IR Spectroscopy

Chapter 12

C-C

1200 cm^-1

C=C

1600 - 1680 cm^-1

C≡C

2100 - 2200 cm^-1

Internal vs Terminal C-C

often not visible; may not even show up vs completely fine

C-H; sp³

< 3000 cm^-1

=C-H; sp²

>3000 cm^-1

≡C-H; sp

3300 cm^-1; only in TERMINAL ALKYNES

Alcohol O-H

3300 cm^-1; broad peak

Acid O-H

3000 cm^-1; VERY broad

N-H

3300 cm^-1; more narrow & sharper

1 spike is secondary amine

2 spikes are primary amine

Carbonyl

1710 cm^-1

Carboxylic Acids

carbonyl (1710 cm^-1) & OH peak (3000 cm^-1)

Aldehydes

carbonyl (1720 cm^-1) & C-H peaks (2700 & 2850 cm^-1)

Conjugated Carbonyls

occurs when there is a ketone, aldehyde, or carboxylic acid; @ 1680 - 1685 cm^-1

Amides

1640 - 1680 cm^-1; STRONGER

Esters

1735 - 1750 cm^-1; RAISES the C=O frequency

Strained Cyclic Ketones

RAISE the C=O frequency

C-N

1200 cm^-1

C=N

1660 cm^-1

C≡N

>2200 - 2300 cm^-1