Polyalcohols,

Glycerol, ethylene glycol and propane-1,2-diol can be separated on air-dried silica gel G layers, using chloroform-acetone-5 N ammonium hydroxide solution (10 + 80 + 10) in a 10 run at chamber saturation [89] the kB/-values are 35, 70 and 85, respectively. The benzidine-periodate reagent (Nos. 158 and 159) is used for detection. 

Pbey and co-workers [70] have separated glycerol hRf 38) from ethylene glycol (hi / 45) on normal silica gel G layers, using butanol-water (90 + 10) the separation may be improved by impregnation with O.IN boric acid. They used dichromate-sulphuric acid (Rgt. No. 46) for detection, obtaining white spots on a yellow-brown background. 

Heomatka and Aub [34] have established for diols a linear relation between the log of the /-value and the number of carbon atoms when using absolute ethanol or dioxan on silica gel G layers they studied ethylene glycol, propane-1,3-diol, hexane-1,6-diol, heptane-1,7-diol, nonane-1,9-diol, decane-1,10-diol and tridecane-1,13-diol. 

Knappe et al. [40] separate technically important polyalcohols on alumina G layers, using chloroform-toluene-formic acid (80 - - 17 + 3) on silica gel G layers with n-butanol, saturated with 1.5N ammonium hydroxide or on kieselguhr-polyamide layers with chloroform. For detection, they recommend a number of spray reagents made up of a strong oxidising agent and an oxidisable base. 

Polyalcohols can be separated on cellulose-gypsum layers (100 + 6) also, for which suitable solvents are n-butanol-25% ammonium hydroxide-water (85 + 5 -f 10), n-butanol-pyridine-water (46 + 31 + 23) or n-butanol-ethanol-25% ammonium hydroxide-water (40 + 15 + 5 + 40) [20]. 

Dihydric alcohol or glycol (two hydroxyl groups) CH2OHCH2OH 

Trihydric alcohol (three hydroxyl groups) CH2OHCHOHCH2OH 

There may be more than one hydroxyl group in an organic molecule. Polyalcohols are widely found in nature as all starchs and sugars are polyalcohols including sucrose (table sugar), and all fats, both vegetable and animal, are derivatives of glycerine. 

Ethylene glycol is the principal ingredient in automobile antifreeze and is also used to make polyester textile hbers such as Dacron. Glycerine is recovered as a by-product in the manufacture of soap and is used in cosmetics. Both glycerine and pentaerythritol are also used in the manufacture of paint and explosives. 

Poly alcohols (diols, triols, etc.), in spite of their high molecular weight, are highly soluble in water, due to the multiplicity of hydroxyl groups. 

Dialcohols, also called glycols, have two alcohol groups. They are liquids in a wide temperature range from —40 to +200 °C. They are very hygroscopic and miscible with water in any proportion. 

Glycols are part of the formulation of anti-icing agents that are sprayed on aircraft in winter before takeoff, as well as brake fluid and fluids for hydraulic circuits. They are a basis for the production of polymers. They are also used as heat exchange fluids in cooling systems, and in systems for the recovery of thermal solar energy. 

Cold glycols and polyalcohols in general have no action on aluminium, whatever their concentration. The dissolution rate increases at alkaline pH values (Table F.3.2). 

Polyalcohols can be stored and transported in equipment in aluminium alloy. Polyalkene-glycol mixtures are used as a quenching fluid for forgings made in aluminium alloys with high mechanical strength such as 7075 [10]. 

---

Polymerization. Carbon monoxide forms copolymers with ethylene and suitable vinyl compounds. No large-scale uses for the copolymers or their further reaction products such as polyalcohols and polyamines have been found (75). 

Polyalcohols, such as glycerol, sugar, sorbitol, and propylene glycol may prevent denaturation (28). Also substrates or substrate analogues often stabilize by conferring an increased rigidity to the enzyme stmcture. 

Microbiol Stability. Microbial growth is hindered by reducing water activity and adding preservatives. An overview is available (30). Reduction in water activity is typically obtained by including approximately 50% of a polyalcohol such as sorbitol or glycerol. Furthermore, 20% of a salt like NaCl has a pronounced growth inhibiting effect. 

In this case the formation of phenol-alcohols is rapid but their subsequent condensation is slow. Thus there is a tendency for polyalcohols, as well as monoalcohols, to be formed. The resulting polynuclear polyalcohols are of low molecular weight. Liquid resols have an average of less than two benzene rings per molecule, while a solid resol may have only three to four. A typical resol would have the structure shown in Figure 23.12. 

When glucose (Problem 19.72) is treated with NaBH4, reaction occurs to yield sorbitol, a polyalcohol commonly used as a food additive. Show how this reduction occurs. 

Treatment of an aldose or ketose with NaBH4 reduces it to a polyalcohol called an alditol. The reduction occurs by reaction of the open-chain form present in the aldehyde/ketone hemiacetal equilibrium. Although only a small amount of the open-chain form is present at any given time, that small amount is reduced, more is produced by opening of the pyranose form, that additional amount is reduced, and so on, until the entire sample has undergone reaction. 

