1,1,1,2-Tetrafluoroethane

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Contents

1,1,1,2-Tetrafluoroethane
Structure 1,1,1,2-Tetrafluoroethane.svg
Structure
3-D structure 1,1,1,2-tetrafluoroethane-3D-balls.png
3-D structure
Names
Preferred IUPAC name
1,1,1,2-Tetrafluoroethane
Other names
HFA-134a
HFC-134a
R-134a
Norflurane
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.011.252 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 212-377-0
KEGG
PubChem CID
RTECS number
  • KI8842500
UNII
UN number 3159
  • InChI=1S/C2H2F4/c3-1-2(4,5)6/h1H2 Yes check.svgY
    Key: LVGUZGTVOIAKKC-UHFFFAOYSA-N Yes check.svgY
  • FCC(F)(F)F
Properties
C2H2F4
Molar mass 102.032 g·mol−1
AppearanceColorless gas
Density 0.00425 g/cm3, gas
Melting point −103.3 °C (−153.9 °F; 169.8 K)
Boiling point −26.3 °C (−15.3 °F; 246.8 K)
0.15 wt%
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Asphyxiant
GHS labelling:
GHS-pictogram-bottle.svg
Warning
H280
P410+P403
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
1
0
1
Flash point 250 °C (482 °F; 523 K)
Related compounds
Related refrigerants
Difluoromethane
Pentafluoroethane
Related compounds
 1-Chloro-1,2,2,2-tetrafluoroethane
1,1,1-Trichloroethane
Supplementary data page
1,1,1,2-Tetrafluoroethane (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

1,1,1,2-Tetrafluoroethane (also known as norflurane (INN), R-134a, Klea 134a, Freon 134a, Forane 134a, Genetron 134a, Green Gas, Florasol 134a, Suva 134a, HFA-134a, or HFC-134a) is a hydrofluorocarbon (HFC) and haloalkane refrigerant with thermodynamic properties similar to R-12 (dichlorodifluoromethane) but with insignificant ozone depletion potential and a lower 100-year global warming potential (1,430, compared to R-12's GWP of 10,900). [1] It has the formula CF3CH2F and a boiling point of −26.3 °C (−15.34 °F) at atmospheric pressure. R-134a cylinders are colored light blue. [2] A phaseout and transition to HFO-1234yf and other refrigerants, with GWPs similar to CO2, began in 2012 within the automotive market. [3]

Uses

1,1,1,2-Tetrafluoroethane is a non-flammable gas used primarily as a "high-temperature" refrigerant for domestic refrigeration and automobile air conditioners. These devices began using 1,1,1,2-tetrafluoroethane in the early 1990s as a replacement for the more environmentally harmful R-12. Retrofit kits are available to convert units that were originally R-12-equipped.

Boiling of Tetrafluoroethane liquid when exposed to normal atmospheric pressure and temperature. Tetrafluoroethane liquid.jpg
Boiling of Tetrafluoroethane liquid when exposed to normal atmospheric pressure and temperature.

Other common uses include plastic foam blowing, as a cleaning solvent, a propellant for the delivery of pharmaceuticals (e.g., inhaler canisters such as forbronchodilators), wine cork removers, gas dusters ("canned air"), and in air driers for removing the moisture from compressed air. 1,1,1,2-Tetrafluoroethane has also been used to cool computers in some overclocking attempts. It is the refrigerant used in plumbing pipe freeze kits. It is also commonly used as a propellant for airsoft airguns. The gas is often mixed with a silicone-based lubricant.

Aspirational and niche applications

1,1,1,2-Tetrafluoroethane is also being considered as an organic solvent, both as a liquid and a supercritical fluid. [4] [5] [6]

It is used in the resistive plate chamber particle detectors in the Large Hadron Collider. [7] [8] It is also used for other types of particle detectors, e.g. some cryogenic particle detectors. [9] It can be used as an alternative to sulfur hexafluoride in magnesium smelting as a shielding gas. [10]

