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:
“More and more, when faced with the world of men, the only reaction is one of individualism. Man alone is an end unto himself. Everything one tries to do for the common good ends in failure.”
—Albert Camus (1913–1960)
“The North has no interest in the particular Negro, but talks of justice for the whole. The South has not interest, and pretends none, in the mass of Negroes but is very much concerned about the individual.”
—Zora Neale Hurston (1891–1960)
“Nothing comes to pass in nature, which can be set down to a flaw therein; for nature is always the same and everywhere one and the same in her efficiency and power of action; that is, nature’s laws and ordinances whereby all things come to pass and change from one form to another, are everywhere and always; so that there should be one and the same method of understanding the nature of all things whatsoever, namely, through nature’s universal laws and rules.”
—Baruch (Benedict)