Wetting solvent selection

Application of stahi l i zera. The fabrics were prepared by applying stabilizers dissolved in solvents selected for their ability to dissolve the additive as well as to swell silk. The concentration of additive in solution was adjusted to give the desired fabric add-on assuming the fabrics would have 100% wet pick-up. If the fabric wet pick-up is indeed 100%, the dried fabric would have the desired addon. 

Today, reactions can be performed under an aerobic atmosphere, with wet solvents indeed, the presence of water is often beneficial to the rate and selectivity of the reaction. The operational simplicity and ready availability of these mostly inexpensive bench-stable catalysts - which are incomparably more robust than... 

The stereochemical results can be explained by the plausible transition state A (Fig. 12.57). Because additional water is added and the reaction is conducted in wet solvents, the transition state is stabilized by hydrogen bonding between the nitrogen atom of the imine and the nitrogen atom of the imidazolium moiety of the catalyst. A switch of the facial selectivity is disfavored because of steric repulsion between the Ar group of the imine and the imidazolium moiety of the catalyst. 

In further examining selectivity issues in alkali metal salt partitioning and exchange, one may notice in Table 13 a distinctly different selectivity between the dry and wet solvents. For dry solvents, a monotonic increase in... 

A solvent additive for OPV can be either a good solvent, selective solvent, or a nonsolvent for both species. The solvent additive must have a higher BP than the carrier solvent so that as the carrier solvent evaporates off, the co-solvent additive concentration increases. This means that the wet film thickness and concentration is created with the main solvent, but the morphology forms under the thermodynamic... 

Solvent extraction—purification of wet-process phosphoric acid is based on preferential extraction of H PO by an organic solvent vs the cationic impurities present in the acid. Because selectivity of acid over anionic impurities is usually not sufficient, precipitation or evaporation steps are included in the purification process for removal. Cmde wet-process acid is typically concentrated and clarified prior to extraction to remove post-precipitated sludge and improve partition of the acid into the solvent. Concentration also partially eliminates fluoride by evaporation of HF and/or SiF. Chemical precipitation of sulfate (as Ba or Ca salts), fluorosiUcates (as Na salt), and arsenic (as sulfides) may also be used as a prepurification step preceding solvent extraction. 

---