History and environmental impacts

1,1,1,2-Tetrafluoroethane was introduced in the early 1990s as a replacement for dichlorodifluoromethane (R-12), which has massive ozone depleting properties. [11] Even though 1,1,1,2-Tetrafluoroethane has insignificant ozone depletion potential (ozone layer) and negligible acidification potential (acid rain), it has a 100-year global warming potential (GWP) of 1430 and an approximate atmospheric lifetime of 14 years. [1] Its concentration in the atmosphere and contribution to radiative forcing have been growing since its introduction. Thus it was included in the IPCC list of greenhouse gases. [12]

HFC-134a measured by the Advanced Global Atmospheric Gases Experiment (AGAGE) in the lower atmosphere (troposphere) at stations around the world. Abundances are given as pollution free monthly mean mole fractions in parts-per-trillion. HFC-134a mm.png
HFC-134a measured by the Advanced Global Atmospheric Gases Experiment (AGAGE) in the lower atmosphere (troposphere) at stations around the world. Abundances are given as pollution free monthly mean mole fractions in parts-per-trillion.
HFC-134a atmospheric concentration since year 1995. Mauna Loa HFC-134a (CH2FCF3) concentration.png
HFC-134a atmospheric concentration since year 1995.

R-134a began being phased out from use in the European Union, starting in the mid 2010s, by a directive of 2006, recommending the replacement of gases in air conditioning systems with a GWP above 100. [13]

1,1,1,2-tetrafluoroethane is subject to use restrictions in the US and other countries as well. The Society of Automotive Engineers (SAE) has proposed that it be best replaced by a new fluorochemical refrigerant HFO-1234yf (CF3CF=CH2) in automobile air-conditioning systems. [14] As of model year 2021, newly manufactured light-duty vehicles in the United States no longer use R-134a. [3]

California may also prohibit the sale of canned R-134a to individuals to avoid non-professional recharge of air conditioners. [15] A ban had been in place in Wisconsin since October 1994 under ATCP 136 prohibiting sales of container sizes holding less than 15 lbs of 1,1,1,2-tetrafluoroethane, but this restriction applied only when the chemical was intended to be a refrigerant. However, the ban was lifted in Wisconsin in 2012. [16] During the time that it was active, this Wisconsin-specific ban contained loopholes. For example, it was legal for a person to purchase gas duster containers with any amount of the chemical because in that instance the chemical is neither intended to be a refrigerant  [16] nor is HFC-134a included in the § 7671a listing of class I and class II substances. [17]

Production and reactions

Tetrafluoroethane is typically made by reacting trichloroethylene with hydrogen fluoride: [18]

CHCl=CCl2 + 4 HF → CF3CH2F + 3 HCl

It reacts with butyllithium to give trifluorovinyl lithium: [19]

CF3CH2F + 2 BuLi → CF2=CFLi + LiF + 2 BuH

Safety

R-134a cylinder R134a container.png
R-134a cylinder

Mixtures with air of the gas 1,1,1,2-tetrafluoroethane are not flammable at atmospheric pressure and temperatures up to 100 °C (212 °F). However, mixtures with high concentrations of air at elevated pressure and/or temperature can be ignited. [20] Contact of 1,1,1,2-tetrafluoroethane with flames or hot surfaces in excess of 250 °C (482 °F) may cause vapor decomposition and the emission of toxic gases including hydrogen fluoride and carbonyl fluoride, [21] however the decomposition temperature has been reported as above 370 °C. [22] 1,1,1,2-Tetrafluoroethane itself has an LD50 of 1,500 g/m3 in rats, making it relatively non-toxic, apart from the dangers inherent to inhalant abuse. Its gaseous form is denser than air and will displace air in the lungs. This can result in asphyxiation if excessively inhaled. [23] [24] This contributes to most deaths by inhalant abuse.

Aerosol cans containing 1,1,1,2-tetrafluoroethane, when inverted, become effective freeze sprays. Under pressure, 1,1,1,2-tetrafluoroethane is compressed into a liquid, which upon vaporization absorbs a significant amount of thermal energy. As a result, it will greatly lower the temperature of any object it contacts as it evaporates.

