Diethylhexyl Adipate (DEHA) is an ester derived from adipic acid and 2-ethylhexanol. It is widely used in cosmetics and personal care products as an emollient, plasticizer, and solvent. Known for its lightweight texture and ability to impart a smooth, non-greasy feel, it enhances product spreadability and provides conditioning benefits to both skin and hair. Its versatility and compatibility with various formulations make it a valuable ingredient in skincare, makeup, and haircare products.

Chemical Composition and Structure

Diethylhexyl Adipate is an ester with the chemical formula C₂₂H₄₂O₄.

• Core Structure: Derived from adipic acid (a dicarboxylic acid) and two molecules of 2-ethylhexanol (a branched alcohol).
• Properties:
  • Hydrophobic, enhancing its emollient qualities.
  • Contributes to the flexibility and softness of formulations.

Physicochemical Properties

• Appearance: Clear, colorless liquid.
• Odor: Neutral, mild.
• Solubility: Insoluble in water but highly soluble in oils and organic solvents.
• Viscosity: Low, contributing to its lightweight feel.
• Stability: High thermal and oxidative stability, suitable for various cosmetic formulations.

Production Process

1. Esterification: Adipic acid reacts with 2-ethylhexanol in the presence of an acid catalyst to form Diethylhexyl Adipate.
2. Purification: The crude product undergoes purification processes to remove unreacted materials and byproducts, yielding a high-purity cosmetic-grade ingredient.
3. Quality Assurance: The final product is tested for stability, purity, and compatibility with other ingredients.

Applications

Medical Applications

• Acts as a solubilizer and carrier for active ingredients in topical formulations.
• Used in dermatological products to enhance skin hydration and improve application texture.

Cosmetics

1. Skincare:

   • Used in creams, lotions, and serums as an emollient to soften and smooth the skin.
   • Improves product spreadability, leaving a lightweight, silky finish.

2. Makeup:

   • Incorporated in foundations, primers, and lipsticks to enhance texture, flexibility, and long-lasting wear.
   • Provides a smooth application and a non-greasy finish.

3. Haircare:

   • Found in conditioners and hair serums for its ability to add softness and shine.
   • Reduces frizz and enhances the manageability of hair.

Industrial Applications

• Used as a plasticizer in formulations to enhance flexibility and reduce brittleness in products such as nail polishes and other coatings.
• Provides excellent solubilization properties for difficult-to-dissolve ingredients.

Environmental and Safety Considerations

• Biodegradability:

  • DEHA is biodegradable under controlled conditions, making it an environmentally friendly choice for cosmetic formulations.

• Safety Profile:

  • Considered safe for cosmetic use within regulated concentrations.
  • Low potential for skin irritation or sensitization, suitable for most skin types.

• Sustainability:

  • Responsible sourcing of raw materials is recommended to minimize the environmental impact of production.

Conclusion

Diethylhexyl Adipate is a multifunctional and reliable ingredient, valued for its emollient, plasticizing, and solvent properties. Its compatibility with a wide range of cosmetic formulations, coupled with its ability to improve texture and spreadability, makes it an essential component in modern skincare, haircare, and makeup products.

Key Properties

• Chemical Structure: Ester of adipic acid and 2-ethylhexanol.
• INCI Functions: Emollient, Plasticizer, Solvent.
• Advantages: Lightweight, non-greasy, enhances texture and spreadability, suitable for various cosmetic applications.

Molecular Formula  C₂₂H₄₂O₄

Molecular Weight  370.6 g/mol

CAS     103-23-1

UNII    MBY1SL921L

EC Number  203-090-1

DTXSID0020606

Nikkaji   J3.602A

Synonyms:

DEHA

Diethylhexyl adipate

References__________________________________________________________________________

Acciaretti, F., & Pasquale, A. (2020). Di (2-ethylhexyl) adipate (DEHA), A NEW HOPE! A sustainable and promising process for the plasticisers industry. bioRxiv, 2020-10.

