Evaluating the Greenness of Synthesis

DavidJ.C. Constable and Concepcion Conchita Jimenez-Conzalez 

General Considerations About Green Chemistry and Green Engineering Metrics 

Over the past several decades, a considerable amount has been written about the characteristics of metrics, or what constitutes a good metric [1-4]. Condensing all the relevant material written on the subject would be a formidable task, but most would agree that metrics must be clearly defined, simple, measurable, objective rather than subjective, and must ultimately drive the desired behavior [5]. 

if you asked most any person who practices synthetic organic chemistry, you are likely to find agreement that the art and science of synthetic chemistry requires an encyclopedic knowledge of many different types of chemistries, named reactions, and approaches to making molecules. While this is a skill that can be learned, it does demand a considerable amount of practice and practical experience before chemical synthesis becomes intuitive and a person has a feel for what needs to be done. 

Handbook of Green Chemistry Volume 7 Green Synthesis, First Edition. Edited by Chao-Jun Li. 

---

At least one of the 12 principles—number 2, design safe products—is a must for pharmaceutical synthesis. Indeed, pharmaceutical products are regulated and tested for safety. Principle number 7, maximize atom economy, refers to a metric against which the greenness of a process may be evaluated. Green metrics are covered in the next section. 

Two important questions encountered when evaluating the suitability of a photochemical method for synthesis, and in particular for green synthesis are the choice of the lamp and that of the solvent. 

RTILs in the double role of green solvents and parents of electrochemically generated intermediates (bases and catalysts) to trigger a prefixed reaction of synthesis must be evaluated. 

---