CHEM263 Lecture Notes - Lecture 6: Rhodopsin, Teratology, Acne Vulgaris
28 Sep 2016
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Chem 263 - lecture #6 - conjugated systems and aromaticity. Double bond conjugated system > non conjugated system: hydrogenation of alkenes release energy, conjugated compound releases 15 kj mol less (lower energy state to begin with) Homo and lumo: butadiene: all 4 c atoms are 2p ---> 4 x 2p ---> 4 molecules. **remember, the # of ao formed = # of mo formed. 2 double bonds = 2 bonding + 2 * antibonding (each bond system made by combining two 2p atomic orbitals) **more conjugation = e between lumo/homo** Causes color (absorption of light) and photosynthesis: uv radiation of ethylene us, molecules with 7 bonds absorb light between 4000 - 8000 and are visible to. 7 bonding and 7 antibonding mo"s ; e is very small between. Absorbs long wavelength --> absorb blue and we see yellow. Woodward rules: predicts the wavelength of absorption, highly conjugated compounds can be measured using a uv spectrometer.