Freon 134a refrigerant for car AC Freon 134a refrigerant for car AC 001 (cropped).jpg
Freon 134a refrigerant for car AC

Medical use

For its medical uses, 1,1,1,2-tetrafluoroethane has the generic name norflurane. It is used as propellant for some metered dose inhalers. [25] It is considered safe for this use. [26] [27] [28] In combination with pentafluoropropane, it is used as a topical vapocoolant spray for numbing boils before curettage. [29] [30] It has also been studied as a potential inhalational anesthetic, [31] but it is nonanaesthetic at doses used in inhalers. [26]

See also

Related Research Articles

<span class="mw-page-title-main">Chlorofluorocarbon</span> Class of organic compounds

Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and propane.

Freon is a registered trademark of the Chemours Company and generic descriptor for a number of halocarbon products. They are stable, nonflammable, low toxicity gases or liquids which have generally been used as refrigerants and as aerosol propellants. These include chlorofluorocarbons and hydrofluorocarbons, both of which cause ozone depletion and contribute to global warming. 'Freon' is the brand name for the refrigerants R-12, R-13B1, R-22, R-410A, R-502, and R-503 manufactured by The Chemours Company, and so is not used to label all refrigerants of this type. They emit a strong smell similar to acetone. Freon has been found to cause damage to human health when inhaled in large amounts. Studies have been conducted in the pursuit to find beneficial reuses for gases under the Freon umbrella as an alternative to disposal of the gas.

<span class="mw-page-title-main">Refrigerant</span> Substance in a refrigeration cycle

A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulated because of their toxicity and flammability and the contribution of CFC and HCFC refrigerants to ozone depletion and that of HFC refrigerants to climate change.

<span class="mw-page-title-main">Hydrofluorocarbon</span> Synthetic organic compounds

Hydrofluorocarbons (HFCs) are synthetic organic compounds that contain fluorine and hydrogen atoms, and are the most common type of organofluorine compounds. Most are gases at room temperature and pressure. They are frequently used in air conditioning and as refrigerants; R-134a (1,1,1,2-tetrafluoroethane) is one of the most commonly used HFC refrigerants. In order to aid the recovery of the stratospheric ozone layer, HFCs were adopted to replace the more potent chlorofluorocarbons (CFCs), which were phased out from use by the Montreal Protocol, and hydrochlorofluorocarbons (HCFCs) which are presently being phased out. HFCs replaced older chlorofluorocarbons such as R-12 and hydrochlorofluorocarbons such as R-21. HFCs are also used in insulating foams, aerosol propellants, as solvents and for fire protection.

<span class="mw-page-title-main">Difluoromethane</span> Chemical compound

Difluoromethane, also called difluoromethylene, HFC-32Methylene Fluoride or R-32, is an organic compound of the dihalogenoalkane variety. It has the formula of CH2F2. It is a colorless gas in the ambient atmosphere and is slightly soluble in water, with a high thermal stability. Due to the low melting and boiling point, (−136.0 and −51.6 °C [−212.8 and −60.9 °F; 137.2 and 221.6 K] respectively) contact with this compound may result in frostbite. In the United States, the Clean Air Act Section 111 on Volatile Organic Compounds (VOC) has listed difluoromethane as an exception (since 1997) from the definition of VOC due to its low production of tropospheric ozone. Difluoromethane is commonly used in endothermic processes such as refrigeration or air conditioning.

Dichlorodifluoromethane (R-12) is a colorless gas usually sold under the brand name Freon-12, and a chlorofluorocarbon halomethane (CFC) used as a refrigerant and aerosol spray propellant. In compliance with the Montreal Protocol, its manufacture was banned in developed countries in 1996, and in developing countries in 2010 out of concerns about its damaging effect on the ozone layer. Its only allowed usage is as a fire retardant in submarines and aircraft. It is soluble in many organic solvents. R-12 cylinders are colored white.

<span class="mw-page-title-main">Gas duster</span> Product used for dusting devices

A gas duster, also known as tinned wind or compressed air, is a product used for cleaning or dusting electronic equipment and other sensitive devices that cannot be cleaned using water.

