59th Annual Report on Research 2014

Our primary goal has been to develop Hammett studies for characterizing heterogeneous catalysts.  Our previous work has examined benzyl alchol oxidation; however, this reaction  is highly sensitive to the amount of water on the catalyst.  Additionally, benzyl alchol oxidation develops a positive charge on the benzyl alcohol in the rate determining step, so we wanted to use a reaction in which a negative charge develops.  Based on substantial literature precedent, we initially studied nitrobenzene reduction to aniline.   After many, many experiments and trials, we ultimately concluded that the reaction mechanism was too complicated and involved too many intermediates to be useful for our studies. We have since begun studying phenyl acetylene hydrogenation as a model reaction.  After experimenting with several soluble reductants, we have had the best success using atmospheric pressure H₂ as the reducing agent.  We have now completed the phenyl acetylene concentration study (Figure 1) for two different catalysts and the kinetics are clean, showing styrene as the only product.  We are now beginning the Hammett study, and expect to initially examine 4 different supports examining particle size effects.    One student, Elisabeth Purdy, a rising senior, was involved in this study.  This was her first independent research experience, and was pivotal in her decision to pursue graduate school in chemistry.  She is continuing to work on this project during the academic year and will present a poster at the spring ACS meeting in Denver.