Merck Patent Gmbh

Poxel

Ewgenij Wakaresko

David Maillard

Harald Hirschmann

Christian Jasper

Andreas Waechtler

Jeremy Maurin

Guntram Koller

Sabine Gottburg-Reininger

A liquid crystal medium having negative dielectric anisotropy and containing one or more compounds of formulae B and C and one or more compounds of formula G and the use thereof for an active-matrix display, in particular based on the VA, SA-VA, IPS, PS-IPS, FFS, PS-FFS, UB-FFS or PS-UB-FFS effect.

Liquid-crystal medium

The present invention relates to methods for the production of enantiopure or enantioenriched Praziquantel precursors and to methods for the production of enantiopure or enantioenriched Praziquantel comprising the methods for the production of the Praziquantel precursors. The present invention further relates to compounds or intermediates useful in such methods.

Method for the production of Praziquantel and precursors thereof

The present invention discloses a process for isolating enantiomer components from a mixture of enantiomers through particle-size-controlled crystallization, comprising the steps of: (a) forming a solution of a mixture of enantiomers (R) and (S) in a solvent in the absence of any further additives or agents; (b) seeding the solution of step (a) simultaneously or consecutively with seed crystals of enantiomer (R) and with seed crystals of enantiomer (S), wherein the seed crystals of enantiomer (R) differ in size and/or in quantity from the seed crystals of enantiomer (S) to allow separation of the crystals composed of a mixture enriched with enantiomer (R) from the crystals composed of a mixture enriched with enantiomer (S); (c) inducing simultaneous crystallization of enantiomer (R) and enantiomer (S); and (d) isolating crystals composed of a mixture enriched with enantiomer (R) from crystals composed of a mixture enriched with enantiomer (S) through size separation of the crystals, preferably through sieving, melting or sedimentation, in particular through sieving.

Process of isolating enantiomer components from enantiomer mixtures by particle-size-controlled crystallization

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Fischbachtal, Germany

Ewgenij Wakaresko