| Popis: |
Nitriles (C—CN), cyanamides (N—CN), cyanates (—O—CN), thiocyanates (—S—CN), selenocyanates (—Se—CN), and isocyanides (C—NC) are the commonly encountered compounds that contain —C≡N (or —N≡C) triple bonds. These compounds have very valuable characteristic —C≡N (or —N≡C) stretching frequencies in a relatively unpopulated spectral region that allows for easy identification. Vibrational spectra of nitrile compounds are best characterized by the sharp C≡N stretching bands. The C≡N stretching mode gives rise to strong IR and Raman bands for alkyl nitriles in the 2250–2230 cm −1 region. A narrower frequency range (2250–2245cm −1 ) is expected when the alkyl group is a straight chain (CH 3 (CH 2 ) n —C≡N). The presence of an electron-attracting atom such as Cl or Ο on the α-carbon next to the nitrile group can markedly reduce the IR intensity of the C≡N band. The band frequency is slightly higher than the frequency for alkyl nitriles. The Raman intensity is not markedly affected. |
