Fluoroform
Encyclopedia
Fluoroform is the chemical compound
with the formula CHF3. It is one of the "haloforms
", a class of compounds with the formula CHX3 (X = halogen
). Fluoroform is used in diverse niche applications and is produced as a by-product of the manufacture of Teflon. It is also generated biologically in small amounts apparently by decarboxylation
of trifluoroacetic acid
.
in the violent reaction of iodoform
with dry silver fluoride
in 1894. The reaction was improved by Otto Ruff
by substitution of silver fluoride by a mixture of mercury fluoride
and calcium fluoride
. The exchange reaction works with iodoform and bromoform
, and the exchange of the first two halogen
atoms by fluorine is vigorous. By changing to a two step process, first forming a bromodifluoro methane in the reaction of antimony trifluoride
with bromoform and finishing the reaction with mercury fluoride the first efficient synthesis method was found by Henne.
industry
in plasma etching
of silicon oxide
and silicon nitride
. Known as R-23 or HFC-23, it is also a useful refrigerant
, sometimes as a replacement for Chlorotrifluoromethane
(cfc-13) and is a byproduct of its manufacture.
When used as a fire suppressant, the fluoroform carries the DuPont
trade name, FE-13. CHF3 is recommended for this application because of its low toxicity, its low reactivity, and its high density. HFC-23 has been used in the past as a replacement for Halon 1301[cfc-13b1] in fire suppression system
s as a total flooding gaseous fire suppression
agent.
. The secretariat of the Clean Development Mechanism estimates that a ton of HFC-23 in the atmosphere has the same effect as 11,700 tons of carbon dioxide. More recent work (IPCC, 2007) suggests that this equivalency, also called a 100-yr global warming potential
, is slightly larger at 14,800 for HFC-23.
The atmospheric lifetime is 270 years.
According to the 2007 IPCC climate report, HFC-23 was the most abundant HFC in the global atmosphere until around 2001, which is when the global mean concentration of HFC-134a (1,1,1,2-tetrafluoroethane), the chemical now used extensively in automobile air conditioners, surpassed those of HFC-23. Global emissions of HFC-23 have in the past been dominated by the inadvertent production and release during the manufacture of the refrigerant HCFC-22 (chlorodifluoromethane).
Data reported to the United Nations Framework Convention on Climate Change (UNFCCC) greenhouse gas emissions databases indicate substantial decreases in developed or Annex 1 countries HFC-23 emissions from the 1990s to the 2000s (UNFCCC greenhouse gas emissions databases). The UNFCCC Clean Development Mechanism projects have provided funding and facilitated the destruction of HFC-23 co-produced from a portion of HCFC-22 produced in developing or non-Annex 1 countries since 2003. Developing countries have become the largest producers of HCFC-22 in recent years according to data compiled by the Ozone Secretariat of the World Meteorological Organization. Emissions of all HFCs are included in the UNFCCCs Kyoto Protocol. To mitigate its impact, CHF3 can be destroyed with electric plasma arc technologies or by high temperature incineration.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with the formula CHF3. It is one of the "haloforms
Trihalomethane
Trihalomethanes are chemical compounds in which three of the four hydrogen atoms of methane are replaced by halogen atoms. Many trihalomethanes find uses in industry as solvents or refrigerants. THMs are also environmental pollutants, and many are considered carcinogenic...
", a class of compounds with the formula CHX3 (X = halogen
Halogen
The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style of the periodic table, comprising fluorine , chlorine , bromine , iodine , and astatine...
). Fluoroform is used in diverse niche applications and is produced as a by-product of the manufacture of Teflon. It is also generated biologically in small amounts apparently by decarboxylation
Decarboxylation
Decarboxylation is a chemical reaction that releases carbon dioxide . Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is the first chemical step in photosynthesis, is called carbonation, the addition of CO2 to...
of trifluoroacetic acid
Trifluoroacetic acid
Trifluoroacetic acid is the simplest stable perfluorinated carboxylic acid chemical compound, with the formula CF3CO2H. It is a strong carboxylic acid due to the influence of the electronegative trifluoromethyl group. TFA is almost 100,000-fold more acidic than acetic acid...
.
