The synthesis of ibuprofen is a famous example of the transition from traditional chemistry to Green Chemistry used often in textbooks. The increase of atom economy from 40% (old pathway) to 77% (new BHC pathway) shows the increase of atomic greenness (that refers to atoms involved in the stoichiometric equation), but I have never found a comparison of values the E-factor between the two. The E-factors measures the material greenness (all matetials involved in the process).
Values of atom economy are provided, for instance, in
Cann & Connelly, Real World Cases in Green Chemistry, ACS (2000), p. 19ff
and repeated often in textbooks.
Adelio A S C Machado
Faculdade de Ciências do Porto
Dear Adelio,
I have attached a segment of a textbook that I hope will be of help to you. There is a table that directly compares and gives a breakdown of the E-factor for the different routes to ibuprofen.
All the best,
Niko
I thank Niko for the text he posted.
I was aware of a similar, altough shorter, discussion by Andraos, in his book THE ALGEBRA OF ORGANIC SYNTHESIS, CRC (2011), p. 49-50 (Table 2.8) & 891-892 (Table 11.19, which is reproduced in the posted text - from a book edited by Dicks, 2012).
However the calcutation of these values are based in the synthesis protocols that don´t provide detailed values of the amounts of all the reagents, for instance solvents and auxiliary reagents, therefore requiring estimated values (obtained by extrapolation of similar steps in other synthesis, educated guesses, etc.). As Andraos comments (p.50, but see Chapter 3 for more detailed discussion of the problem/general situation) this procedure implies "frustation in getting the necessary information to make informed decisions about levels of greennnes of.synthesis plans". The uncertainity of the values of metrics like the E-fatcor is unkown, and these and the comparison of synthesis are not reliable.
What I would like to know is a set of values based in experimental values from laboratory or industrial synthesis for the classical and new (green) routes - probably very hard to obtain from the records (anyway, if these are reachable for the old, pre-GC, synthesis, the information probably is not there - but, who knows, there are miracles!)
Adelio A S C Machado
Faculdade de Ciências do Porto
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