Migration processes

L. Luckner and W. M. Schestakow, Migration Processes in the Soil and Groundwater Zone, Lewis Publ., Chelsea, Mich., 1991. 

While this overall process has been well established for quite. some time, recent attention has focused on the factors controlling the migration process. The... 

Diazoalkanes are u.seful is precursors to ruthenium and osmium alkylidene porphyrin complexes, and have also been investigated in iron porphyrin chemistry. In an attempt to prepare iron porphyrin carbene complexes containing an oxygen atom on the /(-carbon atom of the carbene, the reaction of the diazoketone PhC(0)C(Ni)CH3 with Fe(TpCIPP) was undertaken. A low spin, diamagnetic carbene complex formulated as Fe(TpCIPP)(=C(CH3)C(0)Ph) was identified by U V-visible and fI NMR spectroscopy and elemental analysis. Addition of CF3CO2H to this rapidly produced the protonated N-alkyl porphyrin, and Bit oxidation in the presence of sodium dithionitc gave the iron(II) N-alkyl porphyrin, both reactions evidence for Fe-to-N migration processes. ... 

Suksi J, Rasilainen K, Casanova J Ruskeeniemi T, Blomqvist R, Smellie JAT (2001) U-series disequilibria in a groundwater flow route as an indicator of uranium migration processes. J Contam Hydrol 47 187-196... 

The mobility of a species ut is a parameter connecting diffusion and migration processes. This section will be concerned primarily with the qualitative theory of mobility, which has characteristic properties for... 

Some years ago we began a program to explore the scope of the palladium-catalyzed annulation of alkenes, dienes and alkynes by functionally-substituted aryl and vinylic halides or triflates as a convenient approach to a wide variety of heterocycles and carbocycles. We subsequently reported annulations involving 1,2-, 1,3- and 1,4-dienes unsaturated cyclopropanes and cyclobutanes cyclic and bicyclic alkenes and alkynes, much of which was reviewed in 1999 (Scheme l).1 In recent days our work has concentrated on the annulation of alkynes. Recent developments in this area will be reviewed and some novel palladium migration processes that have been discovered during the course of this work will be discussed. 

About the same time that we discovered this aryl to aryl palladium migration chemistry, we observed a similar vinylic to aryl palladium migration process, which readily affords alkylidene fluorenes (Scheme 25).22 In this case,... 

Several different alkyl to aryl palladium migration processes have been also recently discovered using our standard palladium migration conditions (Scheme 28).24 Thus, both intramolecular Heck and intramolecular arylation... 

When 150 is thermolyzed at 230 °C it rearranges to at least three isomers, 155-157, which comprise approximately 75% of the product mixture100. Very likely this process is initiated by two 1,5-hydrogen shift reactions providing the isomer 154 first. Before this can undergo a third 1,5-hydrogen migration process to the most stable isomer 155 — formally... 

A palladium-mediated Stille-C-H functionalization process was recently disclosed. Deuteration of the fused arene led to 92% D-incorporation in the vinylsilane product, suggesting a Pd-migration process (Equation (159)).133... 

The concept of equilibrium distribution of organic chemicals between medium components is widely used for the mathematical description of their degradation and migration processes in soil and other environmental compartments. This is also useful... 

Thus, virtually the same organic pigments are recommended for coloring thermoplastic PUR as for plasticized PVC. Pigment migration processes are equally as important in both cases. 

The physical transport of dissolved organic compounds through the subsurface occurs by three processes advection, hydrodynamic dispersion, and molecular diffusion. Together, these three cause the spread of dissolved chemicals into the familiar plume distribution. Advection is the most important dissolved chemical migration process active in the subsurface, and reflects the migration of dissolved chemicals... 

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