldehydes near 9 to 10 ppm. Carbon-13 range extends 0 to 220 ppm due to larger paramagnetic shielding effects. Knowing proton window helps students rapidly categorize signals in protein hydrolysates, urine metabolomics, and nucleic acid imino regions, distinguishing aliphatic core from deshielded hydrogen-bonded protons in folded structures.