Details of Glycerol.

Glycerol, a clear, colorless, viscous, sweet-tasting liquid belonging to the alcohol family of organic compounds; molecular formula HOCH₂CHOHCH₂OH.

Pure glycerol has a melting point of 17.8°C. Its boiling point is 290°C but it also decomposes at that temperature. The presence of three hydroxyl groups makes the compound hygroscopic, with a tendency to absorb moisture from the air. This also makes it useful as a humectant in cosmetics and food, retaining water and preventing the substance from drying out.

Glycerol is easily soluble in water, due to the ability of the polyol groups to form hydrogen bonds with water molecules. Glycerol is slightly denser than water with a specific gravity of 1.26. This means that when glycerol is poured into a container of water, it will sink to the bottom. However, due to its solubility, over time and with mild agitation, glycerol will form an aqueous solution.

Glycerol can cause mild irritation to the eyes, nose, lungs and skin, particularly due to its hygroscopic nature. Skin and other internal organs can get dried out when pure glycerol comes into contact with these moist tissues. Since the molecule can bind to water, the same property that makes glycerol a good humectant also desiccates internal tissues. On the other hand, if a cosmetic preparation with high water content is applied on the skin, especially in arid environments, the presence of glycerol can prevent the lotion, cream or gel from drying out quickly.

The three hydroxyl groups of glycerol allow reactions with many organic acids to form esters. When all three reactive groups are esterified with long chain organic fatty acids, a triglyceride is formed. Triglycerides are among the most common lipids in the human body.