Spectral Analysis - Alkene Page

=C-H
Stretch for sp² C-H occurs at values between 3100-3010 cm^-1.

=C-H
Out-of-plane (oop) bending occurs in the range 1000-650 cm^-1.

C=C
Stretch occurs at 1660-1600 cm^-1; often conjugation moves C=C stretch to lower frequencies and increases the intensity.
Symmetrically substituted bonds (e.g., 2,3-dimethyl-2-butene) do not absorb in the infrared (no dipole change).
Symmetrically disubstituted (trans) double bonds are often vanishingly weak in absorption; cis are stronger.

=C-H	Stretch for sp² C-H occurs at values between 3100-3010 cm^-1.
=C-H	Out-of-plane (oop) bending occurs in the range 1000-650 cm^-1.
C=C	Stretch occurs at 1660-1600 cm^-1; often conjugation moves C=C stretch to lower frequencies and increases the intensity. Symmetrically substituted bonds (e.g., 2,3-dimethyl-2-butene) do not absorb in the infrared (no dipole change). Symmetrically disubstituted (trans) double bonds are often vanishingly weak in absorption; cis are stronger.

Infrared Spectroscopy

Spectral Analysis - Alkene

=C-H

=C-H

C=C