Glycolate, determination

Free Propylene Glycol Determine as directed under Free Glycerin or Propylene Glycol, Appendix VII. 

Assay Calculate the percentage of Cellulose Gum by subtracting from 100 the percentages of Sodium Chloride and Sodium Glycolate determined as follows ... 

B) Ethers of Glycol. Determine the solubility of the monomethyl ether (cellosolve) and dioxane in water, alcohol, and ether. Determine the solubility of cellulose acetate in these two ethers. Use 0.1 g in 2 ml of the ether. 

Table 1.3 Contents of glycols determined in wines from four different grape varieties (Barbera, Nebbiolo, Cortese, Chardonnay) and five different harvests (year 1981-1986) (Di Stefano et al., 1988).

Lutsig, M.J., Cadet, J., Boorstein, R.J., andTeebor, G.W. (1992) Synthesis of the diastereomers of thymidine glycol, determination of concentrations and rates of interconversion of their cis-trans epimers at equilibrium and demonstration of differential alkali lability within DNA. Nucleic Acids Res., 20, 4839-4845. 

Table 1 Average molecular weights of polyfethylene glycol) determined by GPC...

The polyesters used in practice are based on e-caprolactone or dicarbonic acids, mostly adipic acid, and glycols. The higher the dissociation constant of the basic acid, the easier the esters are hydrolytically cleaved. In adipic acids, the number of C-atoms in the glycol determines hydrolytic behavior. 1,4-Butanediol and, even more so, 1,6-hexanediol cause more pronounced hydrophobizing in the polyester segment than ethylene glycol, thus inhibiting hydrolytic attack. 

Mono- and diheptanoate of tetraethylene glycol determination of mono- and diester, heptanoic acid, and tetraethylene glycol latroscan MK5 silica 80 20 1 ethyl ether/pentane/ HOAc FID 119... 

Cy alkyl ester of PEG separation of PEG, monoester, diester single peak for each Mono- and dioleate of 10-mole ethoxylate of N,N -his (2-hydroxyethyl)-5,5-dimethyl-hydantoin preparative separation of mono- and diester and free ethoxylate Mono- and di-heptanoate of tetraethylene glycol determination of mono- and diester, heptanoic acid, and tetraethylene glycol... 

Harder P, Grunze M, Dahint R, Whitesides G M and Laibinis P E 1998 Molecular conformation in oligo(ethylene glycol)-terminated self-assembled monolayers on gold and silver surfaces determines their ability to resist protein adsorption J. Rhys. Chem. B 102 426-36... 

DETERMINATION OF THE NUMBER OF HYDROXYL GROUPS IN (ii) GLYCOL. Molecular Weight, 62. 

The determination of the saponification equivalent of an ester by the alcohohc potassium hydroxide method is described in Section 111,106 an alternative procedure using diethylene glycol is given below. This constant should be determined if possible in the prehminary examination, since a knowledge of its value together with the boihng point provides a basis for a fairly good approximation of the size of the ester molecule. 

Determination of the Saponification Equivalent of an Ester BY THE Diethylene Glycol Method... 

As an example of the quantitative testing of Eq. (5.47), consider the polymerization of diethylene glycol (BB) with adipic acid (AA) in the presence of 1,2,3-propane tricarboxylic acid (A3). The critical value of the branching coefficient is 0.50 for this system by Eq. (5.46). For an experiment in which r = 0.800 and p = 0.375, p = 0.953 by Eq. (5.47). The critical extent of reaction, determined by titration, in the polymerizing mixture at the point where bubbles fail to rise through it was found experimentally to be 0.9907. Calculating back from Eq. (5.45), the experimental value of p, is consistent with the value =0.578. 

Alternatively a bonded poly(ethylene glycol) capillary column held at 35°C for 5 min and programmed to 190°C at 8°C/min may be employed to determine all components but water. The Kad-Eischer method for water gives inaccurate results. 

A comparison of coatings formulations based on various glycols to determine the effects of the various glycol stmctures on the performance properties of the coatings has been made. Properties compared included degree of cure, flexibiHty, hardness, hydrolytic stabiHty, processibiHty, chemical and stain resistance, and viscosity (18,19). 

Pure ethylene glycol freezes at —I2,7°C, Exact composition and temperature for eutectic point are unknown, since solutions in this region turn to viscous, glassy mass that makes it difficult to determine the true freezing point. For the concentrations lower than eutectic, ice forms on freezing, while on the concentrated, solid glycol separates from the solution. 

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. 

Figure 4.3 In most a/p-barrel structures the eight p strands of the barrel enclose a tightly packed hydrophobic core formed entirely by side chains from the p strands. The core is arranged in three layers, with each layer containing four side chains from alternate p strands. The schematic diagram shows this packing arrangement in the a/p barrel of the enzyme glycolate oxidase, the structure of which was determined by Carl Branden and colleagues in Uppsala, Sweden.

Figure 18.3 Protein crystals contain large channels and holes filled with solvent molecules, as shown in this diagram of the molecular packing in crystals of the enzyme glycolate oxidase. The subunits (colored disks) form octamers of molecular weight around 300 kDa, with a hole in the middle of each of about 15 A diameter. Between the molecules there are channels (white) of around 70 A diameter through the crystal. (Courtesy of Ylva Lindqvist, who determined the structure of this enzyme to 2.0 A resolution in the laboratory of Carl Branden, Uppsala.)...

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