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A systematic study of adsorption properties of cis-and trons-2-n-alkyl-5-hydroxy-1,3-dioxanes

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alkyl: n-C 12 H 25 , n-C 16 H 33 , n-C 18 H 37 ) were synthesized and characterized. Their structure and purity were confirmed by means of 1 H and 13 C nuclear magnetic resonance analysis and electrospray ionization mass spectrometry. Carbon spectra were verified using a DEPT experiment. The surface and interfacial properties such as critical micelle concentration (CMC), standard free energy of micellization, ∆G CMC , surface excess concentration, Γ CMC , and surface area demand per molecule, A CMC , were determined. The tertiary nitrogen atom seems to have a surprising effect on surfactant packing at the interface.Materials. D(+)-Glucose δ-lactone, α-D-glucoheptonic γ-lactone, lactobionic acid, and alkylamines (n-dodecyl, n-hexadecyl, n-octadecyl) were purchased from Aldrich Chemical Co. (Milwaukee, WI). Other reagents and solvents were of commercial grade and were not additionally purified before use. Water used for all experiments was doubly distilled and purified by means of a Millipore (Bedford, MA) Milli-Q purification system.Synthesis of N-alkyl-N,N-bis(2-cyanoethyl)amines: typical procedure. To n-dodecylamine (92.7 g, 0.5 mol) in methanol

In the reaction of cis-and trans-2-n-alkyl-5hydroxy-1,3-dioxane mixtures with SO 3 · pyridine complex, followed by neutralization with sodium hydroxide or sodium carbonate, a new group of anionic surfactants, i.e., sodium cis-and trans- (2-n-alkyl-1,3-dioxan-5-yl)sulfates were obtained. The hydrophobic intermediates used in the sulfation reaction were obtained in high yields from four-component glycerol acetals by the process of transacetalization and selective crystallization of 1,3-dioxane derivatives. The physical data of the new compounds and some of their surface properties, such as critical micelle concentration (CMC), effectiveness of water surface tension reduction Π CMC , standard free energies of adsorption and micellization, ∆G o ads and ∆G o CMC , surface excess concentration, Γ CMC , and the surface area demand per molecule, A CMC , were determined. It was shown that the surface activity of the standard anionic surfactant sodium dodecyl sulfate should be similar to the surface activity of sodium (2-n-decyl-1,3-dioxan-5-yl)sulfate. JAOCS 74, 33-37 (1997). KEY WORDS:Adsorption, cyclic acetal-type anionic surfactants, micellization, sodium (2-n-alkyl-1,3-dioxan-5-yl)sulfate.Glycerol acetals, i.e., mixtures of cis-and trans-2-alkyl-4hydroxymethyl-1,3-dioxolanes and cis-and trans-2-alkyl-5hydroxy-1,3-dioxanes (1), were first used as hydrophobic intermediates in nonionic surfactant synthesis by Rutzen and Goette (2). However, in this mixture of cyclic acetals, 1,3dioxolane derivatives bear a primary hydroxyl group, whereas the 1,3-dioxane derivatives bear a secondary one. This is inconvenient for further reactions because of the different reactivities of the hydroxyl groups in question. We were the first to synthesize oxyethylenated 2-alkyl-4-hydroxymethyl-1,3dioxolanes, the starting materials being obtained in a reaction of glycerol α-monoacetate with aliphatic aldehydes (3,4). Later, Jaeger et al. (5) and Ono et al. (6) synthesized several glycerol-based surfactants with a 1,3-dioxolane ring in the surfactant's molecules. To obtain surface-active 1,3-dioxane derivatives, there were two possible routes: either a rather difficult isolation of 2-alkyl-5-hydroxy-1,3-dioxanes from a four-component glycerol acetal mixture, or an acetalization procedure with aliphatic aldehydes and other polyols that contain at least three hydroxyl groups in their molecules. Thus, starting with 2,2-bis(hydroxymethyl)-1,3-propanediol, 2-alkyl-5,5-bis(hydroxymethyl)-1,3-dioxanes were obtained and further reacted with oxirane or 1,3-propane sultone to yield nonionic (7) or sulfonate salt-type anionic (8) surfactants, respectively. In a reaction of 1,1,1-tris(hydroxymethyl)propane and 1,1,1-tris(hydroxymethyl)ethane with aliphatic aldehydes, 2-n-alkyl-5-hydroxymethyl-5-ethyl-1,3dioxanes and 2-n-alkyl-5-hydroxymethyl-5-methyl-1,3-dioxanes were synthesized as hydrophobic intermediates for the preparation of oxyethylenated nonionic (9) and sulfate salttype anionic (10) surfactants, respectively. The reaction of aldehydes with diethyl ...