2850-3000 cm-1

strong

[image]

• C–H stretch from 3000–2850 cm^-1
• C–H bend or scissoring from 1470-1450 cm^-1
• C–H rock, methyl from 1370-1350 cm^-1
• C–H rock, methyl, seen only in long chain alkanes, from 725-720 cm^-1

1640-1680 cm-1

various strengths

Alkene C=C stretch

symmetry reduces intensity

3000-3100 cm-1

medium (usually sharp)

Alkene =C-H stretch

[image]

• C=C stretch from 1680-1640 cm^-1
• =C–H stretch from 3100-3000 cm^-1
• =C–H bend from 1000-650 cm^-1

2100-2260 cm^-1

 various strengths

Alkyne –C≡C– stretch

symmetry reduces intensity

3270-3330 cm-1

strong (usually sharp)

alkyne –C≡C–H: C–H stretch

[image]

• –C≡C– stretch from 2260-2100 cm^-1
• –C≡C–H: C–H stretch from 3330-3270 cm^-1
• –C≡C–H: C–H bend from 700-610 cm^-1

[image]

• C–H wag (-CH₂X) from 1300-1150 cm^-1
• C–X stretches (general) from 850-515 cm^-1
  • C–Cl stretch 850-550 cm^-1
  • C–Br stretch 690-515 cm^-1

[image]

• C–H stretch from 3100-3000 cm^-1
• overtones, weak, from 2000-1665 cm^-1
• C–C stretch (in-ring) from 1600-1585 cm^-1
• C–C stretch (in-ring) from 1500-1400 cm^-1
• C–H "oop" from 900-675 cm^-1

1585-1600 cm^-1

1400-1500 cm^-1

medium/weak intensity

arenes (C–C stretch (in-ring) )

two bands (3 if conjugated)

3500-3200 cm^-1

strong (usually broad)

[image]

• O–H stretch, hydrogen bonded 3500-3200 cm^-1
• C–O stretch 1260-1050 cm^-1 (s)

2690-2840 cm-1 (2 bands)

medium intensity

1720-1740 cm-1

strong

1710-1720 cm-1

strong

1675 cm-1

strong

2500-3300 cm-1 (overlaps C-H)

strong (very broad)

1690-1760 cm-1

strong

3250-3400 cm^-1

weak intensity

amine N-H stretch

• 1° amine: two bands from 3400-3300 and 3330-3250 cm^-1
• 2° amine: one band from 3350-3310 cm^-1
• 3° amine: no bands in this region

1000-1250 cm-1

medium intensity

primary amine (aniline)

• shoulder band, which is an overtone of the N–H bending vibration

secondary amine (diethylamine)