Solvent partially water soluble additive

Role of partially water soluble additive solvents. There have been published many studies on the membrane formation mechanism and the effects of solvents, additives (swelling agents or poreformers) and precipitants. Membrane performance and morphology are well correlated to polymer precipitation rate in nascent membrane (. Low precipitation rate generally produces membranes of finely pored sponge substrate structure with low solute permeation. Remarks on solvent-precipitant interaction by Frommer et al. (3) is helpful to speculation on membrane formation. In the following paragraphs is discussed the role of partially water soluble solvent as a plasticizer of nascent membrane matrix. 

As discussed above, the mechanism how the mixed additive, nonsolvent (water) and partially water soluble solvent (cyclohexanone) works is supposedly different from that of well-known additives, such as formamide. 

PVP is a nonionic water-soluble polymer that interacts with water-soluble dyes to form water-soluble complexes with less fabric substantivity than the free dye. Additionally, PVP inhibits soil redeposition and is particularly effective with synthetic fibers and synthetic cotton blends. The polymer comprises hydrophilic, dipolar imido groups in conjunction with hydrophobic, apolar methylene and methine groups. The combination of dipolar and amphiphilic character make PVP soluble in water and organic solvents such as alcohols and partially halogenated alkanes, and will complex a variety of polarizable and acidic compounds. PVP is particularly effective with blue dyes and not as effective with acid red dyes. 

Several important homogeneous catalytic reactions (e.g. hydroformylations) have been accomplished in water by use of water-soluble catalysts in some instances water can act as a solvent and as a reactant for hydroformylation. In addition, formation of aluminoxanes by partial hydrolysis of alkylaluminum halides results in very high activity bimetallic Al/Ti or Al/Zr metallocene catalysts for ethene polymerization which would be otherwise inactive. Polymerization of aryl diiodides and acetylene gas has recently been achieved in water with palladium catalysts. Finally, nickel-containing enzymes, such as carbon monoxide dehydrogenase (CODH) and acetyl-CoA synthase, operate in water with reaction mechanisms comparable with those of the WGSR or of the Monsanto methanol-to-acetic-acid process. ... 

Amino resins are soluble in organic solvents if butanol and i-butanol are used as additional nucleophilic components. Shorter-chain alcohols lead to insufficiently soluble lacquer resins and longer-chain alcohols have an etheration rate that is too slow. The resins are usually delivered as 50% solutions in butanol or butanol/ xylene. Amino resins partially etherated with methanol are lacquer resins with very good water solubility. 

Solubility of the /3-CDs can be improved by derivatization partially substituted hydroxypropyl-/3-CD and hydroxyethyl-CD show better solubility in water and aqueous-organic solvents [29]. The solubility of hydroxypropyl- and hydroxyethyl-/3-CDs increases as the degree of substitution of hydroxyl group increases. Solutions exceeding 0.4 M CD can be made without additives enhancing solubility. 

These can be converted to their uranyl nitrate addition compounds. The crude or partially purified ester is saturated with uranyl nitrate solution and the adduct filtered off. It is recrystallised from -hexane, toluene or ethanol. For the more soluble members crystallisation from hexane using low temperatures (-40°) has been successful. The adduct is decomposed by shaking with sodium carbonate solution and water, the solvent is steam distilled (if hexane or toluene is used) and the ester is collected by filtration. Alternatively, after decomposition, the organic layer is separated, dried with CaCl or BaO, filtered, and fractionally distilled under high vacuum. 

The addition of an amino acid to mixed solvents at selected temperatures can be a means to compensate even partially for the decrease of dielectric constant due to the solvent addition. Limitations are imposed by the solubility of the amino acid in such mixtures for instance, there is a salting-out effect in methanol-water 50 50 at 25°C when the concentration of glycine is about 0.5 Af (8 20). 

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