The continuous enantioselective liquid−liquid extraction of aqueous 3,5-dinitrobenzoyl-d,l-leucine (DNB-d,l-leu) by a cinchona alkaloid extractant (CA) in 1,2-dichloroethane using a centrifugal contact separator (CCS) was studied at 294 K. Typical concentrations were in the order of 1 mM for both DNB-d,l-leu and CA. The best results were found at a pH of 6, with 61% yield for DNB-l-leu and an enantiomeric excess of 34%. Back-extraction studies at different pH values showed that the host can be recovered efficiently in a single CCS, provided that pH > 9. Experimental studies indicate that the CCS behaves as an equilibrium extraction stage, even at total throughputs exceeding 50% of the equipment capacity (1.9 L min−1). A previously developed equilibrium stage extraction model was successfully applied to describe the data for both the extraction and the back-extraction experiments.

Using a cascade of six centrifugal contactor separators in a countercurrent liquid-liquid extraction mode allowed the separation of one of the enantiomers of 3,5-dinitrobenzoyl-leucine in 55% yield and 98% ee using a catalytic amount of a chiral host compound based on a cinchona alkaloid. This method allows the preparation of kilograms of enantiopure material in table-top-sized equipment that can be operated in a fume cupboard. The methodology can be easily scaled up to ton amounts as largevolume centrifugal contactor separators are commercially available as well.

Eight cationic heteroleptic iridium(III) complexes, [Ir(epqc) 2 (N^N)] + , were prepared in high yield from a cyclometalated iridium bridged-chloride dimer bearing two ethyl-2-phenylquinoline-4-carboxylate (epqc) ligands. Two X-ray crystallographic studies were undertaken on selected complexes (where the ancillary ligand N^N = 4,4'-dimethyl-2,2'-bipyridine and 4,7-diphenyl-1,10-phenanthroline) each confirming the proposed formulations, showing an octahedral coordination at Ir(III). In general, the complexes are luminescent (620-630 nm) with moderately long lifetimes indicative of phosphorescence. Hydrolysis of the ethyl ester moieties of the epqc ligands gave the analogous cinchophen-based complexes, which were water-soluble and visibly luminescent (568-631 nm). The spectroscopic and redox characterisation of the complexes was complemented by DFT and TD-DFT calculations, supporting the assignment of dominant 3 MLCT to the emissive character. † Electronic supplementary information (ESI) available: Data collection parameters for the crystallographic studies, electrochemical data for 3a-h, pictorial representations of the calculated frontier orbitals for 3a-h and 4a-h and Cartesian coordinates obtained from DFT calculations. CCDC 907280 and 907282.

Resolution through revolution: It is possible to extract 3,5‐dinitrobenzoyl‐protected amino acids enantioselectively with the aid of a table‐top centrifugal contact separator and a catalytic amount of a chiral host compound based on the Cinchona alkaloids. Enantioselectivities of up to 80 % could be reached in a single pass. This allows the development of a process for the continuous separation of racemates. The resolution of racemates is mostly performed by crystallisation of diastereomeric salts. Direct physical separation could be much more efficient, but so far most concepts, with the exception of SMB, have proven to be non‐scaleable. Here we report the first scalable process for the resolution of N‐protected amino acid derivatives through selective extraction, with the aid of a catalytic amount of a chiral host compound based on Cinchona alkaloids. The method hinges on the use of centrifugal contact separators (CCSs) for fast mixing and separation. Although the highest ee obtained was only 80 %, the concept can be extended through the use of a series of CCSs in countercurrent mode to effect full separation.

C NMR spectroscopy as well as the short bond between the platinum and the C4 atom of the pyridine ring in 1 (1.95 Å) indicate the formation of a novel carbene species. Compound 1 is remarkably stable (m.p. 246°C), probably due to the presence of intramolecular hydrogen bonds, and is formed instead of the expected cyclometalated product. R=n-hexyl.