2
Physical and Chemical Properties And Efficacy

PHYSICAL AND CHEMICAL PROPERTIES

The physical and chemical properties of iodotrifluoromethane (CF3I) are presented in the Army’s updated toxicity review (Chaney 2002). The table of physical properties of CF3I from that report is included here (Table 2-1); the entire update is included as Appendix B. The review briefly discusses the degradation of CF3I in air and during a fire and states that no attempt was made by the Army to determine the toxicity of any CF3I degradation products.

The update’s presentation of the physical and chemical properties of CF3I is well written and concise. However, the subcommittee found three points that merit some clarification:

  • The update states on page 6, lines 9-10, in the section “Regulatory Information” that “cardiac sensitization has been demonstrated at relatively low concentrations. . . .” The Army should specify that the statement refers to dogs.

  • On the same page, the Army should also indicate quantitatively what is meant by “relatively low concentrations.”

  • The Army should have added vapor density to the list of physical and chemical properties as halocarbons are usually much heavier than air and can accumulate in “dead spaces” such as tanks. This information has been added to Table 2-1.



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OCR for page 15
Iodotrifluoromethane: Toxicity Review 2 Physical and Chemical Properties And Efficacy PHYSICAL AND CHEMICAL PROPERTIES The physical and chemical properties of iodotrifluoromethane (CF3I) are presented in the Army’s updated toxicity review (Chaney 2002). The table of physical properties of CF3I from that report is included here (Table 2-1); the entire update is included as Appendix B. The review briefly discusses the degradation of CF3I in air and during a fire and states that no attempt was made by the Army to determine the toxicity of any CF3I degradation products. The update’s presentation of the physical and chemical properties of CF3I is well written and concise. However, the subcommittee found three points that merit some clarification: The update states on page 6, lines 9-10, in the section “Regulatory Information” that “cardiac sensitization has been demonstrated at relatively low concentrations. . . .” The Army should specify that the statement refers to dogs. On the same page, the Army should also indicate quantitatively what is meant by “relatively low concentrations.” The Army should have added vapor density to the list of physical and chemical properties as halocarbons are usually much heavier than air and can accumulate in “dead spaces” such as tanks. This information has been added to Table 2-1.

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Iodotrifluoromethane: Toxicity Review TABLE 2-1 Physical Properties of CF3I Physical or Chemical Property Value or Description Chemical Abstracts Service no. (CAS) 2314-97-8 European Chemical no. (EC) 219-014-5 Molecular weight 195.91 Physical state at 20°C Gas Melting point –110°C (166°F) Boiling point at 1 atm –22.5°C (8.5°F) Liquid density at -32.5°C 2.36 g/mL Liquid density at 25°C g/mL Odor threshold Odorless Solubility in water Slight Vapor pressure at 25°C 78.4 psia Pressure-temperature curve log psia = 5.7411-1146.82/T/K Critical pressure 586 psia (estimated) Critical temperature 122°C (estimated) Critical volume 225 cm3/mole (estimated) Heat of formation –141 kcal/mole Heat of vaporization 5.26 kcal/mole Electron affinity 150 ± 20 kJ/mole Refractive index (liquid) at 42°C 1.379 Dipole moment 1.68 debye Vapor heat capacity 16.9 cal/mole-K C-I bond disassociation energy 54 kcal/mole Vapor density (air = 1) 6.9a aData from PTCL 2003. Abbreviations: g/mL, gram per milliliter; cm3/mol, cubic meter per mole; kcal/mole, kilocalorie per mole; kJ/mole, kilojoule per mole; cal/mole-K, calorie per mole Kelvin; psia, pounds per square inch absolute. Source: Adapted from Moore et al. 1994 (see Appendix B). EFFICACY The “Efficacy” section of the update indicates that the minimal design concentration—that is, the minimal amount of a chemical required to extinguish an n-heptane fire—of CF3I, 3.2 vol%, is slightly lower than that

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Iodotrifluoromethane: Toxicity Review of Halon 1301, 3.3 vol%. One point in the efficacy section (see Appendix B) should be clarified: The phrase “will be slightly lower” does not have biologic meaning. The term “slightly” should be quantified and the actual amounts given.