Alkynes infrared absorption frequencies

Table 12.5 Infrared Absorptions of Alkanes, Alkenes, Alkynes, and Arenas Frequency Hydrocarbon Vibration (cm ) Intensity ... 

Nitriles Nitriles show a characteristic C = N stretching absorption around 2200 cm-1 in the infrared spectrum. This absorption can be distinguished from the alkyne C=C absorption by two characteristics Nitriles usually absorb at frequencies slightly higher than 2200 cm-1 (to the left of 2200 cm-1), while alkynes usually absorb at frequencies slightly lower than 2200 cm-1 and nitrile absorptions are usually stronger because the C = N triple bond is more polar than the alkyne C=C triple bond. 

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