Thermodynamics and Solubility Modeling in Hydrofluoroalkane Systems

Persistent Link:
http://hdl.handle.net/10150/196099
Title:
Thermodynamics and Solubility Modeling in Hydrofluoroalkane Systems
Author:
Hoye, William L
Issue Date:
2008
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The phase-out of chlorofluorocarbons (CFCs) has resulted in an expanding new area of research in alternative ozone friendly propellants, for example hydrofluoroalkanes (HFAs). The HFA solvent system is unique in that many CFC soluble compounds behave differently in the HFA alternatives, such as HFA-134a and HFA-227. The reason for the difference in solubility is not fully recognized. This work investigates the solubility of 22 compounds in HFA-227 with the addition of ethanol as a cosolvent. The physical properties of both solute and solvent were investigated in order to determine the effects on solubility. The solubilities of 5 compounds in HFA-134a were also investigated. A thermodynamic approach was utilized in order to look at the enthalpic and entropic effects on solubility in the propellant. Due to the high vapor pressure of propellants, a liquid model was utilized, owing to its ease of use in characterizing solubility. The correlation between the liquid model 2H,3H-decafluoropentane (DFP) and the propellants HFA-134a and HFA-227 was examined.The solubilities in HFA-227 with ethanol ranged from 0.001 to 3.282 %w/w, where the solubilities always increase when ethanol was added. The experimental solubilities were compared to calculated values obtained from ideal solubility and regular solution theory models. A clear correlation with the ideal solubility (melting point) combined with an intercept term and two physical properties was noted. A regression approach was also used to predict the activity coefficient in HFA-227 with 0 - 20% ethanol. These equations were combined with the extended ideal solubility equation, creating a useful predictive equation with AAE values ranging from 0.32 to 0.36, or factor errors of 2.09 to 2.29. The equations shown in this work are useful for the prediction of solute solubility in HFA-227/ethanol mixtures.Results in the liquid model DFP with 0 - 20% ethanol show that a regression equation results in a useful predictive equation for the solubilities in both HFA-134/ethanol and HFA-227/ethanol systems, where the AAE values ranged from 0.3 to 0.56, or factor errors of 2.0 to 3.6.The solubilities of a series of chlorobenzene compounds along with a group of hydrogen donating and/or accepting compounds was examined in HFA-134a. The entropic effects appear to be the limiting factor in the solubility of these compounds. The compounds capable of hydrogen accepting and donating exhibited negative enthalpy of mixing values when placed in HFA-134a, a stark contrast to the values obtained for the chlorobenzenes. This suggests HFA-134a is able to strongly interact with solutes capable of donating or accepting hydrogen.
Type:
text; Electronic Dissertation
Keywords:
inhaler; solubility; thermodynamics; propellant
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Pharmaceutical Sciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Myrdal, Paul B
Committee Chair:
Myrdal, Paul B

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleThermodynamics and Solubility Modeling in Hydrofluoroalkane Systemsen_US
dc.creatorHoye, William Len_US
dc.contributor.authorHoye, William Len_US
dc.date.issued2008en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe phase-out of chlorofluorocarbons (CFCs) has resulted in an expanding new area of research in alternative ozone friendly propellants, for example hydrofluoroalkanes (HFAs). The HFA solvent system is unique in that many CFC soluble compounds behave differently in the HFA alternatives, such as HFA-134a and HFA-227. The reason for the difference in solubility is not fully recognized. This work investigates the solubility of 22 compounds in HFA-227 with the addition of ethanol as a cosolvent. The physical properties of both solute and solvent were investigated in order to determine the effects on solubility. The solubilities of 5 compounds in HFA-134a were also investigated. A thermodynamic approach was utilized in order to look at the enthalpic and entropic effects on solubility in the propellant. Due to the high vapor pressure of propellants, a liquid model was utilized, owing to its ease of use in characterizing solubility. The correlation between the liquid model 2H,3H-decafluoropentane (DFP) and the propellants HFA-134a and HFA-227 was examined.The solubilities in HFA-227 with ethanol ranged from 0.001 to 3.282 %w/w, where the solubilities always increase when ethanol was added. The experimental solubilities were compared to calculated values obtained from ideal solubility and regular solution theory models. A clear correlation with the ideal solubility (melting point) combined with an intercept term and two physical properties was noted. A regression approach was also used to predict the activity coefficient in HFA-227 with 0 - 20% ethanol. These equations were combined with the extended ideal solubility equation, creating a useful predictive equation with AAE values ranging from 0.32 to 0.36, or factor errors of 2.09 to 2.29. The equations shown in this work are useful for the prediction of solute solubility in HFA-227/ethanol mixtures.Results in the liquid model DFP with 0 - 20% ethanol show that a regression equation results in a useful predictive equation for the solubilities in both HFA-134/ethanol and HFA-227/ethanol systems, where the AAE values ranged from 0.3 to 0.56, or factor errors of 2.0 to 3.6.The solubilities of a series of chlorobenzene compounds along with a group of hydrogen donating and/or accepting compounds was examined in HFA-134a. The entropic effects appear to be the limiting factor in the solubility of these compounds. The compounds capable of hydrogen accepting and donating exhibited negative enthalpy of mixing values when placed in HFA-134a, a stark contrast to the values obtained for the chlorobenzenes. This suggests HFA-134a is able to strongly interact with solutes capable of donating or accepting hydrogen.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectinhaleren_US
dc.subjectsolubilityen_US
dc.subjectthermodynamicsen_US
dc.subjectpropellanten_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePharmaceutical Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMyrdal, Paul Ben_US
dc.contributor.chairMyrdal, Paul Ben_US
dc.contributor.committeememberYalkowsky, Samuelen_US
dc.contributor.committeememberMayersohn, Michaelen_US
dc.identifier.proquest2909en_US
dc.identifier.oclc659749559en_US
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