Interpreting the infrared spectrum of chloroethane

Doc Brown's Chemistry Advanced Level Pre-University Chemistry Revision Study Notes for UK IB KS5 A/AS GCE advanced A level organic chemistry students US K12 grade 11 grade 12 organic chemistry courses involving molecular spectroscopy analysing infrared spectra of chloroethane

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Spectra obtained from a liquid film of chloroethane. The right-hand part of the of the infrared spectrum of chloroethane, wavenumbers ~1500 to 400 cm^-1 is considered the fingerprint region for the identification of chloroethane and most organic compounds. It is due to a unique set of complex overlapping vibrations of the atoms of the molecule of chloroethane.

Interpretation of the infrared spectrum of chloroethane

The most prominent infrared absorption lines of chloroethane

C-H stretching vibrations at wavenumbers ~2880 to 3080 cm^-1.

C-H bending vibrations at wavenumbers ~1300 to 1500 cm^-1.

Characteristic groups of C-Cl vibrations at wavenumbers ~580 to 780 cm^-1.

The absence of other specific functional group bands will show that a particular functional group is absent from the chloroethane molecular structure.