Preparation of finely dispersed O/W emulsion from fatty acid solubilized in subcritical water

A novel method for preparing a finely dispersed oil-in-water emulsion is proposed. Octanoic acid dissolved in water at a high temperature of 220 or 230 degrees C at 15 MPa was combined with an aqueous solution of a surfactant and then the mixture was cooled. When a nonionic surfactant, decaglycerol monolaurate (ML-750) or polyoxyethylene sorbitan monolaurate (Tween 20), was used, fine emulsions with a median oil droplet diameter of 100 nm or less were successfully prepared at ML-750 and Tween 20 concentrations of 0.083% (w/v) and 0.042%, respectively, or higher. The diameters were much smaller than those of oil droplets prepared by the conventional homogenization method using a rotor/stator homogenizer. However, an anionic surfactant, sodium dodecyl sulfate, was not adequate for the preparation of such fine emulsions by the proposed method. Although the interfacial tensions between octanoic acid and the surfactant solutions were measured at different temperatures, they were not an indication for selecting a surfactant for the successful preparation of the fine emulsion by the proposed method.     

Zur Umwandlung von Mackinawit (FeS) in Greigit (Fe3S4) durch Elektronenstrahlen

The continuous variations of reflexion intensities and lattice spacings are observed for the transformation from mackinawite. FeS (tetragonal), to greigite, Fe₃S₄ (cubic). by electron beam heating. At the beginning of the transformation, the (222) reflexion of greigite appears. At the end, the (400) and (220) reflexions of greigite are stronger than those so far reported, and the (311), (422) and (331) reflexions are weaker. The observations suggest, that the (101) plane of mackinawite changes to the (222) plane of greigite. The transformation proceeds by bulk diffusion of sulfur, which initially existed in an amorphous state on the surface of mackinawite.     

Stereocontrolled syntheses of kainoid amino acids from 7-azabicyclo[2.2.1]heptadienes using tandem radical addition-homoallylic radical rearrangement

[reaction; see text] N-Boc syn-7-(2-hydroxyethyl)-4-(alkyl or aryl)sulfonyl-2-azabicyclo[2.2.1]hept-5-enes serve as precursors in syntheses of the neuroexcitants 3-(carboxymethyl)pyrrolidine-2,4-dicarboxylic acid 43, alpha-kainic acid 12, alpha-isokainic acid 14, and alpha-dihydroallokainic acid 77. The key step in these syntheses is the intermolecular radical addition of 2-iodoethanol to a N-Boc 2-(alkyl or aryl)sulfonyl-7-azabicyclo[2.2.1]heptadiene 7 to induce nitrogen-directed homoallylic radical rearrangement. Oxidative cleavage of the resulting 2-azabicyclo[2.2.1]hept-5-enes provide straightforward access to polysubstituted pyrrolidines and, in particular, an efficient entry to the kainoid amino acids.     

Heat of hydrogenation of 1,5-dehydroquadricyclane. A computational and experimental study of a highly pyramidalized alkene

The radical anion of the highly pyramidalized alkene 1,5-dehydroquadricyclane (1) was generated in the gas phase from the Squires reaction of 1,5-bis(trimethylsilyl)quadricyclane with F-/F2. The electron binding energy and proton affinity of 1*- were determined by bracketing experiments to be 0.6 +/- 0.1 eV and 386 +/- 5 kcal/mol, respectively. These values are in good agreement with values predicted by density functional theory (B3LYP/6-31+G*) and ab initio (CASPT2/6-31+G*) calculations. The experimental heat of hydrogenation of 1, obtained from a thermochemical cycle, was found to be 91 +/- 9 kcal/mol. This value of deltaH(H2) leads to values of 67 +/- 9 kcal/mol for the olefin strain energy (OSE) of 1, 172 +/- 9 kcal/mol for its heat of formation, and 23 +/- 9 kcal/mol for its pi bond dissociation enthalpy. Since the retro-Diels-Alder reaction of neutral 1 is computed to be highly exothermic, the finding that 1*- apparently does not undergo a retro-Diels-Alder reaction is of particular interest. The B3LYP/6-31+G* optimized geometry of 1 suggests that the bonding in this alkene is partially delocalized, presumably because the highly pyramidalized double bond in 1 interacts with the distal cyclopropane bonds in a manner that eventually leads to a retro-Diels-Alder reaction. The good agreement of the B3LYP and (2/2)CASPT2 values for the heat of hydrogenation and OSE of 1 with the experimentally derived values provides indirect evidence for the correctness of the B3LYP prediction that the equilibrium geometry of 1 lies part way along the reaction coordinate to the transition structure for the retro-Diels-Alder reaction.     

Tunable metallization by assembly of metal nanoparticles in polymer thin films by photo- or electron beam lithography

