Polyethylene glycol systems

Fig. 10.12 Phase diagram and phase compositions of the dextran-polyethylene glycol system D 48-PEG 4000 at 293 K. All values are % w/w.

Fig. 10.13 Distribution coefficients of several proteins in the dextran-polyethylene glycol system in 0.0005 M KH2PO4, 0.0005 M K2HPO4, and with increasing concentration of NaCl the latter is expressed as moles NaCl added per kilogram standard phase system. 

A sodium hydroxide/polyethylene glycol system was used in the reductive decya-nation of diphenylacetonitriles to give diphenylmethanes in high yield. Thermal reaction times of 60 min could be reduced to 2 min under microwave irradiation (Scheme 4.43)69. 

Although these catalytic partial hydrogenations of alkynes may well be regarded as the procedure of choice for (Z)-alkenes,25 other catalytic systems have been explored. These include a sodium hydride-sodium alkoxide-nickel(n) acetate reagent,26 and a sodium borohydride-palladium chloride-polyethylene glycol system.27 Diisobutylaluminium hydride (DIBAL) has also been used for the conversion of alkynes into (Z)-alkenes.28 ( )-Alkenes are formed when the internal triple bond is reduced with sodium in liquid ammonia.29... 

W.A. Tisel, R.N. Haire, J.G. White, Polyphasic linkage between protein solubility and ligand-binding in the hemoglobin-polyethylene glycol system, J. Biol. Chem. 255 (1980) 8975-8978. 

YOU You, X., Qin, W., and Dai, Y., Phase separation behavior of cocamidopropyl betaine/water/polyethylene glycol system. Chin. J. Chem. Eng., 17, 746, 2009. 

The reaction of aldehyde, malononitrile and a-naphthol was carried out under microwave irradiation in the presence of the water-polyethylene glycol system and nanosized MgO as the catalyst. The product 2-amino-2 chromene was obtained in high yield. The reaction is given in Scheme 11.51 [109]. 

The electrical properties of the alkali metal salt complexes are of interest as solid electrodes for batteries (27, 27a). There is particular interest in alkali metal-thiocyanate salt complexes this interest is related to the anion having a high lyotropic number and a correspondingly high conductivity (see Table 4). The complete phase diagram has been published for the potassium thiocyanate/ and sodium/thiocyanate/polyethylene glycol system (28), and various thermodynamic properties have... 

In certain brilliantine compositions, vegetable and animal oils are used as substitutes for mineral oil. In these systems, because of their potential for rancidity, antioxidants must be included. Other alternatives to mineral oils that have found utiHty in brilliantines are the polyethylene glycols which come in a variety of solubiHties and spreading properties. Use of these materials offers the advantage of chemical stabiHty to rancidity. Other additives found in brilliantines to improve their aesthetics include colorants, fragrance, medicated additives, lanolin, and fatty acid esters. 

Metal complexes prepared by reacting less than one mole of an alkan olamine with an excess of a polyhydric alcohol, such as polyethylene glycol 200—400 or glycerol, reportedly impart a greater degree of thixotropy to systems containing protective organic coUoids (501). 

The basis for the separation is that when two polymers, or a polymer and certain salts, are mixed together in water, they are incompatible, leading to the formation of two immiscible but predominantly aqueous phases, each rich in only one of the two components [Albertsson, op. cit. Kula, in Cooney and Humphrey (eds.), op. cit., pp. 451 71]. A phase diagram for a polyethylene glycol (PEG)-Dextran, two-phase system is shown in Fig. 22-85. Proteins are known to distribute unevenly between these phases. This uneven distribution can be used for the selective concentration and partial purification of the products. Partitioning between the two phases is controlled by the polymer molecular weight and concentration, protein net charge and... 

Stratifying water systems for selective extraction of thiocyanate complexes of platinum metals have been proposed. The extraction degree of mthenium(III) by ethyl and isopropyl alcohols, acetone, polyethylene glycol in optimum conditions amounts to 95-100%. By the help of electronic methods, IR-spectroscopy, equilibrium shift the extractive mechanism has been proposed and stmctures of extractable compounds, which contain single anddouble-chai-ged acidocomplexes [Rh(SCN)J-, [Ru(SCN)J, [Ru(SCN)J -have been determined. Constants of extraction for associates investigated have been calculated. 

Corrective Action Application At a Navy facility in Guam, approximately 25 tons of PCB contaminated soil was treated using the KPEG (potassium polyethylene glycol) process. PCB concentrations were reduced from 3000 ppm to less than 5 ppm. Upon completion of treatment using the KPEG process, the soil was neutralized from a pH of 14 to 7. A full-scale system for this process is currently under development. 

Finally, the 1,3-dione systems prepared by Cram and Alberts deserve special note . These compounds, referred to as hexahosts are similar to the polymer-bound material illustrated as Compound 29 in Chap. 6. The synthesis is based on a methylene-bridged bis-dithiane unit. One of these may be cyclized with a polyethylene glycol, or more than one unit may be incorporated to give multiple 1,3-dione binding sites in the macrocycle. The former case is illustrated in Eq. (3.46). 

The solubility of latex in water can be improved by replacing the solvent used in the system. Initially, the water is removed and than a hydrophobic organic solvent is replaced by a hydrophilic solvent, which has a boiling point above 100 C. This last solvent can be ethylene glycol, diethyl ether of diethylene glycol, monoethyl ether of ethylene glycol, or polyethylene glycols. This treatment results in a pastelike composition that can be easily mixed with water and used as a final product. 

Mueller [103-104] has adopted the polyethylene glycol)-dextran partition system pioneered by Albertson [105] to develop an efficient chromatographic method for the resolution of proteins and nucleic acids. He used supports such... 

A prehminary study of the use of larch AGs in aqueous two-phase systems [394] revealed that this polysaccharide provides a low-cost alternative to fractionated dextrans for use in aqueous two-phase, two-polymer systems with polyethylene glycol (PEG). The narrow molecular-weight distribution (Mw/Mn of 1-2) and low viscosity at high concentration of AG can be exploited for reproducible separations of proteins under a variety of conditions. The AG/PEG systems were used with success for batch extractive bioconversions of cornstarch to cyclodextrin and glucose. 

It is possible to synthesize cobalt complexes which are soluble in polyethylene glycols and not in. solvents like hexane, hexene, heptenal etc. Ritter et al. (1996) have reported the oxo reaction of 1-hexene in such a system. 

---