BRAINCAKECharacteristic IR Absorptions
Each type of bond absorbs in a characteristic range of wavenumbers. The ranges are given on the OCR Data Sheet, so you do not need to learn the numbers, but you must be able to use them.
Key absorptions (cm−1)
• C-O: 1000 to 1300 (alcohols, esters, carboxylic acids)
• C=C: 1620 to 1680 (alkenes)
• C=O: 1630 to 1820 (aldehydes, ketones, carboxylic acids, esters)
• C≡N: 2220 to 2260 (nitriles)
• C-H: 2850 to 3100 (most organic compounds)
• O-H in carboxylic acids: 2500 to 3300, very broad
• N-H: 3300 to 3500 (amines, amides)
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More in Analytical Techniques
- Infrared Spectroscopy
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- Interpreting IR Spectra
- IR in Breathalysers and Pollution Monitoring
- Mass Spectrometry of Organic Compounds
- The Molecular Ion Peak
- The M+1 Peak
- Fragmentation
All 10 lessons in Analytical Techniques · All OCR AS-level Chemistry topics