Tetraglycerol - Humectant Polyol CAS 56491-53-3

Tetraglycerol (Polyglycerin-4) - Properties, Applications, and Safety

1. Introduction

Tetraglycerol (CAS 56491-53-3), also known as polyglycerin-4 or polyglycerol-4, is a hydrophilic polyol belonging to the oligoglycerol family. It consists of four glycerol units linked by ether bonds, resulting in a molecule with multiple hydroxyl groups that confer exceptional water solubility and hydrogen-bonding capacity. Tetraglycerol serves both as a stand-alone humectant and moisturizer in cosmetic formulations and as the hydrophilic backbone for polyglycerol fatty acid esters (PGEs), which are widely used non-ionic surfactants in food, cosmetics, and pharmaceuticals.

2. Chemical and Physical Properties

Tetraglycerol has the molecular formula C₁₂H₃₂O₁₂ and a molecular weight of 368.38 g/mol, according to PubChem.However, the molecular formula may also be reported as C₁₂H₂₆O₉ with a molecular weight of approximately 314 g/mol, depending on the isomeric composition.The compound is typically a yellowish viscous liquid at room temperature.

Key properties include:

• Appearance: Colorless to yellowish viscous liquid

• Hydrogen Bond Donors: 12

• Hydrogen Bond Acceptors: 12

• Topological Polar Surface Area: 243 Ų

• Hydroxyl Value: 1050–1200 mg KOH/g

• Moisture Content: ≤2.0%

• Solidification Point: ≤ -10°C

3. Synthesis

Tetraglycerol is produced by the etherification (condensation) of glycerol. The process typically involves heating glycerol in the presence of an alkaline catalyst, such as sodium carbonate, under controlled conditions.The reaction yields a mixture of polyglycerols, including diglycerol, triglycerol, and tetraglycerol, which are then separated by distillation or other purification methods. Microwave-assisted etherification has also been investigated as a more efficient synthesis route.

4. Applications

Cosmetics and Personal Care: Tetraglycerol is used as a humectant, skin-conditioning agent, and viscosity modifier in creams, lotions, serums, and hair care products.It provides excellent moisturization without a sticky feel and is considered non-irritating and suitable for sensitive skin formulations.

Emulsifier Backbone: Tetraglycerol serves as the hydrophilic head group for polyglycerol fatty acid esters (PGEs), which are non-ionic surfactants widely used in food, cosmetics, and pharmaceuticals.

Polymer Synthesis: Due to its multiple hydroxyl groups, tetraglycerol can act as a branching monomer or crosslinking agent in the production of polyesters, polyurethanes, and other functional polymers.

Pharmaceuticals: Used as a solubilizer and carrier in drug delivery systems.

5. Safety and Toxicology

Tetraglycerol is considered safe for use in cosmetic and personal care products. It is classified as non-hazardous under normal handling conditions.Typical safety data indicate:

• Skin Irritation: Non-irritating

• Eye Irritation: Non-irritating

• Oral Toxicity: Not determined

• Environmental: Not classified as hazardous to the environment

6. Storage and Handling

Tetraglycerol should be stored in tightly sealed containers in a cool, dry place, protected from moisture and direct sunlight. It is hygroscopic and may absorb moisture from the air. Recommended storage temperature is 15–25°C.

7. Conclusion

Tetraglycerol (polyglycerin-4) is a versatile hydrophilic polyol with a wide range of applications in cosmetics, personal care, pharmaceuticals, and polymer synthesis. Its multiple hydroxyl groups provide excellent humectant properties, making it a valuable ingredient for moisturizing formulations. As the backbone for polyglycerol fatty acid esters, it also plays a crucial role in the production of non-ionic surfactants for food and cosmetic applications. With a favorable safety profile and biodegradability, tetraglycerol continues to be a key component in modern formulation chemistry.