Dichlorodifluoromethane

{{chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 442842661

| Name =

| ImageFile =

| ImageFileL1 = Dichlorodifluoromethane.png

| ImageSizeL1 =

| ImageFileR1 = Dichlorodifluoromethane-3D-vdW.png

| ImageSizeR1 =

| PIN = Dichlorodi(fluoro)methane

| SystematicName =

| OtherNames = {{Unbulleted list|Dichlorodifluoromethane|Carbon dichloride difluoride|Dichloro-difluoro-methane|Difluorodichloromethane|Freon 12|R-12|CFC-12|P-12|Propellant 12|Halon 122|Arcton 6|Arcton 12|E940|Fluorocarbon 12|Genetron 12|Refrigerant 12}}

| IUPACName =

| Section1 = {{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 6151

| ChEMBL_Ref = {{ebicite|changed|EBI}}

| ChEMBL = 2106634

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = OFM06SG1KO

| InChIKey = PXBRQCKWGAHEHS-UHFFFAOYAX

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/CCl2F2/c2-1(3,4)5

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = PXBRQCKWGAHEHS-UHFFFAOYSA-N

| CASNo = 75-71-8

| CASNo_Ref = {{cascite|correct|CAS}}

| EINECS = 200-893-9

| PubChem = 6391

| SMILES = ClC(Cl)(F)F

| InChI = 1/CCl2F2/c2-1(3,4)5

| RTECS = PA8200000

| KEGG_Ref = {{keggcite|correct|kegg}}

| KEGG = D03789

| UNNumber = 1028

}}

| Section2 = {{Chembox Properties

| C=1 | Cl=2 | F=2

| Appearance = Colorless gas

| Odor = ether-like at very high concentrations

| Density = 1.486 g/cm³ ({{convert|-29.8|C}})

| MeltingPtC = −157.7

| BoilingPtC = −29.8

| Solubility = 0.286 g/L at {{convert|20|C}}

| Solvent = alcohol, ether, benzene, acetic acid

| SolubleOther = Soluble

| LogP = 2.16

| VaporPressure = 568 kPa ({{convert|20|C}})

| HenryConstant = 0.0025 mol kg⁻¹ bar⁻¹

| MagSus = −52.2·10⁻⁶ cm³/mol

| ThermalConductivity = 0.0097 W/(m·K) (300 K)Touloukian, Y. S., Liley, P. E., and Saxena, S. C. Thermophysical properties of matter – the TPRC data series. Volume 3. Thermal conductivity – nonmetallic liquids and gases. Data book. 1970.

}}

| Section3 = {{Chembox Structure

| MolShape = Tetrahedral

| Dipole = 0.51 DKhristenko, Sergei V.; Maslov, Alexander I. and Viatcheslav P. Shevelko; Molecules and Their Spectroscopic Properties, p. 74 {{ISBN|3642719481}}.

}}

| Section4 = {{Chembox Hazards

| ExternalSDS =

| NFPA-H = 0

| NFPA-F = 0

| NFPA-R = 0

| NFPA-S =

| GHSPictograms = {{GHS07}}

| GHSSignalWord = Warning

| HPhrases = {{H-phrases|336|420}}

| PPhrases = {{P-phrases|261|271|304+340|319|403+233|405|410+403|501|502}}

| FlashPt = Non-flammable

| FlashPt_ref =

| PEL = TWA 1000 ppm (4950 mg/m³){{PGCH|0192}}

| IDLH = 15000 ppm

| REL = TWA 1000 ppm (4950 mg/m³)

| LC50 = 760,000 ppm (mouse, 30 min)
800,000 ppm (rabbit, 30 min)
800,000 ppm (guinea pig, 30 min)
600,000 ppm (rat, 2 h){{IDLH|75718|Dichlorodifluoromethane}}

}}

| Section5 =

| Section6 =

}}

Dichlorodifluoromethane (R-12) is a colorless gas popularly known by the genericized brand name Freon (as Freon-12). It is 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 (non-article 5 countries) in 1996, and in developing countries (Article 5 countries) in 2010 out of concerns about its damaging effect on the ozone layer.{{cite book |title=Scientific assessment of ozone depletion: 2018. |date=2018 |publisher=World Meteorological Organization |location=Geneva, Switzerland |isbn=978-1-7329317-1-8 |page=1.10 |edition=Global Ozone Research and Monitoring Project–Report No. 58 |url=https://www.environment.gov.au/system/files/resources/bde22641-eeb6-4502-9c54-8239c2c64c0f/files/2018-ozone-summary-report.pdf |access-date=22 November 2020 |chapter=1:Update on Ozone-Depleting Substances (ODSs) and Other Gases of Interest to the Montreal Protocol}} 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.

