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Part I. GENERAL INTRODUCTION “Fluorine leaves nobody indifferent; it flames emotions be that affections or aversions. As a substitute, it is rarely boring, always good for a surprise, but often completely unpredictable” (Schlosser and Michel, 1996).
I.1. Fluorine Properties General Introduction Although this work focuses on the study of highly fluorinated compounds and their mixtures, a brief discussion of the properties of elemental fluorine is useful to assist in understanding the unusual properties of these compounds. The Fluorine (F) atom is characterized by a high electronegativity, relatively small size, very low polarizability, tightly bound with three non-bonding electron pairs, excellent overlap between F 2s and 2p orbitals with corresponding orbitals of other second period elements (Smart, 2001). Fluorine has an electronegativity of 4.0 on the Pauling scale, which is the highest of all the elements. This extreme electronegativity results in fluorine drawing electrons from adjacent atoms, thus creating polar bonds. For example, the electronegativity difference between fluorine and carbon is 1.5 units, which indicates that the electrons are shared unequally between the two atoms and that there is a partial negative charge on the fluorine and a partial positive charge on the carbon. The incorporation of fluorine atoms into organic materials imparts dramatic changes in physical properties as well as chemical reactivities of the molecules. Actually, depending upon the site and level of fluorination, organofluorine compounds have solvent properties ranging from extreme non-polar perfluoroalkanes to the extraordinarily polar solvent, hexafluoroisopropanol (Smart, 2001). Also, fluorination always increases the steric size of alkyl groups. The effective van der Waals radius for trifluoromethyl compared to other hydrocarbon alkyl groups clearly shows that it is a much larger group than methyl: 1.80 Å for CH3 and 2.20 for CF3 (Smart, 2001). It is important to notice that, the steric size (van der Waals radious or volume) is an absolute term, an intrinsic molecular property, but whether or not it causes a steric effect is entirely dependent on the nature of the transition state for a particular process, since it defines the degree of coloumbic interaction between the atom or group in question and other atoms. According to Clark (1999), the steric effects are more significant with perfluoroalkanes with only C-F bonds. For example, perfluoroalkanes and Teflon ® have helical chain conformation, instead of the zig-zag chain conformation characteristic of alkanes, to relieve steric impediment and repulsive interactions between adjacent fluorine atoms on alternative carbon atoms, originating a shielding of the carbon backbone by fluorine atoms. - 2 -
Page 1 and 2: Ana Maria Antunes Dias Universidade
Page 3 and 4: o júri presidente Prof. Dr. Joaqui
Page 5 and 6: palavras-chave resumo perfluoroalca
Page 7 and 8: Contents Notation List of Tables Li
Page 9 and 10: Notation Abbreviations AAD EoS LCST
Page 11 and 12: List of Tables Table I.1 Average Bo
Page 13 and 14: Table III.6 Adjusted Binary Paramet
Page 15 and 16: Figure II.9 Comparison between corr
Page 17 and 18: Figure III.8 Temperature-density di
Page 19: Figure III.25 Vapor-phase mole frac
Page 23 and 24: Table I.2. Physicochemical Properti
Page 25 and 26: General Introduction order to compa
Page 27 and 28: General Introduction the numerous a
Page 29 and 30: General Introduction carbon dioxide
Page 31 and 32: General Introduction animals. That
Page 33 and 34: General Introduction Table I.3. Lit
Page 35 and 36: References General Introduction Ban
Page 37 and 38: General Introduction Hildebrand, J.
Page 39 and 40: General Introduction Rowinsky EK. N
Page 41 and 42: II. Part EXPERIMENTAL METHODS, RESU
Page 43 and 44: Experimental Methods, Results and D
Page 49 and 50: Table II.3. (continued) T K ρexp g
Page 51 and 52: ρ / g.cm-3 1.750 1.730 1.710 1.690
Page 55 and 56: I. 3. Vapour pressure I.3.1. Biblio
Page 57 and 58: I.3.2. Apparatus and Procedure Expe
Page 59 and 60: I.3.3. Experimental Results and Dis
Page 63 and 64: Table II.8. (continued) T K Pexp kP
Page 67 and 68: ΔH vap = TΔS vap 2⎛ d ln P ⎞
Page 69 and 70: I.4. Solubility at atmospheric pres
Page 71 and 72:
Experimental Methods, Results and D
Page 73 and 74:
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x2 (T,P2) 7.0E-03 6.0E-03 5.0E-03 4
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L 2,1 0.70 0.60 0.50 0.40 0.30 285
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P / MPa 6 5 4 3 2 1 0 P / MPa 14 12
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II.6. Liquid - Liquid Equilibrium I
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0 τ β Δ1 2Δ1 [ 1+ B τ + B τ +
Page 103 and 104:
References Experimental Methods, Re
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III.1. Introduction Modeling Most c
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Modeling The pioneering work of Wer
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III.2. Soft-SAFT Model Modeling A S
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Modeling The equation of state is w
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Chain Term Modeling Originally Wert
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Modeling The model is easily extend
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( ) ( ) ∑∑∑ 3 2 2 2 2 qq 32π
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Modeling HRT is a promising theory,
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( ρ) ρ , 0 ≤ ρ ( ρ) 2 Modelin
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III.3. Application to Pure Compound
Page 131 and 132:
Modeling From the optimised paramet
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T / K 400 350 300 250 200 150 100 5
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ln Pvap 1.0E+01 1.0E+00 1.0E-01 1.0
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Modeling Table III.2. Absolute Aver
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Modeling The correlation coefficien
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Pvap (MPa) 4.00 3.50 3.00 2.50 2.00
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Modeling The mixture parameters a a
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Modeling the assumptions made by th
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Modeling between oxygen and perfluo
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xSolute 5.5E-03 5.0E-03 4.5E-03 4.0
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Modeling previous work, dealing wit
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Modeling These results confirm that
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Modeling CO2 binary mixtures using
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Modeling average deviation (AAD) be
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P / MPa 14 12 10 8 6 4 2 0 0 0.2 0.
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Modeling Figures III.16, III.17 and
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Modeling calculations from the orig
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Table III.9. References for VLE exp
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P / MPa 20 18 16 14 12 10 8 6 4 2 0
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Modeling Finally, Figure III.24 pre
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III.4.4. VLE and LLE of Alkane and
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Modeling number of perfluro-n-alkan
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y C6F14 1.0 0.8 0.6 0.4 0.2 0.0 0.0
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P / MPa 0.08 0.07 0.06 0.05 0.04 0.
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P / MPa 0.12 0.10 0.08 0.06 0.04 0.
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Modeling approach based on the meth
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Modeling Blas, F. J.; Vega, L. F.,
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DIPPR, Thermophysical Properties Da
Page 187 and 188:
Modeling Hildebrand, J. H.; Fisher,
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Modeling McCabe, C.; Jackson, SAFT-
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Modeling Poling, B.; Prauznitz, J.;
Page 193 and 194:
Modeling Wertheim, M. S., Fluids wi
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