Hexafluoropropene trimer
[CAS# 6792-31-0]

Identification

• Classification: Organic raw materials >> Hydrocarbon compounds and their derivatives >> Hydrocarbon halide
• Name: Hexafluoropropene trimer
• Synonyms: 1,1,1,4,4,5,6,6,6-Nonafluoro-2,3,5-tris(trifluoromethyl)hex-2-ene
• Molecular Formula: C₉F₁₈
• Molecular Weight: 450.07
• CAS Registry Number: 6792-31-0
• EC Number: 633-258-3
• SMILES: C(=C(F)F)(C(F)(F)F)F.C(=C(F)F)(C(F)(F)F)F.C(=C(F)F)(C(F)(F)F)F

Properties

• Density: 1.7±0.1 g/cm³ Calc.^*, 1.83 g/mL (Expl.)
• Boiling point: 152.5±8.0 ºC 760 mmHg (Calc.)^*, 110 - 115 ºC (Expl.)
• Flash point: 50.8±10.2 ºC (Calc.)^*
• Index of refraction: 1.274 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS02;GHS07 Danger
• Hazard Statements: H225-H302-H312-H315-H319-H332-H335
• Precautionary Statements: P261-P280-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H332
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	4	H302
Skin irritation	Skin Irrit.	2	H315
Flammable liquids	Flam. Liq.	3	H226
Flammable liquids	Flam. Liq.	2	H225

• Transport Information: UN 1993

Discovory and Applicatios

Hexafluoropropene trimer is a chemically stable, fluorinated hydrocarbon consisting of three hexafluoropropene (C₃F₆) units joined through \[2+2] or \[2+4] cycloaddition or oligomerization reactions. The general molecular formula for the trimer depends on its mode of formation, but one common form is a cyclic or branched perfluorinated alkene or alkane-like structure, often with the formula C₉F₁₈. It is a clear, colorless, and thermally stable liquid, and its structure lacks hydrogen atoms entirely, making it chemically inert under many conditions.

Hexafluoropropene (HFP), the monomer unit of the trimer, was first synthesized and studied in the mid-20th century as a valuable fluorocarbon intermediate. It is produced industrially by the dehydrofluorination of perfluoropropane or as a byproduct in the production of polytetrafluoroethylene (PTFE). As research into perfluorinated compounds expanded in the 1950s and 1960s, the reactivity and polymerization behavior of HFP became a subject of intense study. Under the influence of Lewis acid catalysts such as antimony pentafluoride or aluminum chloride, HFP was found to oligomerize into dimers, trimers, and higher oligomers. Among these, the trimeric forms received special attention for their unique physical and chemical properties.

The most well-documented hexafluoropropene trimer is a branched perfluorinated alkene with a backbone derived from the head-to-tail linkage of three HFP units. It is typically prepared through acid-catalyzed trimerization reactions conducted under controlled conditions. The product is a chemically stable, non-flammable, high-density liquid with low surface energy and excellent resistance to chemical attack. It is also thermally stable over a broad temperature range and resistant to oxidation.

Applications of the hexafluoropropene trimer are found in several specialized industrial areas. Its low surface energy and high fluorine content make it valuable as a specialty fluid in electronic and aerospace applications. It is used as a base fluid or intermediate in the synthesis of lubricants, dielectric fluids, and coatings for high-performance applications where chemical inertness and thermal stability are required. In particular, fluorinated trimers and higher oligomers derived from HFP have been employed in formulating fluids for heat transfer and immersion cooling in sensitive electronic devices, including semiconductors and high-speed processors.

The compound’s inertness also makes it a candidate for use in chemically resistant coatings and barrier materials. In some cases, the trimer or its derivatives are employed as starting materials for the synthesis of more complex fluorinated compounds, including telomers and functionalized perfluoropolyethers. However, its reactivity is limited due to the full substitution of hydrogen atoms with fluorine, which reduces the number of chemically active sites.

Due to increasing environmental and regulatory attention on the environmental persistence of perfluorinated compounds, including perfluoroalkyl and polyfluoroalkyl substances (PFAS), the use of hexafluoropropene trimer and related substances has been subject to scrutiny. While the trimer itself is considered chemically stable and unlikely to degrade easily in natural environments, its production, use, and disposal are monitored under evolving industrial safety and environmental protocols.

In conclusion, hexafluoropropene trimer is a chemically inert, thermally stable fluorocarbon liquid synthesized from the oligomerization of HFP. Its properties make it suitable for niche industrial applications, especially where chemical resistance and stability are essential. Its use is typically confined to controlled environments due to the persistence of fluorinated materials in ecosystems.

References

S80 PFASGLUEGE Overview of PFAS Uses,
DOI: 10.5281/zenodo.5029173

. S14 KEMIPFAS PFAS Highly Fluorinated Substances List from KEMI,
DOI: 10.5281/zenodo.2621524