Appeal 2007-0711
Reexamination 90/006,706
composition for use in the process. The two steps in the selection of an
achiral liquid mobile phase composition for use in the known SMBC process
identified in Appellants’ claims purportedly indicate whether any particular
achiral liquid mobile phase composition would be effective for use as the
achiral liquid mobile phase of known SMBC processes designed to separate
at least one optically active enantiomer from a mixture of chiral organic
compounds.
In the first of the two selection steps of Appellants’ claims, the
retention capacities (k’), the solubilities, and/or the selectivities of a plurality
of achiral liquid mobile phase compositions for at least one target
enantiomer are compared. In the second of the two selection steps,
separation of at least one target enantiomer from a mixture of chiral organic
compounds is effected using an achiral liquid mobile phase composition
which has a retention capacity (k’) for the at least one target enantiomer such
that 0.1<k’<1.0.
Appellants’ supporting Specification instructs (Priegnitz et al.
(Priegnitz), U.S. Patent 5,518,625, col. 1, ll. 9-17):
[O]ur invention deals with the branch of simulated moving bed
chromatography as applied to the separation of chiral substances from
a racemic mixture. Our contribution to such separations which is the
subject of this application arises from the recognition that operating at
low values of k’, the capacity factor, is quite beneficial in chiral
separations even though classical liquid chromatography theory
teaches operation at high values of k’ as one prerequisite to successful
separations.
According to Appellants’ Specification (Priegnitz, col. 2, ll. 34-43):
Whereas one normally seeks to maximize the difference in retention
time between a component and the mobile phase in order to increase
4
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