The technique of patterning of surfaces with metal-rich structures on micro- or nanoscales was developed by assembling metal nanoparticles into a thin film of polymer in a controllable way. Palladium (Pd) nanoparticles were incorporated into a thin film of poly(methyl methacrylate) (PMMA) using palladium (II) bis(acetylacetonato), Pd(acac)(2), as a precursor vaporized in a nitrogen atmosphere. Depending upon its dose, the irradiation of a PMMA film by UV light or an electron beam (EB) enhances its reducing capability against Pd(acac)(2). This dependency on dose can be used to control the formation and assembly of Pd nanoparticles. Using this technique, binary patterns consisting of metal-rich and metal-poor regions in the polymer film can be created simply by irradiating the surface of the polymer through a binary photomask. Besides the creation of binary patterns, it is also possible to create grayscale patterns where the density of Pd nanoparticles can be tuned to provide shades of gray by the use of light with continuously modulated intensity. Because the electron beam also enhances the reducing power of PMMA against Pd(acac)(2), it is thus possible to obtain highly metallized films with nanoscale pattern features. The PMMA film can be selectively removed by oxygen plasma treatment or by pyrolysis. Thus, highly metallized surfaces with binary or grayscale patterns can be obtained by selective removal of the PMMA films. The metallized regions possess relatively high resistivity against CF(4) plasma compared to the bare silicon surface; therefore, the metallized surface patterns can be transferred onto the underlying silicon substrate by CF(4) plasma treatment. Because of the nanosize effect of metal nanoparticles, the thermal treatment at 900 degrees C, which is significantly lower than the melting temperature of the bulk Pd, yields continuous metallic features by binding the assembled nanoparticles.     

Properties of low temperature swelling hydrogels prepared with partially saponified PVA and drug release using the hydrogels

The hydrogels prepared by the crosslinking of partially saponified poly(vinyl alcohol) (PVA) which has low critical solution temperature (LCST) in water showed characteristics of swelling at low temperature and shrinkage at high temperature. The hydrogels showed repeatable swelling–shrinking behavior. The hydrogels containing release substances such as cyanocobalamin, p‐acetamidophenol, insulin and ovalbumin were prepared by dipping these aqueous solutions and the release substances were studied. Insulin and ovalbumin were not absorbed by the hydrogels when the use of partially PVA with the degrees of polymerization (DPs) of 540 were prepared, but absorbed by the hydrogels with DPs of 1860. The size of the polymer network prepared with a higher DP was suitable for the absorption of insulin and ovalbumin. In accordance with release substances, the release patterns were different. In this way, the polymer network sizes and their swelling behaviors of partially saponified PVAs were estimated. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis of thieno[2,3‐b][1,5]benzoxazepine derivatives

A new series of 4‐(4‐methylpiperazin‐1‐yl)thieno[2,3‐b][1,5]benzoxazepines 1a‐k has been synthesized from 4‐bromo‐2‐methylthiophene 6 or ethyl 2‐amino‐4,5‐dimethyl‐3‐thiophencarboxylate 10 . Preparation of the key intermediate thieno[2,3‐b][1,5]benzoxazepine‐4(5H)‐ones 4a‐i, 4k were carried out by treatment of 2‐bromo‐N‐(2‐hydroxyphenyl)‐3‐thiophencarboxamides 5a‐i, 5k with potassium carbonate in DMSO. Compounds 1 are thienoanalogues of loxapine, a potent antipsychotic drug. Of these compounds, the neu‐roleptic activity of 2‐methyl‐4‐(4‐methylpiperazin‐l‐yl)thieno[2,3‐b][1,5]benzoxazepine 1a (R¹, R³=H, R²=CH₃) demonstrated potent antipsychotic activity.     

Direct catalytic asymmetric aldol-Tishchenko reaction

A direct catalytic asymmetric aldol reaction of propionate equivalent was achieved via the aldol-Tishchenko reaction. Coupling an irreversible Tishchenko reaction to a reversible aldol reaction overcame the retro-aldol reaction problem and thereby afforded the products in high enantio and diastereoselectivity using 10 mol % of the asymmetric catalyst. A variety of ketones and aldehydes, including propyl and butyl ketones, were coupled efficiently, yielding the corresponding aldol-Tishchenko products in up to 96% yield and 95% ee. Diastereoselectivity was generally below the detection limit of 1H NMR (>98:2). Preliminary studies performed to clarify the mechanism revealed that the aldol products were racemic with no diastereoselectivity. On the other hand, the Tishchenko products were obtained in a highly enantiocontrolled manner.     

Catalytic action of triarylstibanes: oxidation of benzoins into benzyls using triarylstibanes under an aerobic condition

Benzoins are simply oxidized to benzils in excellent yields with a catalytic amount of triarylstibanes under an aerobic condition. This catalytic oxidation is heteroatom-specific in the antimony compound and no reaction take place with other group 15 reagents such as triphenylphosphane, -arsane and -bismuthane. The reaction should involve an oxidation-reduction cycle between stibane Sb(III) and stiborane Sb(V) under air.     

Determination of trace iron in indium phosphide wafer by on-line matrix separation and inductively coupled plasma mass spectrometry

A method for the determination of iron in indium phosphide (InP) wafer is proposed. In the present experiment, an on-line matrix separation system using an ion exchange column was combined with inductively coupled plasma mass spectrometry (ICP-MS) for the determination of ng g⁻¹ level of iron. In the on-line matrix separation, indium and iron in the sample solution was passed through a strongly-basic anion exchange resin column with the 9 M HCl carrier solution, where indium was eluted from the column and iron was adsorbed on it. Then, iron was eluted with the carrier solution of 0.3 M HCl containing 1 ng ml⁻¹ cobalt, and it was directly introduced into the ICP-MS nebulizer. In ICP-MS measurement, cobalt in the carrier solution was used as an internal standard to correct the change in sensitivity due to matrix effect, and the peak area integration was performed to quantify iron and cobalt in the integration time range of 20-60 s from the start of the cobalt solution flow. The detection limit (3σ) for iron was 3 ng g⁻¹, and the recoveries for iron in the 0.8, 2.4, and 8.0% indium solutions were almost 100%. The method was applied to the determination of iron in commercially available iron-doped InP wafers. The obtained results for InP wafer samples with the high iron concentration were in good agreement with those obtained by graphite furnace atomic absorption spectrometry (GFAAS).