Perodox® 36 - Di(3,5,5-Trimethylhexanoyl) Peroxide

Di(3,5,5-trimethylhexanoyl) peroxide, often abbreviated as TMHP, is a low-temperature diacyl peroxide in liquid form. It is widely used as an initiator for the polymerization of vinyl monomers, especially in the production of polyvinyl chloride (PVC) by suspension polymerization

The CAS Registry Number is 3851-87-4

The molecular formula is C₁₈H₃₄O₄

The molecular weight is 314.46 g/mo

It is known by many names, including Trigonox 36, Peroyl 355, Initiator CP-10, Initiator P355, USP 355M, Luperox 219, and bis(3,5,5-trimethylhexanoyl) peroxide

The EINECS number is 223-356-0

It is a colorless, oil-like liquid with a characteristic odor

The predicted density is 0.942 ± 0.06 g/cm³

The predicted boiling point is 359.5 ± 25.0 °C at 760 mmHg

It has very low water solubility, approximately 10 mg/L at 5°C. It is insoluble in water but soluble in organic solvents like acetone and chloroform

The vapor pressure is 0.001 Pa at 25°C

The flash point is 149.8°C

The refractive index is 1.445

It should be stored in a tightly sealed container in a cool, dry, well-ventilated place, away from heat, sparks, and incompatible materials. Storage temperatures should not exceed 25°C

The theoretical active oxygen content is approximately 5.09%

It is a strong oxidizing agent and an organic peroxide. Heating can cause fire, and it may cause skin irritation and allergic skin reactions

The UN number is 3106

It is classified under Hazard Class 5.2 (Organic Peroxides)

Packing Group II

It is recommended to wear protective gloves, clothing, eye protection, and face protection. Avoid breathing its dust/fume/vapors

Its primary use is as an initiator for the polymerization of vinyl monomers, particularly for the suspension polymerization of Polyvinyl Chloride (PVC)

It offers a uniform polymerization rate, easy reaction control, uniform product particle size, and results in fewer fish eyes in the final PVC product

Yes, it is suitable for polymerizing styrene, acrylates, methacrylates, and other vinyl monomers

Yes, it is used as a curing agent (initiator) for unsaturated polyester resins in hot molding processes like SMC (Sheet Molding Compound), BMC (Bulk Molding Compound), and ZMC

It acts as an initiator and cross-linking agent, accelerating the curing (vulcanization) process of rubber

Benefits include high efficiency, uniform initiation, and good control over the molecular weight and structure of the resulting polymer

Yes, it can be used as a high-temperature initiator for the polymerization of ethylene in LDPE production

One common downstream product is levelling agent GS

The traditional batch process involves reacting 3,5,5-trimethylhexanoyl chloride (TMHC) with an alkaline hydrogen peroxide solution

The main challenges are the high reaction heat and the extreme instability of the product, which pose significant safety risks like thermal runaway and potential explosion

Continuous-flow microreaction technology has been developed for safer and more efficient synthesis, offering better heat and mass transfer control

Microreactors significantly improve safety by preventing heat accumulation and enhance efficiency, achieving high yields (e.g., 94%) in a very short reaction time (e.g., 2.8 minutes) compared to batch reactors

The post-processing typically includes aging, washing, drying, and formulation steps to meet commercial quality standards

Key hazard statements include H242 (Heating may cause a fire), H304 (May be fatal if swallowed and enters airways), H315 (Causes skin irritation), and H317 (May cause an allergic skin reaction)

Key statements include P210 (Keep away from heat/sparks/open flames), P280 (Wear protective gear), P403 (Store in a well-ventilated place), and P405 (Store locked up)

The SADT is a critical safety parameter. For similar organic peroxides, SADT values determine storage and transport conditions

For small fires, use dry powder or CO₂ extinguishers. For large fires, use water spray from a safe distance to cool containers and prevent re-ignition

Half-life data is crucial for its function as an initiator

The decomposition heat for similar organic peroxides is typically high (often >1000 kJ/kg), indicating the potential energy release upon decomposition

Common commercial brands include Trigonox 36, Peroyl 355, and Luperox 219

It is available in various purities, such as industrial grade (e.g., 75%, 99%) for different applications

It is typically packaged in tightly sealed containers like 25 kg drums or smaller laboratory quantities (e.g., 100g, 500g)

Suppliers include United Initiators, Akzo Nobel (Nouryon), NOF Corporation, and Chinese chemical company Do Sender Chem.

The HS code is often 28299080

Studies have determined the apparent reaction kinetics, showing the reaction orders for NaOH, H₂O₂, and TMHC are 0, 2.6, and 2, respectively. The activation energy (Ea) is 25.0 kJ/mol

The high surface-area-to-volume ratio of microreactors allows for extremely efficient heat removal, preventing dangerous hot spots and thermal runaway, making the process inherently safer than batch reactors

It is speculated that perhydroxyl ions (HOO⁻), generated from the deprotonation of H₂O₂, act as nucleophiles attacking the acid chloride in the organic phase

Key quality indicators include appearance, color, chloride content (inorganic and organic hydrolyzable chloride), and active oxygen content

Yes, it is often used alone or in combination with other low-activity initiators like tert-butyl peroxyneodecanoate to achieve specific polymerization kinetics and product properties

TMHP is a diacyl peroxide, while TBPMH is a peroxyester. They have different decomposition temperatures and half-lives, making them suitable for different initiation temperature ranges in polymerization processes.