Preparation

It can be prepared by reacting carbon tetrachloride with hydrogen fluoride in the presence of a catalytic amount of antimony pentachloride:

:CCl₄ + 2HF → CCl₂F₂ + 2HCl

This reaction can also produce trichlorofluoromethane (CCl₃F), chlorotrifluoromethane (CClF₃) and tetrafluoromethane (CF₄).{{Greenwood&Earnshaw2nd|page=304}}

History

Charles F. Kettering, vice president of General Motors Research Corporation, was seeking a refrigerant replacement that would be colorless, odorless, tasteless, nontoxic, and nonflammable. He assembled a team that included Thomas Midgley Jr., Albert Leon Henne, and Robert McNary. From 1930 to 1935, they developed dichlorodifluoromethane (CCl₂F₂ or R12), trichlorofluoromethane (CCl₃F or R11), chlorodifluoromethane (CHClF₂ or R22), trichlorotrifluoroethane (CCl₂FCClF₂ or R113), and dichlorotetrafluoroethane (CClF₂CClF₂ or R114), through Kinetic Chemicals which was a joint venture between DuPont and General Motors.{{cite book | title=High Performance Polymers: Their Origin and Development | publisher=Elsevier Science Publishing Co., Inc. | author=Plunkett, Roy J. | year=1986 | pages=261–262 | isbn=978-94-011-7073-4}}

Use as an aerosol

The use of chlorofluorocarbons as aerosols in medicine, such as USP-approved salbutamol, has been phased out by the U.S. Food and Drug Administration. A different propellant known as hydrofluoroalkane, or HFA, which was not known to harm the environment, was chosen to replace it.{{Cite web |url=http://www.pittsburghlive.com/x/pittsburghtrib/news/mostread/s_493084.html |title=Asthma inhaler replacements coming to Pa. - Pittsburgh Tribune-Review |date=16 February 2007 |website= |access-date=26 April 2022 |archive-url=https://web.archive.org/web/20070216044756/http://www.pittsburghlive.com/x/pittsburghtrib/news/mostread/s_493084.html |archive-date=16 February 2007 |url-status=dead}} That being said it still listed on the FDA's approved food additive list.

class="wikitable"

!CAS Reg. No. (or other ID)*:

|75-71-8

Environmental Effects

R-12 has the highest ozone depletion potential among chlorocarbons due to the presence of 2 chlorine atoms in the molecule.

R-12 also has intense global warming potential (GWP) with the 20yr, 100yr and 500yr GWP being 11400, 11200 and 5100 times greater than {{chem2|CO2}}.{{Cite web | url=https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_FGD_Chapter07_SM.pdf| title=IPCC Sixth Assessment Report - The Physical Science Basis - Chapter 7 Supplementary Material Table 7 |access-date=1 November 2024 |archive-url=https://web.archive.org/web/20240630195210/https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_FGD_Chapter07_SM.pdf |archive-date=30 June 2024 }}

Retrofitting

R-12 was used in most refrigeration and vehicle air conditioning applications prior to 1994 before being replaced by 1,1,1,2-tetrafluoroethane (R-134a), which has an insignificant ozone depletion potential. Automobile manufacturers began phasing in R-134a around 1993{{CN|date=November 2024}}. When older units leak or require repair involving removal of the refrigerant, retrofitment to a refrigerant other than R-12 (most commonly R-134a) is required in some jurisdictions. The United States does not require such conversion. Retrofitment requires a system flush and a new filter/dryer or accumulator, and may also involve the installation of new seals and/or hoses made of materials compatible with the refrigerant being installed. Mineral oil used with R-12 is not compatible with R-134a. Some oils designed for conversion to R-134a are advertised as compatible with residual R-12 mineral oil. Illegal replacements for R-12 include highly flammable hydrocarbon blends such as HC-12a, the flammability of which has caused injuries and deaths.{{Cite web|url=https://ensegundos.com.pa/2019/10/23/se-cumplen-13-anos-de-la-tragedia-de-la-cresta/|title=Se cumplen 13 años de la Tragedia de la Cresta|website=Ensegundos.com.pa|date=23 October 2019}}{{cite web|url=https://m.metrolibre.com/nacionales/152183-v%C3%ADctimas-de-la-tragedia-de-la-cresta-fueron-recordadas.html|title=Victims of the La Cresta tragedy were remembered|website=M.metrolibra.com|access-date=26 April 2022}}

Dangers

Aside from its environmental impacts, R12, like most chlorofluoroalkanes, forms phosgene gas when exposed to a naked flame.{{cite web |title=False Alarms: The Legacy of Phosgene Gas |url=https://hvacrschool.com/phosgene-gas/ |website=HVAC School |date=4 January 2021 |access-date=9 May 2022}}

