Qualitative Test for Hydrocarbons: A Laboratory Experiment to Reinforce the Different Types of Reactions and Mechanisms in Organic Chemistry

Abstract

Performing qualitative analysis is a common component of the undergraduate Organic Chemistry laboratory for identifying functional groups and unknown compounds. Although the Organic Chemistry 1 lecture dedicates a significant amount of time to discussing the reactions of hydrocarbons such as alkanes, alkenes, alkynes, and aromatics, only a few laboratory practices apply these reactions and emphasize the material discussed in the lecture. Therefore, we developed and implemented a laboratory activity that applied lecture theory to review how to identify the reactants (hydrocarbons), reagents, conditions, and products. In addition, it emphasizes the study of the different types of organic reactions, how to draw suitable mechanisms, and the use of curved arrows to show the formation and breaking of bonds. The experimental part of the laboratory experience consisted of qualitative tests to identify different types of hydrocarbons such as bromine, Baeyer, and Friedel−Crafts tests. This activity was implemented in laboratory courses of Organic Chemistry 1 and 2 and evaluated through a quasi-experimental study to assess the student's learning experience through a pre-test and post-test and a satisfaction survey. The results showed that the laboratory experiment was more effective for the laboratory of the Organic Chemistry 1 students. One of the advantages of this laboratory experiment is that it can be performed in person or can be adapted to a virtual context.