<span class="mw-page-title-main">Chlorodifluoromethane</span> Chemical propellant and refrigerant

Chlorodifluoromethane or difluoromonochloromethane is a hydrochlorofluorocarbon (HCFC). This colorless gas is better known as HCFC-22, or R-22, or CHClF
2. It was commonly used as a propellant and refrigerant. These applications were phased out under the Montreal Protocol in developed countries in 2020 due to the compound's ozone depletion potential (ODP) and high global warming potential (GWP), and in developing countries this process will be completed by 2030. R-22 is a versatile intermediate in industrial organofluorine chemistry, e.g. as a precursor to tetrafluoroethylene.

Fluoroform, or trifluoromethane, is the chemical compound with the formula CHF3. It is a hydrofluorocarbon as well as being a part of the haloforms, a class of compounds with the formula CHX3 with C3v symmetry. Fluoroform is used in diverse applications in organic synthesis. It is not an ozone depleter but is a greenhouse gas.

R-410A is a refrigerant used in air conditioning and heat pump applications. It is a zeotropic but near-azeotropic mixture of difluoromethane (CH2F2, called R-32) and pentafluoroethane (CHF2CF3, called R-125). R-410A is sold under the trademarked names AZ-20, EcoFluor R410, Forane 410A, Genetron R410A, Puron, and Suva 410A.

Organofluorine chemistry describes the chemistry of organofluorine compounds, organic compounds that contain a carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from oil and water repellents to pharmaceuticals, refrigerants, and reagents in catalysis. In addition to these applications, some organofluorine compounds are pollutants because of their contributions to ozone depletion, global warming, bioaccumulation, and toxicity. The area of organofluorine chemistry often requires special techniques associated with the handling of fluorinating agents.

<span class="mw-page-title-main">1,1,1-Trifluoroethane</span> Chemical compound

1,1,1-Trifluoroethane, or R-143a or simply trifluoroethane, is a hydrofluorocarbon (HFC) compound that is a colorless gas. It should not be confused with the much more commonly used HFC gas R-134a, nor confused with the isomeric compound 1,1,2-trifluoroethane. 1,1,1-Trifluoroethane has a critical temperature of 73 °C.

Natural refrigerants are considered substances that serve as refrigerants in refrigeration systems. They are alternatives to synthetic refrigerants such as chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), and hydrofluorocarbon (HFC) based refrigerants. Unlike other refrigerants, natural refrigerants can be found in nature and are commercially available thanks to physical industrial processes like fractional distillation, chemical reactions such as Haber process and spin-off gases. The most prominent of these include various natural hydrocarbons, carbon dioxide, ammonia, and water. Natural refrigerants are preferred actually in new equipment to their synthetic counterparts for their presumption of higher degrees of sustainability. With the current technologies available, almost 75 percent of the refrigeration and air conditioning sector has the potential to be converted to natural refrigerants.

<span class="mw-page-title-main">2,3,3,3-Tetrafluoropropene</span> Chemical compound

2,3,3,3-Tetrafluoropropene, HFO-1234yf, is a hydrofluoroolefin (HFO) with molecular formula CH2=CFCF3. Its primary application is as a refrigerant with low global warming potential (GWP).

<span class="mw-page-title-main">Hydrofluoroolefin</span> Class of chemical compounds

Hydrofluoroolefins (HFOs) are unsaturated organic compounds composed of hydrogen, fluorine and carbon. These organofluorine compounds are of interest as refrigerants. Unlike traditional hydrofluorocarbons (HFCs) and chlorofluorocarbons (CFCs), which are saturated, HFOs are olefins, otherwise known as alkenes.

<i>trans</i>-1,3,3,3-Tetrafluoropropene Chemical compound

trans-1,3,3,3-Tetrafluoropropene (HFO-1234ze(E), R-1234ze(E)) is a hydrofluoroolefin. It was developed as a "fourth generation" refrigerant to replace fluids such as R-134a, as a blowing agent for foam and aerosol applications, and in air horns and gas dusters. The use of R-134a is being phased out because of its high global warming potential (GWP). HFO-1234ze(E) itself has zero ozone-depletion potential (ODP=0), a very low global warming potential (GWP < 1 ), even lower than CO2, and it is classified by ANSI/ASHRAE as class A2L refrigerant (lower flammability and lower toxicity).

