Accession Number : ADA193573

Title :   Colloidal Assemblies Effect on Chemical Reactions.

Descriptive Note : Periodic rept. no. 4, Aug 86-Jan 87,

Corporate Author : TURIN UNIV (ITALY)

Personal Author(s) : Pelizzetti, E

PDF Url : ADA193573

Report Date : Jan 1987

Pagination or Media Count : 5

Abstract : Pursued has been the study on the role of colloidal assemblies in the control of the mechanism and rates of chemical reactions. The properties and applications of functionalized surfactants (in particular with the polar head having complexing capability have been reviewed in order to select proper assemblies for enrichment and catalytic purposes. The phase separation of non-ionic surfactant solutions above the cloud point can be practically exploited for liquid-liquid extraction of hydrophobic metal-chelate complexes, which can be concentrated in the low volume micellar phase. A model reaction system consisting of a series of suitable amphiphilic ligands with a tuned alkyl chain (4-alkylamido-2-hydroxybenzoic acids: PAS-Cn, where Cn = R-CO-) and a reactive metal ion (iron (III)) has been investigated in the presence of non-ionic Brij 35 micelles. The formation of 1:1 complexes in acidic solution has been assessed and the corresponding apparent formation constants have been determined using the usual spectrophotometric techniques. The effect of the micellar system on the ligand acid-base equilibrium has been also investigated and, from the variation of the pKa values with surfactant concentration and from micellar HPLC measurements, the binding constants of the ligands to the aggregates have been evaluated.

Descriptors :   *CHEMICAL REACTIONS, *COLLOIDS, ACID BASE EQUILIBRIUM, ACIDS, CHELATE COMPOUNDS, CLOUDS, CONCENTRATION(COMPOSITION), CONSTANTS, CONTROL SYSTEMS, EQUILIBRIUM(GENERAL), HYDROPHOBIC PROPERTIES, IONS, IRON, LIGANDS, LOW LEVEL, METALS, MODELS, PHASE, POLAR REGIONS, RATES, REACTIVITIES, RESPONSE, SEPARATION, SOLUTIONS(GENERAL), SPECTROPHOTOMETRY, SURFACE ACTIVE SUBSTANCES, VOLUME

Subject Categories : Organic Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE