75-71-8 Dichlorodifluoromethane

It is the use of LIDAR devices as tools for spectroscopic measurements on the various gases present in the atmosphere which concerns us here. These include ozone, carbon dioxide, the CFCs (chlorofluorocarbons, such as CFC-11, trichlorofluoromethane, and CFC-12, dichlorodifluoromethane, used as refrigerants) and all those molecules regarded as atmospheric pollutants. 

CCI2F2 (dichlorodifluoromethane) multiphoton dissociation, 374 CFl4 (methane)... 

Although the CFCs and HCFCs are not as stable as the PFCs, they still can be rather stable compounds (3,11)- Dichlorodifluoromethane, CCI2F2, is stable at 500°C in quartz CCl F and CHCIF2 begin to decompose at 450 and 290°C, respectively (7). The pyrolysis of CHCIF2 at 650—700°C in metal tubes is the basis of a commercial synthesis of tetrafluoroethylene ... 

Economic Aspects. The estimated worldwide production of important industrial CFCs is shown in Table 5. Trichlorofluoromethane, dichlorodifluoromethane, and trichlorotrifluoroethane account for over 95% of the total production. Between 1986 and 1991 the production of CFCs has decreased dramatically due to global adherence to the provisions of the Montreal Protocol and eventually will be phased out entirely. Estimates of the distribution by use in 1986 and subsequent reductions in use are shown in Table 6. 

Chlo r ofluo r oca rho ns. I,I,I-trichloro-2,2,2-trifluoroethane trichlorofluoromethane, dichlorodifluoromethane chlorodifluoro-methane I,2-dichloro-I,I,2,2-tetrafluoroethane chloropentafluoro-ethane... 

Dichloro-1 -nitroethane o-Dichlorobenzene p-Dichlorobenzene 3,3 -Dichlorobenzidine Dichlorodifluoromethane (Refrigerant 12)... 

Refrigerant 113 (1,1,2-trichloro-l, 2,2-fluoroethane) Refrigerant 114 (dichlorotetrafluoroethane) Refrigerant 12 (dichlorodifluoromethane) Refrigerant 21 (dichloromonofluoromethane) Resorcinol Rhodium... 

Primary alkyl chlorides are fairly stable to fluorine displacement. When fluorinated, 1-chloropropane is converted to 1-chloroheptafluoropropane and 1-chloto-2-methylbutane produces 39% l-chlorononafluoro-2-methylbutane and 19% perfluoro-2-methylbutane. Secondary and tertiary alkyl chlorides can undergo 1,2-chlorine shifts to afford perfluonnated primary alkyl chlorides 2-Chloro-2-methylpropane gives l-chlorononafluoro-2-methylpropane, and three products are obtained by the fluorination of 3-chloropentane [7] (equation 1). Aerosol fluorina-tion of dichloromethane produces dichlorodifluoromethane which is isolated in 98% purity [4 (equation 2). If the molecule contains only carbon and halogens, the picture is different. Molecular beam analysis has shown that the reaction of fluorine with carbon tetrachlonde, lodotrichloromethane, or bromotrichloromethane proceeds first by abstraction of halogen to form a trichloromethyl radical [5]... 

Unfortunately, the thermodynamically favored reactions of trichlo-rolluoromethane (CFC-11) and dichlorodifluoromethane (CFC-12) with water do not proceed to a significant degree below 300 C and at least 200 atm (1 atm = 101.325 kPa) or greater [42] (equation 44) Even at 4000 atm randoimzation rather than complete hydrolysis occurs, leaving another chlorofluorocarbon, chlorotri-fluoromethane (CFC-13), which is also potentially harmful to the earth s ozone layer... 

Dichlorodifluoromethane and triphenylphosphine were used to prepare 3-de-oxy 3-C-difluoromethylene nbose analogues in up to 65% yield [47] (equation 45). 

An efficient catalyst for thermal isomenzations of halofluorocarbons [6, 7, 8, 9] IS prepared by treatment of alumina with dichlorodifluoromethane at 200-300 °C [9] or aluminum chloride with chlorofluorocarbons in the presence of metals [W] or palladium on alumina [II These catalysts are far more efficient than aluminum halides themselves (equations 1 and 2)... 

Chlorofluorocarbon-blown foam blocks are used to insulate the walls and roofs of some buildings, thus reducing heat losses and helping to conserve fossil fuels. In this area, polyurethane foam competes with polystyrene foam, which until recently was blown with dichlorodifluoromethane (CFC 12) but is now blown with a mixture of chlorodifluoromethane (HCFC 22) and 1 -chloro-l,l-difluoroethane (HCFC 142b). 

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