Homogenization novel

Organic chemists often use enantiomencally homogeneous starting materials for the synthe SIS of complex molecules (see Chiral Drugs p 296) A novel preparation of the S enantiomer of compound B has been descnbed using a bacterial cyclohexanone monooxygenase enzyme system... 

The sonochemistry of solutes dissolved in organic Hquids also remains largely unexplored. The sonochemistry of metal carbonyl compounds is an exception (57). Detailed studies of these systems led to important mechanistic understandings of the nature of sonochemistry. A variety of unusual reactivity patterns have been observed during ultrasonic irradiation, including multiple ligand dissociation, novel metal cluster formation, and the initiation of homogeneous catalysis at low ambient temperature (57). 

The possibility that the allyl group CH2=CH-CHi- can act as an ligand was recogni2ed independently by several groups in I960 and since then the held bas flourished, partly because of its importance in homogeneous catalysts and partly because of the novel sleric possibilities and inferconversions that can be studied by proton nmr spectroscopy. Many synthetic routes are available of which the following are representative. 

However, research into transition metal catalysis in ionic liquids should not focus only on the question of how to make some specific products more economical or ecological by use of a new solvent and, presumably, a new multiphasic process. Since it bridges the gap between homogeneous and heterogeneous catalysis, in a novel and highly attractive manner, the application of ionic liquids in transition metal catalysis gives access to some much more fundamental and conceptual questions for basic research. 

What can drive the switch from existing homogeneous processes to novel ionic liquids technology One major point is probably a higher cost-effectiveness. This can result from improved reaction rates and selectivity, associated with more efficient catalyst recovery and better environmental compatibility. 

Various novel applications in biotechnology, biomedical engineering, information industry, and microelectronics involve the use of polymeric microspheres with controlled size and surface properties [1-31. Traditionally, the polymer microspheres larger than 100 /urn with a certain size distribution have been produced by the suspension polymerization process, where the monomer droplets are broken into micron-size in the existence of a stabilizer and are subsequently polymerized within a continuous medium by using an oil-soluble initiator. Suspension polymerization is usually preferred for the production of polymeric particles in the size range of 50-1000 /Ltm. But, there is a wide size distribution in the product due to the inherent size distribution of the mechanical homogenization and due to the coalescence problem. The size distribution is measured with the standard deviation or the coefficient of variation (CV) and the suspension polymerization provides polymeric microspheres with CVs varying from 15-30%. 

This thoroughly revised and updated new edition is a must for every synthetic organic chemist. New material has been added on homogene- ous diastereoselective hydrogenations, enantioselective oxidations, and novel chiral auxiliaries. 

Lung volume reduction surgery is a rarely performed treatment option for heterogeneous emphysema patients with high hyperinflation. Novel semi-invasive and invasive alternatives are being developed, such as bronchial valves for heterogeneous emphysema treatment, and bronchial stents for homogeneous emphysema to reduce counteiproductive collateral ventilation. 

Park CH, M Keyhan, B Wielinga, S Fendorf, A Matin (2000) Purification to homogeneity and characterization of a novel Pseudomonas putida chromate reductase. Appl Environ Microbiol 66 1788-1795. 

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