The broad peak at ~3400 cm-1 is due to OH in H 2 O generally. The messy broad peaks just before 3000 are the C-H bonds of the non aryl C. The tiny peak at ~3040 is probably the aryl C-H bonds. However I can't assign the peak at ~3200. 3. (This peak usually appears much broader than the other IR absorptions. Hydrogen-bonded O-H Stretch [Note: This peak can obscure other peaks in this region.] It was first ascended in June 1957 by Fritz Wintersteller, Marcus Schmuck, Kurt Diemberger, and Hermann Buhl of an Austrian expedition. Provides mostly information about the presence or absence of certain functional groups.
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The change in peak shape is a result of the different degree of hydrogen bonds in alcohol and carboxylic acids.
This peak is broad due to H-bonding In rare cases where H-bonding is not present, the peak is sharp and at higher frequency Alcohols ~3300 cm-1 ~3300 cm-1 ~3300 cm-1 If you are using as KBr palate, It should be dry under IR lamp before analysis to remove all moisture.
... are narrow and broad. The O-H-stretching modes from alcohols and phenols (example 5) are mostly broad and very strong (3200-3650 cm-1) The O-H-peaks due to carboxylic acids (example 6) show a very broad and less intense peak between 2500 and 3500 cm-1. Carboxylic Acids: H C OH O Formic Acid 1730-1650 C=O Stretch Ketones: H C 3 C CH 3 O Acetone 1750-1625 C=O Stretch O=P-OH broad IR bands involving OH stretch from 2725-1600 cm-1 maxima at 2725-2525 cm-1 , 2350-2080 cm-1 , and 1740-1600 cm-1 1 –OH group Peak at 1740-1600 cm-1 is strongest P-O stretch at 1040-909 cm-1 2 –OH groups Peak at 1740-1600 -1 cm is weakest, if present at all 3400-2400 (This peak always covers the entire region with a VERY BROAD peak.)
IR Spectroscopy by Functional Group Alkanes Indentification of absorbance Wavenumbers, cm-1 sp3 C-H stretch 2960-2850 (<3000) Alkenes sp2 C-H stretch 3100-3020 cm-1 (>3000) C=C stretch 1680-1620 cm-1 (often weak) Alkynes sp C-H stretch 3333-3267 cm-1 … Just before the fingerprint region at about 1690 is the carbonyl ester peak and to the right of it (also before the fingerprint region) is the benzene C-C bonding peaks. Narrow bands are thin and pointed, like a dagger. CH stretch typically occurs as a broad peak centered @ 3300 cm –1 (spanning 3550-3200 cm–1).
Infrared Spectroscopy (IR) – Triggering molecular vibrations through irradiation with infrared light.