Functionalised silicas, used for selectively removing metal impurities in process streams, are packed in cartridges and inserted into multicartridge filters. The scavenging step that follows a catalytic reaction involves the single pass of the process stream through the multicartridge filter setup at a predetermined linear velocity and temperature. Efficiency in metal reduction as high as 98% has been so far achieved at tens of kilograms scale. Furthermore, the precious metal anchored onto the scavenger’s functionalities can be recovered and refined. Our chronological development of a versatile, general, and easily scalable format for metal scavenging at process scales is described, illustrated by application in real time to a range of projects passing through our Pharmaceutical Pilot Plant, employing a variety of metals (palladium, rhodium, iridium). Benefits of the cartridge format in terms of economics and environmental impact are also initially assessed.

A new series of porphyrins has been synthesised, incorporating four identical chiral binaphthyl derivatives in the mesopositions. Owing to a hindered rotation around the bond between the naphthyl and the porphyrin, four atropisomers are generated, which were fully separated by preparative TLC and thoroughly characterised. The free bases were

The conformation in solution of two atropisomeric meso-tetrabinaphthyl porphyrins, used as catalytic precursors in asymmetric synthesis, was studied by means of experimental ((1)H-NMR ROESY, UV-Vis, and circular dichroism) and computational (semiempirical structure optimization, DeVoe's coupled oscillators calculations) methods. UV-Vis and CD spectra are calculated for several molecular models, with a systematic sampling of the conformational space, and compared to the experimental ones, leading to a structural hypothesis which is confirmed by NMR and PM3.

The successful synthesis of 5,10,15,20-tetrakis[(R,R)-2,6-bis(1-phenylbutoxy)phenyl]porphyrin, with (R)-1-phenylbutoxy substituents on each of the eight ortho-positions, by a 2ϩ2 approach via meso-[(R,R)-2,6-bis(1-phenylbutoxy)phenyl]dipyrromethane rather than a one-pot condensation of (R,R)-2,6-bis(1-phenylbutoxy)benzaldehyde with pyrrole, is described. The synthesis has also been modified using meso-(pentafluorophenyl)dipyrromethane to prepare four further chiral porphyrins containing one, two (cis and trans) and three pentafluorophenyls in place of the bis(phenylbutoxy)phenyl groups. The cross-coupling of the two dipyrromethanes with pentafluorobenzaldehyde gave as one of the products the unexpected cis-disubstituted 5,10-bis(pentafluorophenyl)-15,20-bis[(R,R)-2,6bis(1-phenylbutoxy)phenyl]porphyrin. It seems likely that the formation of the latter compound involves the acidcatalysed reversion of the dipyrromethane synthesis. Both faces of each of the porphyrins are chiral and equivalent in this way the wasteful formation and time-consuming separation of atropisomers is avoided. Four iron() and one manganese() complex of these porphyrins have been prepared. The 1 H and 19 F NMR spectra of the series of porphyrin ligands reveal some interesting structure-and symmetry-dependent splitting patterns and trends which are used to confirm the identities of the compounds. In particular, the 1 H NMR couplings of the β-pyrrole hydrogens are very diagnostic of the substitution patterns of the meso-aryl groups on the porphyrin ring.