Glycerol, properties

IMt tm Mixt. of esters of citric acid and edible fatty acids with glycerol Properties Wh. to ivory oily to waxy material sol. in edible oils and fats ... 

Synonyms Citrem Citroglycerides Fatty acid mono- and diglycerides, citric acid esters Mono- and diglycerides citrates Mono- and diglycerides, citric acid esters Definition Mixt. of esters of citric acid and edible fatty acids with glycerol Properties Wh. to ivory oily to waxy material sol, in edible oils and fats disp, in hot water insol. in cold water HLB 10,0-12,0... 

Physical Properties. All colourless liquids, completely miscible with water, except benzyl alcohol and cyclohexanol, which are slightly soluble. Pure glycol and glycerol have high viscosity, which falls as the hygroscopic liquids absorb water from the air. 

By controlhng the relative amounts of, for example, glycerol and phthahc anhydride and the experimental conditions of the reaction, various pol5 mers of different properties are obtained. Under mild conditions (ca. 150°) only the primary alcohol groups are esterified and the secondary alcohol group remains free. The structural unit of the resulting linear polymer is ... 

The identity of the moiety (other than glycerol) esterified to the phosphoric group determines the specific phosphoHpid compound. The three most common phosphoHpids in commercial oils are phosphatidylcholine or lecithin [8002-45-5] (3a), phosphatidylethanolamine or cephalin [4537-76-2] (3b), and phosphatidjlinositol [28154-49-7] (3c). These materials are important constituents of plant and animal membranes. The phosphoHpid content of oils varies widely. Laurie oils, such as coconut and palm kernel, contain a few hundredths of a percent. Most oils contain 0.1 to 0.5%. Com and cottonseed oils contain almost 1% whereas soybean oil can vary from 1 to 3% phosphoHpid. Some phosphoHpids, such as dipaLmitoylphosphatidylcholine (R = R = palmitic R" = choline), form bilayer stmetures known as vesicles or Hposomes. The bdayer stmeture can microencapsulate solutes and transport them through systems where they would normally be degraded. This property allows their use in dmg deHvery systems (qv) (8). 

Properties. Antimony pentafluoride [7783-70-2], SbF, is a colorless, hygroscopic, very viscous liquid that fumes ia air. Its viscosity at 20°C is 460 mPa-s(=cP) which is very close to the value for glycerol. The polymerization of high purity SbF at ambient temperature can be prevented by addition of 1% anhydrous hydrogen fluoride, which can be removed by distillation prior to the use of SbF. The pure product melts at 7°C (11), boils at 142.7°C,... 

Physical properties of glycerol are shown in Table 1. Glycerol is completely soluble in water and alcohol, slightly soluble in diethyl ether, ethyl acetate, and dioxane, and insoluble in hydrocarbons (1). Glycerol is seldom seen in the crystallised state because of its tendency to supercool and its pronounced freesing point depression when mixed with water. A mixture of 66.7% glycerol, 33.3% water forms a eutectic mixture with a freesing point of —46.5°C. 

Acetins. The acetins are the mono-, di-, and triacetates of glycerol that form when glycerol is heated with acetic acid. Physical properties are shown in Table 4 they are all colorless. 

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). 

Rosin ester resins are used as modifiers in the formulation of chewing gum. The rosin derivative modifies the physical properties of the polymer used, providing the desired masticatory properties. The glycerol ester of hydrogenated rosin is the predominant choice, because stabilized materials have improved aging resistance, which extends the shelf life of the gum. 

Although soaps have many physical properties in common with the broader class of surfactants, they also have several distinguishing factors. First, soaps are most often derived direcdy from natural sources of fats and oils (see Fats and fatty oils). Fats and oils are triglycerides, ie, molecules comprised of a glycerol backbone and three ester-linked fatty oils. Other synthetic surfactants may use fats and oils or petrochemicals as initial building blocks, but generally require additional chemical manipulations such as sulfonation, esterification, sulfation, and amidation. 

Sodium iodide crystallizes ia the cubic system. Physical properties are given ia Table 1 (1). Sodium iodide is soluble ia methanol, ethanol, acetone, glycerol, and several other organic solvents. SolubiUty ia water is given ia Table 2. 

Selected physical and chemical properties of sodium nitrate are Hsted in Table 1. At room temperature, sodium nitrate is an ododess and colodess soHd, moderately hygroscopic, saline in taste, and very soluble in water, ammonia, and glycerol. Detailed physical and chemical properties are also available (3,4). 

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