Chem II - IR Spectroscopy Analysis

O-H

3600-3000 cm^-1

broad peaks, carbox. acid even broader

N-H

3500-3300cm^-1

a little broad; 1° amine: 2 peaks, 2° amine: 1 peak

C-H

3300-2800cm^-1

sp³ C-H less than 3000cm^-1

C-H aldehyde: 2 peaks @ 2830 and 2720

C≡N

2300-2200cm^-1

resonance

C≡C

2200-2100cm^-1

resonance

C=O

1850-1650cm^-1

resonance, very intense

C=N

1700-1650cm^-1

resonance, strong

C=C

1700-1600cm^-1

resonance, aromatic C=C in 1500s

What is the effect of resonance?

weaker bonds, lower wave number

General range for O-H/N-H

~3200cm^-1

General range for C-H

~3000cm^-1

General range for C≡N/C≡C

~2200cm^-1

General range for C=O/C=N/C=C

~1700cm^-1