Full Text for Volume 49 Number 4 (October 2005)

 

This issue contains the following:

Efficient Production of Enantiomerically Pure Secondary Alcohols
The asymmetric reduction of carbonyl groups to produce enantiomerically pure chiral secondary alcohols is highly important to synthetic chemistry, especially in the pharmaceutical industry. Antonio Zanotti-Gerosa, William Hems, Michelle Groarke and Fred Hancock from Johnson Matthey, Catalysis and Chiral Technologies, Cambridge, U.K., describe asymmetric hydrogenation and asymmetric transfer hydrogenation for ketone reduction. The reaction, using ruthenium catalysts with various diphosphine ligands and ancillary ligands, is highly efficient, simple and economic. The process is important for industrial synthesis of pharmaceutical intermediates.

 

The True Melting Point of Osmium
With good reason, osmium is considered the Cinderella of the platinum group metals (pgms), but, as it is now available in very high purities, it may be assessed alongside ruthenium, its analogue, which finds many chemical uses. John W. Arblaster, Coleshill Laboratories, U.K., proposes that 3400 ± 50 K is probably closer to the true melting point of pure osmium than the usually quoted value of 3300 K – for impure metal. However, for proper assessment, accurate melting point determinations are needed on high purity metal in an oxidation-free environment.

 

The 19th North American Catalysis Society Meeting
The 19th NACS meeting on catalysis, held in Philadelphia in May 2005, is selectively reviewed by Alvaro Amieiro-Fonseca, Johnson Matthey Technology Centre, U.K., and Mahesh Konduru and Julian Cox, Johnson Matthey Catalysts, Wayne, U.S.A. The reviewers highlight some of the presentations reported on the pgms. Sections covered include environmental catalysis for gasoline and diesel engines (emissions control), fuel reforming, and surface science in catalysis.

 

Casting Platinum Jewellery Alloys ­ Part II
Part I of this paper, published in this Journal in July, examined the composition and microstructure of two commercially-available casting jewellery alloys: Pt-5%Cu and Pt-5%Ru. In Part II, further comparisons are made. Duncan Miller and colleagues from the University of Cape Town, South Africa, examine the effects of flask temperatures, investments, and centrifugal speeds on microstructure, percentage fill, and porosity over a range of temperatures. Using a Hot Platinum induction melting and casting machine, optimum procedures, conditions and materials for successfully casting high quality platinum jewellery alloys are determined. Pt-5%Ru displayed superior uniformity, hardness and colour as a jewellery alloy when used with this induction melting process.

 

Ruthenium Complexes Bearing NHC Ligands ­ Part II
In Part I of this paper in the July issue, ruthenium complexes with nucleophilic N-heterocyclic carbene (NHC) ligands were reviewed by Valerian Dragutan and Ileana Dragutan, from the Institute of Organic Chemistry, Romanian Academy, Bucharest, Romania, and Albert Demonceau, from the University of Liege, Belgium. In Part II selected applications of these complexes as pre-catalysts in metathesis reactions are highlighted. Particular attention is drawn to metathesis in room temperature ionic liquids, asymmetric catalysis, and in situ generated, very active catalytic systems based on NHC-pgms. Most NHC-pgm complexes are useful as highly active and selective pre-catalysts for fundamental chemical transformations.

 

Silver-Induced Growth of Platinum Nano-Multipods
Scientists from the University of Rochester, U.S.A., report a silver-induced anisotropic growth process for making Pt multipods from Pt(acac)₂ at temperatures below that at which Pt nanoparticles are nucleated and grown. Multipods were formed 2.5 to 4.5 min after Ag(acac) addition at 180 to 200ºC. Further injection of Pt(acac)₂ into the reaction mixture extended the multipod growth process. This method may provide a way for multipods of different metals to be produced and, via self-assembly, become nanoscale building blocks for complex nanostructures.

 

Homogeneous Rhodium Catalyst Polyelectrolyte System
Researchers from the Universität Konstanz, Germany, have developed easily recoverable homogeneous Rh catalysts by electrostatically binding them to hyperbranched polymers. Polyelectrolytes were prepared by ion exchange from hyperbranched polycations with a polyether scaffold and 1,2-dimethylimidazolium end groups. After the polyelectrolytes and [Rh(acac)(CO)₂] were exposed to 1 atm CO/H₂, most of the Rh precursor converted to [(phosphine)₃Rh(H)(CO)]. The hydroformylation of 1-hexene in methanol proceeded with moderate activity at 80ºC and 30 bar CO/H₂.

 

The Use of Platinum and Palladium in Photography
An essay review of the book, "Platinum & Palladium Printing, Second Edition" by Dick Arentz, is presented by Mike Ware (Buxton, U.K.). This book is neither a history nor a chemistry of the process, but a treatise intended as a practical manual of instruction, with a detailed account of one method of accomplishing Pd-Pt prints and of creating the large photographic negatives that are prerequisite. The only other sources of published instructions in these skills are found within multi-topic works on ‘alternative’ photography.

 

Patent and Literature Selection and Yearly Indexes
The issue also contains a selection of abstracts based on recently published patent and scientific literature. The Name and Subject Indexes for 2005 are also included.

Susan V. Ashton
Editor

Contact
The Editor, Platinum Metals Review, Johnson Matthey PLC, Orchard Road, Royston, Hertfordshire SG8 5HE, United Kingdom; Fax +44 (0) 1763 256359; Email jmpmr@matthey.com

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