Appeal 2007-0711
Reexamination 90/006,706
ordinary skill in the art that, at least for ibuprofen, a relatively higher degree
of chromatographic chiral isomer separation (α) of its chiral isomers
reasonably would have been expected using a liquid mobile phase
composition having an isomer retention capacity (k’) within the range of
0.1<k’<1.0. See the data for ibuprofen taken from Pirkle’s Tables 9, 16, 17,
and 18 showing that liquid mobile phase compositions with k’ values
ranging from .19 to .97 afford the greatest degree of chromatographic chiral
isomer separation (α) .
Negawa uses the conventional simulated moving bed chromatography
process for separating chiral isomers from enantiomeric mixtures of, for
example, active medicinals. Negawa does not disclose any specific k’
values for the liquid mobile phase compositions in the now conventional
SMBC process it employed. Nevertheless, Negawa used throughout its
disclosed work a liquid mobile phase composition comprising a mixture of
hexane and isopropanol (2-propanol)(volume ratio: 9/1)(Negawa, cols. 7-
10, Examples 1 and 3).
The question remains whether one of ordinary skill in the art
reasonably would have been directed to the process Applicants claim based
on the prior art as a whole. In our view, a person having ordinary skill in the
art would have been directed by the combined teachings of Negawa and
Pirkle to separate chiral isomers of ibuprofen using a conventional simulated
moving bed chromatography process employing an achiral liquid mobile
phase composition, with reasonable expectation of success, by: (1)
comparing a plurality of achiral liquid mobile compositions based on the
isomer retention capacity (k’) of each for a chiral isomer of the enantiomeric
mixture (especially mixtures of hexane and isopropanol at various volume
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