Hexafluoropropylene Oxide (HFPO)
Fluorointermediates

Properties, Uses, Storage, and Handling

Product Information
Introduction

Table 1. Product Data

Hexafluoropropylene oxide (HFPO) is a versatilefluorointermediate that can be used in the synthesisof fluoromonomers and fluoropolymers and to add
fluorine functionality to a variety of organic precursors.
Perfluorinated vinyl ethers utilized in the production ofcommercial fluoropolymers are produced using HFPO
as the key intermediate. In addition, the commercial
perfluorinated Krytox™ lubricant has HFPO as themonomer unit.

PropertyUnitMinimumMaximum

Organic Purity—HFPO

wt%

98.6

—

HFPwt%—

1.0

HFPO supplied by Chemours has a minimum purity of
98.6 wt% (Table 1). When impurities are detected, theygenerally consist of hexafluoropropene (HFP). HFP is thekey chemical precursor to HFPO, which is synthesized inan oxidation process. This product may also contain a very
low level of hexafluoroacetene (HFA). The HFA isomer isgenerated by a metal catalyzed mechanism that can beinitiated by improper storage and handling methods. See
Storage section and the Safety Data Sheet (SDS) for
more information.
Physical properties of HFPO are given in Table 2. HFPO isa nonflammable gas that is stored as a pressurized liquid.
The vapor pressure equilibrium curve for HFPO is includedin Figure 1.

600

Absolute Pressure, psia

Properties

Figure 1. HFPO Vapor Pressure, est.

500
400
300
200
1000–2002040

Temperature, °C

6080100

Fluorointermediates

Hexafluoropropylene Oxide (HFPO)Table 2. Physical Properties
PropertyUnit

Typical Value

Chemical Name—Oxirane, Trifluoro (Trifluoromethyl)

CAS Number—428-59-1

EINECS Number—

207-050-4

O
Chemical Formula—

F2CFCCF3
Molecular Weight
Boiling Point at 1 atm
Vapor Pressure at 25 °C (77 °F)—

166ºC (ºF)–27 (–17)

kPa-abs (psia)

660 (96)ºC (ºF)–144 (–227)kg/m3 (lb/ft3)

1300 (81.2)

Vapor Heat Capacity at 25 °C (77 °F)

J/mol·K

138

Liquid Heat Capacity at 25 °C (77 °F)

J/mol·K172 (estimated)

Melting Point
Liquid Density at 25 °C (77 °F)

Heat of Vaporization at NBP

kJ/mol

21.8

Critical TemperatureºC (ºF)86 (186.8)

Critical PressurekPa·abs (psia)

2896 (420)

Critical Density

g/cc

0.59

Flammability Limits

vol%None

Figure 2. Infrared Spectrum of Hexafluoropropylene
Oxide Vapor at 3.5 kPa in a 10-cm cell
0.7

Figure 3. Infrared Spectrum of Hexafluoroacetone
Vapor at 4.6 kPa in a 10-cm cell
1.6

HFPO at 26 torr

1.2

AbsorbanceAbsorbance

0.5
0.4
0.3
0.2

1.0
0.8
0.6
0.4

0.1

0.2
0.0

0.0
4000

HFA 36 torr in 10-cm cell

1.40.6

3000

2000

1000

4000

Wavenumbers, cm–13000

2000

Wavenumbers, cm–121000

Hexafluoropropylene Oxide (HFPO)

Fluorointermediates

Uses

HFPO can serve as a source of the heptafluoro-propoxide
ion owing to the equilibrium between PPF and fluoride ion
in solution. The heptafluoro-propoxide ion, as well as otherpolyfluorinated alkoxides, open the HFPO ring to generateoligomers that can be isolated as the acid fluorides.The
acid fluorides in turn may be converted to vinyl ethers thatare themselves useful chemical intermediates.

HFPO is a key intermediate in the synthesis oforganofluorine compounds. Many commercialfluoropolymers use HFPO, either as a monomer or amonomer precursor. The epoxide ring is opened bynucleophiles to give a variety of derivatives. HFPO may
be isomerized to either pentafluoropropionyl fluoride(PPF) or HFA. The thermolysis of HFPO can also serve
as a source of difluorocarbene. A few examples of HFPO
chemistry are given below; the chemistry of HFPO has
been reviewed.1,2

O
CF2

CO

R f OMF

M = Na+, K +, Cs+
CF3

R f O(CFCF2O)n CF C F
CF3

CF3

Reactions of HFPOR f O(CFCF2 O)n CF

HFPO is easily isomerized to PPF by nucleophilic
catalysts, such as halides or amines.

