Glycerol, also known as glycerin, is an important polyol. It appears as a colorless, transparent viscous liquid, odorless, and strongly hygroscopic. It is stable at room temperature and miscible with water and ethanol in any proportion. The three hydroxyl groups in its molecule make it an excellent humectant, solvent, and viscosity modifier. Based on these properties, glycerol is widely used in cosmetics, food, oral care, and pharmaceuticals. Industrially, it is also a key raw material for synthetic resins, polyurethanes, and nitroglycerin.
Chemical Properties
| Property | Value |
| Melting point | 20 °C (lit.) |
| Boiling point | 290 °C |
| Density | 1.25 g/mL (lit.) |
| Vapor density | 3.1 (vs air) |
| Vapor pressure | <1 mmHg (20 °C) |
| FEMA | 2525 | GLYCEROL |
| Refractive index | n20/D 1.474 (lit.) |
| Flash point | 320 °F |
| Storage condition | Store at +5°C to +30°C. |
| Solubility | H₂O: 5 M, 20 °C, clear, colorless |
| Acidity coefficient (pKa) | 14.15 (at 25°C) |
| Form | Viscous liquid |
| Color | APHA: ≤10 |
| Specific gravity | 1.265 (15/15°C) 1.262 |
| Odor | Odorless |
| pH value | 5.5-8 (25°C, 5M in H₂O) |
| pH range (indicator) | 5.5 - 8 |
| Aroma type | Odorless |
| Biological source | Synthetic (organic) |
| Explosive limit | 2.6-11.3%(V) |
| Water solubility | >500 g/L (20 °C) |
| Thermal conductivity | 0.285 W/(m·K) at 25 °C |
| Maximum wavelength (λ_max) | λ: 260 nm Amax: 0.05
λ: 280 nm Amax: 0.04 |
| Sensitivity | Hygroscopic |
| Merck | 144484 |
| JECFA Number | 909 |
| BRN | 635685 |
| Henry's Law Constant | 4.7×106 mol/(m3Pa)4.7×106mol/(m3Pa) at 25°C, Burkholder et al. (2019) |
| Exposure Limits | OSHA: TWA 15 mg/m33; TWA 5 mg/m33 |
| Dielectric Constant | 47.0 (Ambient) |
| Stability | Stable. Incompatible with perchloric acid, alumina, acetic anhydride, nitrobenzene, ammonia, peroxides, strong acids, strong bases. Combustible. |
| Cosmetic Ingredient Function | HUMECTANT
SKIN CONDITIONING - HUMECTANT
DENATURANT
FRAGRANCE
SOLVENT
SKIN PROTECTING
VISCOSITY CONTROLLING
PERFUMING
ORAL CARE
HAIR CONDITIONING |
| Cosmetic Ingredient Assessment | Glycerol (56-81-5) |
| InChI | 1S/C3H8O3/c4-1-3(6)2-5/h3-6H,1-2H2 |
| InChIKey | PEDCQBHIVMGVHV-UHFFFAOYSA-N |
| SMILES | OCC(O)CO |
| LogP | -2.32 |
| Surface Tension | 64 mN/m at 20°C |
| CAS Database | 56-81-5 (CAS DataBase Reference) |
| NIST Chemical Information | 1,2,3-Propanetriol (56-81-5) |
| EPA Chemical Information | Glycerine (56-81-5) |
| Absorption | ≤0.02≤0.02 at 280 nm in H₂O at 0.5M
≤0.07≤0.07 at 260 nm in H₂O at 0.5M |
Safety Information
| Hazard | Non-hazardous substance. Mildly irritating to eyes and skin. |
| Hazard Symbol | None ("Xi" may be used for high concentrations) |
| Transport Classification | Non-restricted goods |
| Toxicity | Rat oral LD50 > 20 mL/kg |
Product Usage
Due to its unique humectant, solubility, and stability properties, glycerol is widely used in many fields. In cosmetics and personal care products, glycerol is a classic humectant and skin conditioning agent, commonly found in face creams, lotions, toothpaste, and shampoos. In the food industry, it serves as a moisture-retaining agent and sweetener, used in candies, baked goods, and beverages. In the pharmaceutical field, glycerol is used to prepare suppositories, cough syrups, and topical formulations. Industrially, glycerol is an important raw material for synthetic resins, polyurethanes, nitroglycerin (explosives), and tobacco humectants. Additionally, it is used as an antifreeze agent, lubricant, and coating additive.