Date of Award
Doctor of Philosophy in Environmental Science - (Ph.D.)
Chemical Engineering, Chemistry and Environmental Science
Howard David Perlmutter
Richard B. Trattner
David S. Kristol
Three water-based organic reactions, Diels-Alder, epoxidation of olefins, and free-radical bromination have been investigated as an approach to pollution prevention. The first two systems were scaled-up by at least a factor of 20. These reactions are of special interest to the pharmaceutical and speciality chemical industries. The photo-induced free-radical bromination of alkanes with bromine in water was studied in a two-phase system. Experimental results show that all reactions have advantages resulting from being conducted in water, such as reaction rate acceleration, reaction selectivity increase, and the absorption of water-soluble gas byproduct by solvent water.
The effects of stirring rates, temperature, ratios of reactants and optimization of reaction conditions were studied for these reactions. Temperature and ratio of reactants exert a large effect on the Diels-Alder reactions, but stirring rate has only a minor effect. For the epoxidation reaction, higher stirring rates always results in faster reaction rates in the range studied and higher temperature also result in faster reaction rate. Higher concentration of Oxone is not always beneficial for the epoxidation reation because mass transfer is reduced as a result of the salting out effect.
Results of free-radical bromination of alkanes show that the reaction can easily occur under mild conditions. Bromination of toluene using an incandescent light source produces benzyl bromide (a free-radical product) as a major product and o-, m-, or p- bromotoluene (ionic substitution products, i.e. non-free-radical) as byproducts. The ratios of benzyl bromide to bromotoluene increase with the increase of the intensity of irradation. Without light irradation, the o-, m-, or p- bromotoluene are the sole products. Bromination of cyclohexane produces mainly di-bromocyclohexane, and a smaller amount of monobromo product. This results from the neighboring bromo participation in substitution of the second bromine.
Water has a very good potential as the medium in which to conduct some organic reactions, bu new operating procedures need to be developed to fully capitalize on this technology.
Gu, Chen, "Scaling up of water-based organic reactions" (1996). Dissertations. 1007.