FLUOROALKYL PHOSPHORUS FIRE EXTINGUISHING AGENTS 

Robert E. Tapscott

GlobeTech Inc. 

8200 Montgomery NE, Suite 218 

Albuquerque, NM 87109-1602 

Phone: +1-505-883-9399 

Fax: +1-505-883-9399 

Email: GlobeTech@speakeasy.net 

Jean'ne M. Shreeve 

Department of Chemistry 

PO Box 442343 

University of Idaho 

Moscow, ID 83844-2343 

Telephone: 1-208-885-6215 

Fax: 1-208-885-9146 

Email: jshreeve@uidaho.edu 

J. Douglas Mather 

Center for Global Environmental Technologies 

University of New Mexico 

Albuquerque, New Mexico 

Phone: 505-272-7259 

Email: mather@nmeri.unm.edu

ABSTRACT 

Phosphorus compounds show extraordinary effectiveness as flame extinguishants, and there is 

evidence for a chemical mechanism. Most work to date, however, has emphasized alkyl 

phosphonates and related materials or phosphonitriles. The former compounds are flammable 

and the latter have low volatilities. Phosphorus compounds containing fluoroalkyl and 

hydrofluoroalkyl groups, however, are often nonflammable and have higher volatilities. We are 

carrying out the identification, synthesis, and laboratory testing of fluoroalkyl-and 

hydrofluoroalkyl-containing phosphorus compounds as fire extinguishants. 

PHOSPHORUS-CONTAINING EXTINGUISHING AGENTS 

A number of compounds of silicon, phosphorus, and other materials based on chemical elements 

other than carbon have been examined [1]. Of particular interest has been compounds of 

phosphorus [2]. Phosphorus compounds appear to provide a chemical fire extinguishment 

mechanism, and some appear to be highly effective [3]. Much work has been performed on 

dimethyl methyl phosphonate (DMMP) and related compounds by Professor Elizabeth Fisher 

and her co-workers at Cornell [4, 5]. Though DMMP shows very promising flame suppression 

characteristics, this compound and most of the related compounds studied to date have some

serious drawbacks. First, this and many related chemicals are flammable. Second, most of the 

standard phosphorus compounds studied to date, including DMMP, have low vapor pressures. 

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FLUOROALKYLPHOSPHORUS COMPOUNDS 

One way to address both of these problems is to work with phosphorus compounds containing 

fluoroalkyl or hydrofluoroalkyl groups. The presence of fluorine decreases or eliminates 

flammability and increases volatility. For example, tris(2,2,2-trifluoroethyl)phosphite 

(P(OCH2CF3)3 ,TFEP) has a cup burner extinguishment concentration of 1.78 vol% for nheptane fuel. This can be compared with the concentration of approximately 3 vol% for Halon 

1301. TFEP has a normal boiling point of approximately 131 °C compared to 181 °C for 

DMMP and is non flammable. 

There is still, however, a major problem with TFEP. Though the volatility is improved, it is still 

not nearly what one would like. For that reason, one needs to examine fluoroalkylphosphorus 

compounds with even lower molecular weights. This Next Generation Program (NGP) project 

has been designed to identify, synthesize, and test the flame extinguishment capability of 

fluoroalkylphosphorus compounds with estimated acceptably low toxicity, ODP, and GWP that 

could be used as replacements for Halon 1301. 

Here we present a very brief overview of the work to date and planned future work. 

OVERVIEW

Eight fluoroalkylphosphorus compounds (Table 1), including TFEP as a baseline material, have 

been selected for testing and are being or have been prepared in the laboratory of Professor 

Jean’ne Shreeve at the University of Idaho. The status of compound acquisition is shown in 

Table 1. These compounds will undergo cup burner extinguishment at the Center for Global 

Environmental Technologies at the University of New Mexico. It is anticipated that the work 

will be completed by 30 June 2002. 

Table 1. Fluoroalkylphosphorus Compounds for Testing 

Compound Status

O=P(CF3)3 6.2 g obtained 2/12/02 

O=P(OCH3)(CF3)2 5.5 g obtained 2/12/02 

P(OCH2CF3)3 13.5 g obtained 9/21/01 and cup burner run 

P(OCH3)(CF3)2 5.5 g to be supplied 5/2/02 

P(OCH2CF3)2CF3 7.6 g to be supplied 5/2/02 

O=P(OCH2CF3)(CF3)2 To be supplied 6/2/02 

P(OCH2CF3)(CF3)2 To be supplied 6/2/02 

O=P(OCF3)3 If possible, to be supplied 6/2/02 

ACKNOWLEDGEMENT 

This research is part of the Department of Defense's Next Generation Fire Suppression 

Technology Program, funded by the DoD Strategic Environmental Research and Development 

Program. 

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REFERENCES 

1. Tapscott, R. E., Moore, T. A., Kaizerman, J. A., Kibert, C. J., and Tetla, R. A., “Advanced 

Agent Halon Substitutes,” Proceedings, International CFC and Halon Alternatives 

Conference, Washington, D.C., pp. 644-648, 23-25 October 1995. 

2. Kaizerman, J. A., and Tapscott, R. E., Advanced Streaming Agent Development, Volume III: 

Phosphorus Compounds, WL-TR-96-XX, NMERI Report No. 96/5/32540, Vol. 3 of 5, 

Wright Laboratory (WL/FIVCF), Tyndall Air Force Base, Florida and Applied Research 

Associates, Inc., Tyndall Air Force Base, Florida, May 1996. 

3. Tapscott, R. E., Mather, J. D., Heinonen, E. W., Lifke, J. L., and Moore, T. A., Identification 

and Proof Testing of New Total Flooding Agents: Combustion Suppression Chemistry and 

Cup Burner Testing, Final Report, NMERI Report No. 97/6/33010, U. S. Department of 

Defense, Strategic Environmental Research and Development Program and Defense 

Advance Research Projects Agency, Arlington, Virginia, May 1998. 

4. MacDonald, M. A., Jayaweera, T. M., Fisher, E. M., and Gouldin, F. C., “Inhibition of NonPremixed Flames by Dimethyl Methylphosphonate,” Technical Meeting, Central States 

Section of The Combustion Institute, Point Clear, Alabama, 27-29 April 1997. 

5. MacDonald, M. A., Jayaweera, T. M., Fisher, E. M., and Gouldin, F. C., “Inhibition of NonPremixed Flames by Phosphorus-Containing Compounds,” Combustion and Flame, Vol. 

116, pp. 166-176, 1999. 

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