Green Chemistry and Associated Metrics

Abstract

This chapter provides an overview of green metrics and their historical role in promoting the development of green chemistry. Starting with the history of the field, the Twelve Principles of Green Chemistry are introduced and discussed in conjunction with a "green-by-design" approach recently applied to the synthesis of Lipitor ® . Various perspectives on synthetic efficiency are briefly outlined with reference to atom economy and E factor. These ideas are further explored in the context of three industrial processes which have received Presidential Green Chemistry Challenge Awards. The synthesis of ibuprofen is examined from the point of view of intrinsic efficiency. Using the BHC process as an example, several benefits associated with the use of catalysis are discussed, with an emphasis placed on designing atom-efficient reactions. A global perspective centered around the production of chemical waste is also outlined with reference to Merck's commercial synthesis of Januvia ® , a medication for the treatment of type II diabetes. Finally, Pfizer's new sertraline process is used to describe ways of improving both quantitative as well as qualitative aspects of an industrial synthesis. The chapter concludes with a brief outline of the future directions of green metrics.

Sustainability in peptide chemistry: current synthesis and purification technologies and future challenges

“…198,199 The increasing popularity and success of ball-milling techniques is due to the fact that the protocols can be carried out under solvent-free conditions or only in the presence of minimum volumes of organic solvents, 200 thereby drastically reducing waste. 201 Moreover, other features have led mechanochemistry to be considered as a state of art technique by the scientific community, such as fast reaction time, high efficiency protocols, stoichiometry control and unique reactivity, opening the way to the synthesis of several compounds not attainable by other synthesis techniques. 202,203 Regarding peptide synthesis, the mechanochemical approach is normally limited to the use of Boc protected amino acids and only to the coupling process.…”

Optimized and Scalable Green Extraction of Pristimerin, an Anticancerigen from Mortonia greggii, by Ethanol–Phosphate Aqueous Two-Phase Systems

“…Conventionally, in triterpene extractions from plants, the use of hazard/toxic solvents such as hexane, chloroform, and petroleum ether has been preferred. , Nonetheless, their extraction with environmentally friendly solvents such as ethanol has been recently encouraged. , On its part, ethanol is recognized as a green solvent, and it has been ranked as “recommended” for the unified version of general solvent selection guides for medicinal chemists and Sanofi’s solvent selection guide; this because of its advantageous properties among which are its low volatility, moderate solubility, low toxicity, and low cost. − …”

Green Chemistry Applied to Transition Metal Chalcogenides through Synthesis, Design of Experiments, Life Cycle Assessment, and Machine Learning

“…For this analysis, five metrics were selected to demonstrate the flexibility of this technique: process mass intensity, material cost, global warming potential, smog formation potential, and ingestion toxicity (Figure 2) [139][140][141]. While LCAs typically focus on environmental and energy impacts they may be broadened or adapted to address a variety of economic and societal impacts as with techno-economic assessments which have been performed for evaluating downstream copper recovery from spent electronics [20,[142][143][144]].…”

“…An additional metric not used here which is relevant when screening metals with TMCs is the abiotic depletion potential, which examines the impacts of elemental scarcity in products including inorganic materials [26]. Process mass intensity (PMI) is a ratio of the masses of the chemical inputs for a process over the products [139]. Similar to E-Factor and related to atom economy, process mass intensity accounts for byproducts and wastes, including solvents [145].…”

“…Interestingly the solvent-free synthesis, method five, has a high process mass intensity and cost due to solvents such as chloroform that are used in the workup. LCA methods may be used to better model whether a system is greener than alternative methods by leveraging common and novel sustainability metrics [139,140].…”