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Minor Enantiomer Recycling—Effect of Two Reinforcing Catalysts on Product Yield and Enantiomeric Excess
Author(s) -
Fransson Linda,
Laurell Anna,
Widyan Khalid,
Wingstrand Erica,
Hult Karl,
Moberg Christina
Publication year - 2010
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.200900327
Subject(s) - yield (engineering) , enantiomeric excess , catalysis , enantiomer , chemistry , enantioselective synthesis , substrate (aquarium) , kinetic resolution , organic chemistry , materials science , metallurgy , oceanography , geology
Kinetic modeling of a recycling procedure in which the minor product enantiomer from an enantioselective catalytic reaction is selectively retransformed to starting material by a second chiral catalyst demonstrates that the enantiomeric excess of the product is not affected by the relative amounts of the two catalysts, but that the yield increases when the amount of the catalyst for the product‐forming reaction is increased. The yield, but not the enantiomeric excess, is also affected by the initial substrate concentration. The recycling process is compared to sequential processes in which either the second catalyst is added after completion of the first reaction or in which the two catalysts are added simultaneously. In the sequential processes, high enantioselectivity can be obtained at the expense of product yield, whereas under recycling conditions both high enantiomeric excess and high yield can be achieved. Experimental data from a recycling procedure providing qualitative support for results from kinetic modeling are presented.