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Barbara Haviland Minor is an American chemical engineer, known for the development of refrigerants. She was technical leader for chemical company DuPont in the development of R-1234yf, a refrigerant which, as of 2018, was used in 50% of all new vehicles produced by original equipment manufacturers, and which represented an important contribution to countering global warming.

Life Cycle Climate Performance (LCCP) is an evolving method to evaluate the carbon footprint and global warming impact of heating, ventilation, air conditioning (AC), refrigeration systems, and potentially other applications such as thermal insulating foam. It is calculated as the sum of direct, indirect, and embodied greenhouse gas (GHG) emissions generated over the lifetime of the system “from cradle to grave,” i.e. from manufacture to disposal. Direct emissions include all climate forcing effects from the release of refrigerants into the atmosphere, including annual leakage and losses during service and disposal of the unit. Indirect emissions include the climate forcing effects of GHG emissions from the electricity powering the equipment. The embodied emissions include the climate forcing effects of the manufacturing processes, transport, and installation for the refrigerant, materials, and equipment, and for recycle or other disposal of the product at end of its useful life.

References

  1. 1 2 "Table 2.14 (Errata). Lifetimes, radiative efficiencies and direct (except for CH4) GWPs relative to CO2". Archived from the original on 6 July 2017. Retrieved 11 July 2017.
  2. ↑ "Example image of a 30 lbs R134a bottle". budgetheating.com. Retrieved 26 March 2018.
  3. 1 2 "Refrigerant Transition & Environmental Impacts". U.S. Environmental Protection Agency. 6 August 2015. Retrieved 1 October 2020.
  4. ↑ Corr, Stuart (2005). "1,1,1,2-Tetrafluoroethane (R-134a): A Selective Solvent for the Generation of Flavor and Fragrance Ingredients". Natural Flavors and Fragrances. ACS Symposium Series. Vol. 908. p. 41. doi:10.1021/bk-2005-0908.ch003. ISBN   0-8412-3904-5.
  5. ↑ Abbott, Andrew P.; Eltringham, Wayne; Hope, Eric G.; Nicola, Mazin (2005). "Solubility of unsaturated carboxylic acids in supercritical 1,1,1,2-tetrafluoroethane (HFC 134a) and a methodology for the separation of ternary mixtures". Green Chemistry. 7 (4): 210. doi:10.1039/B412697A.
  6. ↑ Abbott, Andrew P.; Eltringham, Wayne; Hope, Eric G.; Nicola, Mazin (2005). "Hydrogenation in supercritical 1,1,1,2 tetrafluoroethane (HFC 134a)" (PDF). Green Chemistry. 7 (10): 721. doi:10.1039/B507554H. hdl: 2381/604 . Archived from the original (PDF) on 19 July 2018. Retrieved 18 September 2019.
  7. ↑ Anushree Ghosh STUDY OF GLASS RESISTIVE PLATE CHAMBERS (RPC) AND CALCULATION OF EFFICIENCY Archived 7 August 2011 at the Wayback Machine . INO Graduate Training Programme DHEP, TIFR, Mumbai.
  8. ↑ M. Capeans, I. Glushkov, R. Guida, F. Hahn, S. Haider (CERN, Switzerland) RPC operation at the LHC experiments in an optimized closed loop gas system. Medical Imaging Conference. 25–31 October 2009.
  9. ↑ Norbeck, E.; Olson, J. E.; Moeller, A.; Onel, Y. (2006). "Rad Hard Active Media For Calorimeters" (PDF). AIP Conference Proceedings. 867: 84. Bibcode:2006AIPC..867...84N. doi:10.1063/1.2396941. Archived from the original (PDF) on 23 March 2012.
  10. ↑ Magnesium recycling in the United States in 1998. (PDF). USGS. Retrieved 21 August 2011.
