<unk>  or Freon 31 is a gaseous mixed halomethane (hydrochlorofluorocarbon - HCFC).
Its crystal structure is monoclinic with space group P21 and lattice constants a = 6.7676, b = 4.1477, c = 5.0206 (.10-1 nm), β = 108.205°.
In altitude of 22 km traces of<unk>  occur (148 ppt)
It is used as a refrigerant with ozone depletion potential 0.02.
Chlorofluoromethane
Triphenylmethane
Diazomethane
Chlorodifluoromethane
Chloroethane
Bromomethane
Trichloroethylene
Nitrazine