4. Selected Qualitative Green Metrics

Qualitative green metrics such as the laboratory EcoScale, its modified industrial form and other computational tools are discussed. The first half of the chapter provides the reader with an appreciation of point-based categorical analysis as a means of assessing process greenness. Using calculated values for two benzodiazepine preparations, the EcoScale approach is explained in terms of its virtues and limitations. Simplicity and flexibility are highlighted as key advantages which make the EcoScale particularly effective in evaluating the nature of process operations and materials. Discussion then shifts to a recently proposed modified version of the EcoScale which addresses several drawbacks inherent in the original method. Using a newly defined system based on rewards rather than penalties, the modified EcoScale is shown to be effective at assessing industrial processes. The second portion of the chapter discusses two additional qualitative methods which are based on computational analysis. These approaches are the environmental assessment tool for organic syntheses (EATOS) and the radial polygon approach proposed by Andraos. To highlight their illustrative power and comprehensive scope, a recent article comparing four routes to a cyclic carbamate product is considered.