The electromagnetic spectrum covers a continuous range of wavelengths and frequencies, from radio waves at the low-frequency end to gamma (  ) rays at the high-frequency end 10.5Spectroscopy and the Electromagnetic Spectrum

Infrared (IR) region Ranges from 7.8 x m to m 2.5 x m to 2.5 x m used by organic chemists Wavelengths given in micrometers (1  m = m) Frequencies given in wavenumbers Wavenumber Reciprocal of wavelength in centimeters Expressed in units of cm Infrared Spectroscopy

Molecules stretch or bend at specific frequencies Energy is absorbed if the frequency of the radiation matches the frequency of the vibration IR spectrum → What molecular motions? → What functional groups? Infrared Spectroscopy

Most functional groups have characteristic IR absorption bands that don’t change from one compound to another 10.7 Interpreting Infrared Spectra

Interpreting Infrared Spectra

Fig. 13-5, p. 509

Fig. 13-6, p. 510

Fig. 13-7, p. 510

Fig. 13-9, p. 512

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Fig , p. 513

Fig , p. 514

Fig , p. 515

Table 13-2, p. 522

Fig. 13-8, p. 511

Fig , p. 523

Fig , p. 526

Fig , p. 527

Fig , p. 528

Characteristic aldehyde and ketone IR absorptions Infrared Spectra of Some Common Functional Groups

Characteristic ester IR absorptions

Fig , p. 529