Atom economy describes the conversion efficiency of a chemical process in terms of all Properties For alternative meanings see atom (disambiguation). ...atoms involved. In an ideal chemical process the amount of starting materials or In chemistry, the reactants are the substances that exist at the start of a chemical reaction. ...reactants equals the amount of all products generated (see In chemistry, stoichiometry is the study of the combination of elements in chemical reactions. ...stoichiometry) and no atom is wasted. Recent developments like the advent of Green Chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. ...Green chemistry and high raw material ( Gas prices in Portland, Oregon during the 2004 price increase, up from regular under $2 prices The price of light, sweet crude oil on NYMEX has been above $40/barrel since late July 2004. ...oil) prices increasingly demand high atom economy.

Atom economy can be written as:

% atom economy = The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon_12). ...Molecular weight _{(desired products)} / The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon_12). ...Molecular weight _{(all reactants)}* 100%

Note that atom economy can be poor even when chemical yield is 100%, see for instance the The Cannizzaro reaction named after Stanislao Cannizzaro is a chemical reaction that involves disproportionation of any aldehyde lacking a hydrogen atom in the alpha position, in the presence of a strong base. ...Cannizzaro reaction. A The Diels_Alder reaction is an organic chemical reaction (specifically, a cycloaddition) between a conjugated diene and a substituted alkene (commonly termed the dienophile) to form a substituted cyclohexene system. ...Diels_Alder reaction is an example of a potentially very atom efficient reaction.On the other hand if the desired product is an In chemistry two stereoisomers are said to be enantiomers if one can be superimposed on the mirror image of the other, and vice versa. ...enantiomer the reaction needs to be sufficiently stereoselective even when atom economy is 100%.

Atom economy can be improved upon by carefull selection of starting materials and A catalyst (Greek: καταλύτης) is a substance that accelerates the rate of a chemical reaction, at some temperature, but without itself being transformed or consumed by the reaction (see also catalysis). ...catalyst system. Atom economy is just one way of looking at a chemical process, other criteria are for instance energy consumption, levels of pollution or price.

references

• Atom Economy. A Challenge for Organic Synthesis", B.M. Trost, Angew.Chem. Int. Ed. Engl. 1995, 34, 259.
• Atom Economy: A Green Chemistry Module www.chemsoc.org [1] (http://www.chemsoc.org/pdf/gcn/atomeff.ppt)