Key Assumptions About Atom Economy

The use of excesses of reagents and reactants to maximize reaction yield/selectivity, although a very common practice, is not part of the atom economy calculation. Reaction stoichiometry is, however, part of the calculations. This means that when 2 mol of one reactant combine with a single mole of a second reactant to form a new molecule that is either a reaction or process intermediate, the relevant stoichiometric ratio would be used to calculate the overall atom economy of the reaction. 

Working with Chiral Selectivity Regio-, Stereo-, or Enantioselectivity 

When calculating atom economy for a chiral resolution step, the reaction stoichiometry must be adjusted to account for that portion of the mass to be discarded as the unwanted enantiomer. This includes those cases where the resolving agent is in a 1 1 or 2 1 ratio with respect to the desired enantiomer, or 1 2 as in the case where the desired enantiomer is difunctional. 

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