Hydro Fluorinated Ethers as replacements for Chloro- Fluorinated Carbons Chemistry November, 2011 Richard Madden

Flourinella

Flourinella and her evil sisters Chlora and Broma Apologies to Walt Disney

Fun Facts about Fluorine Fluorine is in Group 17, Period 2 of the Periodic Table with an atomic number of 9 and an atomic mass of amu.

Fun Facts about Fluorine Fluorine is in Group 17, Period 2 of the Periodic Table with an atomic number of 9 and an atomic mass of amu. Fluorine is the most electro-negative element (3.98 on the Pauling Scale of Electro-negativity)

Fun Facts about Fluorine Fluorine is in Group 17, Period 2 of the Periodic Table with an atomic number of 9 and an atomic mass of amu. Fluorine is the most electro-negative element (3.98 on the Pauling Scale of Electro-negativity) It’s Standard State is a gas (298 K) with a boiling point of K ( ˚C)

Fun Facts about Fluorine Fluorine is in Group Periodic Table with an atomic number of 9 and an atomic mass of amu. Fluorine is the most electro-negative element (3.98 on the Pauling Scale of Electro-negativity) It’s Standard State is a gas (298 K) with a boiling point of K ( ˚C) It has a C-F bond enthalpy of 552 KJ/Mol.

Fun Facts about Fluorine Fluorine is in Group Periodic Table with an atomic number of 9 and an atomic mass of amu. Fluorine is the most electro-negative element (3.98 on the Pauling Scale of Electro-negativity) It’s Standard State is a gas (298 K) with a boiling point of K ( ˚C) It has a C-F bond enthalpy of 552 KJ/Mol. Fluorine has a van der Waal’s radius of pm. (H=120 pm)

A Brief History of CFC’s Fluorine was first described in It was used in the form of Fluorspar to remove impurities during metal smelting. Derived from the Latin word Fluo, meaning “to flow”. The electrolytic isolation of Fluorine was accomplished in 1886 by Henri Moissan in a process still used commercially today. Moissan received the Nobel Prize in Chemistry for this process in Belgian scientist Frederick Swarts pioneered the synthesis of CFC’s in the 1890’s. The process was improved by Thomas Midgley Jr. while working for DuPont in 1928.

Ozone is formed by O 2 reacting with atomic oxygen in the stratosphere (Dissociation energy of O 2 bonds supplied by UV radiation)

Problems of Existing Compounds Catalytic Ozone Destruction by ChlorofluoroCarbons Atomic Chlorine is an efficient X catalyst in the destruction of Ozone;

Comparison of the Montreal Protocol and United States Phaseout Schedules Montreal ProtocolUnited States Year to be Implement ed % Reduction in Consumption and Production, Using the Cap as a Baseline Year to be Implement ed Implementation of HCFC Phaseout through Clean Air Act Regulations %2003No production and no importing of HCFC-141b %2010 No production and no importing of HCFC-142b and HCFC-22, except for use in equipment manufactured before 1/1/2010 (so no production or importing for NEW equipment that uses these compounds) %2015 No production and no importing of any HCFCs, except for use as refrigerants in equipment manufactured before 1/1/ %2020No production and no importing of HCFC-142b and HCFC %2030No production and no importing of any HCFCs EPA Regulations, Sections of the Clean Air Act

Hydro ChlorofluoroCarbons Hydro Chloroflouro Carbons (HCFC’s) have distinct advantages over CFC’s. Hydrogen abstraction of HCFC’s leads to much shorter Atmospheric lifetimes. Thus, these compounds are far less likely to migrate to the stratosphere.

Direct Global Warming Potentials (mass basis) relative to carbon dioxide (for gases for which the lifetimes have been adequately characterised). Data from IPCC TAR 2001 GasLifetime (years)Ozone depletion potential (ODP) Global Warming Potential Time horizon 20 years100 years Carbon dioxideCO 2 11 MethaneCH * 6223 Nitrous oxideN2ON2O114* Chlorofluorocarbons CFC-11CCl 3 F CFC-12CCl 2 F CFC-13CClF Hydrochlorofluorocarbons HCFC-21CHCl 2 F HCFC-22CHClF HCFC-123CF 3 CHCl Hydrofluorocarbons HFC-23CHF 3 260< HFC-32CH 2 F HFC-41CH 3 F * The values for CH 4 and N 2 O are adjustment times including emission feedbacks on lifetimes. Ozone depletion potentials are normalized model results from the WMO Scientific Assessment of ozone depletion in 1994.

