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Atom Economy and Yield of Synthesis Sequences
Author(s) -
Eissen Marco,
Mazur Radoslaw,
Quebbemann HeinzGeorg,
Pennemann KarlHeinz
Publication year - 2004
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200490050
Subject(s) - chemistry , yield (engineering) , atom economy , atom (system on chip) , metric (unit) , substrate (aquarium) , product (mathematics) , sequence (biology) , stoichiometry , simple (philosophy) , computational chemistry , thermodynamics , mathematics , organic chemistry , catalysis , computer science , physics , geometry , philosophy , biochemistry , operations management , oceanography , epistemology , economics , embedded system , geology
Atom economy (AE) or atom utilization was one of the first defining terms in the sustainable chemistry movement. In contrast to the often‐cited twelve (qualitative) principles of green chemistry, AE represents a metric for quantification purposes. The theoretical efficiency of a reaction expressed by its stoichiometric equation can be determined by AE=Product [g/mol]/(Substrate 1+Substrate 2+…) [g/mol] and compared with synthetic alternatives. Of course, the atom economy will be of limited use, if starting materials differ much in complexity, i.e. , in the degree of refinement. In these cases, their syntheses have to be taken in consideration, too. But, the further the retrospect goes and the more preceding synthesis steps ramify, the more complex the calculation gets. To overcome this limitation, we introduce a stepwise approach that is enabled by a simple modification of the above formula (P=product; S=substrate; Syn.=synthesis): AE=P [g/mol]/((S1/AE(Syn. of S1))+(S2/AE(Syn. of S2))+…) [g/mol]. To illustrate this equation, which is derived mathematically, the convergent multistep synthesis of the natural product trans ‐chrysanthemic acid is subjected to a stepwise method of calculation. The equation can be understood as a general expression for related ratios, i.e. , there are corresponding modified equations for yield, selectivity, etc. In terms of the yield, it is no longer necessary to decide between the chains of the convergent synthesis, when possibly forced to ignore significant parts of the sequence. For demonstration purposes, the yield of the convergent synthesis of the natural product peridinin has been determined with a correspondingly modified equation.