Atom efficiency

Atom efficiency is a ratio used in green chemistry to analyse the efficiency of a reaction.

Additional recommended knowledge

Essential Laboratory Skills Guide

What is the Correct Way to Check Repeatability in Balances?

What is the Sensitivity of my Balance?

The ratio is measured as (mass of atoms in product)/(mass of atoms in reactants). An assumption in doing this calculation is that the yield is 100%, which is very rare.

For a reaction to be 100% atom efficient, all the atoms of the reagents used must be incorporated into the desired product. Addition reactions, such as hydrogenation of an alkene, for example are 100% efficient. Reactions that result in a undesired by-product are less atom efficient.

References

• Sheldon R. A. (2000). "Atom efficiency and catalysis in organic synthesis". Pure and Applied Chemistry 72 (7): 1233-1246.