A simple synthesis of dialkylketones from alkenes via hydroboration-carbenoidation

Hydroboration of alkenes with sodium acetoxyborohydride(NaBH₃OAc) followed by carbenoidation using NaOCH₃/CHCl₃ system and oxidation with H₂O₂/NaOH give dialkylketones.     

CO2 responsive wormlike micelles based on sodium oleate,potassium chloride and N,N-dimethylethanolamine

The anionic surfactant sodium oleate (NaOA) can self-assemble in aqueous solution in the presence of counter-ion inorganic salts to form wormlike micelles (WLMs), which exhibited viscoelastic behavior. In this paper, KCl was used to induce the formation of wormlike micelles with sodium oleate. In this process, we found that the addition of N, N-dimethylethanolamine (DMEA) can destroy the structure of WLMs leading significant decrease of viscosity. However, after introducing CO₂ into the ternary solution (KCl-NaOA-DMEA), the WLMs can be regenerated due to the electrostatic interaction between the protonated DMEA and the anionic surfactants. The addition of sodium hydroxide (NaOH) causes the electrostatic interaction between OA^- and DMEAH⁺ be destroyed, which results in the wormlike micelles becoming spherical micelles of lower viscosity. The transition of WLMs with high viscosity and low viscosity spherical micelles can be repeated several times by using CO₂ and NaOH.     

Changes in the Inter- and Intra- Fibrillar Structure of Lyocell (TENCEL®) Fibers after KOH Treatment

Lyocell fibers were treated with KOH up to 8 M which was demonstrated to distribute homogeneously at the outer zones of fiber cross section compared to NaOH which accesses more deeply but less homogenously. Both NaOH and KOH solutions can be used to lower significantly the fibrillation of lyocell fibers. However, due to intrafibrillar swelling together with deep penetration ability of alkali seen for NaOH treatments results in great fiber tensile strength loss which is not observed for KOH treatments due to its inability to penetrate the fiber completely. The porous structure of fibers was studied by inverse size exclusion chromatography (ISEC) to identify mean pore diameter, total pore area and accessible pore volume (APV). Mean pore diameter of fibers decreased after KOH treatments which did not change after NaOH treatments. Wide angle X-ray diffraction analyses (WAXD) were applied to identify the crystallinity index and crystallite size. In general, fiber properties such as water retention value, carboxyl content using methylene blue sorption method, depth of color measured after dyeing with C.I. Direct Red 81 and weight loss were distinctly different in the ranges up to 2 M, 2-5 M and 5 to 8 M KOH. KOH treatment suggests new possibilities for the pretreatment of lyocell fibers to lower fibrillation while slightly lowering elongation at break without a distinct loss in tensile strength and with less decrease in carboxyl content and weight loss without changing dyeing properties of fibers compared to NaOH treatment.     

Modification of Tencel with Treatment of Ferric Sodium Tartrate Complex Solution I. Effect of Treatment Condition

Partial dissolution of cellulose by ferric sodium tartrate complex (FeTNa) solution was examined as refining treatment of the organic-solvent spun cellulose fiber (Tencel). The treatment conditions were discussed in terms of solvent strength, temperature, duration of the treatment, and free NaOH concentration by measuring the weight loss, crystallinity, and tenacity of the resultant yarns. For improving fibrillation resistance, the optimized solution of the FeTNa complex was composed of 1–1.5M FeCl₃ with 20% excess sodium tartrate and 1 N free NaOH, and the duration of the treatment was 60 min at 20°C. The loss in weight and tenacity could be maintained as low as 5% and 30–40%, respectively, by the optimized conditions. The resulting yarn showed significantly improved fibrillation resistance.     

