Glycerol, << GLIHS uh rohl, >> also called glycerin, << GLIHS uhr ihn, >> is a thick, sweet-tasting liquid used in the manufacture of many products for homes and industry. Its name comes from the Greek word glykys, which means sweet. Glycerol is found in lipids, a group of compounds that includes fats and oils. The Swedish chemist Carl Wilhelm Scheele made the first glycerol from olive oil in 1783.
Uses.
Glycerol is used to make synthetic resins that harden paints. Cellophane and special papers are treated with glycerol to make them flexible and tough. Processors spray glycerol on tobacco leaves to prevent them from crumbling during treatment.
Glycerol is used to make ice cream, candy, and icings smooth and creamy. It also makes toothpaste and cosmetics smooth. Numerous medicines contain glycerol.
The chemical industry uses glycerol in the manufacture of sealing compounds and antifreeze. Glycerol is a major ingredient of nitroglycerin, also called nitroglycerol, a powerful explosive that is used to make dynamite and gunpowder (see Nitroglycerin ). Air brakes, electrical equipment, and oil-refining machinery are lubricated with glycerol.
Production.
Most glycerol is a by-product of soapmaking (see Detergent and soap (How soap is made) ). However, glycerol can also be made from the hydrocarbon propylene. Crude glycerol is purified to make various grades, such as dynamite grade, yellow distilled, and chemically pure glycerol. Only the highest grades of glycerol are used in foods and medicines.
Properties.
Glycerol is a clear, colorless liquid that has no odor. It is an alcohol with the chemical formula C3H5(OH)3. At low temperatures, glycerol sometimes forms crystals. These melt at 17.9 °C. Liquid glycerol boils at 290 °C. Its specific gravity is 1.26. It dissolves in water and in alcohols, but not in liquid hydrocarbons. Glycerol is hygroscopic—that is, it draws water from its surroundings. Heat produced by the absorption of water makes glycerol feel warm.
