Two-step droplet formation in monodisperse nanodroplet generation in quenched hydrothermal solution as revealed by spontaneous transformation of nanodroplets to swollen micelles in octane‑in‑water nanoemulsions.

Hypothesis: Monodisperse nanodroplet generation in quenched hydrothermal solution (MAGIQ) is a newly developed bottom-up process for preparing nanoemulsions. In this process, homogeneous solutions of oil in supercritical water are quenched by adding cold water containing a surfactant to induce rapid phase-separation, during which oil molecules self-assemble to form nano-sized oil droplets. The droplet size in MAGIQ is known to be influenced by the interplay of the phase-separation dynamics, coalescence kinetics of the droplets, and adsorption kinetics of the surfactant on the droplet surface; however, the primary stages of the droplet formation are still elusive.

Primary structure of gum arabic and its dynamics at oil/water interface.

Gum arabic (GA), an arabinogalactan-based gum, is a well-known powerful emulsifier. However, the poor stability of emulsion has often been pointed out. In order to clarify the origin, the structure-property relationship of GA, especially the interfacial property at oil/water interface, needs to be investigated.

Syn Selective Vinylogous Mukaiyama Aldol Reaction Using Z,E-Vinylketene N,O-Acetal with Acetals.

Stereoselective vinylogous Mukaiyama aldol reactions using the Z,E-vinylketene silyl N,O-acetal possessing a chiral auxiliary, derived from (E)-3-pentenoic acid and l-valine, have been achieved. The reaction proceeded smoothly to give a syn adduct in high stereoselectivity. Since the products possess structures including δ-alkoxy-γ-methyl-α,β-unsaturated imide, this reaction would be applicable to synthesize polyketides in a short procedure.

Remote Asymmetric Induction Using Acetate-Type Vinylketene Silyl N,O-Acetals.

Remote asymmetric induction by the vinylogous Mukaiyama aldol reaction using the acetate-type vinylketene silyl N,O-acetal possessing a chiral auxiliary has been achieved. The silyl N,O-acetal derived from crotonate and l-valine afforded the O-silylated 5R- and 5S-adducts selectively by treatment with SnCl and BF·OEt, respectively. The SnCl-mediated isomerization of silyl dienol ether was found, and the resulting major isomer showed high reactivity to give γ-adduct in high stereoselectivity.

Pronounced Dielectric and Hydration/Dehydration Behaviors of Monopolar Poly(N-alkylglycine)s in Aqueous Solution.

Poly(N-methylglycine) (NMGn) and poly(N-ethylglycine) (NEGn) obtained by polymerization reactions initiated by benzylamine have no carboxy termini, such as those in normal polyamides, but have only amino termini, which exist primarily as cations in aqueous media at a pH value of ca. 9.5, observed in aqueous solutions without any buffer reagents.

Dangling OH Vibrations of Water Molecules in Aqueous Solutions of Aprotic Polar Compounds Observed in the Near-Infrared Regime.

Near-infrared (NIR) absorption spectrum measurements over a frequency range from 4000 to 12000 cm(-1) were employed to investigate the effects of the presence of solute compounds to vibrational modes of water molecules in aqueous solutions of some aprotic hydroneutral polar compounds with large dipole moments, such as nitro compounds and nitriles. The obtained NIR spectra for the aqueous solutions were decomposed into three components: free water, solute, and water molecules affected by the presence of solutes. Newly determined NIR spectra of affected water molecules were well-described with at least four absorption modes observed at 7040, 6850, 6450, and 5640 cm(-1) for both the nitro compounds and nitriles.

Are all polar molecules hydrophilic? Hydration numbers of nitro compounds and nitriles in aqueous solution.

The hydration numbers of typical aprotic polar substances bearing dipole moments larger than 3 D, such as nitro compounds and nitriles, were precisely determined in aqueous solution using high frequency dielectric relaxation techniques up to a frequency of 50 GHz at 25 °C. The hydration number is one of the most quantitative parameters for determining the hydrophilicity or hydrophobicity of a compound. The hydration numbers of various nitriles, such as acetonitrile, propionitrile and n-butyronitrile bearing cyano groups, were determined to be ca.

Hydration behavior of poly(ethylene oxide)s in aqueous solution as studied by near-infrared spectroscopic techniques.

Near-infrared (NIR) absorption measurements over a wavenumber range from 4000 to 12000 cm(-1) were used to investigate hydration behavior of poly(ethylene oxide)s bearing molar masses of 3 × 10(3) (PEO3) and 20 × 10(3) (PEO20) in aqueous solution at a dilute regime. NIR absorption spectra for solutions were perfectly decomposed into three components: bulk water, PEOs, and hydrated water to PEOs. While amounts of each component were proportional to the concentrations of PEOs (cEO), the wavenumber dependence of each spectrum was independent of cEO and also the molar masses of PEOs.