Chapter 9 - Optimizing Catalytic Reactions

Abstract

Catalytic reactions are becoming increasingly important to increase productivity and minimize waste disposal costs. The important performance parameters to optimize a catalytic system must be defined. These may include optimizing the reaction rate, increasing the yield, increasing selectivity, and increasing the ease of workup. Catalysts, especially phase-transfer catalysts, may also be used to eliminate the use of polar, high-boiling solvents that are difficult to recover. Product costs may be decreased by developing catalytic processes using alternative raw materials. One key in optimizing catalytic reactions is to maximize the catalyst efficiency, or turnover. Low levels of catalyst poisons, which are competing ligands, can have great effects on a process. By understanding the influence of factors such as the presence and amounts of impurities, co-catalysts, and catalyst decomposition, a rugged catalytic process can be designed. The selections of transition metal catalysts and ligands are often inextricably connected. Ligands and catalysts may be selected to optimize a synthetic transformation or to optimize process productivity. Extended additions effectively provide reaction conditions with greater concentration of catalyst and can be important. The success of a catalytic reaction is influenced by the choice of catalyst, ligands, solvents, concentration, temperature, aging, and stirring rate. Catalyst decomposition and the influence of impurities, both cocatalytic and inhibitory, can play big roles. The interplay of all these parameters can make search for optimal conditions a time-consuming but reliable scale-up.