OO
F2C

CF3FC

CF3

In the presence of Lewis acids, such as SbF5, HF, orAClxF3–x (x = 0.05–0.3), HFPO isomerizes to HFA. Thiscan even happen in storage containers if precautions are
not taken to prevent the rearrangement reaction fromoccurring.

F

CF3CF2C

Catalyst

In the presence of alcohols or secondaryamines, derivatives of PPF are formed. Methyl
2,3,3,3-tetrafluoro-2-methoxy propionate, preparedfrom methanol and HFPO, may be converted to methyl
3,3,3-trifluoropyruvate, a useful building block inorganofluorine chemistry.

O
F2CO
F2C

CF3CF2C

CF3NR2O
F2C

CF3CF(OR)C

ORoleumO
CF3C(O)COR

Ring-opening the HFPO with halogenating reagents, suchas Me3SiI, gives halogenated perfluoroalkyl-propionic acidderivatives, such as CF3CFIC(O)F.

O
F2CCF

O

SiMe3 I

CF3CFC
CF3C

F
CF3ROHOO

Lewis AcidC
CF3CF3Thermolysis of HFPO gives difluorocarbene andtrifluoroacetyl fluoride. The difluorocarbene may begenerated in situ to prepare useful intermediates, such as
CF2I2 or cyclopropanes.

FCCF
CF3O
NR2H

CF2FI

3O

Δ+C
CF3F:CF2Hexafluoropropylene Oxide (HFPO)

Fluorointermediates

Storage and Handling

The appropriate DOT designation is as follows:

Shipping Containers in the U.S.

Proper Shipping
Name

Liquefied Gas, N.O.S.
Hexafluoropropylene Oxide

Hazard Class

2.2

UN Number

3163

DOT Labels

Nonflammable Gas

DOT Placards

Nonflammable Gas

HFPO is a liquefied, nonflammable compressed gas.
According to the U.S. Department of Transportation(DOT), a nonflammable compressed gas is defined asa nonflammable material having an absolute pressure
greater than 40 psia at 21 ºC (70ºF) and/or an absolutepressure greater than 104 psi at 54 ºC (130 ºF).

Containers
WaterCapacity
17,000 L ISO

Dimensions

DOT
Specification

Neight Weight
HFPO

Liquid Dip
TubePhase
Available

51

15,000 kg

Yes

Liquid orVapor

2.4 m x 2.6 m x 6.1 mL (frame)
6.1 mL x 2.4 m OD

Smaller sizes are available upon request for developmental purposes.

HFPO Rearrangement ConcernsMaterial Compatibility Concerns

HFPO can rearrange to toxic HFA in the presence ofLewis acids. This can occur in shipping containers, storagevessels, or other process equipment. Because higher
temperatures cause faster rearrangement, it is highly
recommended to maintain HFPO below 25 ºC (77 ºF),
unless required for process purposes (i.e., purification orchemistry).

Most metal components are suitable for use with HFPO;
however, corrosion-resistant materials, such as stainlesssteel, are recommended. If less corrosion-resistantmaterials, such as carbon steel, are used in processequipment, toluene-inhibited HFPO is the preferredproduct.
Handling Precautions

Corrosion by-products in carbon steel containers cancatalyze the HFPO rearrangement to HFA. Stainlesssteel is recommended for HFPO containers. In order toinhibit the rearrangement reaction, toluene is commonlyadded to carbon steel containers. Low levels of toluene
have been shown to be effective as an inhibitor in thisrearrangement reaction. If the end user requires evenlower levels of toluene, it is strongly recommended thatshipping containers be constructed of stainless steel
when toluene is not intentionally added as an inhibitor.

