Typical Infrared Absorption Frequencies （典型的红外吸收频率）.pdf

Typical Infrared Absorption Frequencies Stretching Vibrations Bending Vibrations Functional Class Range (nm) Intensity Assignment Range (nm) Intensity Assignment Alkanes 2850-3000 str CH , CH CH 1350- 1470 med CH CH deformation 3 2 2 3 2 or 3 bands 1370- 1390 med CH3 deformation 720-725 wk CH2 rocking Alkenes 3020-3100 med =C-H =CH2 (usually sharp) 880-995 str =C-H =CH2 1630-1680 var C=C (symmetry reduces intensity) 780-850 med (out-of-plane bending) 675-730 med cis-RCH=CHR 1900-2000 str C=C asymmetric stretch Alkynes 3300 str C-H (usually sharp) 600-700 str C-H deformation 2100-2250 var