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| Names | |||
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| Preferred IUPAC name Dichlorodi(fluoro)methane | |||
Other names
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| Identifiers | |||
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3D model (JSmol) | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.000.813 | ||
| EC Number |
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| E number | E940(glazing agents, ...) | ||
| KEGG |
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| RTECS number |
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| UNII | |||
| UN number | 1028 | ||
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| Properties | |||
| CCl2F2 | |||
| Molar mass | 120.91 g·mol−1 | ||
| Appearance | Colorless gas | ||
| Odor | ether-like at very high concentrations | ||
| Density | 1.486 g/cm3 (−29.8 °C (−21.6 °F)) | ||
| Melting point | −157.7 °C (−251.9 °F; 115.5 K) | ||
| Boiling point | −29.8 °C (−21.6 °F; 243.3 K) | ||
| 0.286 g/L at 20 °C (68 °F) | |||
| Solubility in alcohol, ether, benzene, acetic acid | Soluble | ||
| logP | 2.16 | ||
| Vapor pressure | 568 kPa (20 °C (68 °F)) | ||
Henry's law constant (kH) | 0.0025 mol kg−1 bar−1 | ||
| −52.2·10−6 cm3/mol | |||
| Thermal conductivity | 0.0097 W/(m·K) (300 K)[1] | ||
| Structure | |||
| Tetrahedral | |||
| 0.51D[2] | |||
| Hazards | |||
| GHS labelling: | |||
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| Warning | |||
| H336,H420 | |||
| P261,P271,P304+P340,P319,P403+P233,P405,P410+P403,P501,P502 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | Non-flammable[3] | ||
| Lethal dose or concentration (LD, LC): | |||
LC50 (median concentration) | 760,000 ppm (mouse, 30 min) 800,000 ppm (rabbit, 30 min) 800,000 ppm (guinea pig, 30 min) 600,000 ppm (rat, 2h)[4] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 1000 ppm (4950 mg/m3)[3] | ||
REL (Recommended) | TWA 1000 ppm (4950 mg/m3)[3] | ||
IDLH (Immediate danger) | 15000 ppm[3] | ||
| Supplementary data page | |||
| Dichlorodifluoromethane (data page) | |||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Dichlorodifluoromethane (R-12) is a colorless gas popularly known by thegenericized brand nameFreon (asFreon-12). It is achlorofluorocarbonhalomethane (CFC) used as arefrigerant andaerosol spray propellant. In compliance with theMontreal 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 theozone layer.[5] Its only allowed usage is as afire retardant in submarines and aircraft. It issoluble in manyorganicsolvents. R-12 cylinders are colored white.
It can be prepared by reactingcarbon tetrachloride withhydrogen fluoride in the presence of acatalytic amount ofantimony pentachloride:
This reaction can also producetrichlorofluoromethane (CCl3F),chlorotrifluoromethane (CClF3) andtetrafluoromethane (CF4).[6]
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 includedThomas 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), anddichlorotetrafluoroethane (CClF2CClF2 or R114), throughKinetic Chemicals which was a joint venture betweenDuPont andGeneral Motors.[7]
The use of chlorofluorocarbons as aerosols in medicine, such asUSP-approvedsalbutamol, has been phased out by theU.S. Food and Drug Administration. A different propellant known ashydrofluoroalkane, or HFA, which was not known to harm the environment, was chosen to replace it.[8] That being said it still listed on the FDA's approved food additive list.
| CAS Reg. No. (or other ID)*: | 75-71-8 |
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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 thanCO2.[9]
R-12 was used in most refrigeration and vehicle air conditioning applications prior to 1994 before being replaced by1,1,1,2-tetrafluoroethane (R-134a), which has an insignificantozone depletion potential. Automobile manufacturers began phasing in R-134a around 1993[citation needed]. 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 asHC-12a, the flammability of which has caused injuries and deaths.[10][11]
Aside from its environmental impacts, R12, like most chlorofluoroalkanes, formsphosgene gas when exposed to a naked flame.[12]
Table of thermal and physical properties of saturated liquid refrigerant 12:[13][14]
| 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 | — |
| −30 | 1489.56 | 0.8956 | 2.53×10−7 | 0.069 | 5.26×10−1 | 4.8 | — |
| −20 | 1460.57 | 0.9073 | 2.35×10−7 | 0.071 | 5.39×10−1 | 4.4 | — |
| −10 | 1429.49 | 0.9203 | 2.21×10−7 | 0.073 | 5.50×10−1 | 4 | — |
| 0 | 1397.45 | 0.9345 | 2.14×10−7 | 0.073 | 5.57×10−1 | 3.8 | — |
| 10 | 1364.3 | 0.9496 | 2.03×10−7 | 0.073 | 5.60×10−1 | 3.6 | — |
| 20 | 1330.18 | 0.9659 | 1.98×10−7 | 0.073 | 5.60×10−1 | 3.5 | — |
| 30 | 1295.1 | 0.9835 | 1.94×10−7 | 0.071 | 5.60×10−1 | 3.5 | — |
| 40 | 1257.13 | 1.0019 | 1.91×10−7 | 0.069 | 5.55×10−1 | 3.5 | — |
| 50 | 1215.96 | 1.0216 | 1.90×10−7 | 0.067 | 5.45×10−1 | 3.5 | — |
{{cite book}}: CS1 maint: numeric names: authors list (link)| Authority control databases: National |
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