Regulation of the rate of hydrolysis of phosphorus acid esters in organized systems based on amphiphilic pyrimidinophanes |
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Authors: | M A Voronin F G Valeeva L Ya Zakharova R Kh Giniyatullin V E Semenov V S Reznik |
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Institution: | 1.Arbuzov Institute of Organic and Physical Chemistry, Kazan Research Center,Russian Academy of Sciences,Kazan,Tatarstan, Russia;2.Kazan State Technological University,Kazan,Tatarstan, Russia |
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Abstract: | The aggregation and catalytic activity of supramolecular systems based on new macrocyclic dimeric surfactants (pyrimidinophanes)
was studied both in the absence and in the presence of polyethyleneimine (PEI). It was found that the critical micelle concentrations
measured by tensiometry were independent of the structure of surfactants. The morphology of aggregates was responsible for
various characters of the catalytic effects of pyrimidinophanes in the hydrolysis of phosphonic acid esters. A less hydrophobic
pyrimidinophane exhibited a typical effect of cationic surfactants to accelerate the reaction both in the absence and in the
presence of PEI. Unlike cationic micelles, a heminal-type pyrimidinophane exhibited an anomalous behavior: it had no effect
on the rates of hydrolysis of the substrates and did not inhibit the hydrolysis. Upon the addition of lanthanum ions, the
catalytic activity of dimeric surfactants increased. The overall catalytic effect due to the action of supramolecular systems
based on pyrimidinophanes, PEI, and lanthanum ions can increase the rates of hydrolysis of the substrates by three orders
of magnitude, as compared with that of alkaline hydrolysis. |
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