Ethylene glycol physical properties

Nicotinamide is a colorless, crystalline solid. It is very soluble in water (1 g is soluble in 1 mL of water) and in 95% ethanol (1 g is soluble in 1.5 mL of solvent). The compound is soluble in butanol, amyl alcohol, ethylene glycol, acetone, and chloroform, but is only slightly soluble in ether or benzene. Physical properties are Hsted in Table 1. 

The fluids have reasonably good chemical resistance but are attacked by concentrated mineral acids and alkalis. They are soluble in aliphatic, aromatic and chlorinated hydrocarbons, which is to be expected from the low solubility parameter of 14.9 MPa. They are insoluble in solvents of higher solubility parameter such as acetone, ethylene glycol and water. They are themselves very poor solvents. Some physical properties of the dimethylsilicone fluids are summarised in Table 29.2. 

Polyesters are another important class of polyols. There are many polyester types used, so a generic structure is shown in Scheme 4.4. They are often based on adipic acid and either ethylene glycol (ethylene adipates) or 1,4-butanediol (butylene adipates). Polyesters, because of the polar carbonyl groups, contribute more to intermolecular forces, and physical properties such as tear and impact resistance are often improved by using them. They are also utilized for their solvent and acid resistance and light stability. Relatively poor hydrolytic stability is... 

In addition to the desired polymerization reaction, the dialcohol reactants can participate in deleterious side reactions. Ethylene glycol, used in the manufacture of polyethylene terephthalate, can react with itself to form a dialcohol ether and water as shown in Fig. 24.4a). This dialcohol ether can incorporate into the growing polymer chain because it contains terminal alcohol units. Unfortunately, this incorporation lowers the crystallinity of the polyester on cooling which alters the polymer s physical properties. 1,4 butanediol, the dialcohol used to manufacture polybutylene terephthalate, can form tetrahydrofuran and water as shown in Fig. 24.4b). Both the tetrahydrofuran and water can be easily removed from the melt but this reaction reduces the efficiency of the process since reactants are lost. 

Numerous chemical intermediates are oxygen rich. Methanol, acetic acid and ethylene glycol show a O/C atomic ratio of 1, as does biomass. Other major chemicals intermediates show a lower O/C ratio, typically between 1/3 and 2/3. This holds for instance for propene and butene glycols, ethanol, (meth)acrylic acids, adipic acid and many others. The presence of some oxygen atoms is required to confer the desired physical and chemicals properties to the product. Selective and partial deoxygenation of biomass may represent an attractive and competitive route compared with the selective and partial oxidation of hydrocarbon feedstock. 

The key feature of ethylene glycol (EG) is the hydroxyl group, -OH, one on each of the two carbon atoms. The hydroxyls are responsible for its reactivity EG is a monomer used in the production of polyester polymers. The hydroxyls also give EG its most important physical property its solubility in water. That, linked with its low freeze point, makes EG suitable as an antifreeze and as a deicer. When EG is sprayed on ice, it combines with the water crystals and lowers the freeze point. This causes the mixture to melt and effectively keeps it in the liquid state. 

The physical chemical properties of the surfactants that contain an ester bond between the hydrophobic tail and the polar head group are very similar to those of alcohol ethoxylates of the same alkyl chain length and the same number of oxyethylene units. The CMC and the cloud point values of the linear ester surfactant 1 of Fig. 4 are approximately the same as those of the straight chained alcohol ethoxylate tetra(ethylene glycol)monooctyl ether (C8E4), i.e., around 10 mM and 40 °C, respectively. Thus it appears that the... 

TABLE 1. Physical Properties of Polyfethylene oxide-6-[(R)-3-hydroxybutyrate] diol-h-ethylene oxide Prepared by Transesterification of [(R)-3-hydroxybutyrate] with Methoxy Polyethylene Glycol... 

J.S. (1999). Transfection and physical properties of various saccharide, poly(ethylene glycol), and antibody-derivatizedpolyethylenimines (PEI). J. Gene Med., 1 (3), 210-222. 

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