Holistic Green Chemistry Metrics for Use in Teaching Laboratories

A review of the work that has been developed in Oporto on holistic metrics for evaluation of greenness in green chemistry is presented. As an introduction, a discussion on the complex nature of chemistry, greenness and its evaluation is used to show: the systemic nature of the metrification problem; why reductionist one-dimensional metrics have to be used in batteries; and the advantage of adopting holistic metrics conceived under systems thinking. Then the following items are presented: first, conception and construction of simple graphic metrics based in the Twelve Principles of Green Chemistry for holistic assessment of the greenness: green star, green circle and green matrix; second, the use of the metrics for green chemistry teaching, especially of the green star, for greenness optimization of the synthesis used in organic and inorganic teaching laboratories and for evaluation of laboratory course contents in Portuguese secondary schools; finally, a discussion of the advantages and limitations of holistic metrics based on the Twelve Principles.