Chlorodifluoromethane

Structural formula
General
Surname	Chlorodifluoromethane
other names	R-22 Freon 22 Frigen 22 HCFC-22
Molecular formula	CHClF 2
Brief description	colorless, non-flammable gas
External identifiers / databases
CAS number 75-45-6 EC number 200-871-9 ECHA InfoCard 100,000,793 PubChem 6372 Wikidata Q422994
properties
Molar mass	86.47 g mol −1
Physical state	gaseous
density	3.93 kg m −3 (0 ° C)
Melting point	−157.3 ° C
boiling point	−40.9 ° C
Vapor pressure	908 k Pa (20 ° C)
solubility	poor in water (3 g l −1 at 25 ° C)
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 280-420 P: 502-410 + 403
MAK	DFG / Switzerland: 500 ml m −3 or 1800 mg m −3
Global warming potential	2106 (based on 100 years)
Thermodynamic properties
ΔH f 0	−482.6 kJ / mol
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Chlorodifluoromethane is a chemical compound that belongs to the group of partially halogenated hydrocarbons HCFC and is also known as R-22 .

Extraction and presentation

Chlorodifluoromethane is produced in the liquid phase from carbon tetrachloride or from chloroform CHCl ₃ by partial fluorination using antimony (V) chloride fluoride (SbCl ₄ F) as a catalyst .

${\displaystyle \mathrm {CHCl_{3}+2\ HF\longrightarrow CHClF_{2}+2\ HCl} }$

use

Chlorodifluoromethane is used as an intermediate in the manufacture of polytetrafluoroethylene . In the past, the substance was mainly used as a refrigerant in compression refrigeration systems. Atmospheric R22 damages the ozone layer , but less than the fully halogenated hydrocarbons. It was therefore used at times as a substitute for R12 and the transition times until the ban on use according to the CFC-Halon Prohibition Ordinance were longer. Since January 1, 2000, according to the Montreal Protocol, it has been forbidden to import, manufacture or trade R22 for use in new plants or plants already filled with R22. Since January 1st, 2010 you can only use recycled R22. From 2015, production and import will be limited to 10% of the 1989 consumption for each country, and will be banned from 2020. The use of recycled R22 was allowed until 2015.

hazards

If chlorodifluoromethane is burned in the presence of metal and carbon (e.g. when soldering old copper pipes from refrigerators or refrigeration systems), the poisonous gas phosgene can be formed.

Individual evidence

1. ↑ ^{a b c d e f g h i} Entry on chlorodifluoromethane in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
2. ↑ Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 75-45-6 or chlorodifluoromethane ), accessed on November 2, 2015.
3. ↑ G. Myhre, D. Shindell 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 ).
4. ↑ 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.
5. ↑ Johnson Controls: The R22 phase-out and the F-gas regulation ( Memento of the original from November 14, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 158 kB).