Again developed by GSK,iv the reaction mass efficiency takes into account atom economy, chemical yield and stoichiometry. The formula can take one of the two forms shown below:
From a generic reaction where A + B → C Reaction mass efficiency = molecular weight of product C × yield m.w. A + (m.w. B × molar ratio B/A)
Or more simply Reaction mass efficiency = mass of product C × 100 / mass of A + mass of B
Like carbon efficiency, this measure shows the “clean-ness” of a reaction but not of a process, for example, neither metric takes into account waste produced. For example, these metrics could present a rearrangement as “very green” but they would fail to address any solvent, work-up and energy issues arising.
Read more about this topic: Green Chemistry Metrics
Famous quotes containing the words reaction, mass and/or efficiency:
“Sole and self-commanded works,
Fears not undermining days,
Grows by decays,
And, by the famous might that lurks
In reaction and recoil,
Makes flames to freeze, and ice to boil.”
—Ralph Waldo Emerson (1803–1882)
“There is a small steam engine in his brain which not only sets the cerebral mass in motion, but keeps the owner in hot water.”
—Unknown. New York Weekly Mirror (July 5, 1845)
“I’ll take fifty percent efficiency to get one hundred percent loyalty.”
—Samuel Goldwyn (1882–1974)