Chapter 14 Part 2 - Infared (IR) Spectroscopy

Region 1 - around 3000 cm^-1

Region 2 - around 3300 cm^-1

Region 3 - around 1715 cm^-1

Region 4 - around 2200 cm^-1

Region 5 - aromatic region

Region 1

Region 2

Region 3

Region 4

Region 5

Region 1

< 3000 cm^-1

Region 1

sp³ C-H bonds

Region 1

> 3000 cm^-1

Region 1

sp² C-H bonds

Region 1

~3300 cm^-1

Region 1

sp C-H bonds

Region 2

~3700 cm^-1

Region 2

Free R-OH (no hydrogen bonding)

Region 2

~3500 cm^-1 - (Symmetrical/Broad Peak)

Region 2

R-OH (w/ hydrogen bonding)

Region 2

~2500-3500 cm^-1 - (Asymmetrical/Broad)

~1715 cm^-1 - (Sharp/Strong)

Region 2

Carboxylic Acid

Region 2

~3300 cm^-1 - (1 Spike)

Region 2

Secondary Amine (1 H)

Region 2

~3300 cm^-1 - (2 Spikes)

Region 2

Primary Amine (2 H)

Region 3

~1735 cm^-1

Region 3

Ester

Region 3

~1715 cm^-1

Aldehydes also have peaks at 2700/2800 cm^-1

Ketones also have peak at 2800 cm^-1

Carboxylic Acids also have asymmetrical broad peak

Region 3

Aldehyde/Ketone/Carboxylic Acid

Region 3

~1685 cm^-1

Region 3

Amide

Region 3

~1625 cm^-1

Region 3

C=C Bond

Region 4

> 2200 cm^-1

Region 4

C≡N Bond

Region 4

< 2200 cm^-1

Region 4

C≡C Bond

Region 5

~1625 cm^-1

> 3000 cm^-1

~1800-2000 cm^-1

Region 5

C=C from conjugation

sp² C from conjugation

Combination Bands/Overtones