Polyurethane foams are generally made using a polyalcohol rather than a diol as the monomer, so the polymer has a high amount of three-dimensional cross-linking. The result is a rigid but very light foam suitable for use as thermal insulation in building construction and portable ice chests. 

D-myo-inositol is a six carbon polyalcohol in a ring structure arranged in a chair configuration. 

Conduritols and inositols are cyclic polyalcohols with significant biological activity. The presence of four stereogenic centers in the stmcture of conduritols allows the existence of 10 stereoisomers. Enzymatic methods have been reported for the resolution of racemic mixtures or the desymmetrization of meso-conduritols. For example, Mucor miehei lipase (MML) showed enantiomeric discrimination between all-(R) and all-(S) stereoisomers ofconduritol E tetraacetate (Figure 6.52). Alcoholysis resulted in the removal of the four acetyl groups ofthe all-(R) enantiomer whereas the all-(S) enantiomer was recovered [141]. 

A matching search was made of the data available for two highly polar classes of chemicals — polyamines and polyalcohols — to find the polymer likely to be most resistant to chemical permeation by such highly polar compounds. 

Table II. Polyamines and Polyalcohols Matched by Material (Polymer)...

Polyalcohols have been tested against many different vendor models of three polymers, but only ethylene glycol has been tested against most of them. 

The largest single use of maleic anhydride is in the preparation of unsaturated polyester resins. It is first esterihed with a polyalcohol (two or more hydroxyls) and then the double bond is copolymerized (crosslinked) with a vinyl monomer such as styrene to form a rigid structure. Such resins are usually reinforced with hberglass (FRP). Maleic anhydride is also used to make oil additives and agricultural chemicals. 

A corrosion inhibitor with excellent film-forming and film-persistency characteristics is produced by first reacting Cig unsaturated fatty acids with maleic anhydride or fumaiic acid to produce the fatty acid Diels-Alder adduct or the fatty acid-ene reaction product [31]. This reaction product is further reacted in a condensation or hydrolyzation reaction with a polyalcohol to form an acid-anhydride ester corrosion inhibitor. The ester may be reacted with amines, metal hydroxides, metal oxides, ammonia, and combinations thereof to neutralize the ester. Surfactants may be added to tailor the inhibitor formulation to meet the specific needs of the user, that is, the corrosion inhibitor may be formulated to produce an oil-soluble, highly water-dispersible corrosion inhibitor or an oil-dispersible, water-soluble corrosion inhibitor. Suitable carrier solvents may be used as needed to disperse the corrosion inhibitor formulation. 

Polyesters may be used [27-30,223] instead of a fatty acid modifier for imidazoline. Thus a corrosion inhibitor with film-forming and film-persistency characteristics can be produced by first reacting, in a condensation reaction, a polybasic acid with a polyalcohol to form a partial ester. The partial ester is reacted with imidazoline or fatty diamines to result in a salt of the ester. Oil-soluble, highly water-dispersible corrosion inhibitor or oil-dispersible. 

In the same way, a crosslinked oxalkylated polyalkylene polyamine can be obtained by preparing a completely oxalkylated polyalkylene polyamine with a degree of polymerization of 10 to 300, crosslinked with a polyalcohol. The demulsifying agent is made from a mixture of the crosslinked oxalkylated polyalkylene polyamine with 25% to 75% by weight of an oxethylated or oxypropylated isoalkylphenol-formaldehyde resin [154]. 

Hidaka H., and Yamazaki M., 2004, New PCMs prepared from erythrito 1-polyalcohols mixtures for latent heat storage between 80 and 100 °C, J. Chem. Eng. Jap. 37 1155—1162. 

The polymers prepared from thexylborane and diene monomers were reacted with carbon monoxide at 120°C, followed by treatment with NaOH and H202 to produce a polyalcohol (scheme 5).13 This conversion includes migration of the polymer chain and thexyl group from the boron atom to carbon, as shown in scheme 5. When this reaction was carried out under milder condition, poly(ketone) segments were included in the polymer backbone due to an incomplete migration of the thexyl group. 

Moog RS, Ediger MD, Boxer SG, Fayer MD (1982) Viscosity dependence of the rotational reorientation of rhodamine B in mono- and polyalcohols. Picosecond transient grating experiments. J Phys Chem 86 4694-4700... 

Polymer linkages that do not release condensates on being formed include polyurethanes (diisocyanate/polyalcohol) and epoxy (ring opening of the epoxy... 

Lommerts BJ (1994) Structure development in polyketone and polyalcohol fibres. PhD thesis, University of Groningen... 

Asymmetric hydrogenations catalyzed by supported transition metal complexes have included use of both chiral support materials (poly-imines, polysaccharides, and polyalcohols), and bonded chiral phosphines, although there have been only a few reports in this area. 

Latterly, some oil-in-water adjuvants have been developed. Many are squalene-in-water emulsions. Emulsifiers most commonly used include polyalcohols, such as Tween and Span. In some cases, immunostimulatory molecules (including MDP and TDM see Section 13.5.4) have also been incorporated in order to enhance adjuvanticity. These continue to be carefully assessed and may well form a future family of useful adjuvant preparations. 

---