Green Chemistry Metrics as a Quantitative Tool for Evaluating Chemical Reaction Efficiency: A Stoichiometric Comparative Study

Green chemistry provides a design-oriented approach for reducing waste and improving material efficiency. This study develops a transparent stoichiometric framework for comparing six representative reactions using atom economy (AE) and stoichiometric waste potential (SWP), and extends the analysis with stoichiometric E-factor/PMI proxies and yield-sensitivity analysis of reaction mass efficiency (RME). The selected reactions represent addition, dehydration, esterification, acylation, precipitation, and reduction chemistry. Balanced equations, molecular formulas, and standard molar masses were used to calculate reproducible theoretical metrics. Yield sensitivity was extended from the original aspirin example to all six reactions using the restricted relationship RME = AE × yield. The calculated atom-economy values range from 60.90% for ethanol dehydration to 100.00% for ethene hydrogenation. The analysis confirms that yield and atom economy answer different questions and that stoichiometric mass metrics cannot substitute for process-level information. A literature-informed screening framework is also provided for solvent use, energy demand, hazard, process mass intensity, and life-cycle considerations. Because no new experiments or complete process mass balances were available, process-level E-factor, PMI, solvent, energy, and life-cycle values are not presented as measured results. The revised framework therefore provides a reproducible educational and preliminary process-screening tool while clearly defining the data required for a complete sustainability assessment.