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Unformatted text preview: C-H bond! 5) The INTENSITY (i.e. how far the peak points downwards) is proportional to the dipole moment of the bond. C-C has a small dipole so is a small peak; C=O is a strong peak due to the large dipole. Two molecules with weak IR stretches: 6) See page 425 for a more detailed frequencies table. 7) Broad peaks are due to hydrogen bonding and show the presence of O-H or N-H. Carboxylic acids (COOH) are very broad. UV Spectroscopy: 1) A Conjugated π system (multiple double bonds separated by a single bond) is more stable than isolated π bonds due to overlap of p orbitals throughout the system. There can be no sp 3 centers between the double bonds: 2) Conjugated π systems can be observed by Ultraviolet (UV) Spectroscopy. UV absorptions are described by their WAVELENGTH, not frequency. Simple rule of thumb: the more conjugated double bonds, the longer the wavelength of UV absorption....
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This note was uploaded on 02/02/2012 for the course CHEM 112b taught by Professor Marsella during the Spring '11 term at UC Irvine.
- Spring '11
- Infrared Spectroscopy