What is isononyl isononanoate and what is it used for?
Isononyl isononanoate (CAS 59219-71-5) is a light branched-chain ester used as a dry-feel emollient. It is formulated into skin care and color cosmetics as a skin-conditioning emollient, a pigment-wetting agent, and a lubricating and spreading aid.
ISONONYL ISONONANOATE- ▸ Emollient: light, dry-feel skin-conditioning ester
- ▸ Pigment wetting: dispersing/wetting agent for color cosmetics
- ▸ Lubricating agent: slip and spreading aid in formulations
A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.
Request SDS →Isononyl isononanoate (CAS 59219-71-5) is a branched-chain ester emollient — the isononyl alcohol ester of isononanoic acid (3,5,5-trimethylhexanoic acid). Formulators choose it for a dry, silky, non-greasy slip and a light skin feel. Its branched, saturated structure delivers excellent spreadability and good oxidative stability, making it a versatile sensory and dispersing oil-phase ingredient across personal-care categories.
Typical Properties
Typical reference values, not a specification; the Certificate of Analysis (CoA) for the lot governs.
| Property | Typical Value |
|---|---|
| INCI Name | Isononyl Isononanoate |
| CAS Number | 42131-25-9 |
| Molecular Formula | C18H36O2 |
| Appearance | Clear, colorless liquid |
| Character | Light, dry, fast-spreading branched-chain ester emollient |
| Specific gravity (25 °C) | ~0.855 |
| Refractive index (25 °C) | ~1.43 |
| Solubility | Insoluble in water; oil-soluble |
| Flammability / handling | Refer to the current SDS |
Regulatory & registration requirements
- TSCA (US):
- REACH (EU):
- EC number: 261-665-2
Source: EPA TSCA Inventory (July 2025 release) · ECHA CHEM — retrieved 2026-07-12
Why a branched ester
The value of isononyl isononanoate sits in its molecular shape. Because both the acid and the alcohol are branched (rather than straight-chain), the molecule packs loosely, stays low in viscosity, and spreads easily — giving the characteristic dry, cushiony glide that lighter linear esters and heavier vegetable oils struggle to match. The fully saturated backbone means no unsaturation to oxidize, so it resists rancidity better than many natural emollients, supporting formula shelf stability. It is broadly compatible with other esters, volatile silicones, mineral oils, and most cosmetic oils, so it slots into existing oil phases without reformulation headaches.
Applications by sector
Skin care
Used as a dry-touch emollient and skin-conditioning agent in lotions, creams, body oils, and lip care. It carries actives and pigments through the oil phase, improves slip during application, and leaves a light, non-occlusive finish that formulators reach for when a rich oil would feel too heavy. Its low freeze point and low viscosity also help maintain consistent texture across temperature ranges.
Color cosmetics
One of its most-valued roles. The ester wets and disperses pigments efficiently, which supports more uniform color payoff in foundations, concealers, lipsticks, and pressed or loose powders. In lip and stick formats it contributes glide and a glossy, even film; in fluid foundations it improves spreadability and helps avoid a draggy, greasy feel. Better pigment wetting can also aid grind consistency during manufacturing.
Sun care
A useful sensory and spreading aid in sunscreens. It helps distribute the formula evenly across skin, improves the dry, light after-feel that consumers expect, and can support the cohesive oil-phase film that water-resistant systems rely on. As a non-polar, stable ester it pairs well with both organic UV filters and the oils used to disperse inorganic filters.
Hair care
Contributes light conditioning, slip, and shine in serums, leave-ins, and styling products without the weight or buildup of heavier oils. Its antistatic and skin-conditioning character (per its INCI functionality) helps tame flyaways and add gloss while keeping a clean, non-greasy hand.
Forms and grade
RawSource supplies cosmetic-grade isononyl isononanoate as a clear, low-viscosity liquid for personal-care manufacturing. Each lot ships with a Certificate of Analysis and Safety Data Sheet so your QC and regulatory teams can confirm identity and purity against your specification. Grade, purity, and any per-lot parameters are documented on the CoA — request current documentation with your inquiry.
Handling
This ester is not classified as hazardous under GHS by the supplying companies on the ECHA C&L inventory, but handling, storage, and PPE are always governed by the current Safety Data Sheet provided with your order. Store sealed and away from heat and strong oxidizers; consult the SDS for the authoritative guidance for your facility.
Bulk sourcing from RawSource
RawSource supplies isononyl isononanoate in bulk for personal-care manufacturers and contract formulators — drums, IBC totes, and larger volumes, with CoA and SDS per lot. Tell us your target quantity, grade, and destination and we will return current pricing and lead time. Request a quote using the form on this page to start an RFQ.
