Dramatic influence of the nature of the surfactant aggregate on the rate constant for hydrolysis of phosphinate esters in aqueous nematic lyotropic liquid crystals

Article abstract of DOI:10.1021/ja00211a013

The o-iodosobenzoic acid catalyzed hydrolysis of two organophosphinate esters has been studied in the lyotropic nematic phases of myrystyltrimethylammonium bromide in 1-decanol, ammonium bromide, and water. Depending on the concentration of these ingredients, three phases are observed at room temperature consisting of rod-like (N//C), disk-like (N//L), or sphere-like (I) aggregates. There is a three order of magnitude difference in the rate constant for hydrolysis between N//L and N//C phases. The N//L phase serves as a protective environment, preventing the hydrolysis of the ester, whereas the N//C phase allows the reaction to occur rapidly. Based upon infrared evidence, the phosphinate ester is solubilized in the hydrocarbon region of N//L aggregates, but in N// C and I aggregates the solute is nearer the aqueous interface.