Illustrative packaging. Pack format confirmed with your quotation.
About This Product
Dipropylene glycol (DPG) is identified by CAS 25265-71-8 and EC 246-770-3, with the formula C6H14O3. It arises as a co-product in propylene glycol plants, when propylene oxide adds to propylene glycol instead of to water. Since it consists of three structural isomers, it is registered under a single mixture CAS number. DPG is a clear, colourless, slightly viscous and hygroscopic liquid; it boils at about 230 °C, has very low volatility, and is completely miscible with water and with many organic solvents.
There are two common qualities. Industrial grade goes to resin and plasticiser production and to general intermediate use. The fragrance or cosmetic grade, frequently sold as low-odour, receives additional refining to strip out trace impurities that affect smell, and is assessed by odour panel in addition to chemical analysis. This matters because a slight off-note introduced by the solvent cannot be masked later in the fragrance.
No diluent is used more widely in fragrance concentrates. DPG takes most perfume materials into solution, contributes practically no odour, evaporates slowly and is gentle on skin, and those properties also make it a solvent and humectant for reed diffusers, air fresheners, deodorants, creams and hair products. Industrially it is a diol for alkyd and unsaturated polyester resins, giving more flexibility than MPG thanks to its longer chain, and a starting material for acrylate monomers and dipropylene glycol dibenzoate plasticisers. It also appears in some printing inks, cutting fluids and textile auxiliaries.
Specifications normally address purity as the sum of isomers (typically 99.5% min), water (typically 0.1% max), Pt-Co colour (typically 10 max), density at 20 °C (typically 1.020–1.025 g/cm³) and acidity; fragrance grades add odour against an agreed standard. Residual MPG and tripropylene glycol are sometimes limited too. Settle grade and limits in writing and compare each certificate of analysis with them.
DPG has no hazard classification under CLP and is not dangerous goods for transport, which sections 2 and 14 of the SDS should confirm. EU and Great Britain importers need to establish which REACH or UK REACH registration applies to the substance and its intended use, and cosmetic formulators should file the grade documents in the product information file.
Because DPG takes up atmospheric moisture, and odour-sensitive grades readily pick up taints from dirty or previously used equipment, it is best kept in closed stainless steel, aluminium or lined containers in a cool, dry store. Its flash point, around 124–138 °C according to the isomer mix, is well above ambient; even so, keep it clear of ignition sources and strong oxidisers.
For a quotation, specify industrial or fragrance grade, the end use, limits on purity and water, any odour standard, the pack (drum, IBC or ISO tank), the volumes and the destination.
