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Chad breaks down how Infrared Spectroscopy can be used to determine a molecule's functional groups. Chad includes a chart of common IR absorptions.
When analyzing an IR spectrum, it is helpful to overlay the diagram below onto the spectrum with our mind to help recognize functional groups. Figure 1. Group frequency and fingerprint regions of the mid-infrared spectrum. The region of the infrared spectrum from 1200 to 700 cm-1 is called the fingerprint region.
21 Οκτ 2024 · After completing this section, you should be able to use an infrared spectrum to determine the presence of functional groups, such as alcohols, amines and carbonyl groups, in an unknown compound, given a list of infrared absorption frequencies.
By learning where characteristic functional-group absorptions occur, it’s possible to get structural information from IR spectra. Table 12.1 lists the characteristic IR bands of some common functional groups.
Table of Characteristic IR Absorptions m=medium, w=weak, s=strong, n=narrow, b=broad, sh=sharp ... –1 bond functional group 3640–3610 (s, sh) O–H stretch, free hydroxyl alcohols, phenols 3500–3200 (s,b) O–H stretch, H–bonded alcohols, phenols 3400–3250 (m) N–H stretch 1˚, 2˚ amines, amides 3300–2500 (m) O–H stretch ...
Typical IR Absorption Frequencies For Common Functional Groups. Bond. Functional Group. Frequency in cm −1 (Intensity*) C–H. Alkane. 3000–2850 (s) –CH 3. 1450 and 1375 (m)
Interpretation of Infrared Spectra, A Practical Approach. John Coates. Coates Consulting, Newtown, USA. Introduction. The Origins of the Infrared Spectrum. Spectral Interpretation by Application of Vibrational Group Frequencies. 3.1 The Hydrocarbon Species and Molecular Backbone. 3.2 Simple Functional Groups. 6. 9. 3.3 The Carbonyl Group.
