Solid phase surfactants and micellar catalysis

Abstract

The thesis describes an investigation into the use of functionalised polymers and surfactant molecules to influence the rate, regiochemistry and stereochemistry of some carbon-carbon bond forming reactions in aqueous and organic media. To this end, a series or polymer-supported and non-polymer-supported surfactants (e.g. A and B) were synthesised. For comparative purposes these differ from each other in two ways: i) the type/length of the alkyl chain and ii) the type of head group used, i.e. large/small, homochiral/non-chiral, anionic/cationic. Compounds related to these have been reported in the literature and used to induce high enantioselectivity and rate enhancement in the addition of diethyl zinc to aldehydes.1.2,3 The compounds described in the thesis - both polymer-supported and non-polymer- supported - contain a neutral/charged moiety and can be used in aqueous or organic media. Non-polymer-supported surfactants generate micelles in water and reverse micelles in organic media. The critical micelle concentration (CMC) of each non-polymer-supported surfactant in H2O and hexane has been determined and the surfactants are then used at the CMC in reaction systems. Some Diels-Alder cycloaddition reactions are described using aqueous suspensions of the polymer-supported surfactants and aqueous solutions of the non-polymer-supported surfactants. Different yields and product selectivities have been observed compared to the use of water, or conventional organic solvents. The Michael addition and the addition of diethyl zinc to aldehydes in the presence of the polymer-supported and the non-polymer-supported surfactants are investigated. Enantioselectivity has been observed in both cases. The surfactant and the polymer- supported surfactant are both recoverable and reusable

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