3,5,5-Trimethylhexyl 3,5,5-trimethylhexanoate (3,5,5-trimethylhexa-noic acid, 3,5,5-trimethylhexyl ester - Isononyl isononanoate)  is an organic chemical compound derived from pelargonic acid (isononanoic acid). A liquid monoester of odd medium chain branched alcohols and odd medium chain branched fatty acids, low viscosity-6mPa-s/25°C.

Presents as a white powder or colourless and odourless transparent liquid. High solubility for silicone oil, very stable in formulations containing silicone oil where it can solve the problem of silicone oil precipitation at low temperature.

What it is used for and where

Cosmetics

It acts as a coupling agent and stabiliser for silicone oils. Possesses low viscosity, good dispersion capacity for pigments, refreshing skin feel and non-greasy feel. Good dispersion capacity for pigments. Commonly known as synthetic silk oil. Used as an emollient, it has an elasticising effect on the skin and provides some protection to dry skin.  

Skin-conditioning agent - Emollient

Emollients have the characteristic of enhancing the skin barrier through a source of exogenous lipids that adhere to the skin, improving barrier properties by filling gaps in intercorneocyte clusters to improve hydration while protecting against inflammation. In practice, they have the ability to create a barrier that prevents transepidermal water loss.  Emollients are described as degreasing or refreshing additives that improve the lipid content of the upper layers of the skin by preventing degreasing and drying of the skin. The problem with emollients is that many have a strong lipophilic character and are identified as occlusive ingredients; they are oily and fatty materials that remain on the skin surface and reduce transepidermal water loss. In cosmetics, emollients and moisturisers are often considered synonymous with humectants and occlusives.

Used in skin care products, oily powder, foundation cream.

Dosage

• Make-up, skin care cleansing oil: 1-5%.

For more information:

Isononyl isononanoate studies

• Molecular Formula  C₁₈H₃₆O₂
• Molecular Weight     284.5
• Exact Mass   284.27200
• CAS  42131-25-9
• UNII    S4V5BS6GCX
• EC Number   292-767-5
• DSSTox Substance ID  DTXSID80962298
• IUPAC  7-methyloctyl 7-methyloctanoate
• InChI=1S/C18H36O2/c1-16(2)12-8-5-6-11-15-20-18(19)14-10-7-9-13-17(3)4/h16-17H,5-15H2,1-4H3
• InChl Key      LHWUVOILCRBENG-UHFFFAOYSA-N
• SMILES   CC(C)CCCCCCOC(=O)CCCCCC(C)C
• MDL number  
• PubChem Substance ID    
• SCHEMBL5807541

Synonyms

• 7-methyloctyl 7-methyloctanoate
• Lanol 99
• Dermol99
• 7-methyloctyl 7-methyloctanoate
• Salacos 99
• Hatcol 5131
• KAK 99