  11. ↑ Franklin J (1993). "The Atmospheric Degradation and Impact of 1,1,1,2-Tetrafluorethane (Hydrofluorocarbon 134a)". Chemosphere. 27 (8): 1565–1601. Bibcode:1993Chmsp..27.1565F. doi:10.1016/0045-6535(93)90251-Y.
  12. ↑ Forster, P.; et al. (2007). "Changes in Atmospheric Constituents and in Radiative Forcing." (PDF). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Archived (PDF) from the original on 24 July 2010.
  13. ↑ "DIRECTIVE 2006/40/EC relating to emissions from air-conditioning systems in motor vehicles and amending Council Directive 70/156/EEC". eur-lex.europa.eu. 17 May 2006. Retrieved 29 May 2021.
  14. ↑ HFO-1234yf A Low GWP Refrigerant For MAC Archived 27 February 2009 at the Wayback Machine . Refrigerants.dupont.com (17 August 2011). Retrieved 21 August 2011.
  15. ↑ California restricts use of HFC-134a in cars. 27 June 2007. R744.com. Retrieved 21 August 2011.
  16. 1 2 Chapter ATCP 136. MOBILE AIR CONDITIONERS; RECLAIMING OR RECYCLING REFRIGERANT. State.wi.us. (PDF). Retrieved 21 August 2011.
  17. ↑ Class I Ozone-depleting Substances. EPA.gov. Retrieved 21 August 2011.
  18. ↑ "Solvay in North America | Solvay" (PDF).
  19. ↑ Burdon, James; Coe, Paul L.; Haslock, Iain B.; Powell, Richard L. (1996). "The hydrofluorocarbon 1,1,1,2-tetrafluoroethane (HFC-134a) as a ready source of trifluorovinyllithium". Chemical Communications: 49. doi:10.1039/CC9960000049.
  20. ↑ DuPont (2004). DuPont HFC-134a— Properties, Uses, Storage, and Handling (PDF) (Report). Archived from the original (PDF) on 4 October 2016. Retrieved 5 August 2016.
  21. ↑ Honeywell International (December 2005). "MSDS # GTRN-0047 For Genetron 134aUV".
  22. ↑ "SAFETY DATA SHEET according to Regulation (EU) 2015/8301/7 Harp 134a" (PDF).
  23. ↑ Alexander D. J.; Libretto S. E. (1995). "An overview of the toxicology of HFA-134a (1,1,1,2-tetrafluoroethane)". Hum. Exp. Toxicol. 14 (9): 715–20. doi:10.1177/096032719501400903. PMID   8579881. S2CID   19669317.
  24. ↑ G. E. Millward; E. Tschuikow-Roux (1972). "Kinetic analysis of the shock wave decomposition of 1,1,1,2-tetrafluoroethane". The Journal of Physical Chemistry. 76 (3): 292–298. doi:10.1021/j100647a002.
  25. ↑ Sellers, William F. S. (2017). "Asthma pressurised metered dose inhaler performance: Propellant effect studies in delivery systems". Allergy, Asthma & Clinical Immunology. 13: 30. doi: 10.1186/s13223-017-0202-0 . PMC   5492461 . PMID   28670327.
  26. 1 2 Shah, S. B; Hariharan, U; Bhargava, A. K (2015). "Anaesthetic in the garb of a propellant". Indian Journal of Anaesthesia. 59 (4): 258–260. doi: 10.4103/0019-5049.155011 . PMC   4408662 . PMID   25937660. This propellant has been shown to be safe and nonanaesthetic in standard inhaler doses
  27. ↑ Huchon, G; Hofbauer, P; Cannizzaro, G; Iacono, P; Wald, F (2000). "Comparison of the safety of drug delivery via HFA- and CFC-metered dose inhalers in CAO". The European Respiratory Journal. 15 (4): 663–9. doi: 10.1034/j.1399-3003.2000.15d07.x . PMID   10780756.
  28. ↑ "1,1,1,2-Tetrafluoroethane". Occupational Safety & Health Administration. Archived from the original on 3 February 2018. Retrieved 3 February 2018.
  29. ↑ "Norflurane". DrugBank.
  30. ↑ "Norflurane-Pentafluoropropane Aerosol, Spray". WebMD.
  31. ↑ Shulman M, Sadove MS (1967). "1,1,1,2-tetrafluoroethane: an inhalational agent of intermediate potency". Anesthesia and Analgesia. 46 (5): 629–635. doi: 10.1213/00000539-196709000-00029 . S2CID   5868484.
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