Reaction of Amino-Terminated PAMAM Dendrimers with Carbon Dioxide in Aqueous and Methanol Solutions

Polyamines have been used as active materials to capture carbon dioxide gas based on its well-known reaction with amines to form carbamates. This work investigates the reactions between three amino-terminated poly(amidoamine) (PAMAM) dendrimers (G1, G3 and G5) and CO₂(g) in aqueous (D₂O) and methanolic (CD₃OD) solutions. The reactions were monitored using ¹H NMR spectroscopy, and yielded dendrimers with a combination of terminal carbamate and terminal ammonium groups. In aqueous media the reaction was complicated by the generation of soluble carbonate and bicarbonate ions. The reaction was cleaner in CD₃OD, where the larger G5 dendrimer solution formed a gel upon exposure to CO₂(g). All reactions were reversible, and the trapped CO₂ could be released by treatment with N₂(g) and mild heating. These results highlight the importance of the polyamine dendrimer size in terms of driving changes to the solution’s physical properties (viscosity, gel formation) generated by exposure to CO₂(g).     

Reaction of poly(vinyl alcohol) with pentavalent vanadium ion

The reaction of poly(vinyl alcohol) (PVAL) with V(V), i.e., pentavalent vanadium ion, was studied in aqueous H₂SO₄ medium. The viscosity change of reaction mixture with time showed a peculiar feature owing to formation of labile complex between V(V) and PVAL and the subsequent decomposition of the complex. On the other hand, the change of viscosity disappeared when NaOH was added during the reaction to neutralize H₂SO₄ in the reaction mixture. Under a suitable condition, the reaction mixture set to a gel as a result of complex formation. It appeared that reactive sites in PVAL responsive to complexing with V(V) were 1,2-glycol unit and 1,2-ketoalcohol unit resulting from the oxidation of 1,2-glycol by V(V). The rate of oxidation was increased with increasing H₂SO₄ concentration. The main-chain scission of PVAL took place to an insignificant extent, unless the reaction condition was severe. Based on the results obtained a reaction mechanism has been proposed.     

CRITICAL CONCENTRATIONS OF α(1→3)-D-GLUCAN FROM LENTINUS EDODES IN NaOH AQUEOUS SOLUTION

Critical concentrations of α-(1→3)-D-glucan L-FV-Ⅱ from Lentinus edodes were studied by viscometry andfluorescence probe techniques. The dependence of the reduced viscosity on concentration of the glucan in 0.5 mol/L NaOHaqueous solutions with or without urea showed two turning points corresponding to the dynamic contact concentration c_s andthe overlap concentration c~* of the polymer. The values of c_s and c~* were found to be 1×10~(-3) g cm~(-3) and 1.1×10~(-2) g cm~(-3),respectively, for L-FV-Ⅱ in 0.5 mol/L NaOH aqueous solutions. The two critical concentrations of L-FV-Ⅱ in 0.5 mol/LNaOH aqueous solutions were also found to be 1.2×10~(-3) g cm~(-3) fbr c_s and 9.2×10~(-3) g cm~(-3) for c~* from the concentrationdependence of phenanthrene fluorescence intensities. The overlap concentration c~* of L-FV-Ⅱ in 0.5 mol/L NaOH aqueoussolutions was lower than that of polystyrene with same molecular weight in benzene, owing to the fact that polysaccharidetends to undergo aggregation caused by intermolecular hydrogen bonding. A normal viscosity behavior of L-FV-Ⅱ in 0.5 mol/L urea/0.5 mol/L NaOH aqueous solutions can still be observed in an extremely low concentration range at 25℃.     

Poly[3,3-bis(hydroxymethyl) oxetane]—an analog of cellulose: Synthesis,characterization, and properties

Poly[3,3-bis(hydroxymethyl)oxetane], PBHMO, was prepared in high molecular weight (η_inh up to 5.2) by polymerizing the trimethylsilylether of 3,3-bis(hydroxymethyl)oxetane with the i-Bu₃Al–0.7 H₂O cationic catalyst at low temperature, followed by hydrolysis. PBHMO is crystalline, very high melting (314°C) and highly insoluble, much like its analog, cellulose. It is soluble in 75% H₂SO₄ at 30°C, being 65% converted to the acid sulfate ester; these conditions are useful for viscosity measurement, since the degradation rate is low and at least an order of magnitude less than for cellulose in this solvent. PBHMO can be prepared as oriented films and fibers using the lower melting diacetate (184°C) which can be melt or solution (CHCl₃) fabricated and then the oriented forms saponified to oriented PBHMO. BHMO can be directly polymerized to low molecular weight, perhaps somewhat branched, PBHMO (η_inh 0.1) with trifluoromethanesulfonic acid catalyst at room temperature. Poly(3-methyl-3-hydroxymethyloxetane), (PMHMO), prepared in high molecular weight (η_inh up to 3.8) by the same method used for PBHMO, is more soluble and lower melting (165°C) than PBHMO, appears to be atactic and can be compression molded at 195°C to a tough, clear film which is readily oriented. Copolymers of BHMO with MHMO are crystalline over the entire composition range with a linear variation of T_m with composition, a new example of isomorphism in the polymer area.     

