The coupled diffusion of micelles and solubilizates has been studied by measuring ternary mutual diffusion coefficients (D(ik)) for aqueous solutions of dodecylsulfobetaine (SB12) with added butanol, pentanol, or hexanol. SB12 micelles solubilize alcohols, so diffusing SB12(1) might be expected to co-transport alcohol(2). Negative values of cross-coefficient D(21) indicate, however, that the diffusion of SB12 drives substantial counterflows of alcohol. To help interpret the results, measured decreases in critical micelle concentrations with added alcohol (ROH) are used to evaluate equilibrium constants for the formation of (SB12)(m)(ROH)(n) mixed micelles. Increasing the concentration of SB12 along a diffusion path raises the concentrations of micelles and solubilized alcohol while lowering the concentration of free alcohol. The resulting flux of relatively mobile free alcohol molecules up SB12 concentration gradients is larger than the flux of solubilized alcohol down SB12 gradients, producing net countercurrent coupled fluxes of alcohol. The measured D(ik) coefficients are in close agreement (+/- 0.05 x 10(-5) cm(2) s(-1)) with predictions using self-diffusion coefficients (D(i)*) for SB12 and alcohol in solutions at thermodynamic equilibrium and the relations D(ik) = partial differential(C(i)D(i)*)/ partial differentialC(k) proposed recently for mutual diffusion in non-equilibrium solutions of associating solutes. Mutual diffusion coefficients for coupled surfactant-solubilizate diffusion are used to evaluate equilibrium constants for the formation of surfactant-solubilizate mixed micelles.

Ternary mutual diffusion coefficients (D ik ) are reported for aqueous solutions of dodecylsulfobetaine (1) + hexadecylsulfobetaine (2) mixed zwitterionic micelles. Cross-coefficient D 12 reaches values almost as large as the main D ii coefficients, indicating strongly coupled fluxes. As the surfactant concentrations are raised and the extent of micelle formation increases, values of the determinant D 11 D 22 − D 12 D 21 of the D ik matrix drop sharply. Previous studies have shown that the thermodynamic stability constraint μ11μ22 − μ12μ21 ≥ 0 on the concentration derivatives μ ik = ∂μ i /∂C k of the chemical potentials causes D 11 D 22 − D 12 D 21 to vanish at critical points and phase separation boundaries. Consequently, the cross-coefficients become similar in magnitude to the main coefficients. Prompted by the insight that might be gained by demonstrating an analogy between diffusion in micelle solutions and diffusion near phase separation, a model of mixed-micelle formation based on multiple monomer association equilibria [nA1 + mB1 = A n B m ] is used to show that μ11μ22 − μ12μ21 drops almost to zero with increasing extent of micelle formation. This result, which is generalized to other association colloids, points to thermodynamics as the underlying cause of strongly coupled fluxes, incongruent diffusion, and other remarkable features of diffusion in solutions of mixed micelles, solubilizates, and microemulsions. A molecular interpretation of diffusion in these systems, consistent with the Gibbs−Duhem and Onsager reciprocal relations, is developed by relating the D ik coefficients and the Onsager L ik transport coefficients to the concentrations and the mobilities of the free monomers and various A n B m species.

Lewis acid‐mediated geminal acylation of 2‐methoxyoxazolidines with five‐ or six‐membered acyloins followed by heterocyclization afforded 1,4‐oxazines fused to cyclopentenone or cyclohexenone rings. Overall yields ranged from 30 to 73 %. The position of the carbonyl group in the products depended on whether or not water was present during the ring‐expanding acyl migration step. The route lacking water during the acyl migration step was best conducted in one pot. The addition of water effected cleavage of a silyloxy group in the intermediate during the initial Mukaiyama aldol reaction prior to the acyl migration.

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Speed of sound and densities of solution mixtures of four aliphatic alcohols with monoethanolamine were measured over a full range of composition. The density measurements were carried out from 298 to 358 K. Results of these measurements were used to calculate adiabatic compressibilities, excess adiabatic compressibilities, excess volumes and partial molar quantities. From the analysis of the results, the nature of interaction between the aliphatic alcohols and monoethanolamine is deduced.