Dichlorofluoromethane

Dichlorofluoromethane or Freon 21 or R 21 is a halomethane or hydrochlorofluorocarbon with the formula CHCl2F. It is a colorless and odorless gas. It is produced by fluorination of chloroform using a catalyst such as antimony trifluoride:[4]

CHCl3 + HF → CHCl2F
Dichlorofluoromethane
Names
Preferred IUPAC name
Dichloro(fluoro)methane
Other names
Dichlorofluoromethane
Fluorodichloromethane
Monofluorodichloromethane
Dichloromonofluoromethane
Freon 21
Refrigerant 21
R 21
HCFC 21
Algofrene Type 5
Arcton 7
Halon 112
UN 1029
Genetron 21
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.000.791
EC Number
  • 200-869-8
RTECS number
  • PA8400000
UNII
UN number 1029
Properties
CHCl2F
Molar mass 102.92 g/mol
Appearance Colorless gas
Odor Ether-like[1]
Density
  • 1.405 kg/m3 at 9 °C
  • 1.366 kg/m3 at 25 °C
Melting point −135 °C (−211 °F; 138 K)
Boiling point 8.92 °C (48.06 °F; 282.07 K)
9.420 g/l at 30 °C
log P 1.55
Vapor pressure 160 kPa
0.19 (mol·kg·bar)−1
−48.8·10−6 cm3/mol
Thermal conductivity 0.0086 W/m·K (300 K)[2]
Hazards
GHS pictograms
GHS Signal word Warning
H280, H420
P410+403, P502
Flash point Non-flammable [1]
522 °C (972 °F; 795 K)
Lethal dose or concentration (LD, LC):
  • >800,000 mg/m3 (mouse, 2 hr)
  • 49,900 ppm (rat, 4 hr)[3]
  • 100,000 ppm (guinea pig, <1 hr)
  • 100,000 ppm (mouse, <1 hr)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 1000 ppm (4200 mg/m3)[1]
REL (Recommended)
 TWA 10 ppm (40 mg/m3)[1]
IDLH (Immediate danger)
 5000 ppm[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Uses

Dichlorofluoromethane was used as a propellant and refrigerant. Due to its role in ozone depletion, dichlorofluoromethane has been largely phased out. It has ozone depletion potential 0.04. Production and consumption has been since 2004 reduced to 15% of level from 1989 and it is to be phased out in 2015 according to Montreal Protocol.

Pyrolysis of a mixture of dichlorofluoromethane and chlorofluoromethane gives hexafluorobenzene:[4]

3 CHCl2F + 3 CH2ClF → C6F6 + 9 HCl

Additional physical data

Its critical point is at 178.5 °C (451.7 K) and 5.17 MPa (51.7 bar). At temperatures from 5 K to 105 K it has one phase in the space group Pbca.

Safety

Its toxicity is comparable to that of chloroform. Its TLV is 10 ppm.[4]

References
  1. NIOSH Pocket Guide to Chemical Hazards. "#0197". National Institute for Occupational Safety and Health (NIOSH).
  2. 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.
  3. "Dichloromonofluoromethane". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. Dagani, M. J.; = Barda, H. J.; Benya, T. J.; Sanders, D. C. "Bromine Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a04_405.
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