The EcoScale as a framework for undergraduate green chemistry teaching and assessment

Abstract

An upper-year undergraduate practical examination is presented that utilizes the EcoScale (a semiquantitative tool) and several established mass metrics to assess student understanding of green chemistry principles. This activity focuses on the straightforward preparation of a benzodiazepine via three different catalytic methods, and the analysis of individual experimental data during laboratory time. Students learn about the structure of the EcoScale, apply it as a simplistic life cycle assessment, and critique it as a scientific model. The examination complements more traditional expository and self-design experiments within a synthetic course where green chemistry and sustainability are central themes. ARTICLE HISTORY

Transitioning an Upper-Level, Integrated Laboratory Course to Remote and Online Instruction During the COVID-19 Pandemic

“…In addition to addressing the modified learning outcome, the assignment was implemented to develop student skills with respect to finding and referencing data for materials and reagents (physical, chemical, and toxicological), as well as to develop an understanding of LCA methodologies. The assignment was modified from, and combined direct elements found in, three previously reported exercises for the undergraduate study of synthetic LCA. − In short, the GI assignment addressed the modified learning outcome by asking students to compare two multivariate approaches, both using gate-to-gate LCA calculations, to assess their proposed synthetic modifications and determine which modification proved “greenest.” The goal of the assignment was to expose students to multivariate green chemistry metrics in order to compare synthetic modifications, using previously obtained data supplemented with literature values and assumptions. A copy of this assignment is provided in the Supporting Information and, broadly described, follows the format shown in Figure .…”

Evaluating Feedstocks, Processes, and Products in the Teaching Laboratory: A Framework for Students To Use Metrics to Design Greener Chemistry Experiments

“…Since well before the advent of Green Chemistry, metrics have been more numerous than the phenomena they measure and serve to highlight different considerations and facets of the same and seemingly similar measurable quantities. ,− While educators and students are invited to use common and accessible Green Chemistry metrics such as atom economy to introduce reaction efficiency, it is helpful for practitioners of these assessments to be aware of the alternative metrics which seek to measure similar but distinctive aspects of chemical and physical reactions. − Here in Table we have highlighted different mass-focused metrics: E-factor, reaction mass efficiency, atom economy, and product mass intensity, to demonstrate the different natures similar metrics may have and how certain metrics may be inherently better suited for assessing chemical feedstocks, processes, and products . While more rigorous efforts have been made to characterize these measures via metrology, here we briefly review four useful metrics for assessing material efficiency of chemical transformations and how they relate to the framework. ,,, …”

“…Dicks 169,170 designed laboratories focused on considering E-factor and reaction mass efficiency of an aza-Baylis-Hilman reaction 171 and the synthesis of benzodiazepines. 17, 172 Fennie meanwhile developed similar green metric explorations of amine-forming reactions. 173 Most of these examples accompany a laboratory component, but for those in search of an in-class tool, we developed an activity that uses LEGOs as molecular models.…”

“…To meet the diverse learning objectives of introductory and upper-level undergraduate chemistry laboratory courses, novel chemicals and new methods have been suggested to make experiments safer and to incorporate further sustainable practices, thus building upon the 12 principles of green chemistry. − Concurrently, life-cycle assessments, − technoeconomic analyses, − and green metrics − have been used by researchers following a systems thinking approach in academia, industry, and government organizations to address potential economic and environmental, as well as health and human, impacts of chemical transformations by comparing them to other published literature. ,,,, While many of these techniques are too complicated and time-consuming to be used effectively in the teaching laboratory, simplified components and even single metrics from these methods may be included in pre- or postlaboratory assignments to link textbook topics to real-world impacts. By using freely available information from online databases, safety data sheets, and chemical vendors, it is possible to bring simplified elements of these methods into the teaching laboratory to help pinpoint where renovation and inclusion of new methods may begin, as well as where future improvements may be made. − These quantitative methods can be used as tools where students assess various reagents, techniques, and end points to help them identify potential improvements to current methods.…”

“…By using freely available information from online databases, safety data sheets, and chemical vendors, it is possible to bring simplified elements of these methods into the teaching laboratory to help pinpoint where renovation and inclusion of new methods may begin, as well as where future improvements may be made. − These quantitative methods can be used as tools where students assess various reagents, techniques, and end points to help them identify potential improvements to current methods. More importantly they can use these techniques to support their decisions with data-driven insights aided by guided-inquiry initiatives. ,− As green chemistry experiments seek to allow the synthesis of benign products via safer processes in the teaching laboratory, the next generation of experiments in the teaching laboratory must be designed and supported by quantitative evaluations and introduce students to relevant metrics to continue this work. Life-cycle assessment (LCA) and techno-economic analysis (TEA) are two ways to assess the sustainability and safety of green chemistry experiments in the teaching laboratory from different perspectives.…”