Freon products

The chlorine atoms in the upper atmosphere come from the breakdown of CF2 CI2 and other similar chlorofluorocarbons (CFCs), known commercially as Freons. Production of these compounds was more than one million tons in 1988, largely for use in relrigerators and air conditioners. Once released into the atmosphere, CFCs diffuse slowly upward in the atmosphere until they reach the ozone layer. There, ultraviolet light Irom the sun splits off chlorine atoms. These react with ozone, with dramatic results. Annual ozone decreases have exceeded 50% above Antarctica. The background photo shows the Antarctic hole (red-violet) on September 24, 2003. 

The chlorofluorocarbon compounds of methane and ethane are collectively known as freons. They are extremely stable, unreactlve, non-toxic, non-corrosive and easily liquefiable gases. Freon 12 (CCI2F2) Is one of the most common freons In Industrial use. It Is manufactured from tetrachloromethane by Swarts reaction. These are usually produced for aerosol propellants, refrigeration and air conditioning purposes. By 1974, total freon production In the world was about 2 billion pounds annually. Most freon, even that used In refrigeration, eventually makes Its way Into the atmosphere where It diffuses unchanged Into the stratosphere. In stratosphere, freon Is able to Initiate radical chain reactions that can upset the natural ozone balance (Unit 14, Class XI). 

Du Pont Technical Bulletin BA-13. Freon Products Information, Properties of Rigid Urethane Foams. 

Freon Products Information BA-13, E.I. Du Pont de Nemours Co., Freon Products Division. 

E.I. duPont de Nemours Co., Inc., FREON Products Div., Wilmington, DE, "FREON Blowing Agents for Polyurethane Foams," FREON Tech Bulletin BA-1 (September 1959). 

C. N. Masten, director of Du Pont s FREON" Products Division, noted recently in a public statement ... 

Since the ban on CFC production has been adopted, manufacturers are replacing Freon products with two related groups of compounds, the hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). These hydrogen-containing compounds are less energy efficient than the CFCs, but they are considered safer (although not entirely safe) for the environment. 

B. Systemic effects of moderate exposure include headache, nausea and vomiting, confusion, and drunkenness. More severe intoxication may result in coma or respiratory arrest. Ventricular arrhythmias may occur even with moderate exposures. A number of deaths, presumably caused by ventricular fibrillation, have been reported after freon abuse by sniffing or huffing freon products from plastic bags. Hepatic injury may occur. 

Solvent E2 is F-(CFCF3CF20)2CHFCp3, manufactured by DuPont Freon Products Division, Wilmington, Deleware, USA. 

DU PONT DE NEMOURS /E 1/ AND COMPANY INC., WILMINGTON, DELAWARE, FREON PRODUCTS DIVISION 36087... 

By 1974 world freon production was about 2 billion pounds annually. Most freon, even that used in refrigeration, eventually makes its way into the atmosphere where it diffuses unchanged into the stratosphere. In June 1974 F. S. Rowland and M. J. Molina published an article indicating, for the first time, that in the stratosphere freon is able to initiate radical chain reactions that can upset the natural ozone balance. The 1995 Nobel Prize in Chemistry was awarded to P. J. Crutzen, M. J. Molina, and F. S. Rowland for their combined work in this area. The reactions that take place are the following. (Freon-12 is used as an example.)... 

Off-Gas Treatment. Before the advent of the shear, the gases released from the spent fuel were mixed with the entire dissolver off-gas flow. Newer shear designs contain the fission gases and provide the opportunity for more efficient treatment. The gaseous fission products krypton and xenon are chemically inert and are released into the off-gas system as soon as the fuel cladding is breached. Efficient recovery of these isotopes requires capture at the point of release, before dilution with large quantities of air. Two processes have been developed, a cryogenic distillation and a Freon absorption. 

The dephlegmator process recovers a substantially higher purity C2+ hydrocarbon product with 50—75% lower methane content than the conventional partial condensation process. The C2+ product from the cryogenic separation process can be compressed and further separated in a de-ethanizer column to provide a high purity C3+ (LPG) product and a mixed ethylene—ethane product with 10—15% methane. Additional refrigeration for the deethanization process can be provided by a package Freon, propane or propylene refrigeration system. 

Trichlorofluoromethane (Freon 11) is available from E. I. duPont de Nemours and Company, Inc., or Matheson Gas Products. 

With Freon 112 or 113 as a solvent, fluonnation of pnmary butyl halides with bromine trifluonde can give mixtures of primary and secondary fluorides When 1,4 dibromobutane is the substrate, 93% l-bromo-4-fluorobutane and 1% 1-bro-mo-3-fluorobutane is obtained, with 1,4 dichlorobutane, the product contains 65% l-chloro-3-fluorobutane and 35% 1-chloro 4 fluorobutane When 4-bromo- or 4-chlorobutyl trifluoroacetate is used, the ratio of 4-fluorobutyl tnfluoroacetate to 3 fluorobutyl trifluoroacetate is 1 4 The effect of solvent is measured in another set of experiments When the reaction of bromine trifluonde and l,3-dichloro-2-fluoropropane in either Freon 113 or hydrogen fluoride is allowed to proceed to 40% conversion, the product mixture has the composition shown m Table 1 [/O] When 1 chloro 2,3-dibromopropane is combined with one-third of a mole of bromine trifluonde, both 1 bromo 3 chloro-2-fluoropropane and l-chloro-2,3-di-fluoropropane are formed [//] (equation 10)... 

According to Table 11-7 and Figure 11-24, the refrigerant R-11 was to have been phased-out by 1996. In principle the same concept applies to other refrigerant applications as just described. Note that Figure 11-25 for Freon R-12 is used for illustrative purposes, because R-12 was also to be phased-out of availability in 1996 (production) however, similar useful charts can be constructed for other refrigerants. 

The formed mixture is composed of trichlorofluoromethane (Freon-11) and dichlorodifluoromethane (Freon-12). These compounds are used as aerosols and as refrigerants. Due to the depleting effect of chlorofluorocarbons (CFCs) on the ozone layer, the production of these compounds may be reduced appreciably. 

In 1987 an international treaty was signed in Montreal to cut back on the use of CFCs. Production of Freon in the United States ended in 1996. It has been replaced in automobile air conditioners by a related compound with no chlorine atoms, C2H2F4 ... 

As discussed in Section 8.10, dediazoniation in methanol or ethanol yields mixtures of the corresponding aryl ethers and arenes, except with alcohols of very low nucleo-philicity such as trifluoroethanol, in which the aryl ether is the main product. Therefore aryl ethers are, in general, synthesized by alkylation of the respective phenol. Olah and Wu (1991) demonstrated, however, that phenylalkyl and aryl ethers can be obtained in 46-88% yield from benzenediazonium tetrafluoroborate using alkoxy- and phenoxytrimethylsilanes in solution in Freon 113 (l,l,2-trichloro-l,2,2-tri-fluoroethane) at 55-60 °C with ultrasonic irradiation. As seen from the stoichiometric... 

---