Trichlorofluoromethane

Structural formula
General
Surname	Trichlorofluoromethane
other names	Trichlorofluorocarbon Trichloromonofluoromethane Fluorotrichloromethane Freon 11 F11 R-11 CFC-11
Molecular formula	CCl 3 F
Brief description	non-flammable colorless liquid or gas with an ethereal odor
External identifiers / databases
CAS number 75-69-4 EC number 200-892-3 ECHA InfoCard 100,000,812 PubChem 6389 Wikidata Q423000
properties
Molar mass	137.37 g mol −1
Physical state	liquid
density	1.479 g cm −3 (liquid)
Melting point	−111 ° C
boiling point	23.6 ° C
Vapor pressure	0.886 bar (20 ° C) 1.29 bar (30 ° C) 2.4 bar (50 ° C)
solubility	bad in water (1.5 g l −1 ) soluble in most organic solvents
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 312-420 P: 273-280-501
MAK	DFG : 5700 mg m −3 Switzerland: 1000 ml m −3 or 5600 mg m −3
Global warming potential	5352 (based on 100 years)
Thermodynamic properties
ΔH f 0	−301.3 kJ / mol
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Trichlorofluoromethane is a chlorofluorocarbon (CFC) and is used as a refrigerant . Since, like all CFCs , it is classified as destroying the ozone layer , it is increasingly being replaced by more environmentally friendly substances.

Extraction and presentation

Trichlorofluoromethane can be obtained by reacting carbon tetrachloride with hydrogen fluoride at 435 ° C and 70 atm, a mixture of trichlorofluoromethane, carbon tetrachloride and dichlorodifluoromethane in a ratio of 77: 18: 5 being formed. The reaction can also be carried out in the presence of antimony (III) chloride or antimony (V) chloride .

${\displaystyle {\ce {CCl4 + HF -> CCl3F + CCl4 + CCl2F2}}}$

Trichlorofluoromethane is also formed as one of the byproducts when graphite reacts with chlorine and hydrogen fluoride at 500 ° C.

Sodium hexafluorosilicate under pressure at 270 ° C, titanium (IV) fluoride , chlorine trifluoride , cobalt (III) fluoride , iodine pentafluoride and bromine trifluoride are also suitable as fluorinating agents for carbon tetrachloride.

${\displaystyle {\ce {CCl4 + Na2SiF6 -> CCl3F + CCl2F2 + CCl3F + NaCl + SiF4}}}$

${\displaystyle {\ce {CCl4 + BrF3 -> BrF + CCl2F2 + CCl3F}}}$

Also, antimony (III) fluoride in the presence of antimony (V) chloride is useful as a fluorinating agent.

${\displaystyle {\ce {2 CCl4 + SbF3 -> CCl2F2 + CCl3F}}}$

In the laboratory, the Hunsdiecker reaction can also be used to synthesize trichlorofluoromethane (in 63% yield) from silver dichlorofluoroacetate and chlorine .

${\displaystyle {\ce {Cl2FCCO2Ag + Cl2 -> CCl3F + CO2 + AgCl}}}$

properties

When it comes into contact with flames or hot objects, it decomposes and forms very toxic and corrosive vapors ( chlorine , hydrogen chloride , hydrogen fluoride ). A violent reaction occurs with metals such as aluminum , barium , calcium , magnesium and sodium . When heated to high temperatures during soldering, by sparks or cigarettes, the gas breaks down into toxic compounds such as chlorine (HCl) or hydrogen fluoride (HF).

use

Until the 1990s, trichlorofluoromethane was used as R11 in refrigerators or as a propellant , e.g. for foaming polyurethane .

The compound is also used as a solvent in many reactions and as an internal standard in ¹⁹ F-NMR spectroscopy .

Environmental impact

Since 1995, the substance is forbidden in Germany for new installations, since it, like all CFC high ozone depletion potential has, plus a 5352-fold higher global warming potential than carbon dioxide. At the London Conference in 1990 it was decided to end the production of trichlorofluoromethane and other CFCs worldwide by the year 2000.

In 2018, a study was published according to which the decrease in the amount of trichlorofluoromethane in the atmosphere has been slower since 2012 than in previous years. In addition, the salary is higher in the northern hemisphere than in the southern hemisphere. According to the London-based non-profit Environmental Investigation Agency , the ongoing use of trichlorofluoromethane (= CFC-11) to foam polyurethane in China is responsible for this, which in turn is used for insulation purposes. Although the substance has been banned in China since 2010, the ban on trichlorofluoromethane is not monitored by the authorities. A Chinese seller of CFC-11 estimated that around 70% of the polyurethane produced is still foamed with trichlorofluoromethane despite the ban (as of 2018).

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  Concentration in the atmosphere over time

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  Concentration on the sea surface in the late 1990s

Individual evidence

1. ↑ ^{a b c d e f g h i j k} Entry on trichlorofluoromethane in the GESTIS substance database of the IFA , accessed on May 17, 2018(JavaScript required) .
2. ↑ ^{a b} Wiley Online Library: Trichlorofluoromethane - Burton - Major Reference Works - Wiley Online Library , accessed May 17, 2018.
3. ↑ Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 75-69-4 or trichlorofluoromethane ), accessed on November 2, 2015.
4. ↑ ^{a b} G. Myhre, D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nalajima, A. Robock, G. Stephens, T. Takemura, H. Zhang et al .: Climate Change 2013: The Physical Science Basis . Working Group I contribution to the IPCC Fifth Assessment Report. Ed .: Intergovernmental Panel on Climate Change . 2013, Chapter 8: Anthropogenic and Natural Radiative Forcing, pp. 24-39; Table 8.SM.16 ( PDF ).
5. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-19.
6. ↑ ^{a b c d} Alan R. Katritzky, Thomas L. Gilchrist, Otto Meth-Cohn, Charles Wayne Rees: Comprehensive Organic Functional Group Transformations . Elsevier, 1995, ISBN 978-0-08-042704-1 , pp. 220 ( limited preview in Google Book search).
7. ^ AA Banks, HJ Emeléus et al. a .: 443. The reaction of bromine trifluoride and iodine pentafluoride with carbon tetrachloride, tetrabromide, and tetraiodide and with tetraiodoethylene. In: J. Chem. Soc. , 1948, p. 2188, doi : 10.1039 / JR9480002188 .
8. ^ ^{A b} Jennifer Orme-Zavaleta, Jan Connery: Drinking Water Health Advisory Volatile Organic Compounds . CRC Press, 1990, ISBN 978-0-87371-436-5 , pp. 21 ( limited preview in Google Book search).
9. ↑ Data sheet R-11 (PDF; 71 kB) from National Refrigerants, accessed on June 14, 2016.
10. ↑ bauweise.net: Focus on heat pumps - refrigerants
11. ↑ Someone, somewhere, is making a banned chemical that destroys the ozone layer, scientists suspect . In: Washington Post , May 16, 2018. Retrieved May 17, 2018.
12. ↑ Matt McGrath: Ozone hole mystery: China insulating chemical said to be source of rise. In: BBC News. July 9, 2018, accessed July 9, 2018 . 

Web links

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