A Tale of Two Metabolites: Using the Separation of Urea and Cholesterol To Bridge the Gap between General and Organic Chemistry

摘要

We report the development of a collaborative problem-based laboratory project that is designed for implementation at the end of the general chemistry series or at the beginning of organic chemistry. The objectives of this laboratory project are to separate a mixture of two metabolites, urea and cholesterol, and to determine the percent composition of the components of this mixture. In the first of two laboratory periods, students participate in small group discussions in which differences in polarity, and hence solubility, are addressed and used to devise a procedure for the separation and quantification of the metabolites. Procedures are then discussed as a class and further refined. The second laboratory period is dedicated to performing the separation and completed with melting point determination and collecting infrared (IR) spectra of the separated metabolites. This laboratory project provides a review of general chemistry concepts and an introduction to organic chemistry concepts while allowing students to learn experimental techniques (melting point determination, IR determination, and recrystallization). Students expand their skill set by developing their analytical, critical thinking, presentation, and teamwork skills which, in tandem, create a laboratory environment where students work together to solve problems.