Phase ethylene glycol

Figure 9. Isothermal analysis (200 °C) of fatty acid methyl esters on a packed column with stationary phase ethylene glycol succinate (EGS-X)...

CH2C1 CH2C1. Colourless liquid with an odour like that of chloroform b.p. 84 C. It is an excellent solvent for fats and waxes. Was first known as oil of Dutch chemists . Manufactured by the vapour- or liquid-phase reaction of ethene and chlorine in the presence of a catalyst. It reacts with anhydrous ethano-ales to give ethylene glycol diethanoate and with ammonia to give elhylenediamine, these reactions being employed for the manufacture of these chemicals. It burns only with difficulty and is not decomposed by boiling water. 

Acryhc stmctural adhesives have been modified by elastomers in order to obtain a phase-separated, toughened system. A significant contribution in this technology has been made in which acryhc adhesives were modified by the addition of chlorosulfonated polyethylene to obtain a phase-separated stmctural adhesive (11). Such adhesives also contain methyl methacrylate, glacial methacrylic acid, and cross-linkers such as ethylene glycol dimethacrylate [97-90-5]. The polymerization initiation system, which includes cumene hydroperoxide, N,1S7-dimethyl- -toluidine, and saccharin, can be apphed to the adherend surface as a primer, or it can be formulated as the second part of a two-part adhesive. Modification of cyanoacrylates using elastomers has also been attempted copolymers of acrylonitrile, butadiene, and styrene ethylene copolymers with methylacrylate or copolymers of methacrylates with butadiene and styrene have been used. However, because of the extreme reactivity of the monomer, modification of cyanoacrylate adhesives is very difficult and material purity is essential in order to be able to modify the cyanoacrylate without causing premature reaction. 

Two-Phase Aqueous Extraction. Liquid—Hquid extraction usually involves an aqueous phase and an organic phase, but systems having two or more aqueous phases can also be formed from solutions of mutually incompatible polymers such as poly(ethylene glycol) (PEG) or dextran. A system having as many as 18 aqueous phases in equiHbrium has been demonstrated (93). Two-phase aqueous extraction, particularly useful in purifying biological species such as proteins (qv) and enzymes, can also be carried out in combination with fermentation (qv) so that the fermentation product is extracted as it is formed (94). 

Halex rates can also be increased by phase-transfer catalysts (PTC) with widely varying stmctures quaternary ammonium salts (51—53) 18-crown-6-ether (54) pytidinium salts (55) quaternary phosphonium salts (56) and poly(ethylene glycol)s (57). Catalytic quantities of cesium duoride also enhance Halex reactions (58). 

Ethylene glycol is an example of a Class 3 drying agent. Because the solution produced is unsaturated only two phases, solution and vapor, exist ... 

Liquid Third Phase. A third Hquid with coUoidal stmcture has been a known component in emulsions since the 1970s (22) for nonionic surfactants of the poly(ethylene glycol) alkylaryl ether type. It allows low energy emulsification (23) using the strong temperature dependence of the coUoidal association stmctures in the water—surfactant—hydrocarbon systems. 

Fig. 11. In a system of water and hydrocarbon a nonionic emulsifier with a poly(ethylene glycol) chain as the polar part dissolves in the aqueous phase at low temperatures (a) and in the oil phase at high temperatures (c). At an intermediate temperature (b) three isotropic Hquid phases may be found.

The introduction of Hquid crystals as stabilizing elements for emulsions occurred in 1969 when it was found that the sudden stabilization at emulsifier concentrations in excess of 2.5% of a water—% xylene emulsion by a commercial octa(ethylene glycol) nonylphenyl ether was due to the formation of a Hquid crystalline phase in the emulsion (26). Later investigations confirmed the strong stabilizing action of these stmctures (27). 

Membrane Pervaporation Since 1987, membrane pei vapora-tion has become widely accepted in the CPI as an effective means of separation and recovery of liquid-phase process streams. It is most commonly used to dehydrate hquid hydrocarbons to yield a high-purity ethanol, isopropanol, and ethylene glycol product. The method basically consists of a selec tively-permeable membrane layer separating a liquid feed stream and a gas phase permeate stream as shown in Fig. 25-19. The permeation rate and selectivity is governed bv the physicochemical composition of the membrane. Pei vaporation differs From reverse osmosis systems in that the permeate rate is not a function of osmotic pressure, since the permeate is maintained at saturation pressure (Ref. 24). 