Applications and replacements for CFCs ApplicationPreviously used CFCReplacement Refrigeration & air-conditioning CFC-12 (CCl 2 F 2 ); CFC-11(CCl 3 F); CFC-13(CClF 3 ); HCFC- 22 (CHClF 2 ); CFC-113 (Cl 2 FCCClF 2 ); CFC-114 (CClF 2 CClF 2 ); CFC-115 (CF 3 CClF 2 ); HFC-23 (CHF 3 ); HFC-134a (CF 3 CFH 2 ); HFC-507 (a 1:1 azeotropic mixture of HFC 125 (CF 3 CHF2) and HFC-143a (CF 3 CH 3 )); HFC 410 (a 1:1 azeotropic mixture of HFC-32 (CF 2 H 2 ) and HFC-125 (CF 3 CF 2 H)) Propellants in medicinal aerosols CFC-114 (CClF 2 CClF 2 )HFC-134a (CF 3 CFH 2 ); HFC-227ea (CF 3 CHFCF 3 ) Blowing agents for foams CFC-11 (CCl 3 F); CFC 113 (Cl 2 FCCClF 2 ); HCFC-141b (CCl 2 FCH 3 ) HFC-245fa (CF 3 CH 2 CHF 2 ); HFC-365 mfc (CF 3 CH 2 CF 2 CH 3 ) Solvents, degreasing agents, cleaning agents CFC-11 (CCl 3 F); CFC-113 (CCl 2 FCClF 2 )None

Problem Solved??? Both CFC’s and HCFC’s are potent Green House Gases. They Absorb IR radiation between 8 and 13  m.

Nations to ramp up phase- out of ozone-killers 200 nations agree to speed elimination of HCFCs, major greenhouse gas 9/23/2007 TORONTOTORONTO — Governments of almost 200 countries have agreed to speed the elimination of a major greenhouse gas that depletes ozone, U.N. and Canadian officials said Saturday, describing a deal they said was a significant step toward fighting global warming. The agreement reached Friday night will accelerate a treaty to freeze and phase out hydrochlorofluorocarbons (HCFCs) which are used in home appliances, some refrigerators, hair sprays and air conditioners, said Nick Nuttall, spokesman for the United Nations Environment Program.

Nations to ramp up phase- out of ozone-killers 200 nations agree to speed elimination of HCFCs, major greenhouse gas 9/23/2007 TORONTOTORONTO — Governments of almost 200 countries have agreed to speed the elimination of a major greenhouse gas that depletes ozone, U.N. and Canadian officials said Saturday, describing a deal they said was a significant step toward fighting global warming. The agreement reached Friday night will accelerate a treaty to freeze and phase out hydrochlorofluorocarbons (HCFCs) which are used in home appliances, some refrigerators, hair sprays and air conditioners, said Nick Nuttall, spokesman for the United Nations Environment Program.

Hydro Fluorinated Ethers

Atmospheric Oxidation of HCFC-123

Despite Advantages, HFE’s are still relatively unknown. There is growing concern about the atmospheric conversion of HFE’s into Trifluoro Acetic Acid.

Compounds known to produce TFA (CF 3 C(O)OH) in the atmosphere. Compound Molecular weight Common name Molar CF 3 C(O)OH yield Atmospheric lifetime CF 3 CHClBr Halothane years [1] CF 3 CHClOCHF Isoflurane years [2] CF 3 CHCl HCFC years [3] CF 3 CHFCl HCFC years [3] CF 3 CH 2 F 102 HFC-134a years [4] CF 3 CHFCF HFC-227ea years [4] [1] Orkin and Khamagonov (1993); [2] Brown et al. (1989); [3] WMO (1989); [4] IPCC (1996).

Oxidation is initiated by reaction with OH radicals giving a halogenated alkyl radical which adds O2 to give the corresponding peroxy radical (RO2). Peroxy radicals react with three important trace species in the atmosphere: NO, NO2, and HO2 radicals. Reactions with HO2 and NO2 delay, but do not prevent, the conversion of peroxy (CF3CXYO2) into alkoxy (CF3CXYO) radicals. Reactions of haloperoxy radicals with NO are rapid and give the alkoxy radical with essentially 100% yield. The atmospheric fate of the alkoxy radical, CF3CXYO, is either decomposition or reaction with O2. Decomposition occurs by C-C bond fission, or by the elimination of a Br, Cl, or CF3 group. The atmospheric fate of CF3C(O)X (X=F or Cl) is dominated by incorporation into rain-cloud-sea water followed by rapid hydrolysis to trifluoroacetic acid. Photolysis is a competing loss mechanism for CF3C(O)Cl and limits its conversion into CF3C(O)OH to 60% (Cox et al., 1995). There are no competing loss processes for CF3C(O)F; it is converted entirely into CF3C(O)OH. Although CF3C(O)OH is produced in aqueous phase chemistry, is highly soluble and partitions into the water phase (Bowden et al., 1996), the evaporation of cloud droplets can transfer CF3C(O)OH to the gas phase where it can react with OH radicals. However, this reaction is slow (Carr et al., 1994; Møgelberg et al., 1994) and is only a minor (<5%, Kanakidou et al., 1995) loss of CF3C(O)OH. The main atmospheric fate of CF3C(O)OH is rain-out to the surface.

The End Thank You!