Migration with addition

Weak boundary layer. WBL theory proposes that a cohesively weak region is present at the adhesive-substrate interface, which leads to poor adhesion. This layer can prevent the formation of adhesive bonds, or the adhesive can preferentially form bonds with the boundary layer rather that the surface it was intended for. Typically, the locus of failure is interfacial or in close proximity to the silicone-substrate interface. One of the most common causes of a WBL being formed is the presence of contaminants on the surface of the substrate. The formation of a WBL can also result from migration of additives from the bulk of the substrate, to the silicone-substrate interface. Alternatively, molecular... 

The reaction is induced by nucleophilic addition of the hydroxide anion to one of the two carbonyl groups. Then the respective substituent R migrates with the bonding electrons to the adjacent carbon atom (a 1,2-shift). Electron excess at that center is avoided by release of a pair of r-electrons from the carbonyl group to the oxygen ... 

The familiar standard de carbonyl at ion mechanism ( 3, 5) involving a concerted oxidative-addition of aldehyde, CO migration (with subsequent elimination), and reductive-elimination of product, would seem with metalloporphyrins to require coordination numbers higher than six, and in this case Ru(IV) intermediates. Although this is plausible, the data overall strongly suggest a radical mechanism and Ru(III) intermediates. 

Test spots can be identified by comparing their migration with that of reference samples, together with additional evidence, e.g. using a specific colour reagent. The RF value (rate of flow) is a measure of the movement of a compound compared with the movement of the solvent ... 

Identification was based on addition of a standard phosphate solution and then on the relative migration time of the peak of interest. It is noted that dihydrogeno- and hydrogenophosphate ion migrate with the same mobility. The reproducibility of the relative... 

D invasion through ECM layer and filter pores, amenable to different ECM components / additional cell layers (e.g., ECs) and organotypic tissue slices, migration with or against gravity, potential for HT... 

Methods for the synthesis of cyclobutanes with carbon 1,2-migration and additional hydrogen 1,2-migration36-38 are given in Sections 1.1.1. and 5.1. and Houben-Weyl, Vol. 4/4. 

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