Capillary Electrophoresis Analysis of Substituted Benzoic Acids. An Experiment for the Organic Synthesis Laboratory

Capillary electrophoresis is gradually working its way into the undergraduate laboratory curriculum. Typically, experiments utilizing this technology have been introduced into analytical or instrumental courses. We have introduced an experiment into the organic chemistry sequence, in the synthesis laboratory, that utilizes capillary electrophoresis to evaluate the pK a shift on a series of student-prepared substituted benzoic acids. The pK a shift is examined in reference to the electrophoretic-migration behavior of benzoic acid and is a result of the electron-withdrawing or electron-donating characteristics of the substituent. This strategy allows us to increase the exposure of students to modern methods of separation. We are using repeated exposure to increase students' knowledge of separation strategies and techniques. Through this process students will gain a better, fuller understanding of CE than they would have with a single exposure in the analytical or instrumental laboratory. In our curriculum, this is the second time students work with capillary electrophoresis, and it occurs in the second-year laboratory.