Substituted Pyrrolo[3,4-<Emphasis Type="Italic">a</Emphasis>]carbazoles from Reactions between 3-(1-Methoxy-vinyl)indoles and Maleimides

Summary. 5-Methylenolether derivatives of pyrrolo[3,4-a]carbazoles were obtained from cycloadditions between 3-(1-methoxyvinyl)-1-tosylindole and N-substituted maleimides. They were transformed into the hydroxy derivatives by treatment with H₂SO₄, selectively reduced to the ether by H₂/Pd–C, and in the imide moiety by L-Selectride^?. From the analogous BOC protected indole derivative the parent α,β-unsaturated ketones were obtained, which were transformed into hydroxyimino compounds, and which could be deprotected by heating to the melting point. Deprotection of the tosyl derivatives was not successful. The imide part of the molecule was hydrolyzed using methanolic NaOH. The stereochemistry of all products was elucidated mainly by spectroscopic methods, and compared with results of calculations.     

Substituted Pyrrolo[3,4-a]carbazoles from Reactions between 3-(1-Methoxy-vinyl)indoles and Maleimides

5-Methylenolether derivatives of pyrrolo[3,4-a]carbazoles were obtained from cycloadditions between 3-(1-methoxyvinyl)-1-tosylindole and N-substituted maleimides. They were transformed into the hydroxy derivatives by treatment with H₂SO₄, selectively reduced to the ether by H₂/Pd–C, and in the imide moiety by L-Selectride^?. From the analogous BOC protected indole derivative the parent α,β-unsaturated ketones were obtained, which were transformed into hydroxyimino compounds, and which could be deprotected by heating to the melting point. Deprotection of the tosyl derivatives was not successful. The imide part of the molecule was hydrolyzed using methanolic NaOH. The stereochemistry of all products was elucidated mainly by spectroscopic methods, and compared with results of calculations.     

Sucrose ester micellar-mediated synthesis of Ag nanoparticles and the antibacterial properties

Ag nanoparticles with diameter in the range of 10–25 nm had been synthesized using a simple sucrose ester micellar-mediated method. Ag nanoparticles were formed by adding AgNO₃ solution into the sucrose ester micellar solution containing sodium hydroxide at atmospheric condition after 24 h of aging time. Trace amount of dimethyl formamide (DMF) in the sucrose ester solution served as a reducing agent while NaOH acted as a catalyst. The produced Ag nanoparticles were highly stable in the sucrose ester micellar system as there was no precipitation after 6 months of storage. The as-synthesized Ag nanoparticles were characterized using transmission electron microscope (TEM), X-ray diffractometer (XRD), dynamic light scattering (DLS) and UV–vis spectroscopy (UV–vis). Formation mechanism of Ag nanoparticles in the micellar-mediated synthesis is postulated. The antibacterial properties of the Ag nanoparticles were tested against Methicillin-resistant Staphylococcus aureus (MRSA) (Gram-positive) and Aeromonas hydrophila (Gram-negative) bacteria. This work provides a simple and “green” method for the synthesis of highly stable Ag nanoparticles in aqueous solution with promising antibacterial property.     

