The Principles of Green Chemistry – Second Principle: Atom Economy

Our latest blog series is designed to guide readers towards a greener, more sustainable laboratory. Each entry explores one principle. If you missed our previous principles, they are all posted on our blog page, which can be found here.

Second Principle: Atom Economy

Green chemistry conceptThis principle states, “Synthetic methods should be designed to maximize incorporation of all materials used in the process into the final product.”1

Just as Berkeley W. Cue, Jr., Ph.D., was able to distill the First Principle down to its essence,1 so too did the developer of the Second Principle of green chemistry.3 It can be simply stated as the “atom economy” of a reaction. The Atom economy concept, developed by Barry Trost, asks the question, “What atoms of the reactants are incorporated into the final desired product(s), and what atoms are wasted?”2

Going back to 1949, J. Leggett Bailey was involved with the question of atom economy, more likely with the objective to shorten reaction times, simplify preparation, and increase the yield of the target peptide than to advance the idea of “green chemistry”.3,4

Eventually, the formal calculation of atom economy was represented as:1

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% Atom Economy = (FW of atoms utilized/FW of all reactants) X 100 = (137/275) X 100 = 50%

Michael Cann, Ph.D., Professor of Chemistry at the University of Scranton, explains this, “… the percent atom economy is simply the formula weight of the desired product(s) (compound 4, 137 g/mol) divided by the sum of the formula weights of all the reactants (275 g/mol), which gives 50% in this case. Simply put, even if our percent yield is 100%, only half the mass of the reactants’ atoms are incorporated in the desired product while the other half is wasted in unwanted by-products.”2 He succinctly lays out the dilemma as being that: “chemists must not only strive to achieve maximum percent yield but also design syntheses that maximize the incorporation of the atoms of the reactants into the desired product.” 1

However, as many chemists well know, the formula is even more complicated when substituting those reactants for other materials such as solvents and separating agents during a synthesis. These issues will be addressed in the forthcoming “Principles” article.

Using a synthetic method of development that cuts costs, saves time, and reduces waste can be one approach to improving atom economy while reducing waste can improve profit and yield. Solvents and separating agents are addressed in forthcoming “Principles” or principles also. One approach to improving the atom economy is to develop a synthetic method that cuts costs, saves time, and reduces waste. Reducing waste can also improve profit and yield. Solvents and separating agents are addressed in the forthcoming ” Principles.” Cell therapies and small molecule synthesis involve the efficient use of starting materials, reagents, and intermediates.

Many other valuable resources listed below can assist you with adhering to the “Second Principle.”

References

  1. https://www.acs.org/content/acs/en/greenchemistry/principles/12-principles-of-green-chemistry.html
  2. B.M. Trost, Science, 254, 1471 (1991).
  3. J.L. Bailey, Nature, 164, 889 (1949). https://doi.org/10.1038/164889a0
  4. Z. Wang (Editor) Comprehensive Organic Name Reactions and Reagents, 3 Volume Set, ISBN: 978-0-471-70450-8 (2009).

Resources