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The crystalline ethyl hemiketal of saxitoxin, the paralytic shellfish poison, was obtained, and its structure was deduced as 2b by X-ray crystallography. Carbon-l 3 magnetic resonance studies demonstrate that saxitoxin in solution exists primarily as a carbamate rather than a cyclol, and that in aqueous solution, saxitoxin exists as the hydrate 2a.

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respects with an authentic sample of 4-estrene-3,17-dione (4). The minor product was isolated in 5% yield and showed the following physical characteristics: mp 185-187 °C; NMR 0.93 (s, 3 H, C-18 Me), 5.

1259(37) There is the possibility that the solute strongly perturbs micellar structure.However, Beer's law is obeyed for solutions of I-nitronaphthalene over a 32-fold change in concentration in solutions of micellized 0.04 M 3a and 0.02 M 3b, suggesting that changes in total concentration of the solute did not affect its partitioning between water and the micelles, and therefore did not affect micellar structure.(38) Even if /3 is in the low range of ca. 0.6 for a hydroxide ion surfactant, saturation of the Stern layer by OH-would only increase the concentration of micellar-bound OHby ca. 66%, which would not account for the observed rate effects. It would give a micelle of zero net charge which would be unexpected with a hydrophilic counterion. (39) Values of the partial molar values of CTABr and ldodecanesulfonic acid are given in ref 40a and 40b, respectively.(40) (a) A. LoSurdo and H.