Diethylene glycol monoethyl ether [111-90-0] M 134.2, b 201.9", d 0.999, n 1.4273, n 1.4254. Ethylene glycol can be removed by extracting 250g in 750mL of benzene with 5mL portions of water, allowing for phase separation, until successive aqueous portions show the same volume increase. Dried, and freed from peroxides, as described for diethylene glycol mono-n-butyl ether. 

Figure 45. Futjural-ethylene glycol-water phase equilibrium diagram.

Aromatic steroids are virtually insoluble in liquid ammonia and a cosolvent must be added to solubilize them or reduction will not occur. Ether, ethylene glycol dimethyl ether, dioxane and tetrahydrofuran have been used and, of these, tetrahydrofuran is the preferred solvent. Although dioxane is often a better solvent for steroids at room temperature, it freezes at 12° and its solvent effectiveness in ammonia is diminished. Tetrahydrofuran is infinitely miscible with liquid ammonia, but the addition of lithium to a 1 1 mixture causes the separation of two liquid phases, one blue and one colorless, together with the separation of a lithium-ammonia bronze phase. Thus tetrahydrofuran and lithium depress the solubilities of each other in ammonia. A tetrahydrofuran-ammonia mixture containing much over 50 % of tetrahydrofuran does not become blue when lithium is added. In general, a 1 1 ratio of ammonia to organic solvents represents a reasonable compromise between maximum solubility of steroid and dissolution of the metal with ionization. 

Ji-Methoxy-ll, 11-ethylenedioxy-lS-methylestra-1,3,5(lO)-tnene. A solution of (+)3-methoxy-18-methylestra-l,3,5(10)-trien-17-one (5 g) dissolved in ethylene glycol (5 ml) and ethyl orthoformate (10 ml) containing />-toluenesulfonic acid (0.3 g) is heated under reflux for 2 hr in a nitrogen atmosphere. The resulting solution is diluted with methylene chloride and washed with dilute sodium bicarbonate and water. The organic phase is dried over sodium sulfate and evaporated to dryness in the presence of a trace of pyridine. Trituration of the residue with petroleum ether yields 4.7 g (82 %) of the pure ketal. 

Ethylene glycol—High vapor equilibrium with gas so tend to lose to gas phase in contactor. Use as hydrate inhibitor where it can be recovered from gas by separation at temperatures below 50 I ... 

Figure 12.18 LC-SFC analysis of mono- and di-laurates of poly (ethylene glycol) ( = 10) in a surfactant sample (a) normal phase HPLC trace (b) chromatogram obtained without prior fractionation (c) chromatogram of fraction 1 (FI) (d) chromatogram of fraction 2 (F2). LC conditions column (20 cm X 0.25 cm i.d.) packed with Shimpak diol mobile phase, w-hexane/methylene chloride/ethanol (75/25/1) flow rate, 4 p.L/min UV detection at 220 nm. SFC conditions fused-silica capillary column (15 m X 0.1 mm i.d.) with OV-17 (0.25 p.m film thickness) Pressure-programmed at a rate of 10 atm/min from 80 atm to 150 atm, and then at arate of 5 atm/min FID detection. Reprinted with permission from Ref. (23).

In the Oxirane process, ethylene is reacted in the liquid phase with acetic acid in the presence of a Te02 catalyst at approximately 160° and 28 atmospheres. The product is a mixture of mono- and diacetates of ethylene glycol ... 

A two-step methanolysis-hydrolysis process37 has been developed which involves reaction of PET with superheated methanol vapors at 240-260°C and atmospheric pressure to produce dimethyl terephthalate, monomethyl terephthalate, ethylene glycol, and oligomeric products in the first step. The methanolysis products are fractionally distilled and the remaining residue (oligomers) is subjected to hydrolysis after being fed into the hydrolysis reactor operating at a temperature of ca. 270°C. The TPA precipitates from the aqueous phase while impurities are left behind in the mother liquor. Methanolysis-hydrolysis leads to decreases in the time required for the depolymerization process compared to neutral hydrolysis for example, a neutral hydrolysis process that requires 45 min to produce the monomers is reduced... 

Figure 5.2 Liquid-liquid phase diagrams for a) aqueous solutions ofpoly(methacrylic acid) and ib) aqueous solutions of poly (ethylene glycols)...

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