Interconversion of Benzoic Acid Derivatives as an Undergraduate Laboratory Activity for Exploring Green Chemistry Metrics

Green Chemistry metrics provide quantitative approaches for evaluating the environmental performance of chemical reactions, but their interpretation can be challenging when considered independently. This laboratory activity was designed to integrate the interconversion of benzoic acid derivatives with the calculation and critical interpretation of Green Chemistry metrics in an undergraduate Organic Chemistry Laboratory II course. Students investigated alternative synthetic pathways involving benzoic acid derivatives, including phenyl benzoate, benzamide, benzoyl chloride, and benzoic anhydride, and examined both synthesis and hydrolysis reactions. Experimental data were used to calculate percent yield, atom economy, carbon efficiency, and E-factor for comparison of the different reaction pathways. The activity provided opportunities for students to examine the trade-offs among reaction yield, material efficiency, and waste generation when evaluating alternative synthetic routes. The comparison also illustrated that no single Green Chemistry metric is sufficient to describe the overall sustainability of a chemical transformation; practical considerations such as the reagent hazards, reaction conditions, processing requirements, and the potential value and recovery of starting materials may also influence the assessment. This activity provides an integrated approach for connecting organic reaction chemistry with quantitative Green Chemistry concepts and for encouraging students to evaluate chemical transformations using multiple complementary criteria.