Dipropylene Glycol (DPG) is a synthetic organic compound used as a foundational ingredient in countless daily products. It is a clear, colorless, and low-odor liquid, which facilitates its wide adoption across multiple industries. DPG is a type of alcohol that has two hydroxyl groups, giving it unique chemical properties that make it an excellent solvent and carrier. This versatility allows DPG to be incorporated into consumer goods ranging from personal care items to specialized industrial materials.
Chemical Identity and Properties
Dipropylene Glycol is chemically identified by the formula C₆H₁₄O₃ and is classified as a diol. It is produced during the manufacturing of Monopropylene Glycol from propylene oxide and exists as a mixture of three structural variations, known as isomers. These characteristics contribute to its effectiveness as a solvent, allowing it to be fully miscible with water and many organic compounds.
The physical properties of DPG are beneficial for product formulation. It is characterized by very low volatility, meaning it does not readily evaporate, and possesses a high boiling point of approximately 232°C. This low evaporation rate ensures that ingredients dissolved within it, such as fragrance compounds, remain stable for a longer duration. DPG is slightly viscous and has a low odor, making it a preferred carrier.
Primary Commercial Applications
DPG’s exceptional solvency and stability make it widely used in diverse commercial sectors, particularly in consumer products. In the cosmetics and personal care industry, DPG functions as a solvent and viscosity reducer, helping to thin out formulations and ensure a uniform texture. It also acts as a humectant, helping skin and hair retain moisture, and is found in products like lotions, shampoos, and deodorants.
A significant consumer application is within the fragrance industry, often utilizing a specialized “Fragrance Grade” DPG. It serves as an inert carrier solvent, diluting concentrated perfume oils and stabilizing the aromatic compounds. By attaching to fragrance molecules, DPG helps slow their rate of dispersion, which extends the longevity of the scent on the skin.
Beyond consumer goods, DPG is utilized in various industrial processes as a chemical intermediate and solvent. It is a raw material in the production of polymers, such as polyester and alkyd resins, and is also used to manufacture plasticizers and polyurethanes. Its properties make it suitable for use in products like printing inks, industrial cleaners, and functional fluids.
Safety Profile and Regulatory Status
The use of Dipropylene Glycol in consumer products is supported by its favorable toxicological profile. Studies have consistently shown that DPG has a low level of acute toxicity whether exposure occurs orally, dermally, or by inhalation. The oral median lethal dose (LD50) in rats is exceptionally high, classifying DPG as a low-toxicity substance.
Regulatory bodies worldwide have assessed DPG and concluded it is safe for its intended applications. The U.S. Food and Drug Administration (FDA) has permitted its use in food contact materials. Furthermore, the Cosmetic Ingredient Review (CIR) Expert Panel has determined it is safe for use in cosmetic products at typical concentrations.
DPG is non-sensitizing and only mildly irritating to the skin or eyes. Chronic exposure studies have demonstrated that DPG does not cause reproductive or developmental issues and is not considered genotoxic or carcinogenic. This safety and regulatory history ensures DPG remains a trusted compound in products ranging from pharmaceuticals to fine fragrances.