CHEM 235-1 IR Spectroscopy

CC, CN, CO Double Bond Stretching

1850-1620 (cm^-1)

CC, CN Triple Bond Stretching

2300-2100 (cm^-1)

OH, NH, CH Single Bond Stretching

3600-2850 (cm^-1)

Alkanes: C-H Stretch

2850-3000

Alkanes: H-C-H

1375-1465

Alkenes: =C-H

3010-3095

Alkenes: C=C

1600-1660

CC Stretch Frequencies in Rings

Decreases with Ring Size

Alkynes: (triple bond)C-H Stretch

3250-3350

Nitriles: CN Triple Bond

2250

Aromatic: =C-H

>3000

Aromatic: =C-H

>3000

Aromatic: C=C

1475-1600

Alcohols and Phenols: -O-H (Free)

3600-3650

Alcohols and Phenols: -O-H (H-bonded)

3300-3400

Amines: N-H Stretch

3300-3500

Amines: Primary Amine

Two relatively sharp spikes

Amines: Secondary amine

One relatively sharp spike

Aldehydes: C=O

1725

Aldehydes: O=C-H Stretch

Two Absorbances at 2750 and 2850

Ketones: Overtone

3400

Carboxylic Acid: Overlaps of C-H and O-H

OH is broad at 2400-3400 with C-H stretches overlapping

Esters: C=O

1735-1750

Amides: C=O Stretch

1680-1630

Amides: N-H Stretch

Primary gives two bands at 3350-3180 and secondary is at around 3300

Amides: N-H Bending

1640-1550 (could be mistaken for a CC Triple bond)