Synthesis
Fluoroform was first obtained by Maurice MeslansMaurice Meslans
Maurice Meslans was a French pharmacist and chemist, Henri Moissan's advanced student, pioneer organofluorocompounds chemistry.-References:...
in the violent reaction of iodoform
Iodoform
Iodoform is the organoiodine compound with the formula CHI3. A pale yellow, crystalline, volatile substance, it has a penetrating odor and, analogous to chloroform, sweetish taste. It is occasionally used as a disinfectant...
with dry silver fluoride
Silver fluoride
Silver fluoride can refer to:* Silver fluoride , AgF* Silver difluoride , AgF2* Silver subfluoride , Ag2F...
in 1894. The reaction was improved by Otto Ruff
Otto Ruff
-Life:Otto Ruff was born in Schwäbisch Hall, Württemberg. After becoming an pharmacist under the supervision of Carl Magnus von Hell at the University of Stuttgart he joined the group of Hermann Emil Fischer at the University of Berlin. Fischer was noted for his work on carbohydrates and so Ruff...
by substitution of silver fluoride by a mixture of mercury fluoride
Mercury fluoride
Mercury fluoride can refer to:* Mercury fluoride , Hg2F2* Mercury fluoride , HgF2* Mercury fluoride , HgF4...
and calcium fluoride
Calcium fluoride
Calcium fluoride is the inorganic compound with the formula CaF2. This ionic compound of calcium and fluorine occurs naturally as the mineral fluorite . It is the source of most of the world's fluorine. This insoluble solid adopts a cubic structure wherein calcium is coordinated to eight fluoride...
. The exchange reaction works with iodoform and bromoform
Bromoform
Bromoform is a pale yellowish liquid with a sweet odor similar to chloroform, a halomethane or haloform. Its refractive index is 1.595 . Bromoform is produced naturally by phytoplankton and seaweeds in the ocean and this is thought to be the predominant source to the environment...
, and the exchange of the first two halogen
Halogen
The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style of the periodic table, comprising fluorine , chlorine , bromine , iodine , and astatine...
atoms by fluorine is vigorous. By changing to a two step process, first forming a bromodifluoro methane in the reaction of antimony trifluoride
Antimony trifluoride
Antimony trifluoride is the inorganic compound with the formula SbF3. Sometimes called Swart's reagent, is one of two principal fluorides of antimony, the other being SbF5. It appears as a white solid...
with bromoform and finishing the reaction with mercury fluoride the first efficient synthesis method was found by Henne.
Industrial applications
CHF3 is used in the semiconductorSemiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
industry
Industry
Industry refers to the production of an economic good or service within an economy.-Industrial sectors:There are four key industrial economic sectors: the primary sector, largely raw material extraction industries such as mining and farming; the secondary sector, involving refining, construction,...
in plasma etching
Plasma etching
Plasma etching is a form of plasma processing used to fabricate integrated circuits. It involves a high-speed stream of glow discharge of an appropriate gas mixture being shot at a sample. The plasma source, known as etch species, can be either charged or neutral...
of silicon oxide
Silicon oxide
Silicon oxide may refer to either of the following:*Silicon dioxide, SiO2, very well characterized*Silicon monoxide, SiO, not very well characterized...
and silicon nitride
Silicon nitride
Silicon nitride is a chemical compound of silicon and nitrogen. If powdered silicon is heated between 1300° and 1400°C in an atmosphere of nitrogen, trisilicon tetranitride, Si3N4, is formed. The silicon sample weight increases progressively due to the chemical combination of silicon and nitrogen...
. Known as R-23 or HFC-23, it is also a useful refrigerant
Refrigerant
A refrigerant is a substance used in a heat cycle usually including, for enhanced efficiency, a reversible phase change from a liquid to a gas. Traditionally, fluorocarbons, especially chlorofluorocarbons, were used as refrigerants, but they are being phased out because of their ozone depletion...
, sometimes as a replacement for Chlorotrifluoromethane
Chlorotrifluoromethane
Chlorotrifluoromethane, R-13, CFC-13, or Freon 13, is a non-flammable, non-corrosive chlorofluorocarbon and also a mixed halomethane. It is used as a refrigerant, however, due to concerns about its ozone-depleting potential, its use has been phased out due to the Montreal Protocol.-Physical...
(cfc-13) and is a byproduct of its manufacture.
When used as a fire suppressant, the fluoroform carries the DuPont
DuPont
E. I. du Pont de Nemours and Company , commonly referred to as DuPont, is an American chemical company that was founded in July 1802 as a gunpowder mill by Eleuthère Irénée du Pont. DuPont was the world's third largest chemical company based on market capitalization and ninth based on revenue in 2009...
trade name, FE-13. CHF3 is recommended for this application because of its low toxicity, its low reactivity, and its high density. HFC-23 has been used in the past as a replacement for Halon 1301[cfc-13b1] in fire suppression system
Fire suppression system
Fire suppression systems are used in conjunction with smoke detectors and fire alarm systems to improve and increase public safety. Suppression systems are governed by the codes under the NFPA 13 handbook.-Types:...
s as a total flooding gaseous fire suppression
Gaseous fire suppression
Gaseous fire suppression is a term to describe the use of inert gases and chemical agents to extinguish a fire. Also called Clean Agent Fire Suppression. These Agents are governed by the NFPA Standard for Clean Agent Fire Extinguishing Systems - NFPA 2001 in the USA, with different standards and...
agent.
