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1. What functional groups give the following signals in an IR spectrum? A) 1700 cm-1. B) 1550 cm-1. C) 1700 cm-1 and 2510-3000 cm-1. 2. How can you distinguish the following pairs of compounds through IR analysis? A) CH 3 OH (Methanol) and CH 3 CH 2 OCH 2 CH 3 (Diethylether) B) Cyclopentane and 1-pentene. C) 3. The following spectra is for the ...
16 Δεκ 2021 · The broad shape of the absorption band results from the hydrogen bonding of the OH groups between molecules. The OH bond of alcohol group usually has absorption in the range of 3200-3600 cm -1, while the OH bond of carboxylic acid group occurs at about 2500-3300 cm -1 (Figure 6.4a and Figure 6.4c).
IR SPECTRUM OF A CARBOXYLIC ACID. A carboxylic acid functional group combines the features of alcohols and ketones because it has both the O-H bond and the C=O bond. Therefore carboxylic acids show a very strong and broad band covering a wide range between 2800 and 3500 cm-1 for the O-H stretch.
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.
Identifying Functional Groups from an IR Spectrum. The IR spectrum of an unknown compound is shown in Figure 12.28. What functional groups does the compound contain?
IR Chart. Spectroscopy Tutorial: Reference. Table of Characteristic IR Absorptions. You can download this chart as a printable acrobat pdf file. m=medium, w=weak, s=strong, n=narrow, b=broad, sh=sharp.
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.
