Glycerine

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Glycerine (or Glycerol) is a simple polyol compound with the chemical formula C₃H₈O₃. It is a colorless, odorless, viscous liquid that has a sweet taste. Glycerine is a trihydroxy alcohol, meaning it contains three hydroxyl (–OH) groups. It is widely used in various industries such as pharmaceuticals, cosmetics, food, and chemicals. It is also a byproduct of the production of biodiesel and soap.
Glycerine is highly hygroscopic, meaning it absorbs moisture from the air, and is miscible with water and alcohol. It is a non-toxic, biodegradable, and generally recognized as safe (GRAS) substance, making it useful in a wide range of applications.

Properties of Glycerine:

  • Molecular Formula: C₃H₈O₃
  • Molar Mass: 92.09 g/mol
  • CAS Number: 56-81-5
  • Functional Groups: Contains three hydroxyl groups (–OH), making it a tri-alcohol or trihydroxy alcohol.
  • Reactivity:
    • Glycerine is relatively non-reactive under normal conditions but can undergo esterification reactions with fatty acids to produce glycerides, which are important in the production of soaps and biodiesel.
    • It can also participate in oxidation reactions to form glyceric acid.
    • Dehydration of glycerine can produce acrolein, a compound that is highly reactive and toxic.
    • Glycerine is non-toxic and biodegradable, making it environmentally safe in most applications.
  • Appearance: A colorless, odorless liquid.
  • Taste: Sweet.
  • Density: 1.261 g/cm³ at 20°C.
  • Melting Point: 17.8°C (64°F) (Glycerine crystallizes at low temperatures).
  • Boiling Point: 290°C (554°F).
  • Viscosity: 1.49 Pa.s at 20°C (highly viscous, much thicker than water).
  • Solubility:
    • Miscible in water, alcohol, and ether. Glycerine can absorb water from the air and is highly hygroscopic.
    • Insoluble in most non-polar solvents.
  • Vapor Pressure: 0.0013 mmHg at 20°C.
  • Refractive Index: 1.474 at 20°C.

Uses of Glycerine:

  • Pharmaceuticals: Used as a moisturizer in cosmetics and as a laxative in medicine.
  • Food Industry: As a humectant and sweetener in processed foods.
  • Personal Care: Found in soaps, lotions, and other cosmetic products.
  • Industrial Uses: Used in explosives (glycerol trinitrate), antifreeze, and as a solvent in the production of various chemicals.