Atom efficiency

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

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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.