IR Spectroscopy

C-H

Alkane (stretch)

3000-2850

strong

C-H

-CH₃ (bend)

1450 and 1375

medium

C-H

-CH₂- (BEND)

1465

MEDIUM

C-H

Alkenes (stretch)

3100-3000

medium

C-H

Alkenes (bend)

1700-1000

strong

C-H

Aromatic (stretch)

3150-3050

strong

C-H

Aromatic (out-of-plane bend)

1000-700

strong

C-H

Alkyne (stretch)

ca. 3300

strong

C-H

Aldehyde

2900-2800 weak

2800-2700 weak

C=C

Alkene

1680-1600

medium-weak

C=C

Aromatic

1600-1400

medium-weak

C(triple bond)C

Alkyne

2250-2100

medium-weak

C=O

Aldehyde

1740-1720

strong

C=O

Ketone (acyclic)

1725-1705

strong

C=O

Carboxylic acid

1725-1700

strong

C=O

Ester

1750-1730

strong

C=O

Amide

1700-1640

strong

C=O

Anhydride

ca. 1810 strong

ca. 1760 strong

C-O

alcohols, ethers,esters, carboxylic acids

1300-1000

strong

O-H

alcohols, phenols: free

3650-3600

medium

O-H

alcohols, phenols: H-bonded

3400-3200

medium

O-H

Carboxylic acids

3300-2500

medium

N-H

primary and secondary amines

ca. 3500

medium

C (triple bonded) N

Nitrile

2260-2240

medium

N=O

Nitro (R-NO₂)

1600-1500 strong

1400-1300 strong

C-X

Fluoride

1400-1000

strong

C-X

Chloride

800-600

strong

C-X

Bromide, Iodide

<600

strong