Propylene glycol

Overview of the uses and properties of propylene glycol

Propylene glycol

IUPAC Name:	Propane-1,2-diol
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Propylene glycol is a synthetic organic compound with the chemical formula C₃H₈O₂. It is a viscous, colorless liquid, which is nearly odorless but possesses a faintly sweet taste. Chemically, it is classified as a diol, and it is miscible with a broad range of solvents, including water, acetone, and chloroform.

Chemical Properties

Synthesis of 1,2-propanediol

Propylene glycol is produced on a large scale primarily from propylene oxide. It is a chiral molecule, and commercial production typically yields a racemic mixture of the two enantiomers. The compound is stable under normal conditions and does not react with most chemicals.

Uses

Propylene glycol is widely used in various industries due to its versatile properties:

Pharmaceutical and Food Industry

In the pharmaceutical industry, propylene glycol is used as a solvent for oral, injectable, and topical drugs. It is also used as a carrier in e-liquids for vaping. In the food industry, it serves as a humectant, solvent, and preservative in food products and is recognized as safe by the Food and Drug Administration (FDA).

Cosmetics and Personal Care

Propylene glycol is a common ingredient in cosmetics and personal care products, where it functions as a moisturizer, solvent, and carrier for fragrances. It helps to maintain moisture in products and enhances their texture and spreadability.

Industrial Applications

Propylene glycol used in aircraft deicing

In industrial settings, propylene glycol is used as an antifreeze and coolant in systems where leakage might lead to contact with food or potable water. It is also used in the manufacture of polyester resins and as a de-icing fluid for aircraft.

Safety and Environmental Impact

Propylene glycol is generally considered safe for use in food and pharmaceuticals. It is metabolized in the human body to lactic acid, which is a normal component of the metabolic process. However, excessive exposure can lead to adverse effects, such as skin irritation or allergic reactions in sensitive individuals.

Environmentally, propylene glycol is biodegradable and poses minimal risk to aquatic life when used in appropriate concentrations.

Also see

• Ethylene glycol
• Glycerol
• Polyethylene glycol
• Antifreeze
• Solvent