COMP 326 |
| It was proposed that bicyclohexene derivatives are believed to be the immediate precursors of aromatization reactions. There was no evidence to support this hypothesis other than the fact that a thermally allowed mechanism can be written for coversion of bicyclo[3.1.0]hex-2-enes to aromatics. As a part of the exploratory study of thermal aromatization reactions, 2,6,6 trimethylbicyclo[3.1.0]hexan-2-ol and its ester derivative 2-acetoxy-2,6,6-trimethylbicyclo[3.1.0]hexane were synthesized. Pyrolysis of 2-acetoxy-2,6,6-trimethylbicyclo[3.1.0]hexane at 350 oC gave 1,3,3-trimethyl-1,4-cyclohexadiene instead of the expected product, 2,6,6-trimethylbicyclo[3.1.0]hex-2-ene. Computational methods such as PM3, HF/6-31G*, B3LYP/6-31G*, UHF/6-31G*, UB3LYP/6-31G*, and UMP2/6-31G* were employed in order to elucidate the mechanism of this reaction. The Gibbs free energy of activation and the reaction energy were calculated for the proposed polar and biradical mechanisms. The results showed that a two-step mechanism is plausible at 350 oC in which the expected product 2,6,6-trimethylbicyclo[3.1.0]hex-2-ene is the intermediate. |
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Poster Session
6:00 PM-8:00 PM, Tuesday, August 21, 2007 BCEC -- Ballroom Foyer, Poster
Division of Computers in Chemistry |