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Dichlorodifluoromethane

Dichlorodifluoromethane. Synonyms: Freon-12, Genetron-12, Eskimon-12, CFC-12, R-12 ASHRAE Naming: American Society of Heating & Refrigeration Engineering [R or CFC or Brand]-(C-1)(H+1)F Example: Freon - 012. Structure: Fluorine Carbon Chlorine. The History of Ice.

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Dichlorodifluoromethane

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  1. Dichlorodifluoromethane Synonyms: Freon-12, Genetron-12, Eskimon-12, CFC-12, R-12 ASHRAE Naming:American Society of Heating & Refrigeration Engineering [R or CFC or Brand]-(C-1)(H+1)F Example: Freon - 012 Structure: FluorineCarbon Chlorine

  2. The History of Ice Ice has always been important for things: • In the early 1900’s, ice was imported by ship to warm areas at around $500 / Ton! • Mechanical Ice Machines started to become popular around the mid 1900’s. • A mechanical refrigeration loop removes heat from a cold area with a pump, refrigeration gas, and a little physics. • Early refrigerants were toxic, corrosive and flammable: • Ammonia – Corrosive • Sulfur Dioxide – Stinks • Methyl Chloride – Burns ALTERNATIVES PLEASE!

  3. Refrigerant Properties:

  4. Lab Synthesis of R-12: (1) CCl4 + HF –SbCl2F3 (catalyst) → CFCl3 (Freon-11) + HCl + CF2Cl2 (Freon-12) Used by Thomas Midgely of Dupont in 1928. Blew out a candle with R-12 at a 1930 ACS meeting! Catalyst: SbCl5-xFx is a fluorinating catalyst. (2) SbCl5 + excess HF ↔ HCl + SbFCl4 ↔ HCl + SbF2Cl3 ↔ HCl + SbF3Cl2 ↔ HCl + SbF4Cl ↔ HCl + SbF5 Antinomy Pentafluoride is the most effective fluorinator.

  5. EnvironmentalProblems: • R-12 has been used for years as a propellant and refrigerant • Non-toxic due very to stable C-F & C-Cl bonds • Decomposes in the upper stratosphere: • CCl2F2 + hν (λ < 220 nm) → ·Cl + ·CClF2 • Basic Ozone Depletion: • (2) O3 + hν → O + O2 • (3) O3 + Cl → ClO + O2 • (4) O + ClO → Cl + O2 • (5) Net: O + O3 → 2O2 Ozone depletion gives you sun burns or worse! Polar Ozone Depletion: (6) 2ClO + M → Cl2O2 + M (7) Cl2O2 + hν → 2Cl + O2 (8) 2(Cl + O3 → ClO + O2) (9) Net: 2O3 + hν → 3O2 CFC’s are linked to 2/3 of polar ozone loss!

  6. What’s Being Done? • Montreal Protocol phased out CFC’s in industrial countries in 1996 • Kyoto Seeks to further restrict ozone depleting chemicals • CFC’s are replaced with fluorocarbons i.e. R-134a CF3CH2F • Problems with HFC’s: • C-F bonds absorb more IR radiation than C-Cl bonds • HFC’s have zero ODP and high GWP (relative to CO2) • Example: CFC-12 has a GWP100=8500 and life=102 years • FC-116 (C2F6): ODP=0, GWP100=9500 & life=10000 years • An alternative propellant for R-12 is CO2 • Additional alternative refrigerants are hydrocarbon mixes

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