Abstract. Plasticisers are commonly incorporated in plastic materials in order to improve their physico-chemicals properties. In particular, Poly-(vinyl chloride) (PVC) is a polymer which has excellent plasticiser compatibility characteristics. The demand for plasticized-PVC is steadily increasing and its synthesis need to be more sustainable, considering the interest in developing a circular economy in the next years. In order to achieve these goals, a bio-based process to synthesize di(2-ethylhexyl) adipate (DEHA), a widely used plasticiser, could be an interesting approach. The most important starting material for the process is adipic acid, but its synthesis from petrochemical sources is not sustainable. An alternative is using waste materials as substrates for fermentation in a totally green process. Among many strategies, the reverse adipate degradation pathway (RADP) in E. coli seems to be the most interesting one, considering the highest titer of 68 g/L and the yield of 93.1%. The next step is the enzyme-catalysed esterification of adipic acid and 2-ethylhexanol to produce DEHA, using an immobilized lipase from Candida antarctica. Applying a solvent-free system under vacuum condition is convenient as it guarantees a conversion to DEHA of 100 mol%.

Vikhareva, I. N., Aminova, G. K., & Mazitova, A. K. (2021). Ecotoxicity of the adipate plasticizers: Influence of the structure of the alcohol substituent. Molecules, 26(16), 4833.

Abstract. A significant increase in the production of plastic materials and the expansion of their areas of application contributed to the accumulation of a large amount of waste of polymeric materials. Most of the polymer composition is made up of plasticizers. Phthalate plasticizers have been recognized as potentially hazardous to humans and the environment due to the long period of their biodegradation and the formation of persistent toxic metabolites. It is known that the industrial plasticizer dioctyl adipate is characterized by reduced toxicity and a short biodegradation period. The paper describes the synthesis of a number of new asymmetric esters based on adipic acid and ethoxylated butanol by azeotropic esterification. The receipt of the products was confirmed by IR spectra. The physicochemical properties of the synthesized compounds were investigated. The glass transition temperatures of PVC composites plasticized with alkyl butoxyethyl adipates were determined using DSC analysis. The ecological safety of esters was assessed by the phytotesting method. Samples of adipates were tested for fungal resistance, and the process of their biodegradation in soil was also studied. It is shown that the synthesized esters have good plasticizing properties and are environmentally safe. When utilized under natural conditions, they can serve as a potential source of carbon for soil microorganisms and do not form stable toxic metabolites; therefore, they are not able to accumulate in nature; when the plasticizers under study are disposed of in the soil, toxic substances do not enter.

Dalgaard, M., Hass, U., Vinggaard, A. M., Jarfelt, K., Lam, H. R., Sørensen, I. K., ... & Ladefoged, O. (2003). Di (2-ethylhexyl) adipate (DEHA) induced developmental toxicity but not antiandrogenic effects in pre-and postnatally exposed Wistar rats. Reproductive Toxicology, 17(2), 163-170.

Abstract. Di(2-ethylhexyl) adipate (DEHA) has replaced the phthalates in thin plasticized polyvinyl chloride films used for food packaging, mainly because some phthalates induce testis toxicity and antiandrogenic effects. A dose-range finding study followed by a dose–response/effect study in Wistar rats investigated whether pre- and postnatal DEHA doses of 0, 800, or 1200 mg/kg/day body weight and doses of 0, 200, 400, or 800 mg/kg/day (main study) elicited developmental toxicity including antiandrogenic effects. In the main study, DEHA induced a prolonged gestation period (800 mg/kg/day) and a dose-related increase in postnatal death (400 and 800 mg/kg/day). DEHA also induced a permanent decrease in offspring body weight (800 mg/kg/day). No antiandrogenic endpoints were affected. We conclude that DEHA induced developmental toxicity and the NOAEL is 200 mg/kg. DEHA did not induce antiandrogenic effects similar to those of di(2-ethylhexyl) phthalate even though the chemical structures have similarities and the two chemicals have a common metabolite.