Properties

Table of thermal and physical properties of saturated liquid refrigerant 12:{{Cite book |last=Holman |first=Jack P. |title=Heat Transfer |publisher=McGraw-Hill Companies, Inc. |year=2002 |isbn=9780072406559 |edition=9th |location=New York, NY |pages=600–606 |language=English}}{{Cite book |last=Incropera 1 Dewitt 2 Bergman 3 Lavigne 4 |first=Frank P. 1 David P. 2 Theodore L. 3 Adrienne S. 4 |title=Fundamentals of Heat and Mass Transfer |publisher=John Wiley and Sons, Inc. |year=2007 |isbn=9780471457282 |edition=6th |location=Hoboken, NJ |pages=941–950 |language=English}}

class="wikitable mw-collapsible mw-collapsed"

|Temperature (°C)

|Density (kg/m³)

|Specific heat (kJ/kg K)

|Kinematic viscosity (m²/s)

|Conductivity (W/m K)

|Thermal diffusivity (m²/s)

|Prandtl Number

|Bulk modulus (K⁻¹)

−50

|1546.75

|0.875

|3.10×10⁻⁷

|0.067

|5.01×10⁻¹

|6.2

|2.63×10⁻³

−40

|1518.71

|0.8847

|2.79×10⁻⁷

|0.069

|5.14×10⁻¹

|5.4

|{{N/A}}

−30

|1489.56

|0.8956

|2.53×10⁻⁷

|0.069

|5.26×10⁻¹

|4.8

|{{N/A}}

−20

|1460.57

|0.9073

|2.35×10⁻⁷

|0.071

|5.39×10⁻¹

|4.4

|{{N/A}}

−10

|1429.49

|0.9203

|2.21×10⁻⁷

|0.073

|5.50×10⁻¹

|{{N/A}}

|1397.45

|0.9345

|2.14×10⁻⁷

|0.073

|5.57×10⁻¹

|3.8

|{{N/A}}

|1364.3

|0.9496

|2.03×10⁻⁷

|0.073

|5.60×10⁻¹

|3.6

|{{N/A}}

|1330.18

|0.9659

|1.98×10⁻⁷

|0.073

|5.60×10⁻¹

|3.5

|{{N/A}}

|1295.1

|0.9835

|1.94×10⁻⁷

|0.071

|5.60×10⁻¹

|3.5

|{{N/A}}

|1257.13

|1.0019

|1.91×10⁻⁷

|0.069

|5.55×10⁻¹

|3.5

|{{N/A}}

|1215.96

|1.0216

|1.90×10⁻⁷

|0.067

|5.45×10⁻¹

|3.5

|{{N/A}}

Gallery

File:Monthly means of CFC-12.png|CFC-12 measured by the Advanced Global Atmospheric Gases Experiment ([http://agage.mit.edu/ 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.

File:Hats f12 global.png|Hemispheric and global mean CFC-12 concentrations (NOAA/ESRL)

Image:AYool CFC-12 history.png|Time-series of atmospheric concentrations of CFC-12 (Walker et al., 2000)

File:GLODAP sea-surf CFC12 AYool.png|1990s sea surface CFC-12 concentration

File:GLODAP invt CFC12 AYool.png|1990s CFC-12 oceanic vertical inventory

File:CFC-12 CFC-11 H-1211 SF6 vertical profiles Fairbanks Alaska 1976.png|CFC-12, CFC-11, H-1211 and SF₆ vertical profiles

References

External links

[http://www.esrl.noaa.gov/gmd/hats/combined/CFC12.html NOAA/ESRL CFC-12 global measurements]
{{ICSC|0048|00}}
[http://www.wou.edu/~avorder/Refrigeration.htm Overview of Freon-12 and some of its environmental problems]
[https://web.archive.org/web/20071026084802/http://ptcl.chem.ox.ac.uk/MSDS/DI/dichlorodifluoromethane.html MSDS at Oxford University]
[http://www.chemnet.ru/rus/handbook/ivtan/220.html Thermochemistry data at chemnet.ru]
[https://web.archive.org/web/20080528143503/http://www.nist.gov/kinetics/spectra/ir_spectra/CF2Cl2%20(CFC-12)1.pdf IR absorption spectra]
[https://www.cdc.gov/niosh/npg/npgd0192.html CDC - NIOSH Pocket Guide to Chemical Hazards]

Category:Halomethanes

Category:Chlorofluorocarbons

Category:Greenhouse gases

Category:Ozone-depleting chemical substances

Category:Refrigerants

Category:Belgian inventions

Category:Chlorofluoroalkanes