ORGO 2 EXAM 1 - IR stretching frequencies (chapter 12)

fingerprint region of the spectrum

below 1600

IR spectroscopy

measures the bond vibration frequencies in a molecule and is used to determine the functional group

Mass Spectroscopy

fragments the molecule and measures the mass to give the molecular weight of the compound and functional groups

Molecules with no dipole give no IR signal

1200 cm^-1

1660 cm^-1

<2200 cm^-1

1640-1680 cm^-1

1620-1640 cm^-1

1600 cm^-1

2800-3000 cm^-1

3000-3100 cm^-1

3300 cm^-1 (sharp)

O-H

3300 cm^-1 (round)

R2NH (Secondary amine)

3300 cm^-1 (broad with one sharp spikes)

RNH2 (Primary amine)

3300 cm^-1 (broad with two sharp spikes)

R3N (tertiary amine)

No signal (no hydrogen)

Ketone

1710 cm^-1

Aldehyde

1725 cm^-1

Acid

1710 cm^-1

Ester

1735 cm^-1

C-N

1200 cm^-1

1660 cm^-1

>2200 cm^-1

Summary of IR stretching frequencies