I Synthesis and dynamic studies of bifunctional compounds having potential intramolecular interactions II Controlled release antifouling coatings: Approaches to controlled release of gamma-decanolactone and 2-hexanoylfuran into seawater

I. Potentially reactive, bifunctional compounds 1 and 127 have been studied, and both compounds have been found to undergo rapid base-catalyzed degenerate topomerization. The topomerization processes, which in the case of 1 represents a degenerate transamidation and in the case of 127 a degenerate transesterification, have been studied in acetonitrile-d$\sb3$ and D$\sb2$O under a variety of conditions by the DNMR method. In both cases, the presence of a stable tetrahedral anion intermediate can be inferred from analysis of NMR and IR spectra. In the case of 1, the unusually high rate of topomerization can be attributed to the presence of a transannular donor-acceptor interaction and a strained urea functionality. In 127, the rate enhancement is attributed to a favorable entropic situation with respect to an intermolecular reaction of the same type. In addition to the base catalysis studies, acid-catalysis studies of other amino-ureas such as 9 and 10 were carried out in D$\sb2$O. The rate of topomerization of 10 was slow on the NMR time scale under acid catalysis. The rate of topomerization of 9 could be quantified by a 2D NMR method. II. The release characteristics of biofouling inhibitors 160 and 161 from various ablative and nonablative matrices into artificial seawater have been studied. The goal of these release experiments was to achieve 30-day controlled, sustained release of inhibitor from a matrix into artificial seawater at a level which was considered effective to inhibit fouling of marine surfaces. It was found that encapsulation of 161 in a polymeric matrix and dispersion of 161-containing capsules in a vinyl, nonablative coating provided a successful method for achieving this goal. Release rates of inhibitors 160 and 161 from various matrices are summarized and discussed