Organic chemistry
CHF3 is a reagent to generate sources of "CF3-" by deprotonation. The molecule is weakly acidic with a pKa = 25–28. It is a precursor to CF3Si(CH3)3Trimethylsilyl
A trimethylsilyl group is a functional group in organic chemistry. This group consists of three methyl groups bonded to a silicon atom [−Si3], which is in turn bonded to the rest of a molecule...
Greenhouse gas
CHF3 is a potent greenhouse gasGreenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
. The secretariat of the Clean Development Mechanism estimates that a ton of HFC-23 in the atmosphere has the same effect as 11,700 tons of carbon dioxide. More recent work (IPCC, 2007) suggests that this equivalency, also called a 100-yr global warming potential
Global warming potential
Global-warming potential is a relative measure of how much heat a greenhouse gas traps in the atmosphere. It compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped by a similar mass of carbon dioxide. A GWP is calculated over a specific time...
, is slightly larger at 14,800 for HFC-23.
The atmospheric lifetime is 270 years.
According to the 2007 IPCC climate report, HFC-23 was the most abundant HFC in the global atmosphere until around 2001, which is when the global mean concentration of HFC-134a (1,1,1,2-tetrafluoroethane), the chemical now used extensively in automobile air conditioners, surpassed those of HFC-23. Global emissions of HFC-23 have in the past been dominated by the inadvertent production and release during the manufacture of the refrigerant HCFC-22 (chlorodifluoromethane).
Data reported to the United Nations Framework Convention on Climate Change (UNFCCC) greenhouse gas emissions databases indicate substantial decreases in developed or Annex 1 countries HFC-23 emissions from the 1990s to the 2000s (UNFCCC greenhouse gas emissions databases). The UNFCCC Clean Development Mechanism projects have provided funding and facilitated the destruction of HFC-23 co-produced from a portion of HCFC-22 produced in developing or non-Annex 1 countries since 2003. Developing countries have become the largest producers of HCFC-22 in recent years according to data compiled by the Ozone Secretariat of the World Meteorological Organization. Emissions of all HFCs are included in the UNFCCCs Kyoto Protocol. To mitigate its impact, CHF3 can be destroyed with electric plasma arc technologies or by high temperature incineration.
External links
- MSDS at Oxford University
- MSDS at mathesontrigas.com
- Coupling of fluoroform with aldehydes using an electrogenerated base
Additional physical properties
| Property | Value |
|---|---|
| Density Density The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight... (ρ) at -100 °C (liquid) |
1.52 g/cm3 |
| Density Density The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight... (ρ) at -82.1 °C (liquid) |
1.431 g/cm3 |
| Density Density The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight... (ρ) at -82.1 °C (gas) |
4.57 kg/m3 |
| Density Density The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight... (ρ) at 0 °C (gas) |
2.86 kg/m3 |
| Density Density The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight... (ρ) at 15 °C (gas) |
2.99 kg/m3 |
| Dipole moment Electric dipole moment In physics, the electric dipole moment is a measure of the separation of positive and negative electrical charges in a system of charges, that is, a measure of the charge system's overall polarity with SI units of Coulomb-meter... |
1.649 D |
| Critical pressure (pc) | 4.816 MPa (48.16 bar) |
| Critical temperature (Tc) | 25.7 °C (299 K) |
| Critical density (ρc) | 7.52 mol/l |
| Compressibility factor Compressibility factor The compressibility factor , also known as the compression factor, is a useful thermodynamic property for modifying the ideal gas law to account for the real gas behavior. In general, deviation from ideal behavior becomes more significant the closer a gas is to a phase change, the lower the... (Z) |
0.9913 |
| Acentric factor Acentric factor The acentric factor \omega is a conceptual number introduced by Pitzer in 1955, proven to be very useful in the description of matter. It has become a standard for the phase characterization of single & pure components... (ω) |
0.26414 |
| Viscosity Viscosity Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity... (η) at 25 °C |
14.4 μPa.s (0.0144 cP) |
| Molar specific heat at constant volume (CV) | 51.577 J.mol−1.K−1 |
| Latent heat of vaporization (lb) | 257.91 kJ.kg−1 |