Isononyl Isononanoate

Isononyl Isononanoate 1
molecular structure · PubChem CID 100986
AKA: 7-methyloctyl 7-methyloctanoate, 42131-25-9, WE(8:0(7Me)/8:0(7Me)), Isononanoicacid, Isononyl ester (9CI), CHEBI:196213
Synthetic
Skin Conditioner
Synthetic
Clean
OriginSynthesized from isononanoic acid and isononanol, both derived from petrochemical sources or synthetic branched alcohols and carboxylic acids. Produced through Fischer esterification, where the carboxylic acid and alcohol are combined using acid catalysts to form the ester bond.
The CIR Expert Panel concluded that the alkyl esters, listed subsequently, are safe in the present practices of use and concentration described in this safety assessment when formulated to be non-irritating.
Formula
C18H36O2
Mol. Weight
284.50
CAS #
59219-71-5, 42131-25-9
Form
Liquid
Skin Types
●all-skin-types
Best For
General
Functions
Skin Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Reduces Static
Softens & Smooths
Conditions Skin
Reduces Flyaways
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory0 listings
🛡️Safety-assessed3 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
EWG
1
CIR
Insufficient
Pregnancy
—
CIR Safety Findings
Not an Eye Irritant
1 study / 1 not irritating (CIR 558)
Not a Sensitizer
2 studies / 2 not sensitizing / plus 1 case report (CIR 558)
Mixed Skin Irritation Results
3 studies / 2 irritating / 1 not irritating / reactions slight to severe (CIR 558)
Concentration Guide
Leave-on0.07–53%
Rinse-off0.3–25%
0%50%100%
CIR reported use · 2012 survey
Regulatory Status
USAunder review
CANADA✔ permitted
Regulatory Agencies
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR