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Thermodynamics of metal ion cryptates and cryptand 222 in dipolar aprotic solvents.

Ghousseini, Lily. (1985) Thermodynamics of metal ion cryptates and cryptand 222 in dipolar aprotic solvents. Doctoral thesis, University of Surrey (United Kingdom)..

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Abstract

Thermodynamic parameters of transfer of single-ions from water to nitromethane are obtained using the Ph4AsPh4B convention suggested by Parker. Enthalpies of complexing of alkali-metal and silver cations with cryptand 222 in N,N-dimethylformamide, dimethylsulphoxide, propylene carbonate, acetonitrile and nitromethane were determined calorimetrically. The stability constants of alkali-metal and silver cryptates in nitromethane were determined by potentiometric titration. This is the first set of data ever reported for the thermodynamic parameters of complexing of metal-ions with cryptand 222 in nitromethane. Free energies and enthalpies are combined to give entropies of complexing of metal-ion cryptates in the dipolar aprotic solvents. Some enthalpy of complexing data in methanol are reviewed. A correlation is found between the enthalpy of transfer of a given cation and the difference in enthalpy of complexing of metal cation with cryptand 222 among two dipolar aprotic solvents. This correlation could provide a means of evaluating single-ion enthalpies of transfer among dipolar aprotic solvents from enthalpy of complexing data. Enthalpies and free energies of complexation of metal-ion cryptates in N,N-dimethylformamide, dimethylsulphoxide, propylene carbonate, acetonitrile and nitromethane are used with relevant data to obtain the thermodynamic parameters for transfer of metal-ion cryptates from water to these solvents, and from propylene carbonate to the other dipolar aprotic GO solvents. The results obtained show variation in DeltaG°t, DeltaH°t and Deltas°t values for the metal-ion cryptates are predominantly found in transfers from water, with unappreciable variations in these parameters for transfer among dipolar aprotic solvents. The latter conclusion is based on a large number of experimental calorimetric data and suggests that cryptate conventions seem to be valid among dipolar aprotic solvents. The use of cryptand 222 for the extraction of alkali-metal salts from water into nitromethane is discussed. The thermodynamic parameters for extraction process in water-pure nitromethane system are obtained.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
NameEmailORCID
Ghousseini, Lily.
Date : 1985
Contributors :
ContributionNameEmailORCID
http://www.loc.gov/loc.terms/relators/THS
Depositing User : EPrints Services
Date Deposited : 09 Nov 2017 12:18
Last Modified : 20 Jun 2018 11:44
URI: http://epubs.surrey.ac.uk/id/eprint/844423

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