Tetrafluoroethane HFC

Tetrafluoroethane is a hydrofluorocarbon (HFC) or hydro-fluoroalkane (HFA) aerosol propellant (contains hydrogen, fluorine, and carbon) as contrasted to a CFC (chlorine, fluorine, and carbon). The lack of chlorine in the molecule and the presence of hydrogen reduces the ozone depletion activity to practically zero. Hence tetrafluoroethane can be considered as an alternative to CFCs in the formulation of metered-dose inhalers (MDIs). It has replaced CFC-12 as a refrigerant since it has essentially the same vapor pressure. Its very low Kauri-butanol value and solubility parameter indicate that it is not a good solvent for the commonly used surfactants for MDIs. Sorbitan trioleate, sorbitan sesquioleate, oleic acid, and soya lecithin show limited solubility in tetrafluoroethane and the amount of surfactant that actually dissolves may not be sufficient to keep a drug readily dispersed. 

When tetrafluoroethane (P-134a) is used for pharmaceutical aerosols and MDIs, the pharmaceutical grade must be specified. Industrial grades may not be satisfactory due to their impurity profiles. 

Tetrafluoroethane is a liquefied gas and exists as a liquid at room temperature when contained under its own vapor 

Solubility soluble in ethanol (95%), ether, and 1 in 1294 parts of water at 20°C. 

Vapor density (absolute) 4.466 g/cm at standard temperature and pressure. 

---

Hydrofluorocarbon-134a or 1,1,1,2-Tetrafluoroethane (HFC-134a) has been developed as a replacement for fully halogenated chlorofluorocarbons because, compared with chlorofluorocarbons, its residence time in the atmo... 

Bednarek, G M. Breil, A. Hoffmann, J. P. Kohlmann, V. Moers, and R. Zellner, Rate and Mechanism of the Atmospheric Degradation of 1,1,1,2-Tetrafluoroethane (HFC-134a), Ber. Bunsenges. Phys. Chem. Chem. Phys., 100, 528-539 (1996). 

The dipolarity/polarizabiUty parameter 7t, introduced by Kamlet and Taft, was measured for difluoromethane (HFC 32) and pentafluoroethane (HFC 125) and compared with those previously reported for 1,1,1,2-tetrafluoroethane (HFC 134a). This was carried out as a function of temperature and pressure, to cover the liquid and supercritical states over the range 30-130°C and 40-300 bar (Abbott and Eardley, 1999). 

Maezawa, Y., Sato, H., Watanabe, K. (1991b) Liquid densities and vapor pressures of 1,1,2,2-tetrafluoroethane (HFC 134) and 1,1-dichloro-l-fluoroethane (HCFC 141b). J. Chem. Eng. Data 36, 151-155. 

Inaba et al. [29] have introduced a different cell to work with gaseous compounds (Fig. 4). A metal-plated solid polymer electrolyte (SPE) composite electrode faces the gas to be reduced. On the other side, the SPE is in contact with 0.1 M NaOH in which a Pt wire and an Ag/AgCl reference electrode are immersed. This system permits the electroreduction of insoluble reactants in water without employing organic solvents. For example, 2-chloro-l,l,l,2-tetrafluoroethane (HCFC 124) is transformed into 1,1,1,2-tetrafluoroethane (HFC 134a). The cathodic reaction can be written as follows ... 

ECETOC (European Centre for Ecotoxicology and Toxicology of Chemicals). 1995. Joint Assessment of Commodity Chemicals No. 31. 1,1,1,2-Tetrafluoroethane. (HFC-134a) CAS No. 811-97-2. ISSN-0773-6339-31. European Centre for Ecotoxicology and Toxicology of Chemicals, Brussels, Belgium. February. 

Silber, L.S., and G.L. Kennedy. 1979b. Subacute Inhalation Toxicity of Tetrafluoroethane (HFC 134a). Rep. No. 228-79. Haskell Laboratory, Wilmington, DE. 

Hydrofluorocarbons (HFCs), including 1,1,1,2-tetrafluoroethane (HFC-134a), have been developed as alternatives to chlorofluorocarbons (CFCs), which are known to contribute to the breakdown of ozone to oxygen in the stratosphere. HFCs do not contribute to the destruction of stratospheric ozone, but some HFCs have global warming potential. They primarily serve as replacements for CFCs in refrig... 

Refrigerant tetrafluoroethane (HFC-134a) enters the coils of the evaporator of a refrigerator as a saturated vapor liquid mixture at 240 kPa. The refrigerant absorbs 100 kJ of heat from the interior of the refrigerator maintained at 273.15 K, and leaves as saturated vapor at 240 kPa. Estimate the total entropy change. 

A direct one-step route to 1,1,1,2,-tetrafluoroethane (HFC-134a CF3CH2F) can be written as shown in Eq. (6). Currently, no commercially viable process has been described for this approach involving high-conversion single-pass yields. This has to do with equilibrium limitations, as explained below. Because of this, decoupling of the overall process into... 

Supercritical carbon dioxide (SCCO2) has a dielectric constant e = 1.6 (cyclohexane e = 2.0), and even though tetrakis(decyl)ammonium tetraphenylborate has some solubility in SCCO2, the conductivity is too low for practical electrochemistry [442]. 1,1,1,2-Tetrafluoroethane (HFC 134a) has a higher polarity in the supercritically state, and well-behaved CV may be obtained with TBACIO4 a potential window of about 9 V has been obtained [443]. 

FIG. 2-26 Pressure-enthalpy diagram for Refrigerant 134a. Properties computed with the NIST REFPROP Database, Version 7.0 (Lemmon, E. W., McLinden, M. O., and Huber, M. L., 2002, NIST Standard Reference Database 23, NIST Reference Fluid Thermodynamic and Transport Properties—REFPROP, Version 7.0, Standard Reference Data Program, National Institute of Standards and Technology), based on the equation of state of Tillner-Roth, R., and Baehr, H. D., An International Standard Formulation of the Thermodynamic Properties of 1,1,1,2-Tetrafluoroethane (HFC-134a) Covering Temperatures from 170 K to 455 K at Pressures up to 70 MPa, /, Phys. Chem. Ref. Data 23(5) 657-729, 1994. 

---