Glycol system

For ethylene glycol systems copper tubing is often used (up to 3 in), while pumps, cooler tubes, or coils are made of iron, steel, brass, copper, or aluminum. Galvanized tubes should not be used in ethylene glycol systems because of reac tion of the inhibitor with the zinc. Methanol water solutions are compatible with most materials but in sufficient concentration will badly corrode aluminum. 

See also C. B. Reese, Protection of Alcoholic Hydroxyl Groups and Glycol Systems, in Protective Groups in Organic Chemistry, J. F. W. McOmie, Ed., Plenum, New York and London, 1973, pp. 95-143 H. M. Flowers, Protection of the Hydroxyl Group, in The Chemistry of the Hydroxyl Group, S. Patai, Ed., Wiley-Interscience,... 

The authors prepared a number of substituted 2-diazomethylene derivatives of picolyl oxide to use for monopiotection of the cis glycol system in nucleosides. The 3-methyl derivative proved most satisfactoiy. ... 

GPLA Glycol system pressure indicator fails... 

As would be expected in a substrate with a poor leaving group the predominant elimination process is of the Hofmann type. However, the authors did find some unexpected reactions. For example, the p-nitrophenyl sulphone was completely consumed within six hours of heating with the glycolate system, yet alkenes formed only a minor part of the products, the major part not being clearly identified. The p-dimethylaminophenyl sulphone was three to six times more reactive than the other sulphones, but it also underwent elimination at a significant rate with either solvent, even in the absence of alkoxides. The reasons for this are obscure. 

Reaction of 1,2-glycol systems, such as in the hemiacetal sesquiterpene 1751, with Me3SiCl/NaI in acetonitrile for 5 min at ambient temperature affords more than 80% of the corresponding olefin 1752 [15, 16] (Scheme 12.4). On reacting active methylene groups such as in ethyl acetoacetate or acetylacetone with benzal-dehyde in the presence of TCS14/Nal in acetonitrile, the intermediate unsaturated ketones 1753 and 1755 are reduced to ethyl 2-benzylacetoacetate 1754 [17] or 2-benzylacetylacetone 1756 [18] in 82% and 80% yield, respectively. 

The engines in the oil industry are usually heavy stationary diesels that run continuously. Also, aluminum is normally not used in this type of engine. For these types of engines, corrosion inhibitors for glycol systems based on... 

The ability to selectively direct chemistry at indole positions C4 to C7 remains a synthetic challenge. Takayama and co-workers have developed a procedure for masking the 2,3-Jt bond of indole as a bridged ethylene glycol system that allowed for functionalization of the... 

Numerous procedures for the preparation of butenolides have been developed. Font and coworkers (234-236) prepared the 5-O-substituted derivatives 223a-c of D-ribono-1,4-lactone. The cw-glycol system of223a reacted with ATjV-dimethylformamide dimethyl acetal and then with iodomethane to give the trimethylammonium methylidene intermediate 224. Pyrolysis of 224 gave the butenolide 225. 

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. 

Tober A J, Sanders, T G - Glycol System and Production Cooler Optimisation Study for the North Rankin A Platform, Worley Engineering Report No 25, December 1979. 

The trend of log kn in glyoxylate complexes is more aimilar to that of the glycolate system than the acetate system. The gadolinium break... 

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... 

UP Maleate/phthalate/ styrene Bellenger et al., 1992 0.88-1.51 for propylene glycol systems... 

Figure 18 Coexistence curves of tert-butyl acetate/PS and water/poly(ethylene glycol) systems (Yang et al, 2006cb).

Thymidine and 2-deoxycytidine proved to be resistant to oxidation by this reagent, an observation which can best be explained138 by the fact that a furanoid ring (see XXIII), in which the a-glycol system is absent, was known to be present in the former and was suspected in the latter. Independently, Manson and Lampen114 arrived at the same conclusions from similar metaperiodate studies. 

Equation (3.46a) indicates that the solubility of the solute in a mixed solvent system increases as the volume fraction of the cosolvent increases. Figure 3.6 shows the solubilization of hydrocortisone butyrate in a water/propylene glycol system. From the plot of Equation (3.46a), In x2m vs. solubilizing power, o, of the cosolvent for the solute. The solubilizing power is related to the partition coefficient of the solute in a water/octanol system, Kwo, as follows ... 

Hyde, T. J., The Epoxy Resin PMDA Glycol System, ACS Division of Paint, Plastics, Printing Ink Chemistry, Preprints, vol. 19, no. 2, September 1959. 

---