glycerol
glycerol
The simplest trihydroxy alcohol. Molecular formula HOCH2CH(OH)CH2OH. Also known as glycerol. In nature, glycerol mainly exists in animals and plants in the form of glyceride, and a small amount of glycerol is contained in palm oil and other very few oils. Colorless viscous liquid. Has a sweet taste. The melting point is 20℃, the boiling point is 290℃ (decomposition), and the relative density is 1.2613 (20/4℃). Pure glycerin can form a crystalline solid, which is most easily crystallized when cooled to -15~-55℃. It is highly water-absorbent, miscible with water, and soluble in acetone, trichlorethylene and ether-alcohol mixture. Glycerol is similar to monohydric alcohols, for example, it reacts with metallic sodium to form sodium monoglycerol. Reacts with dry hydrogen chloride to generate 2,3-dihydroxy-1-chloropropane and 1,3-dihydroxy-2-chloropropane. It reacts with hydrogen chloride in ether solution to mainly generate 2-hydroxy-1,3-dichloropropane. Glyceraldehyde and glyceric acid are generated during oxidation; propylene glycol is generated during reduction. Glycerin reacts with mixed acids of sulfuric acid and nitric acid at about 10°C to form glycerol trinitrate, commonly known as nitroglycerin. This compound decomposes into a large amount of gas, water vapor and carbon dioxide upon slight collision, causing an explosion. Nitroglycerin is also commonly used as a cardiotonic and antianginal agent. Fatty acid chlorides or anhydrides can esterify glycerol. Glycerol reacts with hydrogen peroxide, peroxyacid, ferrous salt, dilute nitric acid, etc. to generate glyceraldehyde and dihydroxyacetone; it reacts with concentrated nitric acid to generate glyceric acid. Glycerol can also be oxidized by lead tetraacetate or periodic acid. When glycerin is heated with potassium sulfate or concentrated sulfuric acid, intramolecular water loss occurs and acrolein is generated.
Glycerin is a by-product of the soap industry and can also be produced by fermenting molasses with special yeast. Glycerin can also be synthesized from propylene. Glycerin is widely used as a chemical raw material in the manufacture of synthetic resins, plastics, paints, nitroglycerin, grease and beeswax, etc. It is also used in pharmaceuticals, spices, cosmetics, sanitary products and other industries.