Description

Chemical Identity

IUPAC Name: Propane-1,2,3-triol

Molecular Formula: C₃H₈O₃

Molar Mass: 92.09 g/mol

Structure: Three carbon atoms, each bonded to a hydroxyl (-OH) group:

HO-CH2-CH(OH)-CH2-OH

Physical Properties Relevant to Chemistry

Appearance: Colorless, odorless, viscous liquid

Solubility: Highly soluble in water due to hydrogen bonding; also miscible with alcohols.

Boiling Point: 290 °C (decomposes before boiling significantly)

Melting Point: 17.8 °C

Chemical Properties

Hydroxyl Groups Reactivity:

The three –OH groups make glycerin highly hydrophilic and capable of forming hydrogen bonds.

Can undergo esterification with acids to form triglycerides.

Acid-Base Behavior:

Mildly acidic due to hydroxyl hydrogens but largely neutral in solution.

Can act as a polyol (multi-hydroxy alcohol) in reactions with acids and oxidizing agents.

Oxidation Reactions:

Can be oxidized to form compounds like glyceraldehyde, dihydroxyacetone, or glyceric acid.

Strong oxidizers may completely oxidize glycerin to CO₂ and water.

Reduction Reactions:

Can be reduced further in specialized reactions, though it’s already an alcohol.

Dehydration:

Heating with strong acids (like H₂SO₄) causes dehydration, producing acrolein (a toxic aldehyde).

Combustion:

Glycerin is combustible and burns with a smoky flame, producing CO₂ and H₂O.

Key Chemical Traits

Hygroscopic: Absorbs water from the air.

Stable under normal conditions, but reactive with strong acids, bases, and oxidizers.

Polyfunctional: Its multiple hydroxyl groups allow it to act as a building block in pharmaceuticals, cosmetics, and food chemistry.

1. Pharmaceutical and Medical Uses

Humectant and Moisturizer: Keeps skin soft in creams, ointments, and lotions.

Laxative: Used in suppositories to relieve constipation.

Cough Syrups and Elixirs: Serves as a sweetening agent and stabilizer.

Wound Care: Helps maintain moisture in dressings and topical medications.

Drug Carrier: Acts as a solvent for certain medications.

2. Cosmetic Uses

Skin Care: Moisturizers, soaps, and facial masks.

Hair Care: Shampoos and conditioners to retain moisture.

Toothpaste: Prevents drying and maintains texture.

3. Food Industry Uses

Sweetener: Mildly sweet and calorie-containing.

Humectant: Keeps baked goods and candies moist.

Solvent: For food colorings, flavorings, and extracts.

Preservative: In some processed foods to prevent drying.

4. Industrial Uses

Antifreeze and Coolants: Lowers freezing point in some industrial solutions.

Explosives: Precursor for nitroglycerin (used in dynamite and propellants).

Plasticizer: In plastics, it makes materials more flexible.

Lubricant: For certain machinery and metalworking fluids.

Resins and Polymers: Used in production of alkyd resins.

5. Miscellaneous Uses

Personal Care Products: Deodorants, shaving creams, and hand sanitizers.

Veterinary Uses: Moisturizer and laxative in animal care.

Laboratory Uses: Solvent, reagent, and cryoprotectant (protects cells during freezing).