Description and features

Iniper 42S (Tert-butyl peroxy-3,5,5-trimethylhexanoate) is a clear liquid which has C13H26O3 as chemical formula. It is used as initiator in the production of acrylic polymers, polyethylene and styrene. Further it is applied as curing agent in the production of unsaturated polyester resins.

Tert-butyl peroxy-3,5,5-trimethylhexanoate is also known as TBPIN and tert-butyl 3,5,5-trimethylperoxyhexanoate.


Europe: Provided Iniper 42S (TBPIN) is on stock in our local warehouses our lead time is about one week if delivered in 25 KG PE drums.

United States, Canada, South America, South Africa and other markets can also be served, please contact our sales department for more details.

➔ Limited available in the European Union as this product has not been REACH registered (yet).

Product Identification

CAS number 13122-18-4
EC number 236-050-7
HS code 2915 90 70

Half-life data

Activation energy 140.78 kcal/mol
10 hr. half-life temp 94 °C
1 hr. half-life temp 114 °C
0.1 hr. half-life temp 135 °C


Appearance Clear liquid
Assay ≥97.0 %
Density 0.893 @ 20 °C
Hydro peroxide ≤0.10 %
Water Content ≤0.025 %


Available packaging 25 KG PE drum.
Special packaging is available on request


Store Tert-butyl peroxy-3,5,5-trimethylhexanoate in a cool, dry and well-ventilated area and in line with legal requirements.
Keep Iniper 42S (TBPIN) away from heat sources and oxidizing agents.


A Material Safety Data Sheets (MSDS) is available for Iniper 42S (TBPIN) and all other products supplied by Vesta Chemicals bv.

An MSDS describes the hazards of a product and explains how a product can be safely handled, used and stored. Besides it provides important regulatory and emergency response information for the purchased product.

Molecular and structural information

Molecular formula C13H26O3
Molecular weight 230.35 g/mol
Smiles notation COOC(C)(CC(CC(=O)OC(C)(C)C)OOC)OOC
Structural formula 13122-18-4

Physicochemical information

Density 0.890 g/cm3 @ 20 °C
Flash point 94 °C @ 1013.25 hPa
Melting point -69.15 °C
Partition coefficient (log Pow) 4.40 @ 25 °C
SADT 60 °C
Solubility in water Slightly soluble (14.20 mg/l)
Vapour pressure 0.03 mBar @ 30 °C
Viscosity 5.0 mPa @ 20°C.
Tert-butyl peroxy-3,5,5-trimethylhexanoate | CAS: 13122-18-4 | Disclaimer. This information is supplied solely for informational purposes and Vesta Chemicals bv makes no guarantees or warranties, either expressed or implied, with respect to the accuracy and use of this data. All product warranties and guarantees shall be governed by the Standard Terms of Sale. Nothing in this document is legal advice or is a substitute for competent legal advice.