Organic Chemistry Semester 1 LABORATORY MANUAL - Moravian ...

Infrared Spectroscopy Appendix C2 Part V. Techniques and Theory
Assignment of IR Vibrational ν's to Specific Bonds in Molecules:
Data:
Symbols used in Figure 1:
st = strong (high intensity) absorption wk = weak intensity absorption
sh = sharp (narrow peak) br = broad (wide peak)
Figure 1: Vibrational Frequencies of some Organic Molecules
STRUCTURE Important IR ν's (cm -1 )
1. CH 3 (CH 2 ) 6 CH 3 2945
2. (CH 3 ) 2 C=C(CH 3 )(CH 2 ) 6 CH 3 2950, 1645 wk
3. CH 2 =C(CH 3 ) 2 3075, 2935, 1660 wk
4. CH 3 (CH 2 ) 3 C≡C-H 3268 sh, 2945, 2110 (sh & wk)
5. CH 3 (CH 2 ) 2 C≡C-CH 3 2950, 2200 (sh & wk)
6. CH 3
3040, 2925, 1600, 1500, 1460
7. CH 3 CH 3
3030, 2940, 1510, 1450
8. C
9.
10.
11.
O
O
O
H
CH 3
C
O
H
O
CH 3
C
O
CH 2
O
3300 ->2900 (br & st), 2955, 1710 st, 1240
3300-2500 (br & st), 2960, 1710 st, 1290
CH 3
2970, 1740 st, 1230, 1100
C CH 2945, 1740 st, 1250, 1100
3
CH 3 CH 2 O
12. CH 3 (CH 2 ) 3 C≡N 2945, 2250 sh
13.
14.
C N
CH 3
O
C
CH 3 CH3
3035, 2925, 2210 sh, 1600, 1490, 1460
2930, 1725 st