Practice question

Functional group identification relies on high-wavenumber region from 4000 to 1000 cm-1, where characteristic stretching vibrations remain relatively isolated from coupling. O-H stretching near 3600, N-H near 3300, C-H near 2900-3100, triple bonds near 2100-2260, carbonyl C=O near 1700 cm-1 appear prominently here. This window allows rapid recognition of alcohols, amines, alkanes, alkynes and carbonyls in proteins, lipids and nucleic acids. Below 1000 cm-1 skeletal vibrations overlap extensively, creating fingerprint pattern useful for confirmation rather than initial functional assignment, distinguishing primary chemistry from overall architecture.