Date of Award
Honors Thesis (Open Access)
Colby College. Chemistry Dept.
Bradford P. Mundy
D Whitney King
This project was developed from previous reports concerned with the pinacol coupling and rearrangement methodologies. It is hoped that the results and conclusions of this study may provide someone in the future a chance to gain a more complete view of this material. Analysis of the pinacol coupling reaction shows that the yields of the pinacol products are not statistical for the asymmetric cycloalkanone systems. Also, the yields of the 5-7 and 6-7 systems plotted versus ab initio gas phase calculations of HOMG-LUMO gaps showed r values at or near 1.00. This correlation is excellent and offers an example of how product yields may be predicted computationally. As exciting as this is, the 5-6 system did not match up well, experimentally vs. computationally, and further work is needed to gain a better understanding of this system. The AMI gas phase calculations used on pinacol rearrangement mechanistic species proved to be very useful. First, they substantiated that the stepwise mechanism was occurring rather than the concerted mechanism in the rearrangement of cyclopentylcyclohexane-l,l'-diol. Also, the calculations were used to plot reaction diagrams of the various conditions. These show that, in the gas phase, the 6-6 spiroketone is lower in energy than the 5-7 spiroketone. This is consistent with experimental data which indicate that the 6-6 product is favored when the reactions are stirred for a long time at room temperature. The 5-7 product is only favored when the reaction is short (30 min.) and performed at low temperature (00 C). These results indicate that a thermodynamic vs. kinetic effect is occurring in this system. Furthermore, calculations appear to be adept at predicting the most thermodynamically stable molecule.
pinacol methodology, rearrangement of a cyc1opentylcyclohexane-l, l'-diol, computational techniques, Pinacol Coupling, Experimental Investigation, Rearrangement Reactions
Recommended CitationSullivan, Ryan, "A Computational and Experimental Investigation of the Pinacol Coupling and Rearrangement Reactions" (1996). Honors Theses. Paper 333.
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