CHEAT SHEET for IR Spectroscopy
• 3250 - 3550 cm-1 : OH groups in H-bond show a very broad/ large peak
• 3280 - 3320 cm-1 : —C≡C—H: C—H stretch (has a sharp stretch, easily identifiable, appears only
in terminal alkynes)
• at 3200 cm-1, 1° amine and 1° amide show with two "fangs", while the 2° amine and 2° amide
(those with only 1 H bonded N) appear as single bands
• Slightly above 3000 cm-1 indicate C=C—H bonds from alkenyl and aromatic groups
• Slightly below 3000 cm-1 indicate alkyl groups
• 3030 - 3140 cm-1: =C—H stretch
• 2850-3000 cm-1: C—H stretch (asymmetric stretching appears at a higher frequency than
symmetric stretching)
• 2100-2260 cm-1: —C≡C— stretch from (internal)
• 2000 - 2500 cm-1: Triple bond stretches occurs
• 1640 - 1680 cm-1: Alkene stretching occurs (very close to carbonyl stretching region)
• 1630 - 1780 cm-1: Look for carbonyl; location depends on type
• 1600 - 1680 cm-1: C=C stretch
• 1450 - 1470 cm-1: C—H (CH2)bend or scissoring
• 1360 - 1385 cm-1: CH3 symmetric (umbrella) bend
• 710 - 730 cm-1: Long chain (4 or more carbons) C—H rock
• -1
650 - 1000 cm : =C—H bend
• 610 - 700 cm-1: C≡C—H: C—H bend from (not recorded, but overtones can be found, about
as twice as much as the frequency corresponding to the fundamental vibration)