Base cleavage of epichlorohydrin polymers

Epichlorohydrin polymers cleave much more readily with organolithium compounds than do other poly(alkylene oxides). In dilute toluene solution (1–2%) at ?78°C, the cleavage of polyepichlorohydrin occurs as rapidly as BuLi is added. The end-groups formed are about equimolar amounts of hydroxyl and carbonyl with small amounts of acetylene ends. This same cleavage reaction but without acetylene ends can be obtained with NaOH or NaOCH₃ in dimethyl sulfoxide at 65°C. The carbonyl groups can be reduced with LiAlH₄ in tetrahydrofuran to give hydroxyl-ended polymers. A mechanism is presented for this unusual cleavage reaction.     

Condensation polymers containing silicon and germanium in the main chain

Poly(carbonates), poly(thiocarbonates) and poly(esteres) containing silicon and/or germanium in the main chain were obtained under phase transfer conditions. Polymers were synthesized in a biphasic system NaOH/CH₂Cl₂ at 20°C using several phase transfer catalysts, and characterized by IR and ¹H and ¹³C NMR. The results were evaluated by the yields and the inherent viscosity values. The process was effective observing an increase of both parameters in comparison with the essays without catalyst. The increases depended of the nature of the polymer and the catalyst. In poly(ester) synthesis there was an increase of these parameters when the NaOH concentration was increased due to a salting out effect of the diphenolate from the aqueous phase to the organic one. Also poly(amides) containing silicon or germanium were synthesized by solution polymerization.     

Ion-exchange rate limitation on a polymer-supported phase transfer catalytic reaction

The ion-exchange rate limitation on the kinetics of the series substitution reactions between hexachlorocyclotriphosphazene (NPCl₂)₃ and 2,2,2-trifluoroethanol (HOCH₂CF₃) by polystyrene-bound tri-n-butylammonium ion in an organic solvent/alkaline solution was studied. It was found that the diffusional limitation involves both ion diffusion and organic reactant diffusion within the catalyst pellet. The displacement reaction rate of (NPCl₂)₃ in the organic phase was limited by the particle diffusion and the intrinsic reactivity together. The film diffusion in the bulk solution limited the rate of ion exchange. The mass transport of the ion-exchange step in the aqueous phase was not improved by increasing the concentration of NaOCH₂CF₃. Drastic kinetic rate improvement was achieved with proper adjustment of the volume of the aqueous solution which was a low concentration of salt in the aqueous phase.     

Sol‐Gel Related Solvothermal Procedure to Prepare Iron Oxide Fibers

A sol‐gel‐related solvothermal process is developed to prepare iron oxide fibers. Continuous iron oxide gel fiber was drawn from spinnable sol using ferric alkoxide as the precursor, and hollow hematite fiber was obtained after the gel fiber was treated by hydroncarbon thermal reaction. The as‐prepared hollow fiber was several millimeters in length, 4～15 µm in outer diameter, and ～3 µm in wall thickness. Substituting the hydrocarbon with triethylamide, Fe₃O₄ solid fiber composed of nanorods can be obtained. Incubated at 200°C in air for only 1 hour, Fe₃O₄ was oxidated to γ‐Fe₂O₃ fiber. Possible mechanisms involved in formation of these nanostructured iron oxide fibers also are discussed.     

Chemical processes on active carbon surface: A new example of nitrogen fixation

The behavior of activated carbon fibers (ACF) and activated carbon (AC) in water and aqueous solutions of H₂O₂, NaOH, NaCN and KI₃ in the presence of atmospheric air is studied by physicochemical methods: X-ray photoelectron spectroscopy (XPS), ESR, and attenuated total reflectance IR (ATR-IR) and Fourier Transform IR (FT-IR) spectroscopy. The superoxide radical anion O ₂ ^?· is shown to exist on the ACF surface in aqueous solutions, whose formation is explained by reaction of molecular oxygen with radical active centers of surface defects. It is found that in aqueous solutions of inorganic compounds, both possessing (H₂O₂, KI₃) and not possessing (NaOH, NaCN) pronounced oxidative properties, the ACF surface is oxidized more rapidly than on aging in air. Evidence for fixation of atmospheric nitrogen on contact of ACF and AC with H₂O or aqueous solutions of NaOH, NaCN, and KI₃ is obtained. Possible conjugate redox reactions resulting in fixation of N₂ molecules and oxidation of the surface of carbon materials are discussed.     

