Polyhydric alcohols glycerol

Lahr, D.G. and Shanks, B.H. 2003. Kinetic Analysis of the Hydrogenolysis of Lower Polyhydric Alcohols Glycerol to Glycols. Ind. Eng. Chem. Res., 42, 5467-5472. 

Glucose, sucrose, and polyhydric alcohols, glycerol, sorbitol, and mannitol, display nucleophilic reactivity with simple activated esters in aqueous solution buffered at neutral to alkaline pH. This nu-cleophylic reactivity is attributed to the anion resulting from ionization of a hydroxyl group. These polyhydric alcohols have been shown to be catalyt-ically active in the hydrolysis of cephalosporins in... 

After treatment using polyhydric alcohols (glycerol, glycol, glycol ethers), thiogelatine, controlled drying and heat setting. Twenty-two... 

The most common alkyd raw materials are polybasic acids (phthalic anhydride, isophthalic acid, maleic anhydride, fumaric, azelaic, succinic, adipic, and sebacic acids), oils (linseed, soya, dehydrated castor, tung, fish, safflower, oiticica, cotton seed, and coconut), polyhydric alcohols (glycerol, pentaerythritol, dipen-taerythritol, trimethylolethane, sorbitol, trimethylolpropane, ethyleneglycol, propylene glycol, neopentyleneglycol, and dipropylene glycol), and monobasic acids (tail-oil fatty acids and synthetic saturated fatty acids). 

Alkyd resin A synthetic resin made by condensation reaction (release of water) between a polyhydric alcohol (glycerol, etc.) and dibasic acid (or phthalic anhydride). Binder The non-volatile portion of the vehicle of a paint. After drying, it binds the pigment particles together with the paint film as a whole. 

These derivatives are generally liquids and hence are of little value for characterisation the polyhydric alcohols, on the other hand, afford solid benzoates. Thus the benzoates of ethylene glycol, trimethylene glycol and glycerol melt at 73°, 58°, and 76° respectively (see Section 111,136). 

Polyhydric alcohols are compounds containing two or more hydroxyl groups in the molecule. The two most important are ethylene glycol HOCHjCHjOH (a dihydric alcohol) and glycerol HOCHjCH(OH)CH. OH (a trihydric alcohol). Ethylene glycol may be obtained by the hydrolysis of ethylene dibromide or ethylene dichloride with dilute aqueous sodium hydroxide or sodium carbonate solution ... 

Benzoates. The preparation of benzoates of polyhydric alcohols may be illustrated by reference to glycerol. They are usually crystaUine solids. 

Polyesters from polybasic acids and polyhydric alcohols. Alkyd resins. The condensation of polyhydric alcohols and polybasic acids or anhydrides leads to polj esters known as alkyd resins. The most common member of the group is a glycerol - phthahc acid polymer, and this has led to the term glyptal resins being frequently apphed to the whole group. 

When dealing with esters of water-soluble, non steam-volatile, poly-hydric alcohols e.g., ethylene glycol or glycerol), the distillate consists of water only (density 1 00). The water soluble, non-volatile alcohol may be isolated by evaporation of the alkahne solution to a thick syrup on a water bath and extraction of the polyhydric alcohol from the salt with cold ethyl alcohol. 

Humectants. In certain foods, it is necessary to control the amount of water that enters or exits the product. It is for this purpose that humectants are employed. Polyhydric alcohols (polyols), which include propylene glycol [57-55-6], C2Hg02, glycerol [56-81-5], C HgO, sorbitol [50-70-4], and mannitol [69-65-8], contain numerous hydroxyl groups (see Alcohols,polyhydric). Their stmcture makes them hydrophilic and... 

Glycerol, the simplest trihydric alcohol, forms esters, ethers, haUdes, amines, aldehydes, and such unsaturated compounds as acrolein (qv). As an alcohol, glycerol also has the abiUty to form salts such as sodium glyceroxide (see also Alcohols, polyhydric). 

Alkyd resins are produced by reaction of a polybasic acid, such as phthaUc or maleic anhydride, with a polyhydric alcohol, such as glycerol, pentaerythritol, or glycol, in the presence of an oil or fatty acid. The resulting polymeric material can be further modified with other polymers and chemicals such as acryhcs, siUcones, and natural oils. On account of the broad selection of various polybasic acids, polyhydric alcohols, oils and fatty acids, and other modifying ingredients, many different types of alkyd resins can be produced that have a wide range of coating properties (see Alkyd resins). 

The most important derivatives of the carboxyl group are formed by esterification with monohydric or polyhydric alcohols. Typical alcohols used iaclude methyl alcohol, ethylene glycol, glycerol, and pentaerythritol. These rosia esters have a wide range of softening poiats and compatibiUties. 

Metal complexes prepared by reacting less than one mole of an alkan olamine with an excess of a polyhydric alcohol, such as polyethylene glycol 200—400 or glycerol, reportedly impart a greater degree of thixotropy to systems containing protective organic coUoids (501). 

These resins are produeed by reacting a polyhydric alcohol, usually glycerol, with a polybasic acid, usually phthalic acid and the fatty acids of various oils such as linseed oil, soya bean oil and tung oil. These oils are triglycerides of the type shown in Figure 25.30. R], R2 and R3 usually contain unsaturated groupings. The alkyd resins would thus have structural units, such as is shown in Figure 25.31. 

Its acidity is considerably enhanced by chelation with polyhydric alcohols (e.g. glycerol, mannitol) and this forms the basis of its use in analytical chemistry e.g. with mannitol p T drops to 5.15,... 

Paraplex. A trademark for a group of alkyd type polymeric materials known as polyester resins. These resins are primarily long chain polybasic acids esterified with polyhydric alcohols such as glycol sebacate, glycerol, or ethylene glycol. Some are oil-modified while others are unmodified polyesters... 

Hydrogen iodide not only esterifies polyhydric alcohols but also reduces them. Thus glycerol passes by way of 1 2 3-triiodopropane into isopropyl iodide ... 

Fuels cells are of interest both from energetic and environmental considerations. When methanol is fed directly to an anode, as in Direct Methanol Fuel Cells , electric power is generated, making the devices suitable for small and lightweight uses [53], Alternative fuels such as polyhydric alcohols like ethylene glycol and glycerol are much less volatile and toxic, on the one hand, and electrochemically oxidizable on the other [54]. Therefore, the electrochemical oxidation of various polyhydric alcohols has been investigated in acidic as well as in alkaline conditions. 

The electrochemical oxidation of polyhydric alcohols, viz. ethylene glycol, glycerol, meso-erythritol, xilitol, on a platinum electrode show high reactivity in alkaline solutions of KOH and K2C03 [53]. This electro-oxidation shows structural effects, Pt(lll) being the most active orientation. This results from different adsorption interactions of glycerol with the crystal planes [59]. 

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