The following rules for handling HFPO containers arestrongly recommended:• Use proper personal protective equipment, such as sideshield safety glasses, gloves, and safety shoes, whenhandling containers.
• Exposure to HFPO should be prevented or minimized
using proper ventilation and chemical hygiene practices.
• Always treat HFPO containers as though they contain
HFA, unless a recent analysis indicates otherwise.
• Use proper backflow prevention methods whenconnecting and disconnecting HFPO cylinders.
Introduction of water into an HFPO cylinder can leadto HFA formation by slowly generating HF, leading tocorrosion and ultimately HFA.

Because the potential for rearrangement of HFPO toHFA is always present, it is recommended that HFPO betreated as though it always contains HFA, unless a recent
analysis suggests otherwise.

• To reduce the rearrangement of HFPO to HFA, carbon
steel cylinders should be maintained below 25 ºC(77 ºF).

4

Hexafluoropropylene Oxide (HFPO)

Fluorointermediates• To reduce rearrangement of HFPO to HFA, it isrecommended that product shipped in carbon steel
containers be used within 90 days of shipping.

References• Skin contact with HFPO liquid or escaping vapor canlead to frostbite.

2. Millauer, H.; Schwertfeger, W.; Siegemund, G.
Angew. Chem. Int. Ed. Engl. 1985, 24, 161-179.

1. Tarrant, P.; Allison, C. G.; Barthold, K. P.
Fluorine Chem. Rev. 1971, 5, 77-113.

• Never heat a container to temperatures higher than
45 ºC (113 ºF).
• Maintain filled containers with the correct orientation
as indicated on cylinders to ensure relief protection islocated in the vapor phase.
• Never apply direct flame or live steam to a container orvalve.
• Never refill disposable cylinders with anything. The
shipment of refilled disposable cylinders is prohibitedby DOT regulations.
NOTE: Disposable cylinders are often used when
supplying lab-scale samples.
• Never refill returnable cylinders without Chemours
consent. DOT regulations forbid the transportationof returnable cylinders refilled without Chemours
authorization.
• Never use a lifting magnet or sling (rope or chain) whenhandling containers. A crane may be used when a safe
cradle or platform is used to hold the container.
• Never use containers as rollers, supports, or for any
other purpose other than originally intended.
• Protect containers from any object that will result in acut or other abrasion in the surface of the metal.
• Never tamper with the safety devices in valves orcontainers.
• Never attempt to repair either containers or valves.
• Never force connectors that do not fit properly. Make
sure threads on the regulators or auxiliary equipment
are the same as those on the container valve outlets.
• Keep valves tightly closed and valve caps and hoods inplace when containers are not in use.
NOTE: Storage and Handling: Store and handle inaccordance with all current regulations and standards
subject to storage regulations: U.S. OSHA 29 CFR
1910.101.

5

Hexafluoropropylene Oxide (HFPO)

Fluorointermediates

CAUTION: Do not use or resell Chemours™ materials in medical applications involving implantation in the human body or contact with internal body fluids or tissues unless agreed to by Seller in a writtenagreement covering such use. For further information, please contact your Chemours representative. For medical emergencies, spills, or other critical situations, call (866) 595-1473 within the UnitedStates. For those outside of the United States, call (302) 773-2000.
The information set forth herein is furnished free of charge and based on technical data that Chemours believes to be reliable. It is intended for use by persons having technical skill, at their own discretion
and risk. The handling precaution information contained herein is given with the understanding that those using it will satisfy themselves that their particular conditions of use present no health or safety
hazards. Because conditions of product use are outside our control, Chemours makes no warranties, express or implied, and assumes no liability in connection with any use of this information. As with anymaterial, evaluation of any compound under end-use conditions prior to specification is essential. Nothing herein is to be taken as a license to operate under or a recommendation to infringe any patents.
NO PART OF THIS MATERIAL MAY BE REPRODUCED, STORED IN A RETRIEVAL SYSTEM OR TRANSMITTED IN ANY FORM OR BY ANY MEANS ELECTRONIC, MECHANICAL, PHOTOCOPYING, RECORDING OR OTHERWISEWITHOUT THE PRIOR WRITTEN PERMISSION OF CHEMOURS.

For more information, visit www.chemours.com/fluorointermediates© 2018 The Chemours Company FC, LLC. Chemours™ and the Chemours Logo are trademarks of The Chemours Company.
Replaces: K-05132-2
C-11707 (10/18)