Polymerization and polymers of silicic acid

Linear relationships among molecular weight, polymerization time, and gelation for the condensation of any monomer, including those of unknown size and functionality, are developed and applied to data on soluble silicic acids generated from tetraethyl silicate and from sodium silicate. The results suggest the formation of monomers containing ca. 12–15 ? OSi units with functionality of ca. 2.05 that condense with a rate constant of ca. 10^?4 liter/mole sec and an activation energy of 40–70 kJ/mole. One model compatible with these characteristics and the stoichiometry involved is a ladder polymer ca. 3 ? SiO units wide. Polymer isolation was achieved by replacing residual ? OH with (CH₃)₃Sio? , as well as by freezing of of aqueous solutions, which yielded fibers under special conditions. Solutions of the uncapped and capped polymers and melts of the latter had low viscosity even for fractions with M?_n ～100,000. This implies a coiled or globular nature for the polymers, which is supported by their limited propensity for film and fiber formation. Attemps to improve this situation by copolymerization, the use of other capping agents, and by the polymerization of precapped monomers were unsuccessful.     

A morphological study of mullite long fiber prepared using polyvinyl butyral as spinning aids

Morphologies of aluminosilicate gel fiber and mullite long fiber prepared from spinning sol of Al(NO₃)₃·9H₂O, tetraethylorthosilicate and ethanol using polyvinyl butyral as a spinning aids have been studied experimentally. The weight loss of fibers as function of drying time and calcination temperature was summarized and the fiber morphologies at different temperature were also discussed. The results indicated that fiber sample lost the main weight at the first several minutes at 40°C. A main axial crack was observed due to the heat stress if gel fiber was not pre-dried before calcination. Accompanied by weight loss during heat treatment, “black” fibers were shown at the temperature range of 300–500°C and some attachment was observed among fiber surface attributed by the decomposition of organic materials. The actual elimination temperature of organic materials was different from our former heat analysis measurement result, and it could be explained by the pre-treating procedure and high heating rate of heat analysis. The morphological study of mullite fiber calcined at different temperature could help to understand and obtain the mullite fiber with smooth surface.     

Fabrication of PbTiO3 Ceramic Fibers by Sol-Gel Processing

The sol-gel processing was applied to the fabrication of PbTiO₃ fibers. Pb(CH₃COO)₂·3H₂O and Ti(OC₃H ₇ ⁱ )₄ were refluxed with stirring in 2-methoxyethanol to form Pb-methoxyethoxide and Ti-methoxyethoxide, respectively, followed by mixing with stirring in 2-methoxyethanol to form Pb−Ti double alkoxide. The hydrolysis and polycondensation reaction of this double alkoxide gave polymerized products, and as a result the viscosity of the solution increased, suggesting that linear polymers were produced through the hydrolysis and polycondensation reaction. Homogeneous PbTiO₃ gel fibers were drawn from the spinnable viscous solutions, which were wellcrystallized into perovskite type PbTiO₃ at 650°C. The heat-treated fibers were a few centimeters long and from 10 to 100 μm in diameter. The fiber was made up of extremely uniform grains. Electron diffraction revealed a preferred growth of (101) planes along the fiber axis, which might be due to the linear molecular characteristics of the alkoxide.     

Study on the cationic modification and dyeing of ramie fiber

A modification procedure for ramie fiber using 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTAC) as a cationic agent and NaOH as a catalyst was developed in this paper. The morphological and structural transformations of the fiber induced by modification were determined by XRD (XRD), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). XRD results show that the crystal structure of the modified fiber was still preserved although its crystallinity was decreased, which was confirmed from the TGA results. The mechanisms for the modification and dyeing of ramie fiber were analyzed, and the optimum modification conditions were determined to be the CHPTAC concentration of 30 g L⁻¹, the NaOH concentration of 15 g L⁻¹, the reaction temperature of 50 °C, and the reaction time of 60 min. The raw and the modified fibers were dyed with C.I. reactive red 2. The K/S values for the cationic modified fiber increased to be three times as high as the unmodified fiber. The dye uptakes increased greatly with an increase in the nitrogen contents up to 0.4% on the modified fibers.