Reviewed and updated July 2026 by the RawSource technical team.
Isononyl isononanoate (CAS 59219-71-5) is a branched-chain ester emollient, produced by reacting isononyl alcohol with isononanoic acid, used in cosmetics as a dry-feel skin-conditioning and pigment-wetting agent.
Isononyl Isononanoate: Key Figures
- 687 cosmetic formulations reported this ester to FDA’s Voluntary Cosmetic Registration Program in 2013, roughly double the 343 logged in 2009 (Cosmetic Ingredient Review, 2013).
- Reported use concentrations span 0.07% to 53% across cosmetic product categories, per the Personal Care Products Council’s 2012 concentration-of-use survey (CIR Final Amended Report, 2013).
- Specific gravity 0.849 to 0.855 and refractive index 1.430 to 1.436, both at 25 °C, with a molecular weight of 284.48 g/mol (Cosmetic Ingredient Review, 2013).
- US imports classified under HTS subheading 2915.90.50 enter at a 3.8% column 1 general duty rate, duty-free under listed free-trade programs (USITC Harmonized Tariff Schedule, 2026).
Frequently Asked Questions
What is isononyl isononanoate used for?
It is a branched-chain ester emollient used in cosmetic and personal-care formulations as a light, dry-feel skin-conditioning agent, as a pigment-wetting and dispersing aid in color cosmetics, and as a slip and spreading agent in skin care, sun care, and hair care. It improves application feel and pigment dispersion in formulated products.
Why use a branched ester instead of a heavier oil?
The branched, saturated structure of isononyl isononanoate keeps viscosity low and spreading high, producing a dry, silky, non-greasy slip that heavier vegetable oils and straight-chain esters cannot match. Being fully saturated, it also resists oxidation better than many unsaturated natural emollients, which supports formula stability.
Is isononyl isononanoate a silicone?
No. Isononyl isononanoate (CAS 59219-71-5) is an ester — the isononyl ester of isononanoic acid — with no silicon-oxygen backbone, so it is not a silicone. It is often used to deliver a dry, silicone-like slip in formulations that avoid silicones.
What is another name for isononyl isononanoate?
Isononyl isononanoate is the INCI name. Chemically it is the isononyl ester of isononanoic acid (3,5,5-trimethylhexanoic acid), IUPAC name 3,5,5-trimethylhexyl 3,5,5-trimethylhexanoate, CAS 59219-71-5 (also cited as 42131-25-9 in some references for the same material). Lot identity is confirmed on the Certificate of Analysis.
How is isononyl isononanoate supplied in bulk?
RawSource supplies it in bulk industrial packaging including drums and IBC totes, with a CoA and SDS per lot. The HS classification is 2915.90. Request a bulk quote with your quantity, grade, and destination for current pricing and lead time.
What is isononyl isononanoate made of?
Isononyl isononanoate is produced by reacting branched-chain nonyl alcohols with branched-chain nonanoic acid (3,5,5-trimethylhexanoic acid). The Cosmetic Ingredient Review defines the commercial material as the mixture of esters obtained from that reaction. The molecule has formula C18H36O2 and a molecular weight of 284.48 g/mol. Fully saturated and branched on both the acid and alcohol sides, it functions as a skin-conditioning emollient under the INCI name Isononyl Isononanoate.
Is isononyl isononanoate comedogenic?
The 2013 Cosmetic Ingredient Review assessment of alkyl esters records irritation, sensitization, and toxicology data for this ester but no comedogenicity assay. In human repeat-insult patch tests, lipstick formulations containing 3.552% and 3.128% were not irritants or sensitizers. The CIR panel concluded the alkyl esters are safe as used when formulated to be non-irritating. Substantiate any non-comedogenic claim on the finished formulation, not the raw material.
Is isononyl isononanoate in sunscreen?
Yes, as an inactive ingredient. Sun-care formulators use it as an emollient and spreading aid in the oil phase, where it improves coverage and lightens after-feel. It is not a UV filter: FDA’s OTC sunscreen monograph at 21 CFR 352.10 lists the permitted sunscreen active ingredients, and isononyl isononanoate is not among them. On a sunscreen label it therefore appears under inactive ingredients.
What is the REACH and TSCA regulatory status of Isononyl Isononanoate?
Isononyl Isononanoate (CAS 59219-71-5) is subject to U.S. TSCA Inventory requirements; supplying it into the EU requires valid REACH registration ((EC) No 1907/2006). RawSource cannot verify a third-party supplier's registrations — buyers should require documented TSCA and REACH compliance for their jurisdiction and volume (EC 261-665-2).